Tropical Storm Nora

Tropical Storm Nora Track 0300 Hours August 30 2021
Tropical Storm Nora Track 0300 Hours August 30 2021

Tropical Storm Nora Wind Speed FieldTropical Storm Nora NWS National Hurricane Center Miami FL 300 AM MDT Mon Aug 30, 2021 (see video below)

Satellite analysts have been unable to identify a low-level center associated with Nora, and scatterometer and synoptic data show no surface circulation. Therefore the system has dissipated and this is the last advisory on this system. However, the moisture field of Nora’s remnants will continue to move poleward over the next few days and could contribute to rainfall enhancement over the southwestern United States later this week.

Key Messages:

  • 1. Heavy rain associated with Nora’s remnants is expected across the states of Sinaloa and Sonora. This rain will likely result in life-threatening flash flooding and mudslides. Rainfall from the remnants of Nora is also likely to spread into the southwestern U.S. and central Rockies beginning Wednesday, bringing the potential for flash flooding to the region.
FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 25.3N 108.1W   25 KT  30 MPH - Depression (WNW Campo el General,MX)
 12H  30/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 PM MDT Sun Aug 29, 2021 

Nora appears to have moved inland, and it is unclear if it still has a well-defined surface center. Earlier microwave data was inconclusive regarding the existence of the low level center, while the Dvorak analysts from TAFB and SAB were each unable to fix Nora’s center over water. The intensity has been lowered to 35 kt, assuming weakening has occurred due to continued interaction with land. Baring an unexpected redevelopment of the center over water, Nora should continue to weaken inland, and could dissipate as soon as early Monday. Quick dissipation is now supported by all of the dynamical guidance. Accordingly, the NHC intensity forecast has been adjusted much lower than in the previous advisory. Nora is forecast to become post-tropical tomorrow and dissipate by Tuesday. Based on recent trends, this forecast is probably generous.

Despite the uncertainty associated with Nora’s position, the system still appears to be moving generally north-northwestward, with an initial motion of 330/10 kt. None of the dynamical guidance is able to track a low-level center more than about 24 h. However,there is good agreement that the mid-level remnants of Nora will continue moving generally northwestward and could contribute to heavy rain across northwest Mexico and portions of the southwestern U.S. during the middle to latter portion of the week.

Key Messages:

  • 1. Heavy rain associated with Nora is expected across the west coast of Mexico from the states of Nayarit northward to southern Sonora. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora is likely to spread into the southwestern U.S. and central Rockies during the middle to latter portion of the week, bringing the potential for flash flooding to the region
FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z 24.8N 107.9W   35 KT  40 MPH - Tropical Storm (WSW Casa Blanca,MX)
 12H  30/1200Z 25.4N 108.4W   35 KT  40 MPH - Tropical Storm (ENE Las Playas,MX)
 24H  31/0000Z 26.3N 109.1W   30 KT  35 MPH - Post Tropical (WSW Bacorehuis,MX)
 36H  31/1200Z 27.0N 109.6W   25 KT  30 MPH - Post Tropical (WNW Los Tejabanes,MX)
 48H  01/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 300 PM MDT Sun Aug 29, 2021 

Visible satellite imagery and surface observations along the west-central coast of Mexico suggest that the center of Nora has re-formed closer to a mass of deep convection that has persisted today over the southern Gulf of California. Various satellite data sets indicate that Nora is weakening. The latest SSMIS microwave data reveal that the structure of Nora has degraded since this morning, especially in the mid-levels where an eyewall structure is no longer evident. Additionally, a 15 UTC ASCAT-A pass shows the winds are substantially weaker than previously estimated. Thus, the initial intensity has been lowered to 50 kt for this advisory.

The initial motion is somewhat uncertain given the earlier center relocation, but it is estimated to be north-northwestward, or 330/10 kt. The global models suggest the tropical cyclone will move generally northwestward over the next couple of days, between an upper-level low offshore the Baja California peninsula and a mid-level ridge to the east of Nora. This motion should keep the center of Nora along the coast, or just inland over mainland west-central or northwestern Mexico. The official NHC track forecast is once again shifted a little to the right based on the latest track guidance, which brings the cyclone further inland by Tuesday.

Nora is forecast to gradually weaken over the next few days as the system continues to interact with the coastline of Mexico. Despite warm SSTs in the Gulf of California and weak environmental shear, it appears unlikely that Nora will move far enough away from the coast to take advantage of this favorable environment. In fact, it is certainly plausible that the center of Nora could move well inland earlier than forecast and weaken more rapidly. The NHC intensity forecast has been adjusted about 10 kt weaker at all forecast hours based on today’s data supporting a much weaker initial intensity.

Key Messages:

  • 1. Nora is forecast to be at or near tropical storm strength while it moves near the coast of Sinaloa and southern Sonora through early Tuesday, and tropical storm warnings and watches are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora.
  • 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the states of Colima northward to southern Sonora. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora is likely to spread into the southwestern U.S. and central Rockies during the middle to latter portion of the week bringing the potential for flash flooding to the region.
FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 24.3N 107.5W   50 KT  60 MPH - Tropical Storm (WSW Las Bocas,MX)
 12H  30/0600Z 25.1N 108.2W   45 KT  50 MPH - Tropical Storm (WSW Costa Azul,MX)
 24H  30/1800Z 25.8N 108.8W   40 KT  45 MPH - Tropical Storm (ENE Juan José Ríos,MX)
 36H  31/0600Z 26.5N 109.3W   40 KT  45 MPH - Tropical Storm (WSW Camahuiroa,MX)
 48H  31/1800Z 27.2N 109.9W   35 KT  40 MPH - Tropical Storm (ENE Allende,MX)
 60H  01/0600Z 28.2N 110.6W   30 KT  35 MPH - Depression (WNW Nicolás Bravo,MX)
 72H  01/1800Z 28.9N 111.1W   30 KT  35 MPH - Depression (ESE La Puerca,MX )
 96H  02/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 AM MDT Sun Aug 29, 2021

Nora has a healthy satellite appearance this morning. The deep convection near and to the west of the estimated center is maintaining a fairly large central dense overcast with very cold infrared cloud tops. Recent ATMS and SSMIS microwave data indicate Nora still has a pronounced mid-level eye structure, with the center very near the coast of extreme southern Sinaloa. A blend of the UW-CIMSS objective ADT estimate and 12 UTC subjective Dvorak classifications from TAFB and SAB support holding the initial intensity at 65 kt for this advisory. The estimated initial motion of Nora is north-northwestward or 345/9 kt, although this is somewhat uncertain due to the lack of in-situ observations. A mid-level ridge should continue to steer the tropical cyclone generally north-northwestward to northwestward during the next few days. This motion will bring the center over the eastern Gulf of California and very near or over the coast of west-central Mexico. The official NHC track forecast is adjusted just slightly to the right of the previous one, in line with the latest track guidance.

Nora’s intensity forecast remains highly dependent on whether the center moves inland over mainland Mexico or along the Gulf of California, parallel to the west-central coast of Mexico. Given the slight eastward track adjustment, the official NHC intensity forecast shows gradual weakening over the next few days due to at least intermittent land interaction as Nora skirts the coast. This is consistent with the general intensity guidance consensus, which no longer supports strengthening given Nora’s proximity to land. Due to the complex geography of western Mexico, even a slight eastward deviation from the forecast track would result in more rapid weakening as Nora moves further inland. Conversely, a more northwestward motion over the warm Gulf of California waters could allow Nora to remain a stronger tropical storm early this week. As previously mentioned, confidence in the intensity forecast is lower than normal.

Key Messages:

  • 1. Nora is forecast to be at or near hurricane strength while it moves near the coasts of Nayarit and Sinaloa today and into Monday, and hurricane warnings or watches are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the states of Colima northward to southern Sonora. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora is likely to spread into the southwestern U.S. and central Rockies during the middle to latter portion of the week, bringing the potential for flash flooding to the region.
  • 3. Nora is forecast to move north-northwestward to northwestward near or over the Gulf of California Tuesday and Wednesday, bringing a risk of wind impacts to portions of the Mexican states of Baja California Sur, northern Sinaloa, and Sonora. Given the above-average uncertainty in the intensity forecast, confidence is not high enough to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  29/1500Z 23.3N 106.4W   65 KT  75 MPH - Category 1 (ENE Mazatlán,MX)
 12H  30/0000Z 23.8N 106.9W   60 KT  70 MPH - Tropical Storm (WSW San Miguel,MX)
 24H  30/1200Z 24.3N 107.5W   55 KT  65 MPH - Tropical Storm (WSW California,MX)
 36H  31/0000Z 24.9N 108.2W   55 KT  65 MPH - Tropical Storm (WSW La Reforma,MX)
 48H  31/1200Z 25.6N 109.0W   50 KT  60 MPH - Tropical Storm (WNW Lázaro Cárdenas,MX)
 60H  01/0000Z 26.5N 109.6W   50 KT  60 MPH - Tropical Storm (WSW Las Bocas,MX)
 72H  01/1200Z 27.5N 110.0W   40 KT  45 MPH - Tropical Storm (WSW Providencia,MX)
 96H  02/1200Z 29.5N 111.2W   30 KT  35 MPH - Depression (WNW La Coruba,MX)
120H  03/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Aug 28, 2021 

Surface data from Mexico, data from an Air Force Reserve Hurricane Hunter aircraft, and microwave imagery from an 2344 UTC SSMIS indicate that the center of Nora moved over the far northwestern coast of Jalisco earlier this evening. Since then, the cloud pattern of the hurricane has degraded, but not enough to bring the latest Dvorak estimates below hurricane strength. The advisory intensity is therefore set at 65 kt based on the assumption that interaction with land has caused weakening, however there is low confidence in this assessment.

The ever-so-slight rightward deviation from the forecast track that brought Nora inland, at least briefly, highlights the sensitivity of the system’s future to its exact track. A sizable portion of the latest dynamical guidance, including the GFS, ECMWF, and HWRF models indicate that Nora will move inland tonight or early Sunday and dissipate. All three models also indicate it could reform over the Gulf of California in a few days. Other models, like the UKMET and CMC global models maintain Nora as a coherent tropical cyclone much longer. While the models can easily flip flop from run to run, the NHC forecast cannot drastically change solutions so cavalierly. Therefore, the official forecast is based on the condition that Nora will stay far enough offshore to persist as a tropical cyclone. Regardless of its exact state, Nora is forecast to turn toward the northwest on Sunday and then move along the coast toward northern Mexico early next week. This general solution is supported by all of the available guidance. A slight eastward adjustment has been made to the NHC track forecast to account for the slightly east initial position.

Given Nora’s recent movement over land, the intensity forecast has been lowered substantially at all forecast hours, but still maintains Nora near hurricane strength for the next couple of days. This is well above the most recent intensity consensus, which is heavily influenced by the dynamical models that move Nora inland. If it doesn’t move inland sooner, Nora will likely quickly weaken as it moves permanently inland by around 96 h, and become a remnant low by the end of the forecast period.

Key Messages:

  • 1. Nora is forecast to be at or near hurricane strength while it moves near the coasts of Nayarit and Sinaloa through the weekend, and hurricane warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the states of Michoacan northward to southern Sonora, including Baja California Sur. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora may spread into the southwestern U.S. and central Rockies during the middle to latter portion of next week.
  • 3. Nora is forecast to continue moving northward over the Gulf of California Tuesday and Wednesday, bringing a risk of wind impacts to portions of the Mexican states of Baja California Sur, northern Sinaloa, and Sonora. Given the above-average uncertainty in the forecast intensity, confidence is not high enough to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 21.3N 105.5W   65 KT  75 MPH - Category 1 (WNW Chacala,MX)
 12H  29/1200Z 22.8N 106.2W   65 KT  75 MPH - Category 1 (WSW Caimanero,MX)
 24H  30/0000Z 23.7N 107.1W   60 KT  70 MPH - Tropical Storm (WSW Dimas,MX)
 36H  30/1200Z 24.4N 107.9W   60 KT  70 MPH - Tropical Storm (WNW Lucenilla,MX)
 48H  31/0000Z 24.9N 108.6W   60 KT  70 MPH - Tropical Storm (WSW Isla Altamura,MX)
 60H  31/1200Z 25.6N 109.4W   55 KT  65 MPH - Tropical Storm (WSW Santa Maria,MX)
 72H  01/0000Z 26.8N 110.1W   55 KT  65 MPH - Tropical Storm (WSW Borabampo,MX)
 96H  02/0000Z 28.6N 110.7W   35 KT  40 MPH - Tropical Storm (WSW Cajón,MX)
120H  03/0000Z 30.2N 110.9W   20 KT  25 MPH - Post Tropical (WSW El Tule, MX)

NWS National Hurricane Center Miami FL 400 PM CDT Sat Aug 28, 2021 

Nora developed a cloud-filled eye during the past few hours, with the center now grazing the coast and the eyewall moving across western Jalisco, Mexico. An Air Force Reserve Hurricane Hunter aircraft has been investigating the hurricane, but unfortunately the storm is now too close to the mountainous coastline for the plane to safely locate the surface center or sample the likely-stronger wind field on the eastern side of the circulation. Based mainly on T4.5/77 kt Dvorak estimates from TAFB and SAB, the initial intensity is estimated to be 75 kt.

The center has been moving a little faster to the west of due north, or 350/12 kt. The track models are in agreement that Nora should turn toward the north-northwest and northwest during the next few days, generally keeping the center of the hurricane over the waters of the Gulf of California. However, due to the complex geography and mountainous topography of the region, the track forecast is challenging, and it’s almost impossible to know if Nora’s center will remain over water or graze the coastlines of Nayarit and Sinaloa over the next few days. By days 4 and 5, Nora’s center is forecast to move inland over Sonora after traversing a significant length of the Gulf of California.

Assuming a path that keeps Nora just offshore, low shear and very warm sea surface temperatures in the Gulf of California should be sufficient to at least maintain hurricane intensity for the next 3 days. However, any slight deviations of the track could cause Nora to weaken and fall below hurricane intensity sooner than is indicated in the official forecast. Given the uncertainties, however, the government of Mexico has extended the hurricane warning farther north along the coasts of Nayarit and Sinaloa out of an abundance of caution. Weakening will become more likely the farther north Nora gets up the Gulf of California, both due to possible land interaction and ingestion of drier air off the Mexican plateau.

Key Messages:

  • 1. Nora is forecast to be a hurricane while it moves near or along the coasts of the Mexican states of Jalisco, Nayarit, and Sinaloa through Monday, and hurricane warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the Mexican states of Guerrero, northward to southern Sonora, including Baja California Sur. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora may spread into the southwestern U.S. and central Rockies during the middle to latter portion of next week.
  • 3. Nora is forecast to continue moving northward over the Gulf of California Tuesday and Wednesday, bringing a risk of wind impacts to portions of the Mexican states of Baja California Sur, northern Sinaloa, and Sonora. Given the above-average uncertainty in the forecast intensity, confidence is not high enough to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 19.7N 105.4W   75 KT  85 MPH - Category 1 (WSW Chola,MX)
 12H  29/0600Z 21.5N 105.9W   75 KT  85 MPH - Category 1 (WSW San Blas,MX)
 24H  29/1800Z 22.9N 106.7W   75 KT  85 MPH - Category 1 (WSW Mazatlán,MX)
 36H  30/0600Z 23.5N 107.4W   75 KT  85 MPH - Category 1 (WSW La Cruz,MX)
 48H  30/1800Z 24.2N 108.1W   75 KT  85 MPH - Category 1 (WSW Altata,MX)
 60H  31/0600Z 24.8N 108.9W   70 KT  80 MPH - Category 1 (WSW Angostura,MX)
 72H  31/1800Z 25.6N 109.5W   70 KT  80 MPH - Category 1 (WSW Santa María,MX)
 96H  01/1800Z 27.6N 110.4W   55 KT  65 MPH - Tropical Storm (ESE  Pótam,MX)
120H  02/1800Z 29.4N 110.6W   30 KT  35 MPH - Depression (ENE Calabazas,MX)

NWS National Hurricane Center Miami FL  1000 AM CDT Sat Aug 28, 2021 

Nora continues to show signs of strengthening with the center embedded beneath a Central Dense Overcast, where clouds tops are now as cold as -85 degrees Celsius. Dvorak fixes from TAFB and SAB are T4.0/65 kt and T4.5/77 kt, and the most recent objective numbers are near 75 kt. Nora’s initial intensity is conservatively estimated to be 70 kt, but an Air Force Reserve Hurricane Hunter aircraft should help us verify the maximum winds later this afternoon. The latest fixes indicate that Nora is moving west of due north, or 350/10 kt. A shortwave trough over the northern Rockies has created a weakness in the subtropical ridge over the southwestern U.S., which should allow Nora to continue moving northward or north-northwestward through tonight. This motion will take Nora’s center and hurricane-force winds very close to or over portions of Jalisco, Mexico, later today and this evening.

On Sunday, the track guidance suggests that Nora will make a turn back toward the northwest, bringing the center over the Gulf of California by Monday at a much slower forward speed. The track guidance is in good agreement on this scenario, but the narrow width of the Gulf of California means that hazards away from the center could affect both the coast of mainland Mexico and the east coast of Baja California Sur. Due to this uncertainty, new watches and warnings have been extended northward along both coasts. The track guidance–and the NHC official forecast–suggest that Nora’s center could move inland over Sonora, Mexico, in 4 to 5 days.

Assuming Nora’s center remains over water, low shear and warm waters should allow for additional strengthening during the next 24-36 hours. After that time, possible land interaction, influences of nearby topography, and potential ingestion of dry air from the Mexican plateau could all conspire to cause at least gradual weakening while Nora begins to move into the Gulf of California. That said, there is still a lot of uncertainty in the intensity prediction, and Nora is forecast to remain as a hurricane through early Tuesday, a scenario supported by the ECMWF model. One thing the models do agree on is that Nora’s wind field should contract after it passes Cabo Corrientes and heads into the Gulf of California, and this is reflected in the NHC forecast.

Key Messages:

  • 1. Nora is forecast strengthen through tonight as it moves near the coasts of the Mexican states of Colima, Jalisco, Nayarit, and southern Sinaloa, and hurricane warnings are in effect for portions of that coastline. Interests in these areas and points farther north should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the Mexican states of Guerrero, northward to southern Sonora, including Baja California Sur. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora may spread into the southwestern U.S. and central Rockies during the middle to latter portion of next week.
  • 3. Nora is forecast to move over the Gulf of California as a hurricane by Monday, bringing a risk of wind impacts to portions of the Mexican states of Baja California Sur, Sinaloa, and Sonora. Given the above-average uncertainty in the forecast intensity, confidence is not high enough to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 18.4N 105.4W   70 KT  80 MPH - Category 1 (WSW Acapulco,MX)
 12H  29/0000Z 20.1N 105.8W   75 KT  85 MPH - Category 1 (WSW Ipala,MX)
 24H  29/1200Z 22.0N 106.5W   80 KT  90 MPH - Category 1 (WSW Campamento Nayarit,MX)
 36H  30/0000Z 23.1N 107.3W   80 KT  90 MPH - Category 1 (WSW Mazatlán,MX)
 48H  30/1200Z 23.8N 108.0W   75 KT  85 MPH - Category 1 (WSW Costa Rica,MX)
 60H  31/0000Z 24.5N 108.9W   70 KT  80 MPH - Category 1 (WSW Altata,MX)
 72H  31/1200Z 25.2N 109.6W   65 KT  75 MPH - Category 1 (WSW Topolobampo,MX)
 96H  01/1200Z 26.9N 110.5W   60 KT  70 MPH - Tropical Storm (WSW Bahía de Lobos,MX)
120H  02/1200Z 29.3N 111.0W   40 KT  45 MPH - Tropical Storm (WSW Nuñez,MX)

NWS National Hurricane Center Miami FL 1000 PM CDT Fri Aug 27, 2021

Nora’s cloud pattern has not become much better organized since earlier today. The central convection has diminished, but this is likely a diurnal fluctuation. Upper-level outflow appears to be fairly well-defined, with convective banding features most prominent over the southern portion of the circulation. Dvorak intensity estimates from both TAFB and SAB remain at 55 kt, so the advisory intensity will be held at that value for now. The storm has been moving a little to the east of the previous track over the past few hours, but the longer-term motion estimate is still northwestward, or 325/9 kt. Nora should move on a northwestward or north-northwestward heading for the next 2-3 days on the southwestern side of a mid-tropospheric anticyclone. Late in the forecast period, the cyclone is forecast to turn northward as the ridge to its north weakens. The official forecast track has been nudged just a bit to the east of the previous one during the next 72 hours or so, but not as far east as the latest dynamical model consensus, TVCE. Nora is expected to be in a moist, low-shear environment for the next few days, so the atmospheric conditions should favor intensification into a hurricane. Nonetheless, the majority of the intensity guidance does not show much strengthening beyond 24 hours, probably due to land interaction. The official intensity forecast shows gradual strengthening for the next couple of days or so, and is similar to the previous one. This is close to the LGEM guidance based on the ECMWF global model fields. It should be noted that there is significant uncertainty in the future strength of Nora because of the possible influence of land.

Key Messages:

  • 1. Nora is forecast to strengthen to a hurricane on Saturday while passing nearby the coasts of the Mexican states of Jalisco and Nayarit, and hurricane watches and tropical storm warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2.Heavy rain associated with Nora is expected across coastal sections of the Mexican states of Guerrero, Michoacan, Colima, and Jalisco, as well as Baja California Sur. Life-threatening flash flooding and mudslides are expected.
  • 3. Nora is forecast to move over the Gulf of California as a hurricane early next week, bringing a risk of wind and rain impacts to portions of the Mexican states of Baja California Sur, Sinaloa, and Sonora. Given the above-average uncertainty in the forecast, it is still too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 16.3N 105.1W   55 KT  65 MPH - Tropical Storm (WSW Acapulco,MX)
 12H  28/1200Z 17.6N 105.6W   60 KT  70 MPH - Tropical Storm (WSW Maruata,MX)
 24H  29/0000Z 19.6N 106.2W   65 KT  75 MPH - Category 1 (WSW Pérula,MX)
 36H  29/1200Z 21.6N 107.0W   70 KT  80 MPH - Category 1 (WSW Campamento Nayarit,MX)
 48H  30/0000Z 22.7N 107.9W   75 KT  85 MPH - Category 1 (WSW Mazatlán,MX)
 60H  30/1200Z 23.6N 108.6W   80 KT  90 MPH - Category 1 (ENE Cabo San Lucas,MX)
 72H  31/0000Z 24.5N 109.3W   80 KT  90 MPH - Category 1 (ENE Isla Cerralvo,MX)
 96H  01/0000Z 26.5N 111.0W   70 KT  80 MPH - Category 1 (ESE El Rosarito,MX)
120H  02/0000Z 29.5N 111.5W   45 KT  50 MPH - Tropical Storm (WNW San Jorge,MX)

NWS National Hurricane Center Miami FL 400 PM CDT Fri Aug 27, 2021

A 1656 UTC ASCAT-B scatterometer pass showed that Nora still does not have a tight inner core and instead has a 30-35 n mi region of winds 20 kt or less. However, the pass did show maximum wind vectors a little over 50 kt, so the storm has been strengthening, and maximum winds are estimated to be 55 kt. This is supported by Dvorak estimates of T3.5/55 kt from TAFB and SAB.

A slight adjustment was made to Nora’s initial position based on the scatterometer data, but the storm is still moving toward the northwest (310/10 kt). Nora is expected to maintain a motion toward the northwest or north-northwest as it heads in the direction of a weakness in the subtropical ridge which has developed over the U.S. southern Rockies and northern Mexico. The track guidance envelope appears to have tightened up compared to the past few days, with nearly all the model trackers showing Nora’s center passing offshore just west of Cabo Corrientes, Mexico, in about 24 hours and then continuing northwestward either across the waters of the Gulf of California or inland over Baja California Sur. The new NHC track forecast has been nudged westward from this morning’s forecast, but this is mainly due to the adjustment of the storm’s initial position. This track is very close to the HCCA and other consensus aids.

Nora’s convective structure appears to be responding to a decrease in northeasterly shear, which is analyzed to be out of the northeast at 10-15 kt. This shear is forecast to decrease to 10 kt or less by tonight. Although Nora’s broad structure could limit the storm’s rate of strengthening, warm waters and upper-level divergence should allow it to become a hurricane over the next day or so. After that time, Nora’s intensity will be strongly modulated on whether its center moves over mainland Mexico or the Baja California peninsula. If the center remains over water, as is shown in the official forecast, then environmental conditions appear conducive for Nora to remain as a hurricane for several more days, and the NHC forecast still closely follows the ECMWF-based SHIPS and LGEM models. That said, there is still greater-than- normal uncertainty in the intensity forecast after 48 hours.

Key Messages:

  • 1. Nora is forecast to strengthen to a hurricane on Saturday while passing nearby the coasts of the Mexican states of Jalisco and Nayarit, and hurricane watches and tropical storm warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across coastal sections of the Mexican states of Oaxaca, Guerrero, Michoacan, Colima, and Jalisco, as well as Baja California Sur. Life-threatening flash flooding and mudslides are expected.
  • 3. Nora is forecast to move over the Gulf of California as a hurricane early next week, bringing a risk of wind and rain impacts to portions of the Mexican states of Baja California Sur, Sinaloa, and Sonora. Given the above-average uncertainty in the forecast, it is still too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  27/2100Z 15.5N 104.9W   55 KT  65 MPH - Tropical Storm (ESE Acapulco,MX)
 12H  28/0600Z 16.5N 105.6W   60 KT  70 MPH - Tropical Storm (ESE Acapulco,MX)
 24H  28/1800Z 18.3N 106.2W   65 KT  75 MPH - Category 1 (WSW Manzanillo,MX)
 36H  29/0600Z 20.3N 107.0W   70 KT  80 MPH - Category 1 (WSW Puerto Vallarta,MX)
 48H  29/1800Z 21.9N 107.8W   75 KT  85 MPH - Category 1 (WSW Mazatlán,MX)
 60H  30/0600Z 22.9N 108.6W   80 KT  90 MPH - Category 1 (ESE Cabo San Lucas,MX)
 72H  30/1800Z 23.9N 109.4W   80 KT  90 MPH - Category 1 (WSW Los Barriles,MX)
 96H  31/1800Z 25.9N 110.9W   70 KT  80 MPH - Category 1 (ESE Isla del Carmen,MX)
120H  01/1800Z 28.4N 111.8W   55 KT  65 MPH - Tropical Storm (WSW El Cardonal,MX)

NWS National Hurricane Center Miami FL 1000 AM CDT Fri Aug 27, 2021 

As was expected, vertical shear appears to be decreasing, with deep convection expanding over Nora’s surface center just within the past few hours. Water vapor imagery also suggests an expansion of upper-level outflow to the north of the storm. Since Dvorak data-T numbers are 3.0/45 kt from TAFB and SAB, Nora’s intensity is being held at that value for now.

Nora has turned toward the northwest (310/10 kt) in response to a weakness in the subtropical ridge that has developed over the U.S. southern Rockies. Little change to this steering pattern is expected during the next several days, and Nora is forecast to move toward the northwest or north-northwest for the entire 5-day forecast period. Compared to the last few days, nearly all the track models now have Nora’s center staying just offshore of Cabo Corrientes, Mexico, in about 36 hours. The GFS and HMON model fields still show a landfall in that area, but their interpolated trackers–which have been shifted to begin at our estimated initial position–also stay just offshore. After 36 hours, the track guidance has shifted slightly eastward, and the new NHC track forecast now keeps Nora’s center over water up into the Gulf of California from days 2 through 5. That will be a small needle to thread, however, and any future shifts in the models could increase the risk of impacts to either the Baja California peninsula or the northwestern coast of mainland Mexico through the middle of next week.

SHIPS model diagnostics indicate that the northeasterly deep-layer shear over Nora has decreased to about 15 kt, and this shear is expected to decrease further to below 10 kt in about 12 hours. Along with warm waters of about 29 degrees Celsius and significant upper-level divergence (at least for the next 36 hours), these conditions should foster strengthening, and Nora is still forecast to become a hurricane on Saturday. The part of the forecast after 48 hours remains uncertain depending on how much Nora interacts with land, but based on the new forecast that keeps the cyclone over water in the Gulf of California (where SSTs are even warmer — around 31 degrees Celsius), Nora could maintain hurricane intensity through at least day 4. The NHC intensity forecast continues to hedge on the side of the ECMWF-based SHIPS and LGEM models, since most of the other models show Nora’s center interacting with land to at least some degree.

The new forecast has necessitated an extension of the Tropical Storm Warning northward to San Blas, Mexico, and the issuance of a new Tropical Storm Watch north of there to Mazatlan.

Key Messages:

  • 1. Nora is forecast to strengthen to a hurricane on Saturday while passing nearby the coasts of the Mexican states of Colima, Jalisco, and Nayarit, and hurricane watches and tropical storm warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across coastal sections of the Mexican states of Oaxaca, Guerrero, Michoacan, Colima, and Jalisco, as well as Baja California Sur. Life-threatening flash flooding and mudslides may occur.
  • 3. Nora is forecast to move over the Gulf of California as a hurricane early next week, bringing a risk of wind and rain impacts to portions of the Mexican states of Baja California Sur, Sinaloa, and Sonora. Given the above-average uncertainty in the forecast, it is still too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 15.4N 104.3W   45 KT  50 MPH - Tropical Storm (WSW Acapulco,MX)
 12H  28/0000Z 16.3N 105.2W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas,MX)
 24H  28/1200Z 17.9N 105.9W   60 KT  70 MPH - Tropical Storm (WSW Maruata,MX)
 36H  29/0000Z 19.9N 106.5W   65 KT  75 MPH - Category 1 (WSW Puerto Vallarta,MX)
 48H  29/1200Z 21.7N 107.4W   70 KT  80 MPH - Category 1 (WSW Mazatlán,MX)
 60H  30/0000Z 23.1N 108.3W   75 KT  85 MPH - Category 1 (ENE Cabo San Lucas,MX)
 72H  30/1200Z 24.2N 109.1W   75 KT  85 MPH - Category 1 (ESE Isla Cerralvo,MX)
 96H  31/1200Z 26.1N 110.7W   65 KT  75 MPH - Category 1 (ENE Isla del Carmen,MX)
120H  01/1200Z 28.4N 111.7W   50 KT  60 MPH - Tropical Storm (WSW El Cardonal,MX)

NWS National Hurricane Center Miami FL 1000 PM CDT Thu Aug 26, 2021 

A large area of deep convection has developed over the southern and western portions of Nora’s circulation over the past several hours. Almost all of the convection is displaced to the southwest of Nora’s center by some moderate northeasterly shear. Based on the slightly improved satellite appearance of the cyclone, the initial intensity is raised to 40 kt for this advisory. This is in best agreement with the objective UW-CIMSS ADT and SATCON estimates of around 40 kt.

Nora has turned a bit to the right and accelerated slightly this evening, and it is now moving west-northwestward or 295/10 kt. The mid-level ridge over the southern United States that is steering Nora is being eroded by a shortwave trough over the Rocky Mountains. In response, Nora is expected to turn toward the northwest on Friday and then the north-northwest on Saturday. This will bring the center of the cyclone close to the southwestern coast of Mexico. The ECMWF and UKMET as well as almost all the ECMWF ensemble members keep Nora offshore, passing just offshore of Cabo Corrientes before moving toward the entrance to the Gulf of California and Baja California Sur. However, the GFS and many of its ensemble members still show Nora moving inland over southwestern Mexico on Saturday. Overall, the multi-model track guidance consensus changed little this cycle, and so the official NHC track forecast remains very close to the previous one. The extended forecast still shows Nora moving near or over Baja California Sur and the Gulf of California on days 4 and 5. However, it is worth noting that the degree of uncertainty in this portion of the forecast is above average.

The moderate northeasterly wind shear over Nora is expected to diminish over the next 12-24 h, which should allow the cyclone to intensify within a moist and unstable environment over SSTs around 29 deg C. Thus, Nora is forecast to strengthen over the next few days and become a hurricane on Saturday. Of course, this is highly dependent on Nora remaining offshore and not moving inland over mainland Mexico. Since the NHC track forecast keeps Nora offshore, the official intensity forecast lies on the high end of the intensity guidance and is closest to the ECMWF-based SHIPS and LGEM models. In this case, the normally reliable intensity consensus aids are of limited use since several of the consensus members bring Nora inland. Weakening is forecast on days 4-5 due to expected land interaction with Baja California Sur.

The government of Mexico has extended the Tropical Storm Warning northward from Manzanillo to Cabo Corrientes, and issued a Tropical Storm Watch north of Cabo Corrientes to San Blas. Additional watches and warnings may be required on Friday.

Key Messages:

  • 1. Nora is forecast to strengthen to a hurricane on Saturday while it is near the coast of southwestern Mexico, and a hurricane watch and tropical storm warning are in effect for portions of that area. Interests along the southwestern coast of Mexico should closely monitor the progress of this system and updates to the forecast.
  • 2. Heavy rain associated with Tropical Storm Nora is expected across coastal sections of the Mexican states of Oaxaca, Guerrero, Michoacan, Colima, and Jalisco. Life-threatening flash flooding and mudslides may occur.
  • 3. Nora is forecast to be near or over the southern portion of Baja California Sur as a hurricane early next week, bringing a risk of wind and rain impacts to that area. Given the above average uncertainty in the forecast, it is still too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 14.1N 102.6W   40 KT  45 MPH - Tropical Storm (WSW Puerto Escondido,MX)
 12H  27/1200Z 14.9N 103.6W   45 KT  50 MPH - Tropical Storm (WSW Puerto Escondido,MX)
 24H  28/0000Z 16.3N 104.7W   55 KT  65 MPH - Tropical Storm (WSW Acapulco,MX)
 36H  28/1200Z 18.0N 105.6W   60 KT  70 MPH - Tropical Storm (WNW Lázaro Cárdenas,MX)
 48H  29/0000Z 19.9N 106.5W   65 KT  75 MPH - Category 1 (WSW Puerto Vallarta,MX)
 60H  29/1200Z 21.5N 107.5W   70 KT  80 MPH - Category 1 (WSW Tepic,MX)
 72H  30/0000Z 22.7N 108.7W   75 KT  85 MPH - Category 1 (ESE Cabo San Lucas,MX)
 96H  31/0000Z 24.4N 110.6W   65 KT  75 MPH - Category 1 (ENE San Juan de la Costa,MX)
120H  01/0000Z 26.0N 112.1W   45 KT  50 MPH - Tropical Storm (ENE Pabellón,MX)

NWS National Hurricane Center Miami FL 1000 AM CDT Thu Aug 26, 2021

Satellite images show that deep convection embedded within the sprawling circulation of the depression is gradually becoming better organized, and 91-GHz SSMIS data from 1117 UTC showed improved curvature to the bands, especially within the western semicircle. Subjective Dvorak estimates are now a consensus T2.5/35 kt from TAFB and SAB, while objective numbers from UW-CIMSS are running a little higher. Therefore, the depression is being upgraded to Tropical Storm Nora with 35-kt winds.

The microwave data, as well as first-light visible imagery, suggest that the center may be consolidating or re-forming a little farther east of where we had been tracking it. Nora is moving slowly toward the west-northwest (296/6 kt), steered by a strong mid-level ridge located over the southern United States. This ridge is expected to dissolve over the next 24 hours as a shortwave trough moves across the Rocky Mountains, allowing Nora to turn toward the northwest and north-northwest through the weekend. Most of the differences among the track models still appear to be related to the initial location of Nora’s center. The GFS continues to show the system having multiple low-level vortices, with a dominant one forming well to the east and moving inland along the southwestern coast of Mexico as early as late Friday, and many more GEFS ensemble members show a similar scenario compared to yesterday. The HWRF and HMON are also in the camp of bringing Nora’s center inland over Mexico. Other models, including the ECMWF (and most of its ensemble members), the UKMET, and the consensus aids, still show Nora’s center staying just offshore. The new NHC track forecast has been shifted eastward, primarily due to the adjustment of the initial position, and shows Nora’s center very close to the coast of southwestern Mexico over the weekend. If Nora’s center re-forms, then additional shifts in the track forecast will be likely. By early next week, Nora is likely to head towards Baja California Sur, but here is still a lot of uncertainty on the exact track at that time.

Moderate northeasterly vertical shear continues to affect Nora, but this shear is expected to decrease to 10 kt or less in 36-48 hours. In addition, the storm will be moving over warm waters of 28-29 degrees Celsius and through an environment of high mid-level moisture. These factors should allow for continued strengthening, although the system’s large size could be one limiting factor in how fast that strengthening happens. Nora is expected to be near or at hurricane strength when it approaches the coast of southwestern Mexico in 2-3 days. However, the intensity forecast, especially on days 3-5, hinges on whether or not the center moves inland. If it does not, Nora will have greater opportunity to strengthen while it heads toward the Baja California Peninsula. Since several of the intensity models assume a scenario where Nora moves inland, the NHC intensity forecast more closely follows the no-land versions of the GFS and ECMWF SHIPS models through day 4 to be consistent with what is shown in the track forecast.

Given the high uncertainty in Nora’s future track, and its roughly shore-parallel path, a larger-than-normal hurricane watch area has been issued for the southwestern coast of Mexico by the Mexican government.

Key Messages:

  • 1. Nora is forecast to strengthen to a hurricane by late Saturday while it approaches the coast of southwestern Mexico, and hurricane and tropical storm watches are now in effect for portions of that area. Interests along the southwestern coast of Mexico should closely monitor the progress of this system and updates to the forecast.
  • 2. Heavy rain associated with Nora is expected across coastal sections of the Mexican states of Oaxaca, Guerrero, Michoacan, Colima, and Jalisco. As a result, life-threatening flash flooding and mudslides could occur.
  • 3. Nora is forecast to be near the southern portion of Baja California Sur as a hurricane early next week, bringing a risk of wind and rain impacts to that area. Given the above average uncertainty in the forecast, it is too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 12.5N 100.8W   35 KT  40 MPH - Tropical Storm (ESE Puerto Escondido,MX)
 12H  27/0000Z 13.2N 101.9W   40 KT  45 MPH - Tropical Storm (ESE Puerto Escondido,MX)
 24H  27/1200Z 14.3N 103.0W   50 KT  60 MPH - Tropical Storm (WSW Puerto Escondido,MX)
 36H  28/0000Z 15.7N 103.7W   55 KT  65 MPH - Tropical Storm (WSW Acapulco,MX)
 48H  28/1200Z 17.4N 104.5W   60 KT  70 MPH - Tropical Storm (WSW Lázaro Cárdenas,MX)
 60H  29/0000Z 19.0N 105.3W   65 KT  75 MPH - Category 1 (WSW San Patricio,MX)
 72H  29/1200Z 20.2N 106.3W   70 KT  80 MPH - Category 1 (WSW Puerto Vallarta,MX)
 96H  30/1200Z 22.3N 108.6W   75 KT  85 MPH - Category 1 (ESE Cabo San Lucas,MX)
120H  31/1200Z 24.0N 110.5W   55 KT  65 MPH - Tropical Storm (WSW La Paz,MX)

NWS National Hurricane Center Miami FL 1000 PM CDT Wed Aug 25, 2021

Recent satellite imagery and microwave data indicate that the depression has not become better organized this evening. It is producing a ragged area of convection over the northwestern portion of its circulation, which appears somewhat elongated along an east-west axis. The latest UW-CIMSS objective ADT estimate and subjective 00z Dvorak classifications from TAFB and SAB support an initial intensity of 30 kt for this advisory.

The estimated initial motion of the poorly organized depression is an uncertain 280/6 kt. The cyclone is being steered generally westward along the southern extent of a mid-level ridge over the south-central United States. A deep-layer trough over the western U.S. is forecast to weaken the steering ridge during the next couple of days. Thus, the depression is forecast to gain some latitude and move west-northwestward overnight and Thursday, and then northwestward or north-northwestward on Friday and Saturday.

Although the track guidance consensus and many GEFS and ECMWF ensemble members still keep the center of the cyclone offshore, there was a pronounced eastward shift in the guidance envelope this cycle. In fact, the GFS and several GEFS members show the system moving inland along the coast of southwestern Mexico in 2-3 days. The official NHC track forecast has been adjusted to the right of the previous one from 48 h onward and lies along the HFIP corrected consensus approach (HCCA) aid. This brings the center of the cyclone closer to the coast of southwestern Mexico, but remains offshore and to the left of much of the latest guidance. The extended forecast takes the system near the southern portion of Baja California Sur early next week, but overall there is above average uncertainty in the extended portion of the track forecast. Interests along the coast of southwestern Mexico and in Baja California Sur should closely monitor future updates to the forecast.

The depression is located within a favorable thermodynamic environment for strengthening, but moderate to strong northeasterly vertical wind shear should limit its intensification rate in the short-term period. The shear is expected to weaken by Friday, and the system is forecast to become a hurricane this weekend over very warm SSTs. There remains a large amount of spread in the intensity guidance beyond 48 h, due to the potential for land interaction earlier in the forecast period. Since the latest NHC track forecast keeps the system offshore, the intensity forecast is much higher than the consensus aids during this period and trends toward the stronger statistical-dynamical guidance. Again, confidence is lower than normal in the day 3-5 forecast.

Key Messages:

  • 1. The depression is forecast to strengthen to a tropical storm on Thursday and be near hurricane intensity by Saturday. While the core of the storm is currently expected to pass near but offshore the southwestern coast of Mexico, strong winds and heavy rainfall, possibly resulting in flash floods and mudslides, could affect portions of that area over the next several days. Interests in this area should closely monitor the progress of this system and updates to the forecast.
  • 2. The system is forecast to pass near the southern portion of Baja California Sur as a hurricane early next week, bringing a risk of wind and rain impacts to that area. Given the above average uncertainty in the forecast, it is too soon to determine the magnitude and location of these potential impacts.
FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 11.9N 100.1W   30 KT  35 MPH - Depression (WSW San Miguel,El Salvador)
 12H  26/1200Z 12.3N 101.2W   35 KT  40 MPH - Tropical Storm (WSW Tapachula,MX)
 24H  27/0000Z 13.1N 102.7W   40 KT  45 MPH - Tropical Storm (WSW Puerto Escondido,MX)
 36H  27/1200Z 14.2N 103.9W   45 KT  50 MPH - Tropical Storm (WSW Puerto Escondido,MX)
 48H  28/0000Z 15.6N 104.8W   55 KT  65 MPH - Tropical Storm (WSW Acapulco,MX)
 60H  28/1200Z 17.2N 105.6W   60 KT  70 MPH - Tropical Storm (WSW Lázaro Cárdenas,MX)
 72H  29/0000Z 18.8N 106.5W   65 KT  75 MPH - Category 1 (WSW Manzanillo,MX)
 96H  30/0000Z 21.3N 108.7W   70 KT  80 MPH - Category 1 (ESE Cabo San Lucas,MX)
120H  31/0000Z 23.0N 111.0W   60 KT  70 MPH - Tropical Storm (WNW Cabo San Lucas,MX)

NWS National Hurricane Center Miami FL 500 PM PDT Tue Aug 24, 2021

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

The National Hurricane Center has issued the last advisory on Post-Tropical Cyclone Marty, located more than 600 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. Showers and thunderstorms have increased in coverage since yesterday and continue to show signs of organization in association with a low pressure system located a couple of hundred miles south-southwest of the Gulf of Tehuantepec. Environmental conditions remain conducive for additional development, and a tropical depression is expected to form during the next day or so. The system is forecast to move westward to west-northwestward at 10 to 15 mph this week, remaining offshore of the coast of southwestern Mexico. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Tue Aug 24, 2021

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

The National Hurricane Center is issuing advisories on recently downgraded Tropical Depression Marty, located more than 500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. Recent satellite-derived surface wind data indicate that the low pressure system located less than 200 miles offshore of the southeastern coast of Mexico has become a little better defined since yesterday. Shower and thunderstorm activity is also beginning to show some signs of organization, and a tropical depression is expected to form during the next day or so. The system is forecast to move westward to west-northwestward at 10 to 15 mph this week, remaining offshore the coast of southwestern Mexico. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Tue Aug 24, 2021

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

The National Hurricane Center is issuing advisories on Tropical Storm Marty, located about 500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A broad area of low pressure located less than 200 miles offshore of Guatemala and southern Mexico continues to produce disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression is likely to form by the middle to latter part of this week. The system is expected to move westward to west-northwestward at 10 to 15 mph this week, remaining offshore the coast of southwestern Mexico. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 1100 PM PDT Mon Aug 23 2021

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

The National Hurricane Center is issuing advisories on Tropical Storm Marty, located about 400 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A broad area of low pressure located less than 200 miles offshore of Guatemala and southern Mexico continues to produce disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression is likely to form by the middle to latter part of this week. The system is expected to move westward to west-northwestward at 10 to 15 mph this week, passing offshore the coast of southwestern Mexico. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Mon Aug 23 2021

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

The National Hurricane Center is issuing advisories on Tropical Storm Marty, located about 300 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A broad area of low pressure located less than 200 miles offshore of Guatemala and southern Mexico is producing some disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression is likely to form by the middle to latter part of this week. The system is expected to move westward to west-northwestward at 10 to 15 mph this week, passing offshore of the coast of southwestern Mexico. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Mon Aug 23 2021

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

The National Hurricane Center is issuing advisories on Tropical Storm Marty, located more than 200 miles south-southwest of the southern tip of the Baja California peninsula.

  • 1. An area of disturbed weather centered less than 200 miles south of Guatemala and southeastern Mexico is producing a broad area of disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression is likely to form by the middle to latter part of this week. The disturbance is expected to move westward to west-northwestward at 10 to 15 mph, remaining offshore the coast of southwestern Mexico through this week. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Mon Aug 23, 2021

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

The National Hurricane Center is issuing advisories on newly formed Tropical Storm Marty, located more than 200 miles south-southwest of the southern tip of the Baja California peninsula.

  • 1. An area of disturbed weather located just south of the coast of southern Mexico is producing disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for some gradual development of this system, and a tropical depression is likely to form by late this week offshore of the southwestern coast of Mexico while the system moves generally west-northwestward at around 10 mph. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 1100 PM PDT Sun Aug 22 2021

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

  • 1. Showers and thunderstorms association with an area of low pressure located a couple of hundred miles south-southwest of the southern tip of the Baja California peninsula continue to show signs of organization. Recent satellite wind data indicate that the circulation has become better defined since early today. Environmental conditions appear conducive for continued development, and if these development trends continue, a tropical depression or tropical storm is likely to form later tonight or early Monday while the system moves westward at 10 to 15 mph, away from the coast of Mexico. Additional information on this system can found in high seas forecasts issued by the NOAA National Weather Service. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.
  • 2. An area of disturbed weather off the coast of southern Mexico is associated with some disorganized shower activity. Environmental conditions are forecast to be favorable for some gradual development of this system, and a tropical depression is likely to form by late this week offshore of the southwestern coast of Mexico while the system move west-northwestward or northwestward at around 10 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high...70 percent.

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