Tropical Storm Vicente

Post Tropical Storm Vicente Track 1000 Hours October 23 2018
Post Tropical Storm Vicente Track 1000 Hours October 23 2018

NWS National Hurricane Center Miami FL 1000 AM CDT Tue Oct 23 2018

Tropical Storm Vicente (see 5 videos below) – Satellite imagery indicates that Vicente crossed the coast of the Mexican state of Michoacan a little while ago, and is now inland. The system, if in fact it still has a center, lacks sufficient organized deep convection to be considered a tropical cyclone. Therefore Vicente has become a post-tropical remnant low, and this is the last advisory on this system.

The motion is around 330/10 kt. A 12-hour forecast point is shown for continuity, but the cyclone will probably have dissipated by that time. Vicente’s remnants, along with southwesterly flow around the larger circulation of Hurricane Willa, will probably continue to produce locally heavy rains over portions of southwestern Mexico into Wednesday.Post Tropical Storm Vicente Tropical Force Wind Probability 0700 Hours October 23 2018

FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 18.4N 102.4W   25 KT  30 MPH - Post Tropical (Arteaga, Mexico)
 12H  24/0000Z 19.5N 103.2W   20 KT  25 MPH - Post Tropical (Tamazula de Gordiano, Mexico)

NWS National Hurricane Center Miami FL 400 AM CDT Tue Oct 23 2018

Tropical Storm Vicente’s  Cells of heavy showers and thunderstorms are still forming near Vicente’s center, but overall the convective organization has continued to deteriorate. Scatterometer data from 0418 UTC showed maximum winds of around 25 kt, so assuming some undersampling of the small circulation, the initial intensity is lowered to 30 kt.

WindSat and ASCAT data revealed that Vicente’s center had moved a little to the east of earlier fixes, and the depression’s initial motion estimate is north-northwestward, or 330/10 kt. This motion should continue as Vicente gets drawn up between Hurricane Willa’s circulation and a low- to mid-level ridge over the Gulf of Mexico, and the depression is therefore forecast to move inland over the Mexican state of Michoacan later today. Once inland, the tiny circulation is likely to dissipate quickly over mountainous terrain. A 12-hour remnant low position is provided for continuity to show a track moving inland, but in all likelihood Vicente will have dissipated by that time.

FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 17.2N 102.0W   30 KT  35 MPH - Tropical Storm (WSW Zihuatanejo, Mexico)
 12H  23/1800Z 19.2N 103.2W   20 KT  25 MPH - Post Tropical (Tecalitlán, Mexico)
 24H  24/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Mon Oct 22 2018

Tropical Storm Vicente’s  Satellite imagery indicates that Vicente continues to lose organization. Deep convection has been sporadic and is generally limited to the east and south of the storm’s center. Unfortunately, the most recent ASCAT pass missed the center of the system, so we are unable to verify if Vicente’s circulation is still closed. Due to Vicente’s deteriorating satellite presentation, the initial intensity has been lowered to 35 kt, which is a blend of Dvorak Current Intensity estimates from TAFB and SAB. This intensity estimate may be generous, however.

Although sea-surface temperatures near Vicente are quite warm (29 degrees C), the storm continues to be negatively affected by northeasterly vertical wind shear. Moreover, the cyclone’s small size has likely made it more susceptible to shear. Although the shear is forecast to weaken slightly over the the next day or so, the influence of the large circulation of Hurricane Willa and the interaction with land is likely to cause the storm to dissipate in 24-36 hours, or less. The majority of the dynamical guidance models dissipate Vicente by tomorrow afternoon and the official forecast calls for dissipation by 36 h. It should be noted that, given the current tenuous state of Vicente, the system could dissipate at any time.

Vicente’s current motion is west-northwestward, or 300/10 kt. The system is forecast to turn toward the northwest and north-northwest while moving between the mid-level ridge over the Gulf of Mexico and the southeastern portion of the circulation of Willa. The official track forecast is a little faster than the previous one and roughly in the middle of the model guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 15.4N 101.5W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  23/0600Z 16.8N 102.7W   30 KT  35 MPH - Tropical Storm (WSW San Luis de la Loma, Mexico)
 24H  23/1800Z 19.0N 104.0W   25 KT  30 MPH - Post Tropical (Armería, Mexico)
 36H  24/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Mon Oct 22 2018

Tropical Storm Vicente’s  Satellite imagery and microwave data this morning are indicating that the early morning re-strengthening of Vicente has ended. The system appears elongated, with the low-level center becoming increasingly difficult to locate. Radar imagery from Acapulco, Mexico, does not suggest a well-organized tropical cyclone at this time. The averages of the subjective Dvorak analyses from SAB and TAFB support an initial intensity of 40 kt, which may be a little generous.

Moderate northeasterly shear is forecast to continue over the cyclone the next couple of days which should support ongoing steady weakening. The GFS, HWRF, and HMON models show the cyclone dissipating tonight, with some of the other global model guidance showing little change in intensity until landfall. Given the current disorganized appearance, a weakening trend appears to be the most realistic scenario, with Vicente forecast to weaken to a tropical depression before it makes landfall over southwestern Mexico in about 36 hours. Regardless of the forecast intensity, the primary hazard will be heavy rainfall across portions of southern and southwestern Mexico, which could cause life-threatening flash flooding.

Vicente appears to have begun a turn to the west-northwest, and the initial motion is now estimated to be 290/10 kt as the system begins to round the southwestern periphery of a mid-level ridge over Mexico. As the cyclone rounds the western periphery of the ridge later today and Tuesday, a turn to the northwest and then north-northwest is expected. The latest NHC forecast track is similar, and just slightly to the right of the previous one, and is near the tightly clustered model guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 14.9N 100.8W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  23/0000Z 15.8N 101.8W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  23/1200Z 17.4N 103.0W   30 KT  35 MPH - Tropical Storm (WSW Caleta de Campos, Mexico)
 36H  24/0000Z 18.9N 104.0W   30 KT  35 MPH - Tropical Storm (Armería, Mexico)
 48H  24/1200Z 20.3N 104.8W   20 KT  25 MPH - Post Tropical (Sierra de San Miguel, Mexico)
 72H  25/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 AM CDT Mon Oct 22 2018

Tropical Storm Vicente’s  cloud pattern has become better organized during the past several hours. A burst of deep convection has developed near the surface center, and a developing curved band with associated cold cloud tops of -80C is wrapping around nearly 70 percent of the cyclone’s circulation. A SATCON analysis, subjective and objective satellite intensity estimates from TAFB and SAB, and an earlier 0325 UTC ISRO ScatSAT-1 overpass support an initial intensity increase to 40 kt for this advisory.

Despite this temporary strengthening interlude, modest northeasterly shear as indicated by the statistical intensity aids and the UW-CIMSS shear product should induce weakening soon. In fact, most of the large-scale models agree with dissipation in 36 hours, or show the cyclone reaching the Mexico coastline around the 48-hour period as a depression. Although the majority of the models support dissipation over water, the NHC forecast will reflect landfall as a tropical depression for continuity purposes. Regardless of the forecast intensity scenarios, the primary hazard will be heavy rainfall across portions of southern and southwestern Mexico, which could cause life-threatening flash flooding.

The initial motion is estimated to be westward, or 275/9 kt, within southeast to easterly steering flow produced by a mid-tropospheric ridge extending westward over southern Mexico from the central Gulf of Mexico. Vicente is expected to round the southwestern to western periphery of the aforementioned ridge during the next 36 hours, or prior to dissipation. The track forecast is a little slower than the previous advisory, and is based on a blend of the Florida State Superensemble and the TVCN multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 14.1N  99.7W   40 KT  45 MPH - Tropical Stoem (WSW Acapulco, Mexico)
 12H  22/1800Z 14.8N 100.8W   40 KT  45 MPH - Tropical Stoem (WSW Acapulco, Mexico)
 24H  23/0600Z 16.1N 102.3W   35 KT  40 MPH - Tropical Stoem (WSW Petatlán, Mexico)
 36H  23/1800Z 17.7N 103.5W   30 KT  35 MPH - Tropical Stoem (WSW Las Naranjas, Mexico)
 48H  24/0600Z 19.5N 104.4W   20 KT  25 MPH- Post Tropical (Cuautitlán de García Barragán, Mexico)
 72H  25/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sun Oct 21 2018

Tropical Storm Vicente’s  satellite presentation hasn’t changed much, with the low-level circulation located near the northeastern edge of a rather elongated area of deep convection. Satellite classifications remain unchanged, so the initial intensity is held at 35 kt based on continuity with the earlier ASCAT pass. Northeasterly shear is expected to continue affecting Vicente, and the global models show the cyclone dissipating within the next 24 to 48 hours. The NHC forecast brings Vicente near the coast of southwestern Mexico as a depression in 36 hours and inland as a remnant low by 48 hours, but it wouldn’t be surprising if the small cyclone dissipated sooner. Regardless of the eventual details of Vicente’s demise, the main hazard will be heavy rainfall across portions of southern and southwestern Mexico, which could cause life-threatening flash flooding.

The initial motion estimate remains south of due west or 260/09. Vicente should be steered around the southwestern and western edge of a mid-level ridge centered over the Gulf of Mexico through dissipation. The spread in the model trackers remains quite large, as they are having difficulty tracking the small cyclone. For this cycle, the new NHC forecast has been adjusted to the left of the previous one through 12 to 24 hours due to the initial position and motion. After that time, the NHC track generally follows a blend of the previous official forecast and the fields from the latest global models.

FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 13.9N  98.7W   35 KT  40 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 12H  22/1200Z 14.3N  99.9W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  23/0000Z 15.7N 101.7W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 36H  23/1200Z 17.5N 103.1W   30 KT  35 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 48H  24/0000Z 18.8N 103.7W   20 KT  25 MPH - Post Tropical (Tecomán, Mexico)
 72H  25/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sun Oct 21 2018

Tropical Storm Vicente’s cloud pattern has become less organized today, with the low-level center becoming exposed near the northeastern edge of a ragged-looking area of deep convection. Data from a recent scatterometer overpass indicated that the maximum winds have decreased to near 35 kt. North-northeasterly vertical wind shear should prevent strengthening of the system and, in fact, the global models show the cyclone dissipating in a couple of days. The official forecast shows, perhaps generously, Vicente weakening to a depression in 1-2 days and is similar to the latest intensity model consensus. Obviously, the system could weaken sooner than shown here.

The storm has been moving just slightly south of due west, or 260/9 kt. Vicente is expected to move around the southwestern and western periphery of a mid-level ridge extending from the Gulf of Mexico for the next couple of days. The official forecast is somewhat faster than the previous one, but is very close to the dynamical model consensus, TVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 14.2N  97.9W   35 KT  40 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 12H  22/0600Z 14.2N  99.3W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  22/1800Z 15.2N 101.0W   35 KT  40 MPH - Tropical Storm (WSW Acapulco, Mexico)
 36H  23/0600Z 16.7N 102.6W   30 KT  35 MPH - Tropical Storm (WSW Petatlán, Mexico)
 48H  23/1800Z 18.0N 103.7W   30 KT  35 MPH - Tropical Storm (WSW Colola, Mexico)
 72H  24/1800Z 20.5N 104.3W   25 KT  30 MPH - Tropical Storm (Santa Isabel de Quililla, Mexico)
 96H  25/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sun Oct 21 2018

Tropical Storm Vicente remains a tiny tropical cyclone, and its cloud pattern consists of a small Central Dense Overcast with disorganized convection over the southwestern portion of the circulation. There is little evidence of banding features at this time. The current intensity is held at 45 kt in agreement with subjective Dvorak estimates from both TAFB and SAB. North-northeasterly vertical shear is likely to limit intensification during the next couple of days. Vicente should quickly dissipate when it interacts with the land mass of Mexico by mid-week.

Satellite fixes and images from the Puerto Angel, Mexico radar indicate that the storm is still moving a little south of west, and the motion estimate continues to be 255/8 kt. There has been little change in the track forecast or the reasoning behind it. Vicente should gradually turn toward the west and northwest while moving along the southwestern periphery of a mid-level high pressure area. The official track forecast is similar to the previous one and close to the multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 14.4N  96.8W   45 KT  50 MPH -Tropical Storm (WSW Santa María Huatulco, Mexico)
 12H  22/0000Z 14.2N  98.1W   45 KT  50 MPH -Tropical Storm (WSW Puerto Escondido, Mexico)
 24H  22/1200Z 14.4N  99.8W   45 KT  50 MPH -Tropical Storm (WSW Marquelia, Mexico)
 36H  23/0000Z 15.4N 101.2W   45 KT  50 MPH -Tropical Storm (WSW Acapulco, Mexico)
 48H  23/1200Z 16.9N 102.3W   45 KT  50 MPH -Tropical Storm (WSW San Luis de la Loma, Mexico)
 72H  24/1200Z 19.7N 104.4W   30 KT  35 MPH -Tropical Storm (Autlán, Mexico)
 96H  25/1200Z...DISSIPATED INLAND

NWS National Hurricane Center Miami FL 400 AM CDT Sun Oct 21 2018

Tropical Storm Vicente  remains a tiny tropical cyclone as evidenced by ASCAT passes around 03Z-04Z, which showed a very small but well-defined circulation, with peak wind speed values of 38 kt. Those peak winds were likely undersampled given the small radius of maximum winds of only 10-15 nmi. Based on Vicente’s small size and the ASCAT wind data, the initial intensity remains 45 kt for this advisory, which above all of the other the intensity estimates, and lies closest to the UW-CIMSS SATCON estimate of 43 kt. Little change in intensity is forecast due to moderate northerly shear expected to affect the cyclone throughout the forecast period, along with Vicente’s proximity to land and occasional dry intrusions. Rapid weakening and dissipation are expected after landfall due to the mountainous terrain of Mexico.

The initial motion is now west-southwestward or 255/08 kt. Vicente is expected to move westward later today and then turn toward the west-northwest on Monday and northwest on Tuesday when the cyclone will come under the influence of the Hurricane Willa’s larger circulation. Landfall is expected to occur along the southwestern coast of mainland Mexico on Wednesday. The latest NHC model guidance is tightly packed about the previous advisory track, and only minor forward speed changes were required, except for a more rightward shift in the track at 72 hours resulting in landfall.

FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 14.5N  96.0W   45 KT  50 MPH -Tropical Storm (WSW La Crucecita, Mexico)
 12H  21/1800Z 14.3N  97.2W   45 KT  50 MPH -Tropical Storm (WSW Puerto Escondido, Mexico)
 24H  22/0600Z 14.4N  99.0W   45 KT  50 MPH -Tropical Storm (WSW Puerto Escondido, Mexico)
 36H  22/1800Z 15.2N 100.7W   40 KT  45 MPH -Tropical Storm (WSW Puerto Marques, Mexico)
 48H  23/0600Z 16.6N 102.1W   40 KT  45 MPH -Tropical Storm (WSW Zihuatanejo, Mexico)
 72H  24/0600Z 19.2N 104.2W   30 KT  35 MPH -Tropical Storm (Manzanillo, Mexico)
 96H  25/0600Z...DISSIPATED INLAND

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Oct 20 2018

Tropical Storm Vicente consists of a tight but mostly exposed low-level swirl producing intermittent bursts of deep convection. We have expected an imminent westward or west-southwestward turn for the past 24 hours now, but it still hasn’t happened, and the initial motion estimate is a little north of due west (280/6 kt). All of the generally best performing track models, except the UKMET, forecast that a turn toward the west-southwest should occur at any time, and even that model forecasts that a turn toward the due west is imminent. The NHC forecast dutifully follows the model guidance, but is a little north of the model consensus for the first 24 hours, based on recent trends. Beyond that time, a turn toward the west-northwest or northwest is still anticipated, assuming Vicente is steered by the southerly flow on the outer fringes of the much larger Willa to its west, and the NHC forecast closely follows the HCCA and TVCN consensus aids. A few members of the ECMWF and GFS ensembles do not show the two cyclones interacting, resulting in a significantly different and much farther west track for Vicente. While this scenario does not seem likely at this point, it does illustrate that the uncertainty in the track forecast has increased since earlier today.

The intensity of Vicente is still estimated at 45 kt, based on earlier ASCAT data and the UW-CIMSS SATCON. While the small size of Vicente could make it susceptible to short-term swings in intensity that are very difficult to predict, the intensity guidance generally forecasts little change in the maximum winds over the next day or two. Beyond 48 h, close proximity to land and interaction with Willa is expected to cause Vicente to weaken and eventually dissipate. No changes of note were made to the intensity forecast in this advisory.

FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 14.8N  95.0W   45 KT  50 MPH - Tropical Storm (ESE Salina Cruz, Mexico)
 12H  21/1200Z 14.4N  96.0W   45 KT  50 MPH - Tropical Storm (ESE Santa María Huatulco, Mexico)
 24H  22/0000Z 14.3N  97.8W   45 KT  50 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 36H  22/1200Z 14.9N  99.6W   45 KT  50 MPH - Tropical Storm (WSW Acapulco, Mexico)
 48H  23/0000Z 16.0N 101.2W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 72H  24/0000Z 18.0N 103.4W   35 KT  40 MPH - Tropical Storm (WSW Colola, Mexico)
 96H  25/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sat Oct 20 2018

Tropical Storm Vicente  – The cloud pattern associated with Vicente is quite peculiar. In addition on being unusually small, it has an intermittent eye feature surrounded by moderate to shallow convection. A very useful ASCAT pass a few hours ago showed that Vicente has a very tight circulation with maximum winds of 40 to 45 kt, and the tropical-storm-force winds extend only 20 n mi from the center. On this basis, and an average of Dvorak estimates from TAFB and SAB, the initial intensity has been adjusted upward to 45 kt. Now that the circulation is farther from land, the chances of some slight strengthening have increased in the next 24 to 36 hours before Vicente encounters the larger circulation of Willa. In fact, most of the global models advertise that in about 3 days or so Vicente will dissipate, and so does the official forecast.

Satellite fixes indicate that Vicente is moving toward the west or 265 degrees at 8 kt. The nose of a strong subtropical ridge is forecast to amplify and expand westward. This flow pattern should force Vicente to move on a west or even west-southwest track for the next 24 to 36 hours. Then as the cyclone reaches the southwestern end of the ridge and encounters the eastern portion of Willa’s circulation, Vicente should turn toward the northwest and north. Vicente should become absorbed by the larger Willa and dissipation could occur earlier than indicated in the forecast at this time given the solution of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 14.6N  94.3W   45 KT  50 MPH - Tropical Storm (WNW Tapachula, Mexico)
 12H  21/0600Z 14.0N  95.5W   45 KT  50 MPH - Tropical Storm (WSW Salina Cruz, Mexico)
 24H  21/1800Z 13.7N  97.2W   50 KT  60 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 36H  22/0600Z 14.0N  99.0W   40 KT  45 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 48H  22/1800Z 15.0N 101.0W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 72H  23/1800Z 17.5N 103.5W   30 KT  35 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 96H  24/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sat Oct 20 2018

Tropical Storm Vicente – Conventional satellite imagery and microwave data continue to reveal that Vicente is an unusually small tropical cyclone. Data show a ring of convection defining the center with most of the thunderstorm activity on the southwestern portion of the circulation. Dvorak estimates from TAFB and SAB yield an initial intensity of 35 kt. The cyclone is not in the best environment for intensification given that the circulation has been interacting with land, however the shear is not high, and the cyclone is over 29 degree Celsius water. Once the circulation separates from land, some slight strengthening is then forecast. After that time, Vicente will be approaching the much larger circulation of strengthening Tropical Cyclone Willa, and the most likely scenario is that at least by 96 hours, Vicente will become absorbed within an outer band of Willa.

This is the same scenario which occurred with Hurricane John and Tropical Storm Ileana back in August this year. Vicente is moving toward the west or 270 degrees at 6 kt. The nose of a strong subtropical ridge is forecast to amplify and expand westward. This flow pattern should force Vicente to move on a west to west-southwest track for about 36 hours. Then as the cyclone reaches the southwestern end of the ridge and encounters the eastern portion of Willa’s circulation, Vicente should turn toward the northwest until it becomes absorbed. It is interesting to note that unanimously, the track guidance forces Vicente to acquire a west-southwesterly component due to the expansion of the ridge, increasing the confidence in the the track forecast during the next 2 to 3 days.

FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 14.3N  93.6W   35 KT  40 MPH - Tropical Storm (WSW Puerto Madero, Mexixo)
 12H  21/0000Z 14.2N  94.5W   35 KT  40 MPH - Tropical Storm (WSW Tapachula, Mexico)
 24H  21/1200Z 13.5N  96.3W   40 KT  45 MPH - Tropical Storm (WSW Santa María Huatulco, Mexico)
 36H  22/0000Z 13.3N  98.0W   40 KT  45 MPH - Tropical Storm (WSW Puerto Escondido, Mexico)
 48H  22/1200Z 13.8N 100.0W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 72H  23/1200Z 16.5N 103.5W   35 KT  40 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
 96H  24/1200Z 19.0N 106.0W   25 KT  30 MPH - Tropical Storm (WSW San Patricio, Mexico)
120H  25/1200Z...ABSORBED BY WILLA

NWS National Hurricane Center Miami FL 400 PM CDT Fri Oct 19 2018

Tropical Storm Vicente – Although tiny, the cyclone continues to display well-defined convective banding. The system’s quick formation and small size make it difficult to have high confidence in its current intensity, and the various subjective and objective estimates range from T1.8/28 kt from the ADT to T3.0/45 kt from SAB. As a compromise, the intensity is set at 35 kt, which is closest to the TAFB estimate and the most recent SATCON number, and the depression is upgraded to Tropical Storm Vicente.

As noted this morning, warm waters and low shear should induce further strengthening during the next 48 hours. On one hand, this intensification could be more than what is being indicated by the models, since small systems can have a tendency to gain strength quickly. On the other hand, Vicente will be interacting with a Gulf of Tehuantepec gap wind event during the next 48 hours, and the storm could end up ingesting some drier, more stable air into its circulation. The NHC intensity forecast favors the former scenario and is a little above the guidance envelope for the first 2-3 days. After day 3, an increase in shear, interaction with another possible tropical cyclone to the west, and possible interaction with land could all conspire to arrest the intensification trend, and weakening is expected by the end of the forecast period. It is also possible that Vicente could dissipate before the end of the 5-day period. This scenario is reminiscent of, and has similarities to, the interaction of Tropical Storm Ileana and Hurricane John back in early August.

Vicente is moving very slowly northwestward, or 305/2 kt. The track models are indicating that the ongoing gap winds over the Gulf of Tehuantepec may have a greater influence of Vicente than previously thought, forcing the storm to turn west-southwestward in the next 24-48 hours. After 48 hours, Vicente should gradually enter the flow between mid-level ridging over Mexico and low pressure west of Mexico, causing it to turn back to the west and northwest on days 3 through 5. The new NHC track forecast is not too different from the morning forecast during that period, and it’s closest to the paths shown by the GFS, HCCA, and FSSE guidance, which would bring the center close to the coast of Mexico later in the forecast period. There are considerable speed differences, however, and the NHC forecast splits the difference between the fast ECMWF solution and the slow GFS scenario.

Even though Vicente should begin to slowly pull away from the coast tonight and on Saturday, heavy rainfall, with possible life-threatening flash flooding, is expected over portions of El Salvador, Guatemala, and southeastern Mexico during the next few days.

FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 13.3N  92.2W   35 KT  40 MPH - Tropical Storm (WSW Tulate, Mexico)
 12H  20/0600Z 13.6N  93.3W   45 KT  50 MPH - Tropical Storm (WSW Tulate, Mexico)
 24H  20/1800Z 13.3N  94.2W   50 KT  60 MPH - Tropical Storm (WSW Tulate, Mexico)
 36H  21/0600Z 12.9N  95.2W   55 KT  65 MPH - Tropical Storm (WSW Salina Cruz, Mexico)
 48H  21/1800Z 12.7N  96.5W   55 KT  65 MPH - Tropical Storm (WSW Salina Cruz, Mexico)
 72H  22/1800Z 13.7N  99.8W   55 KT  65 MPH - Tropical Storm (ESE Acapulco, Mexico)
 96H  23/1800Z 16.5N 103.0W   55 KT  65 MPH - Tropical Storm (WSW Lázaro Cárdenas, Mexico)
120H  24/1800Z 20.0N 106.0W   45 KT  50 MPH - Tropical Storm (W La Cruz de Loreto, Mexico )

NWS National Hurricane Center Miami FL 1000 AM CDT Fri Oct 19 2018

Tropical Storm Vicente Forming – Two distinct areas of low pressure formed late yesterday within a sprawling area of disturbed weather that stretched from Central America westward over the eastern Pacific waters south of Mexico. The easternmost low south of Guatemala is small and has spun up quickly, with deep convection continuing to burst near the center of circulation. Microwave data, first-light visible images, and valuable radar data from Guatemala also show a tight core and increasing convective bands. Maximum winds are set at 30 kt, slightly above last evening’s ASCAT pass and a T1.5 Dvorak classification from TAFB, given the system’s well-developed structure.

The depression is located over warm waters (28-29 degrees Celsius) and in a light-shear environment. These conditions should support further strengthening, and the depression’s small size may allow for intensification higher than what is indicated by the intensity models. For this first advisory, the NHC intensity forecast is near the top end of the guidance envelope and levels off the maximum winds in 3-5 days when there could be an increase in shear.

Since the low formed recently, the depression’s current motion is uncertain. However, microwave fixes indicate that it hasn’t moved much since last evening, and the initial motion estimate is slowly west-northwestward, or 300/2 kt. A strong mid-level ridge spanning across the Gulf of Mexico and northern Mexico should steer the cyclone generally westward for the next 3 days or so. After day 3, the ridge is expected to retreat eastward a bit, and the cyclone should begin to turn northwestward between the ridge and another low pressure system to the west. The track models are in good agreement on this general scenario, but there is not agreement on how close the system could get to the coast of Mexico during the forecast period. Therefore, interests along the southern and southwestern coast of Mexico should monitor the progress of this system during the next few days. Regardless of how close it gets to the coast, heavy rainfall, with possible life-threatening flash flooding, is expected over portions of El Salvador, Guatemala, and southeastern Mexico during the next few days.

FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 13.3N  91.9W   30 KT  35 MPH - Tropical Storm (WSW Tulate, Mexico)
 12H  20/0000Z 13.7N  93.2W   35 KT  40 MPH - Tropical Storm (ESE Tapachula, Mexico)
 24H  20/1200Z 13.5N  94.2W   40 KT  45 MPH - Tropical Storm (ESE Tapachula, Mexico)
 36H  21/0000Z 13.3N  94.9W   45 KT  50 MPH - Tropical Storm (ESE Salina Cruz, Mexico)
 48H  21/1200Z 13.3N  96.1W   50 KT  60 MPH - Tropical Storm (WSW San Pedro Pochutla, Mexico)
 72H  22/1200Z 13.8N  99.5W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, Mexico)
 96H  23/1200Z 16.0N 103.0W   55 KT  65 MPH - Tropical Storm (WSW Petatlán, Mexico)
120H  24/1200Z 19.0N 105.5W   55 KT  65 MPH - Tropical Storm (WSW San Patricio, Mexico)

NWS National Hurricane Center Miami FL 500 AM PDT Fri Oct 19 2018

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

Tropical Storm Willa Forming – Showers and thunderstorms associated with a low pressure system centered less than 100 miles off the coast of Guatemala continue to show signs of organization, and it is possible that a tropical depression could be forming. If this trend continues, then advisories could be initiated on this system later today.

This disturbance is forecast to move generally westward near the coast of southern Mexico, and interests in that area should monitor the progress of the low during the next several days.

* Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high...80 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Oct 18 2018

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

A trough of low pressure has developed within a large area of disturbed weather that extends from Central America westward to south of the Gulf of Tehuantepec. Some gradual development of this system is possible over the next few days while it moves slowly westward, near the coast of southern Mexico.

Additional information on the broad area of disturbed weather that extends from Central America to south of the Gulf of Tehuantepec can be found in High Seas Forecasts issued by the National Weather Service.

* Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.

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