Tropical Storm Xavier

Tropical Storm Xavier Track 2000 Hours November 5 2018
Tropical Storm Xavier Track 2000 Hours November 5 2018

NWS National Hurricane Center Miami FL 800 PM MST Mon Nov 05 2018

Tropical Storm Xavier (see 7 videos – 1 Spanish below)– Deep convection has now remained absent in Xavier for about twelve hours. Given the hostile southwesterly vertical shear, dry mid-levels, and only lukewarm waters to be encountered by the system during the next couple of days, it is unlikely that persistent deep convection will make a comeback. Therefore, Xavier is now considered to be a post-tropical cyclone and this is the last advisory to be issued by the National Hurricane Center.

Despite the lack of thunderstorms, Xavier is showing a well- pronounced, though small, low-level circulation in the last few visible images. Peak winds in the system are around 40 kt, assuming that some spindown has occurred since the 45 kt observed from the ASCAT scatterometer several hours ago. Continued gradual weakening is very likely and Xavier is anticipated to become a remnant low by Tuesday night and dissipate in about three days. The post-tropical cyclone is moving west-northwestward at around 5 kt. The system should turn toward the west or west-southwest during the next couple of days until dissipation, under the influence of a lower tropospheric ridge north of Xavier.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 19.1N 107.5W   40 KT  45 MPH - Post Tropical (WSW Emiliano Zapata, Mexico)
 12H  06/1200Z 19.2N 108.5W   35 KT  40 MPH - Post Tropical (WSW Tomatlán, Mexico)
 24H  07/0000Z 19.3N 109.7W   30 KT  35 MPH - Post Tropical (ENE Socorro Island, Mexico)
 36H  07/1200Z 19.2N 110.9W   25 KT  30 MPH - Post Tropical (WSW San Benedicto Island, Mexico)
 48H  08/0000Z 19.1N 112.0W   20 KT  25 MPH - Post Tropical (WNW Socorro Island, Mexico)
 72H  09/0000Z 18.8N 113.4W   15 KT  15 MPH - Post Tropical (WNW Socorro Island, Mexico)
 96H  10/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 200 PM MST Mon Nov 05 2018

Tropical Storm Xavier – All of Xavier’s deep convection dissipated around 1500 UTC, leaving a swirl of low- to mid-level clouds with embedded shower activity. The initial intensity is lowered to 45 kt based on a pair of recent ASCAT passes over the circulation. Strong southwesterly shear and the surrounding dry environment finally appear to have cut off the production of deep convection, and although intermittent bursts of thunderstorms are still possible, it is unlikely that the circulation will be able to produce persistent organized convection. Therefore, Xavier’s degeneration into a remnant low has been moved up by 24 hours in the official forecast, although it is entirely possible that it could become a post-tropical low as early as tonight. Xavier’s winds are also expected to continue to gradually diminish, likely falling below tropical-storm-force overnight or early Tuesday. The remnant low should then dissipate by day 4.

The initial motion is a little faster toward the west-northwest (300 degrees) at 4 kt. A low-level ridge extending from northern Mexico westward over the Pacific should drive the now-shallow circulation west-northwestward to westward at a slightly faster speed during the next few days. The new NHC track forecast has been adjusted northward to account for recent motion trends, but it otherwise lies through the middle of the guidance envelope, close to the HCCA and Florida State Superensemble guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 19.0N 106.9W   45 KT  50 MPH - Tropical Storm (WSW San Patricio, Mexico)
 12H  06/0600Z 19.2N 107.6W   35 KT  40 MPH - Tropical Storm (WSW Tomatlán, Mexico)
 24H  06/1800Z 19.3N 108.9W   30 KT  35 MPH - Post Tropical (WNW San Patricio, Mexico)
 36H  07/0600Z 19.3N 110.1W   25 KT  30 MPH - Post Tropical (ESE San Benedicto Island, Mexico)
 48H  07/1800Z 19.1N 111.2W   20 KT  25 MPH - Post Tropical (WNW Socorro Island, Mexico)
 72H  08/1800Z 19.0N 112.8W   15 KT  15 MPH - Post Tropical (WNW Socorro Island, Mexico)
 96H  09/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 800 AM MST Mon Nov 05 2018

Tropical Storm Xavier – A burst of deep convection occurred over the low-level center around the time of the last advisory, but that activity has again been scoured off to the northeast due to 30 kt of southwesterly shear. Satellite intensity estimates have not changed, and the initial intensity remains 50 kt, which is very close to the latest UW-CIMSS ADT and SATCON estimates. Xavier has been tenaciously resisting the ill effects of shear for the time being. However, the circulation will be moving westward toward a drier environment where mid-level relative humidity values are 30-40 percent. In theory, the combination of strong shear and drier air should put an end to deep convection production, but relatively warm waters could still allow the cyclone to produce intermittent bursts of shower and thunderstorm activity over the next several days. Based on the latest intensity guidance, no changes were made to the official forecast, which continues to show Xavier becoming a remnant low in 48 hours and dissipating by day 4.

Caught within a break in the subtropical ridge, Xavier is only creeping west-northwestward, or 295/3 kt. As deep convection gradually dwindles near the cyclone, the shallower circulation is expected to be steered westward to the south of a low-level ridge stretching across northern Mexico and the Baja California peninsula. The new NHC track forecast is nearly identical to the previous one during the first 24 hours. After 24 hours, it has been nudged southward toward the various consensus aids, continuing the trend that was noted by the previous forecaster.

Even though Xavier is slowly moving away from the coast of Mexico, inclement weather is still occurring near the coasts of Colima and Jalisco, and tropical-storm-force winds could still be occurring in that vicinity. Therefore, it’s prudent to continue the Tropical Storm Warning until we have confirmation that the strong winds have shifted farther offshore.

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 18.5N 106.2W   50 KT  60 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 12H  06/0000Z 18.7N 107.0W   40 KT  45 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 24H  06/1200Z 18.9N 108.3W   35 KT  40 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 36H  07/0000Z 18.9N 109.7W   30 KT  35 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 48H  07/1200Z 18.8N 111.0W   25 KT  30 MPH - Post Tropical (Socorro Island, Mexico)
 72H  08/1200Z 18.5N 113.1W   20 KT  25 MPH - Post Tropical (WSW Socorro Island, Mexico)
 96H  09/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 300 AM CST Mon Nov 05 2018

Tropical Storm Xavier   The satellite presentation of Xavier has degraded somewhat overnight, with the main area of convection decreasing in coverage and becoming more separated from the low-level center. Somewhat surprisingly, a couple of ASCAT passes between 0345 and 0500 UTC indicated peak winds of around 50 kt. This suggests that Xavier may have been slightly stronger than previously estimated since the overall structure of the storm was better defined yesterday afternoon and evening. Based on these data, the intensity was adjusted to 50 kt on the 0600 UTC intermediate advisory, and remains at that value for now. The intensity forecast reasoning remains unchanged. Strong shear and an increasingly drier mid-level air mass are expected to cause the tropical storm to weaken fairly quickly over the next day or so, and the global models suggest that Xavier will degenerate into a remnant low in 36 to 48 hours.

Xavier has been moving slowly northwestward or 305/3 kt. A low- to mid-level ridge that is building to the north of Xavier should cause the cyclone to turn west-northwestward, and then westward during the next 12 to 24 hours. As the system weakens it is forecast to move westward or west-southwestward within the low-level flow until dissipation occurs in 3 to 4 days. The track guidance envelope shifted somewhat southward this cycle, and as a result, the official forecast was adjusted in that direction but it remains to the north of the consensus models out of respect for continuity with the previous NHC track.

FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 18.4N 105.9W   50 KT  60 MPH - Tropical Storm (WSW San Juan de Alima, Mexico)
 12H  05/1800Z 18.7N 106.8W   40 KT  45 MPH - Tropical Storm (WSW El Colomo, Mexico)
 24H  06/0600Z 18.9N 108.0W   35 KT  40 MPH - Tropical Storm (WSW San Patricio , Mexico)
 36H  06/1800Z 19.1N 109.3W   30 KT  35 MPH - Tropical Storm (WSW Puerto Vallarta, Mexico)
 48H  07/0600Z 19.2N 110.6W   25 KT  30 MPH - Post Tropical (ESE San Benedicto Island, Mexico)
 72H  08/0600Z 19.0N 112.8W   20 KT  25 MPH - Post Tropical (WNW WSW Socorro Island, Mexico)
 96H  09/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 600 PM CST Sun Nov 04 2018

SUMMARY OF WATCHES AND WARNINGS IN EFFECT: Tropical Storm Xavier

A Tropical Storm Warning is in effect for… * Punta San Telmo to Playa Perula, Mexico A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area.

DISCUSSION AND OUTLOOK

At 600 PM CST (0000 UTC), the center of Tropical Storm Xavier was located near latitude 18.3 North, longitude 105.6 West. Xavier is moving toward the north near 6 mph (9 km/h). A turn toward the northwest and west-northwest at a similar forward speed is expected tonight and on Monday, followed by a westward motion by Tuesday. On the forecast track, Xavier’s center is expected to remain offshore the coast of southwestern Mexico and begin to move farther away from the coast tonight and on Monday.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Weakening is forecast during the next few days, and Xavier is expected to degenerate into a remnant low by Tuesday.

Tropical-storm-force winds extend outward up to 150 miles (240 km) from the center.

The estimated minimum central pressure is 1001 mb (29.56 inches).

HAZARDS AFFECTING LAND

RAINFALL: Xavier is expected to produce total rain accumulations of 1 to 3 inches over coastal sections of the Mexican states of Guerrero, Michoacan, Colima, and Jalisco through Monday. Isolated maximum amounts of 4 inches are possible over Michoacan and Colima. This rainfall may produce flooding.

WIND: Tropical storm conditions are expected within the warning area through early Monday.

SURF: Swells generated by Xavier will affect portions of the coast of southwestern Mexico during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

NWS National Hurricane Center Miami FL 1200 PM CST Sun Nov 04 2018

Tropical Storm Xavier

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for… * Punta San Telmo to Playa Perula, Mexico A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area.

DISCUSSION AND OUTLOOK

At 1200 PM CST (1800 UTC), the center of Tropical Storm Xavier was located near latitude 17.8 North, longitude 105.4 West. Xavier is moving toward the north near 6 mph (9 km/h). A turn toward the northwest and west-northwest at a similar forward speed is expected tonight and on Monday, followed by a westward motion by Tuesday. On the forecast track, Xavier’s center is expected to remain offshore the coast of southwestern Mexico and begin to move farther away from the coast tonight and on Monday.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Weakening is forecast during the next few days, and Xavier is expected to degenerate into a remnant low by Tuesday.

Recent satellite-derived wind data indicate that tropical-storm- force winds extend outward up to 150 miles (240 km) from the center. These winds are occurring very near the coast of southwestern Mexico.

The estimated minimum central pressure is 1003 mb (29.62 inches).

HAZARDS AFFECTING LAND

RAINFALL: Xavier is expected to produce total rain accumulations of 1 to 3 inches over coastal sections of the Mexican states of Guerrero, Michoacan, Colima, and Jalisco through Monday.

WIND: Tropical storm conditions are expected within the warning area through early Monday.

SURF: Swells generated by Xavier will affect portions of the coast of southwestern Mexico during the next few days. These swells are likely to cause life-threatening surf and rip current conditions.

NWS National Hurricane Center Miami FL 900 AM CST Sun Nov 04 2018

Tropical Storm Xavier’s surprised us a little bit this morning when most of its deep convection was sheared away, revealing that the center of circulation was farther northeast than previously estimated. A 1234 UTC SSMIS microwave pass showed that the mid-level center was moving onshore the coast of Mexico with the deep convection, but the low-level center remains well offshore. Some new convection has recently developed near the low-level center, as well as in a band to the northwest. Objective and subjective Dvorak T-numbers have begun to fall given the decrease in deep convection, and Xavier’s initial intensity is therefore lowered to 45 kt.

Various shear calculations indicate that Xavier is now being affected by 20-25 kt of southwesterly shear, which is expected to increase further during the next 24 hours. In addition, GOES-16 low-level water vapor imagery shows that dry air has infiltrated Xavier’s circulation. The shear and dry air should make it harder and harder for Xavier to maintain organized deep convection, and the cyclone is therefore forecast to steadily weaken and degenerate into a remnant low in about 48 hours. The NHC intensity forecast lies within the tightly packed intensity guidance envelope and is generally an update of the previous forecast. The remnant low of Xavier is likely to dissipate by day 5.

Xavier’s surface center appears to have been tugged northeastward by deep convection over the past 12 hours, which suggests a longer-term motion of 020/9 kt. Now that most of the convection has been sheared away, however, the surface center seems to have slowed down, and the advisory motion is 005/5 kt. The track guidance continues to insist that Xavier will turn northwestward and west-northwestward during the next 24 hours as its circulation becomes shallower and is steered by lower-level easterly winds. The UKMET is the notable outlier, keeping Xavier as a deeper circulation and moving it more northward, closer to the coast of Mexico. The new NHC track forecast is generally between the multi-model consensus aids (near the northern side of the guidance envelope) and the GFS/ECMWF solutions (near the southern side), and it lies north of the previous forecast to account for the adjusted initial position.

Large swells, locally heavy rainfall, and gusty winds could affect portions of the coast of southwestern Mexico during the next day or two, even with the center forecast to remain offshore.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 17.6N 105.3W   45 KT  50 MPH - Tropical Storm (WSW Colola, Mexico)
 12H  05/0000Z 18.1N 105.8W   40 KT  45 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 24H  05/1200Z 18.5N 106.7W   35 KT  40 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 36H  06/0000Z 18.8N 107.8W   30 KT  35 MPH - Tropical Storm (WSW Puerto Vallarta, Mexico)
 48H  06/1200Z 19.1N 109.1W   25 KT  30 MPH - Post Tropical (WSW Puerto Vallarta, Mexico)
 72H  07/1200Z 19.3N 111.6W   20 KT  25 MPH - Post Tropical (WSW San Benedicto Island, Mexico)
 96H  08/1200Z 19.2N 113.8W   15 KT  15 MPH - Post Tropical (WSW Cabo San Lucas, Mexico)
120H  09/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Nov 03 2018

Tropical Storm Xavier’s overall structure has not changed since this afternoon. The tropical storm is still strongly sheared and deep convection is primarily occurring to the northeast of its low-level center. Recent objective and subjective intensity estimates range from 45 to 50 kt. Earlier ASCAT data explicitly contained several vectors near 45 kt, but the instrument could have under-sampled the maximum winds. Based on all these data, 50 kt seems most representative of the tropical storm’s intensity at this time.

Regardless of Xavier’s exact maximum winds, it is likely nearing its peak intensity now. Some slight additional strengthening in the short term can not be ruled out, however the global models indicate that strong wind shear will continue through the forecast period and the flow aloft will become less supportive for convection by late Sunday or early Monday. All of the intensity models forecast that Xavier will begin to weaken in about 24 h. By 96 h, if not sooner, the dynamical models indicate that Xavier will lose all deep convection and become a remnant low. Virtually no change was made to the official intensity forecast, which is merely an update of the previous advisory.

Xavier is now moving toward the northeast, and the initial motion estimate is 035/6 kt. With the continued exception of the UKMET model, the typically reliable track guidance is in good agreement on the track of the tropical storm. The cyclone will likely turn northward tonight or tomorrow, and is then forecast to turn steadily westward in another day or two as it weakens and becomes vertically shallow. The UKMET does not show this turn and shows a stronger/deeper Xavier that moves farther north, though this scenario appears unlikely given the strong agreement among the intensity models that Xavier will weaken. Only minor adjustments were made to the NHC track forecast, which blends the previous official forecast with the HCCA and GFEX consensus aids at most forecast hours.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 16.1N 105.7W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 12H  04/1200Z 16.7N 105.6W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 24H  05/0000Z 17.4N 105.9W   45 KT  50 MPH - Tropical Storm (WWSW Lázaro Cárdenas, Mexico)
 36H  05/1200Z 17.8N 106.6W   40 KT  45 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 48H  06/0000Z 17.9N 107.7W   35 KT  40 MPH - Tropical Storm (WSW Manzanillo, Mexico)
 72H  07/0000Z 18.1N 110.1W   30 KT  35 MPH - Tropical Storm (ESE Socorro Island, Mexico)
 96H  08/0000Z 18.3N 112.5W   25 KT  30 MPH - Post Tropical (WSW Socorro Island, Mexico)
120H  09/0000Z 18.5N 115.0W   20 KT  25 MPH - Post Tropical (WNW Clarion Island, Mexico)

NWS National Hurricane Center Miami FL 300 PM MDT Sat Nov 03 2018

Tropical Storm Xavier continues to show a sheared cloud pattern in conventional satellite imagery this afternoon, with the low-level center located near or just southwest of the main convective mass. The various subjective and objective satellite intensity estimates are near 45 kt, and recent scatterometer data also indicate winds near 45 kt. Thus, the initial intensity remains at that value. Analyses from CIMSS and from the SHIPS model indicate that Xavier is still in an environment of 20-25 kt of southwesterly vertical shear.

There is little change in the intensity forecast philosophy from the last advisory. During the next 12-24 h, the dynamical models suggest that an upper-level trough located to the north and west of Xavier should provide upper-level divergence over the cyclone. This could allow some additional strengthening despite the ongoing shear. After that time, the trough is forecast to dissipate, leaving the tropical storm in an area of upper-level convergence, moderate to strong shear, and a dry surrounding air that should cause it to weaken. Based on this evolution, the intensity forecast calls for a little more strengthening early in the forecast, followed by gradual weakening through the remainder of the forecast period. As in the previous forecast, Xavier is expected to degenerate to a remnant low in about 96 h. The forecast again follows the overall trend of the intensity guidance and lies near the upper edge of the guidance through 48 h.

The initial motion is now 060/8. As mentioned previously, Xavier should turn northeastward and then northward during the next 24 h toward a weakness in the subtropical ridge created by the aforementioned trough. As Xavier weakens and becomes a shallow system, the cyclone should turn toward the west-northwest and west as it is steered by the low-level flow to the south of the subtropical ridge. All of the dynamical models follow this scenario except for the UKMET, which shows a much more northward motion toward the southern Gulf of California. The new forecast track will follow the model consensus in showing the westward motion, and the new NHC forecast track is similar to the previous track.

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 15.6N 106.1W   45 KT  50 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 12H  04/0600Z 16.1N 105.7W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 24H  04/1800Z 16.9N 105.7W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 36H  05/0600Z 17.3N 106.1W   45 KT  50 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 48H  05/1800Z 17.5N 106.8W   40 KT  45 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 72H  06/1800Z 18.0N 109.5W   30 KT  35 MPH - Tropical Storm (ESE Socorro Island, Mexico)
 96H  07/1800Z 18.0N 112.0W   25 KT  30 MPH - Post Tropical (WSW Socorro Island, Mexico)
120H  08/1800Z 18.5N 114.0W   20 KT  25 MPH - Post Tropical (ENE Clarion Island, Mexico)

NWS National Hurricane Center Miami FL 900 AM MDT Sat Nov 03 2018

Although Tropical Storm Xavier is being affected by 20-25 kt of westerly vertical shear, the cyclone continues to generate a large burst of convection and the low-level center is now located under the southwestern edge of the convective mass. The initial intensity is increased to 45 kt, which is at the upper end of the various satellite intensity estimates.

During the next 24 h, the dynamical models suggest that an upper-level trough located to the north and west of Xavier should provide upper-level divergence over the cyclone. This could allow some additional strengthening despite the ongoing shear. After that time, the trough is forecast to dissipate, leaving the tropical storm in an area of upper-level convergence and moderate to strong shear that should cause it to weaken.

Based on this evolution, the intensity forecast calls for a little more strengthening during the next 12-24 h, followed by gradual weakening through the remainder of the forecast period, with the cyclone becoming a remnant low in about 96 h. The forecast follows the overall trend of the intensity guidance and lies near the upper edge of the guidance. Based on a combination of conventional and microwave satellite fixes, the initial motion is estimated to be 060/7. There is again little change to the forecast track philosophy. Xavier should turn northeastward and then northward during the next 24 h toward a weakness in the subtropical ridge created by the aforementioned trough. As Xavier weakens and becomes a shallow system, the cyclone should turn toward the west-northwest and west as it is steered by the low-level flow to the south of the subtropical ridge. The new forecast track is nudged just a little to the east and north of the previous track, but it remains close to the various consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 15.3N 107.0W   45 KT  50 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 12H  04/0000Z 15.8N 106.4W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 24H  04/1200Z 16.6N 106.0W   50 KT  60 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 36H  05/0000Z 17.3N 106.1W   45 KT  50 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 48H  05/1200Z 17.4N 106.5W   40 KT  45 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 72H  06/1200Z 17.5N 108.0W   30 KT  35 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 96H  07/1200Z 17.5N 111.0W   25 KT  30 MPH - Post Tropical (WSW Socorro Island, Mexico)
120H  08/1200Z 18.0N 113.5W   20 KT  25 MPH - Post Tropical (ESE Clarion Island, Mexico)

NWS National Hurricane Center Miami FL 300 AM MDT Sat Nov 03 2018

Tropical Storm Xavier – A large burst of deep convection has developed over the northeastern and eastern portions of Xavier’s circulation overnight. An earlier GMI microwave overpass indicated that the center was located near the southwestern edge of the convection, but there was evidence of an increase in banding over the northeastern portion of the storm. Dvorak data T-numbers from TAFB and SAB were T2.5 and T3.0, respectively, so the initial intensity has been increased to 40 kt for this advisory.

Xavier is expected to remain embedded within an area of moderate to strong southwesterly shear during the next 24 to 36 hours, and these conditions are likely to prevent significant strengthening. Although the statistical guidance shows no additional intensification, the dynamical models deepen the system over the next day or so, and the NHC forecast calls for a slight increase in wind speed today, followed by little change in strength through Sunday. This is in good agreement with the latest HFIP corrected consensus model. By 48 hours the shear is expected to become even stronger, and as a result, gradual weakening should occur thereafter. Xavier is forecast to degenerate into a remnant low by day 4, if not sooner.

The aforementioned microwave pass was very helpful in locating the center of Xavier. Based on that data and recent satellite fixes, the initial motion estimate is east-northeastward at about 6 kt. The track forecast reasoning has not changed from the previous advisory. Xavier should turn northeastward, then northward by tonight toward a weakness in the subtropical ridge created by a deep-layer trough over central Mexico. After Xavier weakens, the cyclone should turn toward west-northwestward or westward as it is steered by the low-level flow. Since there is still a fair amount of spread among the track models as to how far north Xavier will move before it weakens and turns westward, the NHC track is close to the various consensus aids at 48 hours and beyond. Most of the track models have trended a little faster after 48 hours, and the official forecast has been adjusted accordingly.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0900Z 14.7N 107.7W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  03/1800Z 15.2N 107.0W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  04/0600Z 16.0N 106.4W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, Mexico)
 36H  04/1800Z 16.6N 106.3W   45 KT  50 MPH - Tropical Storm (WSW Zihuatanejo, Mexico)
 48H  05/0600Z 17.1N 106.5W   40 KT  45 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 72H  06/0600Z 17.5N 107.7W   30 KT  35 MPH - Tropical Storm (WSW Colola, Mexico)
 96H  07/0600Z 17.6N 110.2W   25 KT  30 MPH - Post Tropical Storm (ESE Socorro Island, Mexico)
120H  08/0600Z 18.0N 112.5W   20 KT  25 MPH - Post Tropical Storm (WSW Socorro Island, Mexico)

NWS National Hurricane Center Miami FL 300 PM MDT Fri Nov 02 2018

Microwave data received during the past several hours indicate that the broad area of low pressure we’ve been monitoring southwest of the coast of Mexico has developed a sufficiently well-defined center of circulation and improved low-level curved bands. Visible images, however, still suggest that multiple swirls are revolving around a common center, with the deepest convection offset to the east of that center due to southwesterly shear. Now that the system has a well-defined center, advisories are being initiated on Tropical Depression Twenty-Five-E, with maximum winds of 30 kt based on Dvorak classifications of T2.0 and T1.5.

Although the depression should remain over sufficiently warm waters to support strengthening, southwesterly shear is expected to increase from its current value of about 15 kt to over 25 kt during the next couple of days. Therefore, only some intensification is anticipated during the next 36 hours or so, with weakening beginning by day 3. The system is likely to degenerate into a remnant low in 4 or 5 days once it can no longer produce organized deep convection. The statistical-dynamical guidance show little to no strengthening, so this initial forecast most closely follows the HWRF, HCCA, and GFS models.Tropical Storm Xavier Forming Distances 1100 Hours November 2 2018

The depression appears to be moving east-northeastward, or 75 degrees, at about 7 kt. The depression is trapped between two mid-tropospheric ridges to its east and west, and to the south of an expansive mid-level trough which extends across much of Mexico and the Gulf of Mexico. The resulting steering pattern should cause the cyclone to move slowly northeastward and then northward toward the trough during the next 48 hours, but the system should then turn sharply westward on days 4 and 5 once it becomes a shallower system and is steered by lower-level easterly flow.

The UKMET model is the main outlier among the model guidance, showing the system reaching the coast of southwestern Mexico, but it appears to keep the circulation too deep in the face of strong southwesterly shear. The NHC track forecast is therefore just slightly left of the TVCN multi-model consensus and the HCCA model, keeping the cyclone well offshore of the coast of Mexico.

INIT  02/2100Z 14.4N 109.0W   30 KT  35 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  03/0600Z 14.7N 108.3W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  03/1800Z 15.2N 107.6W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 36H  04/0600Z 15.9N 107.1W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, Mexico)
 48H  04/1800Z 16.7N 107.0W   45 KT  50 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 72H  05/1800Z 17.5N 107.4W   35 KT  40 MPH - Tropical Storm (WSW Colola, Mexico)
 96H  06/1800Z 17.8N 109.0W   30 KT  35 MPH - Tropical Storm (ESE Socorro Island, Mexico)
120H  07/1800Z 18.0N 111.5W   25 KT  30 MPH - Post Tropical (WSW Socorro Island, Mexico)

NWS National Hurricane Center Miami FL 1100 AM PDT Fri Nov 2 2018

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

Satellite imagery indicates that shower activity associated with the low pressure area centered about 600 miles south of the southern tip of the Baja California peninsula has become better organized, and that the circulation of the low is becoming better defined. If current trends continue, advisories will be initiated on a tropical depression this afternoon or tonight as the system moves northeastward. Interests along the southwestern coast of mainland Mexico should monitor the progress of this system

* Formation chance through 48 hours…high…near 100 percent. * Formation chance through 5 days…high…near 100 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Fri Nov 2 2018

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

Shower and thunderstorm activity continues to show signs of organization in association with a well-defined low pressure system centered more than 600 miles south of the southern tip of the Baja California Peninsula.

A tropical depression is likely to form during the next day or so while the system moves slowly northeastward.

* Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Nov 1 2018

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

A low pressure system centered about 700 miles south of the southern tip of the Baja California Peninsula has become better defined since yesterday.

Shower and thunderstorm activity is beginning to show some signs of organization, and environmental conditions are forecast to be conducive for the development of a tropical depression during the next day or so while the system moves slowly northward or northeastward.

* Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high...90 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Thu Nov 1 2018

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

Tropical Storm Xavier forming – Shower activity associated with an area of low pressure centered about 700 miles south of the southern tip of the Baja California Peninsula has become better organized during the past several hours.

Environmental conditions are forecast to be conducive for additional development during the next several days, and a tropical depression is likely to form during the next few days while the system moves slowly northward or northeastward.

* Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Thu Nov 1 2018

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

An elongated low pressure system located several hundred miles south of the southern tip of the Baja California peninsula is producing a broad area of disorganized showers and thunderstorms. Environmental conditions are forecast to be conducive for gradual development during the next several days, and a tropical depression is likely to form during the next few days while the system moves slowly northward.

* 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 Wed Oct 31 2018

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

A large, but poorly organized, area of disturbed weather is located several hundred miles south and southwest of the southwestern coast of Mexico. Environmental conditions are forecast to be conducive for gradual development of this system during the next several days, and a tropical depression could form later this week or this weekend while it moves west-northwestward to northwestward at 5 to 10 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 Oct 31 2018

Tropical Storm Xavier forming – For the eastern North Pacific…east of 140 degrees west longitude:

* Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium...60 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Tue Oct 30 2018

Tropical Storm Xavier forming – For the eastern North Pacific…east of 140 degrees west longitude:

* Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Tue Oct 30 2018

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

1. A weak area of low pressure located about 800 miles south-southwest of the southern tip of the Baja California peninsula is producing disorganized showers and thunderstorms. Development of this system, if any, is likely to be slow to occur while it moves westward or west-northwestward at about 10 mph.

* Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…10 percent.

2. An elongated area of low pressure is producing showers and thunderstorms over a broad area about 1200 miles southwest of the southern tip of the Baja California peninsula. Some slow development of this system is possible over the next few days while the disturbance moves toward the west or west-northwest at 5 to 10 mph.

* Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.

3. A third area of disturbed weather is located several hundred miles south-southwest of Acapulco, Mexico. Environmental conditions are forecast to support gradual development of this system through the weekend while it moves west-northwestward at about 10 mph.

* 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 Tue Oct 30 2018

2. An elongated area of low pressure located about 1200 miles southwest of the southern tip of the Baja California peninsula is producing disorganized showers and thunderstorms. Some slow development of this system is possible over the next few days while the disturbance moves toward the west or west-northwest at 5 to 10 mph.

* Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.

3. A third area of disturbed weather is located several hundred miles south-southwest of Acapulco, Mexico. Environmental conditions appear conducive for gradual development of this system through the weekend while it moves west-northwestward at about 10 mph.

* Formation chance through 48 hours…low…near 0 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Mon Oct 29 2018

2. Satellite wind data indicate that the circulation associated with an area of low pressure located about 1175 miles south-southwest of the southern tip of the Baja California peninsula has become elongated. However, some slow development of this system is possible over the next few days while the disturbance moves toward the west or west-northwest at about 10 mph.

* Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Mon Oct 29 2018

For the eastern North Pacific…east of 140 degrees west longitude: 1. An elongated area of low pressure is located several hundred miles south of Manzanillo, Mexico. Although upper-level winds are only marginally conducive, and a tropical depression could still form during the next couple of days while the system moves westward at about 10 mph. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…50 percent.

2. A well-defined low pressure system located about 1100 miles south-southwest of the southern tip of the Baja California peninsula continues to produce disorganized shower and thunderstorm activity. However, some slow development of this system will be possible over the next several days while the low moves toward the west or west-northwest at about 10 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Sun Oct 28 2018

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

1. Showers and thunderstorms associated with a small well-defined low pressure system located several hundred miles south-southwest of Acapulco, Mexico have increased during the past few hours. Some additional development of this system is possible and a tropical depression could form during the next couple of days while it moves westward at about 10 mph.

* Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Sat Oct 27 2018

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

1. A small well-defined low pressure area located several hundred miles south of Acapulco, Mexico, has changed little during the past several hours. However, environmental conditions could become a little more conducive for some development of this system over the next few days while it moves westward at about 10 mph.

* Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Sat Oct 27 2018

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

A well-defined low pressure system located several hundred miles south of Acapulco, Mexico, has changed little during the past several hours. However, environmental conditions could become a little more conducive for some development of this system over the next few days while it moves westward at about 10 mph.

* Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low...40 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Fri Oct 26 2018

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

A small area of disorganized showers and thunderstorms located several hundred miles south of the Gulf of Tehuantepec is associated with a trough of low pressure.

Although strong upper-level winds and nearby dry air may limit development during the next couple of days, some slow organization of this disturbance is possible late this weekend and early next week while it moves generally westward at 10 to 15 mph.

* Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Oct 25 2018

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

A trough of low pressure continues to produce a small area of showers several hundred miles south of the Gulf of Tehuantepec.

Although nearby dry air is likely to limit development for the next couple of days, some slow organization of this disturbance is possible thereafter through early next week while the system moves generally westward at 10 to 15 mph.

* Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Thu Oct 25 2018

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

A trough of low pressure continues to produce a small area of showers several hundred miles south of the Gulf of Tehuantepec. Some gradual development of this system is possible through early next week while the system moves generally westward at 10 to 15 mph, far from land.

* Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Thu Oct 25 2018

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

A trough of low pressure is producing limited shower activity several hundred miles south of the Gulf of Tehuantepec. Some gradual development of this system is possible through early next week while the system moves generally westward at 10 to 15 mph, far from land.

* Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

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