Tropical Storm Hilda

Post Tropical Hilda Track 0800 Hours August 6 2021
Post Tropical Hilda Track 0800 Hours August 6 2021

Tropical Storm Hilda Wind Speed FieldTropical Storm Hilda NWS National Hurricane Center Miami FL 800 AM PDT Fri Aug 06, 2021 (see Friday video below)

Hilda has been devoid of organized deep convection for at least 12 hours, and since the cyclone is moving over sub-23C sea surface temperatures, regeneration of deep convection is unlikely. Therefore, Hilda is designated as a 25 kt post-tropical remnant low, and this is the last advisory from National Hurricane Center. The low should continue to move further into a dry and stable air mass and over even cooler waters. Consequently, weakening is forecast and the remnant low of Hilda should open up into a trough of low pressure over the weekend.

The initial motion is estimated to be west-northwestward, or 300/9 kt, and this general heading, within the low-level flow, is forecast to continue until dissipation.

FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 23.1N 134.1W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 12H  07/0000Z 23.6N 135.5W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 24H  07/1200Z 24.1N 137.0W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 36H  08/0000Z 24.5N 138.2W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 48H  08/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 AM PDT Thu Aug 05, 2021 

After an earlier brief burst of thunderstorm activity northeast of the center around 0600Z, associated convection since then has been on a rapid decline and warming of the cloud tops which now barely reach -30 deg C near the center. The initial intensity has been lowered to 30 kt based on a blend of Dvorak T- and CI-numbers of T2.5 and T1.5 from both TAFB and SAB, and an objective satellite intensity estimate of 2.0/30 kt from UW-CIMSS ADT, making Hilda a tropical depression. Further weakening is expected now that Hilda is located over sub-23 deg C sea-surface temperatures and moving into a drier and more stable air mass. The cyclone is forecast to degenerate into a remnant low later today and open up into a trough by the weekend, well east of the Hawaiian Islands.

The initial motion estimate is 305/11 kt, which is faster and a little to the right of the previous advisory motion. This is likely due to the low- and upper-level circulations having decoupled now, owing to the lack of significant convection. The weakening cyclone should be steered west-northwestward for the next 48 hours by a sprawling subtropical ridge located to the north. The new NHC forecast track is similar to the previous advisory track and lies down the middle of the tightly packed consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 21.0N 130.2W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 12H  06/0000Z 21.7N 131.8W   25 KT  30 MPH - Depression (WSW Acapulco, MX)
 24H  06/1200Z 22.5N 133.9W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 36H  07/0000Z 23.2N 136.1W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 48H  07/1200Z 23.9N 138.3W   15 KT  15 MPH - Post Tropical (WSW Hilo, Hawaii)
 60H  08/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 PM PDT Wed Aug 04, 2021

Hilda’s satellite appearance has changed little over the past several hours. Small bursts of moderate to deep convection persist in the eastern semicircle of the system, and the low-level center is still partially exposed to the west of the convective cloud mass. Without any recent scatterometer data, the initial intensity is held at 35 kt for this advisory, in best agreement with a T2.5/35 kt Dvorak classification from TAFB.

A subtropical ridge over the eastern North Pacific continues to steer Hilda west-northwestward, or 290/7 kt. This general motion is expected to continue for the next day or so, followed by a slight westward turn on Friday as the shallow cyclone becomes steered by a low-level ridge to its north. While most of the models show limited interaction between Hilda and TD Nine-E to its southwest, it is worth noting that the GFS moves both Nine-E and Hilda much farther northward than the rest of the guidance. The GFS solution is not favored at this time, and the latest NHC track forecast remains very similar to the previous one and lies near the multi-model guidance consensus.

Hilda is not expected to remain a tropical storm for much longer. As sea surface temperatures decrease along its track and the cyclone moves into a drier, more stable environment, it will become increasingly difficult for Hilda to sustain organized convection near its center. The latest NHC forecast calls for Hilda to weaken to a tropical depression on Thursday and degenerate to a 25-kt remnant low on Friday morning. Then, the global models agree that the system should open into a trough and dissipate by Saturday morning well east of the Hawaiian Islands.

FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 19.6N 128.7W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  05/1200Z 20.2N 130.2W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 24H  06/0000Z 21.3N 132.4W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 36H  06/1200Z 22.1N 134.6W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 48H  07/0000Z 22.6N 137.0W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 60H  07/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 200 PM PDT Wed Aug 04, 2021

Convection associated with Hilda continues to weaken and shrink in areal coverage due to modest northwesterly vertical wind shear, sub-25C sea-surface temperatures (SSTs), and entrainment of stable, cold-air stratocumulus clouds. A 1656Z partial ASCAT-A scatterometer pass revealed two 33-kt vectors in the southeastern quadrant in the radius-of-maximum winds. Even allowing for some undersampling, this indicates that Hilda is barely hanging on to tropical storm status, and the initial intensity will remain at 35 kt for this advisory.

Model analyses show virtually no instability in the center of and north of Hilda right now, and with the cyclone forecast to move over even cooler water and into increasing westerly wind shear during the next 12-24 hours, a rapid decrease in both the convection and cyclone’s intensity appears to be forthcoming soon. Hilda is forecast to become a depression later tonight and a remnant low on Thursday. Dissipation is expected by late Friday or Saturday well to the east of the Hawaiian Islands. The latest NHC official intensity forecast is similar to the previous advisory, and follows a blend of the HCCA and IVCN consensus intensity models.

Hilda continues on a steady west-northwestward course or 295/08 kt. This general motion is expected to continue into Thursday, followed by a more westward motion on Friday and Saturday as a low- to mid-level ridge builds to north of Hilda on days 2 and 3. The official NHC track forecast is essentially just an update of the previous advisory track, and lies along the southern edge of the guidance envelope between the tightly packed consensus track models to the north and the ECMWF model to the south.

FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 19.4N 128.0W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  05/0600Z 20.0N 129.4W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 24H  05/1800Z 21.0N 131.4W   25 KT  30 MPH - Depression (WSW Acapulco, MX)
 36H  06/0600Z 21.8N 133.7W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 48H  06/1800Z 22.4N 136.1W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 60H  07/0600Z 23.0N 138.4W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 72H  07/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 AM PDT Wed Aug 04, 2021 

Hilda continues to weaken early this morning due to cool sea-surface temperatures (SST) and modest northerly vertical wind shear. The current intensity is estimated to be 35 kt based on an average of subjective satellite classifications of T2.5/35 kt from both TAFB and SAB, and objective estimates of 31 kt and 41 kt from UW-CIMSS ADT and SATCON, respectively. Hilda is currently moving over sub-25C SSTs with even cooler water and increasing westerly wind shear still ahead of the cyclone. As a result of these unfavorable environmental parameters, Hilda is forecast to weaken further, becoming a depression later today and a remnant low by late tonight or early Thursday. Dissipation is expected by late Friday or Saturday well to the east of the Hawaiian Islands. The new NHC official intensity forecast is similar to the previous advisory, and follows a blend of the HCCA and IVCN consensus intensity models.

Hilda has been moving west-northwestward or 295/08 kt. This general motion should continue into Thursday. Low- to mid-level ridging to the north of Hilda is expected to gradually build westward over the next several days, forcing the cyclone and its remnants more westward on Friday and Saturday. The new NHC forecast track is essentially just an update of the previous advisory, and lies down the middle of the tightly packed consensus track models.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 19.1N 127.4W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  05/0000Z 19.7N 128.7W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 24H  05/1200Z 20.6N 130.6W   25 KT  30 MPH - Depression (WSW Acapulco, MX)
 36H  06/0000Z 21.5N 132.6W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 48H  06/1200Z 22.2N 135.0W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 60H  07/0000Z 22.7N 137.3W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)
 72H  07/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 PM PDT Tue Aug 03 2021

Hilda is a weakening tropical cyclone. Its low-level center is now exposed in visible satellite imagery, and infrared cloud top temperatures have rapidly warmed as the system is currently not producing any deep convection. Despite this lack of convection, earlier scatterometer data revealed several 45-kt wind vectors in the northern and eastern portions of the circulation. The initial intensity is lowered to 45 kt for this advisory, which is supported by a blend of the final-T numbers and current intensity estimates from TAFB and SAB, and the objective UW-CIMSS SATCON estimate.

A mid-level ridge centered over the southwestern U.S. continues to steer Hilda northwestward at around 7 kt. As the vortex spins down and becomes vertically shallow, Hilda is expected to turn west-northwestward and accelerate a bit as a low-level ridge builds westward across the eastern Pacific. The official NHC track forecast is largely unchanged from the previous one and lies close to the multi-model consensus.

Hilda is moving over cooler waters and into a more stable environment, so continued weakening is expected over the next few days. The official NHC forecast now shows Hilda weakening to a tropical depression by Thursday morning and degenerating to a remnant low soon thereafter. The remnant low is still expected to open up into a trough this weekend well east-northeast of the Hawaiian Islands.

FORECAST POSITIONS AND MAX WINDS
 
INIT  04/0300Z 18.4N 125.5W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  04/1200Z 19.1N 126.5W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  05/0000Z 19.9N 128.0W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  05/1200Z 20.7N 129.8W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 48H  06/0000Z 21.6N 132.0W   30 KT  35 MPH - Post Tropical (WSW Hilo, Hawaii)
 60H  06/1200Z 22.3N 134.4W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 72H  07/0000Z 22.9N 136.7W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 96H  08/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 200 PM PDT Tue Aug 03, 2021 

Deep convection in Hilda’s central dense overcast has been weakening today, with the low-level center still on the northern side of the cloud mass. Satellite classifications have decreased since the last advisory, and a partial ASCAT pass around 1700 UTC showed maximum winds of about 45 kt. Assuming some undersampling and that the eastern radius-of-maximum winds could have been missed, the initial wind speed is set to 50 kt. A combination of shear, cool water temperatures, and a more stable environment should keep Hilda on a weakening trend throughout the forecast period. Model guidance continues to be in very good agreement, and the new NHC forecast is basically an update of the previous one. Hilda is expected to degenerate into a remnant low by Friday and dissipate as a trough this weekend well east of the Hawaiian Islands.

The storm continues moving northwestward, now a little slower at about 6 kt. A mid-level ridge centered over southern California should build westward during the next few days as a mid-latitude trough along 135W moves northward out of the area. This pattern is expected to turn Hilda west-northwestward tomorrow and accelerate the cyclone in that direction as it encounters stronger low- to mid-level flow. Model guidance is a shade faster and to the left of the last cycle, and the new NHC track forecast follows that trend.

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 17.8N 125.0W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  04/0600Z 18.5N 125.9W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  04/1800Z 19.4N 127.2W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  05/0600Z 20.2N 128.6W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 48H  05/1800Z 21.1N 130.5W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 60H  06/0600Z 21.9N 132.7W   30 KT  35 MPH - Post Tropical (WSW Hilo, Hawaii)
 72H  06/1800Z 22.5N 135.5W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 96H  07/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 AM PDT Tue Aug 03, 2021 

There’s been little change with the structure of Hilda overnight as deep convection continues to be mostly south of the center due to persistent northeasterly shear. The low-level eye feature in 37 GHz microwave data remains on the latest passes, but it isn’t very deep because of the shear. A blend of the T- and CI-numbers from TAFB/SAB, plus the UW-CIMSS SATCON, yields 60 kt as the initial wind speed. Hilda should weaken during the next several days, first primarily due to shear, then cool water temperatures and a more stable environment on Wed-Fri. Model guidance is in good agreement on this scenario, and the latest forecast is close to the previous NHC advisory and the model consensus. Hilda should decay into a remnant low by Friday and dissipate as a trough this weekend well east of the Hawaii.

The initial motion estimate, 315/7 kt, is the same as the previous advisory. Hilda is maintaining this motion as it is steered by a mid-level ridge centered over southern California. The global models are consistently building this ridge westward over the eastern Pacific during the next several days as a shortwave trough lifts out along 135W, causing Hilda to turn west-northwestward by Thursday. The only significant forecast difference is how quickly the cyclone moves, mostly in the latter stages, with more of the guidance showing a faster motion, perhaps because the models are showing a weaker Hilda being steered by the quicker low-level flow. The new NHC prediction shows that acceleration at long-range as well, near or just behind the latest model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 17.5N 124.5W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  04/0000Z 18.2N 125.3W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  04/1200Z 19.1N 126.4W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  05/0000Z 19.9N 127.7W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 48H  05/1200Z 20.8N 129.4W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 60H  06/0000Z 21.6N 131.4W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 72H  06/1200Z 22.3N 133.5W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
 96H  07/1200Z 23.0N 138.0W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
120H  08/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 PM PDT Mon Aug 02, 2021

Moderate northeasterly wind shear continues to take a toll on Hilda this evening. The upper-level outflow on the northern and eastern sides of the circulation has a sharp edge in satellite imagery. Recent SSMIS microwave data show the structure of Hilda has changed little since earlier today, with a weakness in the upshear portion of the eyewall and a slight displacement of the low- and mid-level centers. The various objective intensity estimates and subjective Dvorak classifications from TAFB and SAB support holding the initial intensity at 65 kt for this advisory.

Hilda is moving northwestward, or 315/6 kt, under the influence of a subtropical ridge to its northeast. This general motion is expected to continue through midweek, and the track guidance remains tightly clustered during this period. As Hilda continues weakening and the ridge builds westward, Hilda is forecast to move west-northwestward and then westward within the low-level flow through the rest of the period. However, a complicating factor is the potential for some interaction with the remnants of TD Nine-E, which now have a high chance of redevelopment during the next couple of days. The official NHC track forecast has been adjusted slightly poleward once again at day 3 and beyond, bringing it closer to the reliable consensus aids TVCE and HCCA and accounting for the aforementioned possibility of some interaction between the two systems.

Moderate northeasterly shear will persist for the next day or so, and afterwards the cooler sea-surface temperatures along Hilda’s forecast track will offset any reduction in shear over the system. Therefore, weakening is expected during the next several days. The official NHC intensity forecast lies slightly above the multi-model consensus aids in the near-term, but then closely follows IVCN and HCCA once Hilda reaches the cooler waters. The system is forecast to degenerate into a remnant low by 96 h, but this transition could occur soon after 72 h based on some of the latest GFS and ECMWF simulated satellite imagery.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 16.4N 123.3W   65 KT  75 MPH - Category 1 (WSW Acapulco, MX)
 12H  03/1200Z 17.1N 123.9W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  04/0000Z 18.0N 124.8W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  04/1200Z 18.9N 125.9W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, MX)
 48H  05/0000Z 19.8N 127.2W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 60H  05/1200Z 20.8N 128.9W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 72H  06/0000Z 21.6N 130.9W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 96H  07/0000Z 22.5N 135.0W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
120H  08/0000Z 22.6N 139.5W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)

NWS National Hurricane Center Miami FL 800 AM PDT Mon Aug 02, 2021

The satellite presentation of Hilda hasn’t changed much in the past several hours, with a round central dense overcast and perhaps a ragged eye trying to form. The intensity estimates range from 60-77 kt, and since the hurricane’s presentation is about the same as the last advisory, the current wind speed will remain 70 kt. This is one of those times that in situ reconnaissance data would be helpful since there has been lots of spread in the intensity estimates for quite some time, and Hilda is at an intensity where it is hard to get more precise measurements.

The hurricane has finally turned northwestward and should continue in that general direction for the next couple of days on the southwestern side of the subtropical ridge, with some influence from Ignacio to the northeast. Model guidance is in decent agreement that Hilda will turn back to the west-northwest by midweek and then west under the restrengthened subtropical ridge. While there are still some outlier solutions, the latest consensus guidance is near the previous NHC forecast, so only small changes were made on this advisory.

Hilda is maintaining good inner-core structure on the latest microwave data despite northeasterly shear (perhaps because of a fairly moist mid-level environment around the hurricane), so little intensity change is forecast for today. Thereafter, the system should move over cooler waters into a drier environment, which should cause gradual weakening for the next several days. Very little change was made to the NHC intensity forecast, and it is close to the HCCA and IVCN consensus aids throughout. Remnant-low status is expected by 96 h, if not sooner.

FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 15.4N 122.6W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 12H  03/0000Z 16.0N 123.1W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 24H  03/1200Z 16.9N 123.8W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  04/0000Z 17.9N 124.7W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 48H  04/1200Z 18.9N 126.0W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 60H  05/0000Z 19.7N 127.5W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 72H  05/1200Z 20.4N 129.3W   30 KT  35 MPH - Depression (WSW Acapulco, MX)
 96H  06/1200Z 21.5N 133.9W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)
120H  07/1200Z 21.5N 138.5W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)

NWS National Hurricane Center Miami FL 800 PM PDT Sun Aug 01, 2021 

Hilda’s satellite appearance is showing effects of easterly vertical wind shear this evening. Recent imagery shows a sharp edge to the upper-level outflow on the eastern side of the system. A 2130 UTC AMSR2 microwave pass reveals that the eyewall is no longer closed, as the inner core convection has been eroded on the eastern side of the circulation. Microwave data also indicate the vortex has become vertically tilted, with the mid-level center displaced about 10-15 n mi to the west-northwest of the low-level center. Thus, the initial intensity is lowered slightly to 70 kt for this advisory, in best agreement with the objective UW-CIMSS Dvorak estimates.

Hilda is still moving west-northwestward at 285/8 kt, to the south of a ridge over the western U.S. and northern Mexico. A turn to the northwest is expected on Monday as the ridge weakens, likely in response to T.D. Ten-E located to the east-northeast of Hilda. A northwestward motion should continue through midweek before the ridge becomes reestablished and Hilda turns westward through the rest of the forecast period. There is greater track uncertainty later in the week due to possible interaction with another system that could redevelop from the remnants of T.D. Nine-E. The official NHC track forecast has been adjusted to the right of the previous one at 48 h and beyond based on the latest guidance, but it still lies slightly left of the multi-model consensus aids TVCE and HCCA.

Environmental conditions are not expected to become any more favorable for strengthening during the next couple days, so Hilda’s intensity has likely peaked. Moderate northeasterly shear is forecast to persist for the next 36-48 h, and the NHC forecast track brings Hilda north of the 26 deg C isotherm by the time these upper-level winds subside. Once over cooler waters, Hilda is forecast to quickly spin down and weaken to a tropical depression by 96 h. The NHC intensity forecast has again been lowered by 5-10 kt from the previous one at all forecast times, but it still lies slightly above the IVCN and HCCA consensus aids through 72 h. The system is forecast to degenerate to a remnant low by day 5.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 15.1N 121.6W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 12H  02/1200Z 15.5N 122.5W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 24H  03/0000Z 16.2N 123.4W   65 KT  75 MPH - Category 1 (WSW Acapulco, MX)
 36H  03/1200Z 17.3N 124.3W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 48H  04/0000Z 18.4N 125.3W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 60H  04/1200Z 19.5N 126.6W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 72H  05/0000Z 20.3N 128.3W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, MX)
 96H  06/0000Z 21.0N 132.3W   25 KT  30 MPH - Depression (WSW Hilo, Hawaii)
120H  07/0000Z 21.5N 136.0W   20 KT  25 MPH - Post Tropical (WSW Hilo, Hawaii)

NWS National Hurricane Center Miami FL 200 PM PDT Sun Aug 01, 2021 

Hilda has had a similar appearance all day with an elongated cloud pattern from southeast to northwest on satellite imagery. Recent microwave passes show that the center is located on the northern side of the central dense overcast. The current intensity estimates have a very wide range from 65 to 90 kt, and with the apparent steady-state of the hurricane, Hilda’s wind speed will stay at 75 kt until clearer data emerges.

Hilda continues moving west-northwestward at about 7 kt. The trends from the last advisory have continued with more interaction shown with new Tropical Depression 10-E to the east, leading to a weaker ridge and a faster northwestward turn of Hilda in a day or so. By midweek, Hilda should turn back to the west-northwest and westward later in the period under the influence of a stronger portion of the ridge. The new official forecast is shifted about a half a degree to the northeast, near the model consensus, although the corrected-consensus models are even farther to the right.

With the forecast track shift, it is becoming unlikely that Hilda will get significantly stronger since it will move over cooler waters sooner. In addition, easterly shear should increase tomorrow, probably leading to the start of weakening. Guidance has trended downward since the last cycle, and considering the new track forecast moves over cooler waters faster, the latest NHC wind speed forecast has been lowered 5-10 kt at all time periods, and this still might be too high. In about 4 days, most of the models show little convection remaining with Hilda due to cold water and drier mid-level air, so the system should transition to a remnant low by day 5.

FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 14.8N 120.8W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 12H  02/0600Z 15.2N 121.8W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 24H  02/1800Z 15.8N 122.9W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 36H  03/0600Z 16.6N 123.7W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 48H  03/1800Z 17.6N 124.6W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 60H  04/0600Z 18.7N 125.8W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 72H  04/1800Z 19.6N 127.5W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, MX)
 96H  05/1800Z 20.7N 131.6W   35 KT  40 MPH - Tropical Storm (WSW Hilo, Hawaii)
120H  06/1800Z 21.0N 135.5W   25 KT  30 MPH - Post Tropical (WSW Hilo, Hawaii)

NWS National Hurricane Center Miami FL 800 AM PDT Sun Aug 01, 2021 

Hilda is a bit of a mess this morning with an elongated cloud pattern from southeast to northwest and no signs of an eye in conventional satellite imagery. However, microwave data near 1155 UTC from GPM still shows a well-defined low-level eye, although the mid-level structure remains degraded from easterly shear. The current wind speed is held at 75 kt, with this being an uncertain estimate due to a large spread in the various intensity techniques.

Hilda is moving west-northwestward at about 7 kt, with microwave data helping to pinpoint the slower movement. The track forecast is no piece of cake this morning with some interaction anticipated with Invest 91E to the east in a day or two. While a mid-level ridge persists to the northwest of Hilda, the southern periphery of the ridge weakens due to 91E, causing Hilda to take a northwestward turn in a couple of days. Hilda then should turn back toward the west-northwest and west by midweek due to the ridge remaining in place and 91E weakening. This is a tricky forecast because the guidance is shifting to the right, which at some point will bring Hilda over cold waters and closer to 91E, changing which atmospheric layers will dominate steering the tropical cyclone. In addition, interactions between two systems this close together aren’t easy to forecast in the best of circumstances, and the latest guidance isn’t in great agreement on the future strength of 91E either. As a compromise, the NHC track forecast is more conservative in shifting the track to the northeast than the guidance (remaining on the westerly side of the track envelope), then gradually comes close to the previous NHC forecast by the end of the 5-day period. This forecast is obviously rather uncertain, and a lot of generally better performing aids are to the northeast of the latest NHC track.

The hurricane still has some chance to intensify during the next day or so with moderate easterly shear and good inner-core structure. Still, it is becoming more likely that Hilda is close to its peak intensity with no signs of the easterly shear abating until the hurricane moves over cool waters in a few days. Model guidance generally is lower than the last cycle, and only a few show strengthening. I’m going to keep the chance for slight strengthening in the near term, then show a steady drop in intensity due to persistent (or stronger) easterly shear and marginal water temperatures. The new intensity forecast is 5 kt lower than the last one at 36 hours and beyond and that could still be too high, especially if the track shifts any farther to the north.

FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 14.6N 120.2W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 12H  02/0000Z 14.9N 121.2W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 24H  02/1200Z 15.4N 122.4W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 36H  03/0000Z 16.1N 123.4W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 48H  03/1200Z 16.9N 124.2W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 60H  04/0000Z 18.0N 125.5W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 72H  04/1200Z 19.0N 127.0W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 96H  05/1200Z 20.2N 131.2W   40 KT  45 MPH - Tropical Storm (ESE Hilo, Hawaii)
120H  06/1200Z 20.5N 135.5W   30 KT  35 MPH - Post Tropical (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 800 PM PDT Sat Jul 31, 2021 

Hilda has resumed strengthening during the past several hours, including the short-lived appearance of an eye in the central dense overcast. Recent 37-GHz microwave imagery confirms an eye is developing, but indicates that the eyewall is not yet closed on the northeastern side of the eye. Satellite intensity estimates from TAFB and SAB are 77 kt, while the CIMSS satellite consensus is near 80 kt. Based on these data, the initial intensity is increased to a possibly conservative 75 kt.

Although Hilda is experiencing some easterly vertical shear, conditions are generally conducive for strengthening during the next 24 h, and the early part of the intensity forecast has been adjusted upward based mainly on current trends. After that time, decreasing moisture and decreasing sea surface temperatures along the forecast track should cause steady weakening. The latter part of the intensity forecast has only minor changes from the previous forecast and follows the trend of the intensity guidance.

The initial motion is now a little slower at 285/9. The subtropical ridge to the north should steer Hilda generally west-northwestward for the next several days, with a more northwestward motion around 96 h as the cyclone passes south of a weakness in the ridge. Overall, the guidance envelope has shifted a little northward since the previous advisory, and the new forecast track is also adjusted northward. It should be noted, though, that the global models continue to show the possibility of erratic motion due to Hilda interacting with TD-9E to the west and the weaker, but larger, low pressure area to the east. The most drastic example of this is in the Canadian model, which shows Hilda taking a significant turn to the south before resuming a northward motion.

FORECAST POSITIONS AND MAX WINDS

INIT  01/0300Z 14.3N 118.7W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 12H  01/1200Z 14.7N 120.0W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 24H  02/0000Z 15.2N 121.7W   90 KT 105 MPH - Category 2 (WSW Acapulco, MX)
 36H  02/1200Z 15.8N 123.1W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 48H  03/0000Z 16.4N 124.2W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 60H  03/1200Z 17.2N 125.4W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 72H  04/0000Z 18.3N 126.8W   65 KT  75 MPH - Category 1 (WSW Acapulco, MX)
 96H  05/0000Z 20.0N 130.5W   50 KT  60 MPH - Tropical Storm (ESE Hilo, Hawaii)
120H  06/0000Z 20.5N 134.0W   40 KT  45 MPH - Tropical Storm (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 200 PM PDT Sat Jul 31, 2021

After strengthening quickly overnight and early this morning, Hilda’s intensity appears to have leveled off for now. There continues to be hints of an eye feature in satellite images and deep convection is organized in curved bands around that feature. The latest Dvorak estimates are 3.5/55 kt from TAFB, 4.0/65 kt from SAB, and 4.1/67 kt from CIMSS at the University of Wisconsin. A recent ASCAT-B overpass showed a maximum wind of around 50 kt southeast of the center, but the coarse resolution of the instrument is unlikely to capture the storm’s true intensity. Based on a combination of this data, the initial intensity is held at 60 kt, but this could be a little conservative and Hilda is very near hurricane strength. The aforementioned ASCAT data was also used to adjust the wind radii inward at the initial and short range forecast times.

Steady strengthening seems likely during the next 24 to 36 hours as the environment remains generally favorable, consisting of relatively warm SSTs, low wind shear, and a high amount of moisture. The NHC intensity forecast during that time period is the same as before and lies at the high end of the model guidance, near HCCA. Beyond 36 hours, however, decreasing moisture and progressively cooler SSTs should end the strengthening trend and gradually cause weakening during the remainder of the forecast period. The NHC intensity forecast lies near the middle of the guidance envelope for that portion of the forecast.

Hilda is moving west-northwestward at 12 kt. A subtropical ridge should keep the storm on a general west-northwest heading during the next several days, but the more skillful models like the GFS and ECMWF show some interaction with Tropical Depression Nine-E to the west and a low-pressure area to the east. These interactions will likely cause some slow downs and an erratic motion at times during the forecast period. There continues to be a fair amount of spread in the models, especially in terms of forward speed, and the new forecast is a little to the north of the previous based on the latest guidance. This track prediction is slightly slower than the consensus aids, and has given more weight to the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 14.1N 117.9W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  01/0600Z 14.5N 119.3W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 24H  01/1800Z 15.0N 121.0W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 36H  02/0600Z 15.5N 122.5W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 48H  02/1800Z 16.0N 123.8W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 60H  03/0600Z 16.8N 125.1W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 72H  03/1800Z 17.8N 126.7W   65 KT  75 MPH - Category 1 (WSW Acapulco, MX)
 96H  04/1800Z 19.3N 129.8W   50 KT  60 MPH - Tropical Storm (ESE Hilo, Hawaii)
120H  05/1800Z 20.4N 133.7W   40 KT  45 MPH - Tropical Storm (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 800 AM PDT Sat Jul 31, 2021 

Hilda is strengthening quickly this morning. Satellite images show an eye feature trying to form, and convection has deepened and become increasingly symmetric around the center. The latest Dvorak estimates supported raising the initial intensity to 55 kt at 12Z, and since Hilda continues to organize, the initial intensity is set a little higher at 60 kt for this advisory. This makes Hilda just below hurricane strength.

The current favorable environmental conditions of low wind shear, high amounts of moisture, and warm SSTs should continue to allow Hilda to intensify during the next day or so. In addition, given that Hilda now has a tight inner core, rapid intensification (RI) is a decent possibility, and the SHIPS RI index now shows a 30 percent chance of that occurring during the next 24 hours. In a couple of days, however, decreasing moisture and progressively cooler SSTs should end the strengthening trend and gradually cause weakening during the remainder of the forecast period. The NHC intensity forecast is above than the previous one in the short term and it lies at the high end of the model guidance. The long term forecast is largely similar to the previous one and lies near the middle of the guidance envelope.

Hilda is moving west-northwestward at 11 kt. A subtropical ridge should keep the storm on a general west-northwest heading during the next several days, but there could be some interaction with Tropical Depression Nine-E to the west and a low pressure area to the east that could cause slow downs and wobbles in the future track. There is a fair amount of spread among the models, especially at the longer range forecast times, but the latest consensus models are right on top of the previous track. Therefore, the NHC track forecast is largely just an update of the previous one.

FORECAST POSITIONS AND MAX WINDS

INIT  31/1500Z 13.7N 116.7W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  01/0000Z 14.0N 118.2W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 24H  01/1200Z 14.4N 119.9W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 36H  02/0000Z 15.0N 121.5W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 48H  02/1200Z 15.5N 122.9W   85 KT 100 MPH - Category 2 (WSW Acapulco, MX)
 60H  03/0000Z 16.1N 124.3W   80 KT  90 MPH - Category 1 (WSW Acapulco, MX)
 72H  03/1200Z 16.9N 125.7W   70 KT  80 MPH - Tropical Storm (ESE Hilo, Hawaii)
 96H  04/1200Z 18.5N 128.6W   55 KT  65 MPH - Tropical Storm (ESE Hilo, Hawaii)
120H  05/1200Z 19.3N 132.6W   45 KT  50 MPH - Tropical Storm (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 900 PM MDT Fri Jul 30, 2021

Satellite imagery indicates that Hilda has gotten a little better organized during the past several hours, with the low-level center now near the eastern end of a long convective band that is present in the southwestern semicircle. Satellite intensity estimates are 35 kt from TAFB and 45 kt from SAB, and based on these the initial intensity remains 40 kt. The storm is currently in an environment of light northwesterly vertical wind shear with the bulk of the outflow to the south.

Conditions generally appear favorable for strengthening during the next 72 h or so, as Hilda is expected to be over warm sea surface temperatures and in an environment of light to moderate shear. Based on this, the first part of the intensity forecast is unchanged from the previous forecast and calls for Hilda to become a hurricane between 24 and 36 h and peak in intensity around 60 h. After that, the forecast becomes less confident. The cyclone is expected to move over decreasing sea surface temperatures after 72 h, and this should cause gradual weakening as indicated in the official forecast. The official forecast for this period has been nudged downward due to the forecast motion over cooler water. However, the GFS and ECMWF models suggest the possibility that Hilda will interact with other nearby systems – the GFS forecasting with Tropical Depression Nine-E to the west and the ECMWF forecasting interaction with a disturbance to the east. Should either of these interactions occur, Hilda could weaken at a different rate than currently forecast.

The initial motion is 290/13. Hilda is located on the south side of a subtropical ridge, and if the storm does not interact with other nearby weather systems a general west-northwestward motion with a decrease in forward speed is expected through the forecast period. The new forecast track is shifted a little north of the previous track, and it lies just to the south of the various consensus models. If Hilda does interact with either Tropical Depression Nine-E or the disturbance to the east, it will lead to erratic motion.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 13.2N 114.6W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  31/1200Z 13.5N 116.3W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  01/0000Z 14.1N 118.4W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  01/1200Z 14.7N 120.3W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 48H  02/0000Z 15.3N 122.0W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 60H  02/1200Z 15.8N 123.3W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 72H  03/0000Z 16.5N 124.8W   70 KT  80 MPH - Category 1 (ESE Hilo, Hawaii)
 96H  04/0000Z 18.0N 127.0W   60 KT  70 MPH - Tropical Storm (ESE Hilo, Hawaii)
120H  05/0000Z 19.5N 131.0W   50 KT  60 MPH - Tropical Storm (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 300 PM MDT Fri Jul 30, 2021 

A pair of ASCAT passes from a few hours ago indicated that the area of low pressure located about 800 miles south-southwest of the southern tip of the Baja California peninsula has strengthened, and is producing 35-40 kt winds on its east side. In addition, satellite images show a fairly persistent area of showers and thunderstorms on the south side of the circulation and the center appears to be fairly well defined in recent visible images. Based on these data, advisories are now being initiated on Tropical Storm Hilda and the initial intensity is estimated to be 40 kt.

Hilda is moving westward at about 14 kt and is embedded in the flow on the south side of a sprawling subtropical ridge that extends from the south-central U.S. westward across the subtropical eastern Pacific. A general west-northwestward motion at about the same forward speed is expected during the next day or two as the synoptic pattern holds. After that time, a decrease in forward speed is predicted due to a combination of the subtropical ridge weakening and the interactions with the areas of low pressure to the east and west of Hilda. The ECMWF is the slowest model at long range due to it showing the most interaction with the low to Hildas east. The NHC track forecast lies generally near the model consensus and roughly between the GFS and ECMWF models.

Hilda appears to be in generally conducive conditions for strengthening with SSTs currently around 28 C, abundant mid-level moisture, and fairly low wind shear. Given that these conditions are expected to persist for another couple of days, steady strengthening is forecast during that time period and Hilda is predicted to become a hurricane in 24 to 36 hours. Beyond a couple of days, however, moderate easterly shear, progressively drier air, and decreasing SSTs should end the strengthening trend and induce gradual weakening of the cyclone. The NHC intensity forecast lies near the middle of the guidance envelope, closest to the intensity model consensus IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 12.1N 113.6W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, MX)
 12H  31/0600Z 12.6N 115.4W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, MX)
 24H  31/1800Z 13.2N 117.6W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, MX)
 36H  01/0600Z 13.8N 119.7W   70 KT  80 MPH - Category 1 (WSW Acapulco, MX)
 48H  01/1800Z 14.3N 121.6W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 60H  02/0600Z 14.9N 123.1W   75 KT  85 MPH - Category 1 (WSW Acapulco, MX)
 72H  02/1800Z 15.3N 124.4W   70 KT  80 MPH - Category 1 (ESE Hilo, Hawaii)
 96H  03/1800Z 16.6N 126.4W   65 KT  75 MPH - Category 1 (ESE Hilo, Hawaii)
120H  04/1800Z 18.3N 129.5W   55 KT  65 MPH - Tropical Storm (ESE Hilo, Hawaii)

NWS National Hurricane Center Miami FL 500 AM PDT Fri Jul 30, 2021 

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Showers and thunderstorms continue to show signs of organization in association with an elongated area of low pressure located about 650 miles southwest of the coast of southwestern Mexico. Environmental conditions are conducive for development, and a tropical depression or tropical storm is expected to form later today or Saturday while the system moves west-northwestward at 10 to 15 mph. For more information on this system, please see High Seas forecasts issued by the NOAA Tropical Analysis and Forecast Branch. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high...90 percent.
  • 2. Showers and thunderstorms have changed little overnight in association with an area of low pressure located about 1300 miles southwest of the southern tip of the Baja California peninsula. Upper-level winds are expected to become more conducive for development during the next day or two, and a tropical depression is expected to form over the weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.
  • 3. Disorganized showers and thunderstorms located a few hundred miles off the coast of southern Mexico are associated with a trough of low pressure. Gradual development of this system is expected during the next several days, and it could become a tropical depression early next week while it moves west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium...60 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Jul 29, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Showers and thunderstorms are gradually becoming better organized in association with an area of low pressure located about 600 miles southwest of the coast of southwestern Mexico. Environmental conditions are conducive for continued development, and a tropical depression or tropical storm is expected to form during the next day or two while the system moves west-northwestward at 10 to 15 mph. For more information on this system, please see High Seas forecasts issued by the NOAA Tropical Analysis and Forecast Branch. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.
  • 2. Another area of low pressure is located about 1100 miles southwest of the southern tip of the Baja California peninsula. At this time, the associated shower and thunderstorm activity is poorly organized and confined to an area southeast of the center. Upper-level winds are expected to become more conducive for development during the next couple of days, and a tropical depression is likely to form over the weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high...80 percent.
  • 3. An area of disturbed weather has formed several hundred miles south-southeast of the Gulf of Tehuantepec. Additional gradual development is possible during the next several days while the system moves west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Thu Jul 29, 2021 

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Showers and thunderstorms are gradually organizing in association with an area of low pressure located about 500 miles south-southwest of the coast of southwestern Mexico. Environmental conditions are conducive for continued development, and a tropical depression is expected to form during the next day or two while the system moves west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.
  • 2. Another area of low pressure is located about 1100 miles southwest of the southern tip of the Baja California peninsula. Although the circulation appears well defined, showers and thunderstorms are poorly organized and confined to an area southeast of the center. Upper-level winds are expected to become more conducive for development during the next couple of days, and a tropical depression is likely to form over the weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Thu Jul 29, 2021 

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An area of low pressure located about 1000 miles southwest of the southern tip of the Baja California peninsula is producing persistent shower and thunderstorm activity, mainly to the southeast of the center. Upper-level winds are expected to become more conducive for development during the next couple of days, and a tropical depression is likely to form by this weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high...80 percent.
  • 2. A broad area of low pressure located several hundred miles offshore of the southwestern coast of Mexico is producing shower and thunderstorm activity with increased signs of organization since yesterday. Environmental conditions remain conducive for continued development, and a tropical depression is likely to form this weekend while the system moves westward or west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Wed Jul 28, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Satellite imagery indicates that an area of low pressure located about 900 miles southwest of the southern tip of the Baja California peninsula continues to produce some showers and thunderstorms, mainly to the east and southeast of its center. Environmental conditions are expected to gradually become more favorable for development during the next couple of days, and a tropical depression is likely to form by this weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…low…40 percent. * Formation chance through 5 days…high…70 percent.
  • 2. Satellite imagery indicates that a broad area of low pressure has formed several hundred miles offshore of the southwestern coast of Mexico. Environmental conditions are forecast to be conducive for continued gradual development, and a tropical depression could form this weekend or early next week while the system moves westward or west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Wed Jul 28, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Showers and thunderstorms have become slightly better organized since yesterday in association with a low-pressure system located about 900 miles southwest of the southern tip of the Baja California peninsula. Environmental conditions remain conducive for some additional development, and a tropical depression could form late this week or this weekend while the system moves generally westward at 5 to 10 mph. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. An area of low pressure is expected to develop later this week several hundred miles offshore of the southwestern coast of Mexico. Environmental conditions are forecast to be favorable for some gradual development thereafter, and a tropical depression could form this weekend or early next week while the system moves westward or west-northwestward at 10 to 15 mph. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Mon Jul 26, 2021 

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An elongated area of low pressure located over 1000 miles east-southeast of the Hawaiian Islands is producing disorganized showers and thunderstorms. Environmental conditions are gradually becoming less conducive for development of a tropical depression while the system moves westward at about 15 mph. By Tuesday, conditions are expected to become unfavorable for any further development. The disturbance is moving into the Central Pacific basin, and future information on this system can be found in products issued by the Central Pacific Hurricane Center. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. An area of low pressure is forecast to develop in a few days several hundred miles south of the Gulf of Tehuantepec. Environmental conditions appear conducive for some gradual development thereafter, and a tropical depression could form late this week while the system moves west-northwestward at 10 to 15 mph, remaining several hundred miles offshore of the coast of southern Mexico. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium...40 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Sun Jul 25, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. Recent satellite and microwave imagery indicate that an area of low pressure located over 1300 miles east-southeast of the Hawaiian Islands continues to show signs of organization. Environmental conditions remain conducive for further development, and a tropical depression is likely to form within the next day or so while the system moves westward at 10 to 15 mph. By Tuesday night, conditions are expected to become unfavorable for further development of this system. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…70 percent.
  • 2. An area of low pressure is forecast to develop by midweek a few hundred miles south or southeast of the Gulf of Tehuantepec. Thereafter, some gradual development is possible through late this week while the system moves generally west-northwestward at 10 to 15 mph, remaining a couple of hundred miles offshore of the coast of southern Mexico. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Sat Jul 24, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. A broad area of low pressure located about 1400 miles west-southwest of the southern tip of the Baja California peninsula continues to produce disorganized showers and thunderstorms. Environmental conditions are generally conducive for development, and this system could become a tropical depression this weekend or early next week before it reaches cooler waters while moving westward at 10 to 15 mph. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Fri Jul 23, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An area of disturbed weather located about 1200 miles southwest of the southern tip of the Baja California peninsula continues to produce a large area of showers and thunderstorms. Environmental conditions are generally conducive for additional development, and this system could become a tropical depression this weekend or early next week before it reaches cooler waters while moving westward to west-northwestward at 10-15 mph. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Fri Jul 23, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An area of disturbed weather located about 1200 miles southwest of the southern tip of the Baja California peninsula continues to produce a large area of showers and thunderstorms. Environmental conditions are generally conducive for some development, and this system could become a tropical depression this weekend or early next week before it moves over cooler waters while moving westward to west-northwestward at 10-15 mph. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 1100 PM PDT Thu Jul 22, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An area of disturbed weather located about 1150 miles southwest of the southern tip of the Baja California peninsula is still producing a large area of showers and thunderstorms. Environmental conditions are generally conducive for some development, and this system could become a tropical depression this weekend before it moves across cooler waters early next week while it heads westward to west-northwestward at 10-15 mph. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Jul 22, 2021

For the eastern North Pacific…east of 140 degrees west longitude:

  • 1. An area of disturbed weather located about 1100 miles southwest of the southern tip of the Baja California peninsula is producing a large area of disorganized showers and thunderstorms. Environmental conditions are generally conducive for some slow development of this system through the weekend before it moves across cooler waters early next week while it moves westward to west-northwestward at 10-15 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.

Video: Weather Forecast Honolulu, Hawaii ▶ Honolulu weather Forecast 08/06/2021