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Tropical Storm Bud Forecast Discussion Number 21

2018-06-14 22:59:53| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Thu Jun 14 2018 000 WTPZ43 KNHC 142059 TCDEP3 Tropical Storm Bud Discussion Number 21 NWS National Hurricane Center Miami FL EP032018 300 PM MDT Thu Jun 14 2018 Satellite imagery and scatterometer wind data indicate that Bud's wind field and convective pattern have changed little during the past 6 hours. Some new modest convective banding has developed in the inner-core region, but overall cloud pattern remains primarily a large swirl of low clouds. Some of the convective bands in the northern semicircle have been bringing stronger winds aloft based on surface obs Mexican Navy automated weather station in the port of Cabo San Lucas where sustained winds of 50 kt and a gust to 60 kt have been observed. However, those winds may have been enhanced by local terrain. Closer to the surface, a Mexican CONAGUA weather station in Cabo San Lucas recently reported a sustained wind of 34 kt and a gust to 41 kt. Based on these data, Bud's intensity remains at 40 kt. Bud has maintained a steady motion of 345/06 kt. No changes were required to the previous forecast track. The model guidance remains in excellent agreement that Bud should turn northward by 12 h while crossing over the southern Baja California peninsula, and emerge over the warmer waters of the Gulf of California by Friday afternoon. As the cyclone rounds the western periphery of a large subtropical ridge oriented east-to-west across north-central Mexico, a turn toward the north-northeast and northeast is anticipated by 36 hours and beyond. The new NHC advisory track is similar to the previous forecast track, and remains near the eastern edge of the model guidance suite. Bud's intensity will likely change little during the next 12 hours or so. By 24 hours, however, interaction with the mountainous terrain of southern Baja California should disrupt the circulation, inducing a steady weakening of the wind field. Due to the waters of the Gulf of California being around 27 deg C, some convective banding could persist in the northeastern quadrant and some enhancement of wind flow in the northeastern quadrant due to funneling could occur. For those reasons, Bud has been maintained as a tropical depression until the second landfall occurs in about 30 hours. After landfall, rapid weakening and dissipation by 48 hours is expected over the high terrain of mainland Mexico. Despite weakening or dissipation, Bud's remnant moisture plume is expected to spread northward and northeastward into northwestern Mexico and the U.S. Desert Southwest on Friday and Saturday, resulting in significant rainfall and possible flash flooding across those areas. For further information on the heavy rainfall threat, please see products issued by your local weather service office. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 22.2N 109.8W 40 KT 45 MPH 12H 15/0600Z 23.5N 110.1W 35 KT 40 MPH...INLAND 24H 15/1800Z 25.6N 110.3W 30 KT 35 MPH...OVER WATER 36H 16/0600Z 28.0N 110.2W 25 KT 30 MPH...INLAND 48H 16/1800Z 30.3N 109.6W 15 KT 15 MPH...POST-TROP/INLAND 72H 17/1800Z...DISSIPATED $$ Forecaster Stewart

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Tropical Depression Four-E Forecast Discussion Number 1

2018-06-14 22:35:47| National Hurricane Center (East Pacific)

Issued at 400 PM CDT Thu Jun 14 2018 ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Depression Four-E Discussion Number 1 NWS National Hurricane Center Miami FL EP042018 400 PM CDT Thu Jun 14 2018 Overnight scatterometer data indicate that the circulation of the system was open on the northwestern side. High-resolution GOES-16 1-min visible data indicate that the low is now closed, with a well-enough defined circulation center. Since there is plenty of banded convection, this system is being designated as a tropical depression, and the initial wind speed of 30 kt is based off the overnight scatterometer data. The initial motion estimate is an uncertain 325/5 kt. A weak mid-level ridge over Mexico is forecast to break down by tomorrow, leaving the depression in an area of light steering currents. Much of the model guidance linger the system just south of the coast of Mexico for the next couple of days until the cyclone gets drawn northward into a larger trough currently seen over the western Gulf of Mexico. There is considerable uncertainty in the timing of this poleward motion, however, with the UKMET, HMON, and COAMPS-TC models faster than the rest of the guidance. This seems like a pretty clear case of staying near the model consensus, given the weak steering flow that makes it nearly impossible to choose one model over another one. Thus, the official forecast shows a slow northward motion, near the eastern Pacific model consensus TVCE, and it should be emphasized that the forecast timing of landfall is subject to large changes in the future. The system is not particularly well organized at the moment, with a few swirls seen in the visible imagery rotating around the larger gyre. After the low consolidates, light-to-moderate shear with very warm waters, and high mid-level humidity should lead to steady intensification. This is a tricky forecast, however, since land is so close to the north, which would prevent much strengthening. The official forecast is a blend of the statistical-dynamical guidance and the regional hurricane guidance, a bit lower than the model consensus since the HWRF keeps the cyclone well offshore (unlike the official prediction), leading to a stronger storm. It has been an active early part of the eastern Pacific season. This is the 2nd earliest 4th tropical cyclone on record in the basin during the satellite era (1966-present), only 6 hours behind the previous record in 1974. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 15.5N 100.1W 30 KT 35 MPH 12H 15/0600Z 16.1N 100.5W 30 KT 35 MPH 24H 15/1800Z 16.3N 100.6W 35 KT 40 MPH 36H 16/0600Z 16.5N 100.5W 40 KT 45 MPH 48H 16/1800Z 16.7N 100.3W 50 KT 60 MPH 72H 17/1800Z 17.1N 100.3W 40 KT 45 MPH...INLAND 96H 18/1800Z 17.5N 100.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 19/1800Z...DISSIPATED $$ Forecaster Blake NNNN

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Tropical Storm Bud Forecast Discussion Number 20

2018-06-14 16:53:50| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Thu Jun 14 2018 000 WTPZ43 KNHC 141453 TCDEP3 Tropical Storm Bud Discussion Number 20 NWS National Hurricane Center Miami FL EP032018 900 AM MDT Thu Jun 14 2018 Bud's overall structure and convective pattern have changed little since the previous advisory, with the tropical storm consisting of mainly a large swirl of low clouds and fragmented cyclonically curved bands of moderate convection. Despite this unimpressive satellite appearance, Bud is still producing tropical-storm-force winds in the the convective band in the northern semicircle. A Mexican Navy automated weather station in the port of Cabo San Lucas recently reported a 2-minute average wind of 39 kt and a gust to 53 kt, and also reported 36-kt winds for a 5-minute period shortly after 1200 UTC. The observing site has also recorded a pressure of 1004.5 mb thus far. Based on these wind data, the initial intensity is being maintained at 40 kt for this advisory, and the central pressure is estimated to be 1000 mb. Bud has a broad inner-core wind field and a small-scale vortex has been rotating counter-clockwise within the larger cyclonic gyre. After smoothing through all the wobbles of the center, a motion of 345/06 kt is computed over the past 18 hours. No significant changes were made to the previous track forecast. The model guidance is tightly packed around the previous advisory track and remains in excellent agreement that Bud will gradually turn northward during the next 36 hours around the western periphery of a deep-layer ridge located across north-central Mexico. A turn toward the north-northeast is expected by 48 hours as the steering flow becomes more southwesterly ahead of an approaching mid-level trough, which will also act to accelerate Bud. The new NHC forecast track is just a tad to the west of the previous track through 24 hours, and lies along the eastern edge of the guidance envelope. During the next 24 hours, Bud will be moving over cool waters and interacting with the mountainous terrain of southern Baja California, which should result in a gradual erosion of the deep convection and spin down of the circulation. Some enhanced wind flow in the northeastern quadrant due to funneling between Bud's center and the higher terrain of mainland Mexico is possible once Bud's center emerges over the Gulf of California in 24 hours. For that reason, Bud is being maintained as a tropical depression until the second landfall occurs in about 36 hours. After landfall, rapid weakening and dissipation by 48 hours is expected over the high terrain of mainland Mexico. Despite weakening or dissipation, Bud's remnant moisture plume is expected to spread northward and northeastward into northwestern Mexico and the U.S. Desert Southwest on Friday and Saturday, resulting in significant rainfall and possible flash flooding across those areas. For further information on the heavy rainfall threat, please see products issued by your local weather service office. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 21.7N 109.6W 40 KT 45 MPH 12H 15/0000Z 22.8N 109.9W 35 KT 40 MPH 24H 15/1200Z 24.6N 110.3W 30 KT 35 MPH 36H 16/0000Z 27.0N 110.3W 25 KT 30 MPH 48H 16/1200Z 29.4N 110.1W 20 KT 25 MPH...POST-TROP/INLAND 72H 17/1200Z...DISSIPATED $$ Forecaster Stewart

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Tropical Storm Bud Forecast Discussion Number 19

2018-06-14 10:37:12| National Hurricane Center (East Pacific)

Issued at 300 AM MDT Thu Jun 14 2018 000 WTPZ43 KNHC 140837 TCDEP3 Tropical Storm Bud Discussion Number 19 NWS National Hurricane Center Miami FL EP032018 300 AM MDT Thu Jun 14 2018 Bud consists of a broad area of circulation, mostly of low clouds, and a cyclonically curved band of weak to moderate convection to the north of the center. Both objective and subjective Dvorak T-numbers from all agencies have continued to decrease, and on this basis, the initial intensity is lowered to 40 kt in this advisory. No ASCAT data is available over Bud tonight. The cyclone is moving over cool waters, the shear is forecast to increase, and the circulation will be over the high terrain of Baja California Sur for about 12 hours. All these factors are for Bud to continue weakening, and perhaps this could occur even faster than indicated in the forecast. Bud has not changed in track and is still moving north-northwestward at 6 kt along the on the southwestern side of a mid-level ridge over Mexico and the southwestern U.S. The southerly flow ahead of an approaching mid-level trough will steer Bud northward with some increase in forward speed during the next day or two. The NHC forecast is in the middle of the tight guidance envelope through 48 hours. After that time, the model trackers no longer depict the cyclone. Despite weakening or dissipation, Bud's remnant moisture plume is expected to spread northward and northeastward into northwestern Mexico and the U.S. Desert Southwest on Friday and Saturday, resulting in significant rainfall and possible flash flooding across those areas. For further information on the heavy rainfall threat, please see products issued by your local weather service office. FORECAST POSITIONS AND MAX WINDS INIT 14/0900Z 21.3N 109.4W 40 KT 45 MPH 12H 14/1800Z 22.3N 109.7W 40 KT 45 MPH 24H 15/0600Z 23.8N 110.0W 30 KT 35 MPH 36H 15/1800Z 26.0N 110.5W 25 KT 30 MPH 48H 16/0600Z 28.5N 110.0W 20 KT 25 MPH...POST-TROP/INLAND 72H 17/0600Z...DISSIPATED $$ Forecaster Avila

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Tropical Storm Bud Forecast Discussion Number 18

2018-06-14 06:21:44| National Hurricane Center (East Pacific)

Issued at 900 PM MDT Wed Jun 13 2018 000 WTPZ43 KNHC 140421 TCDEP3 Tropical Storm Bud Discussion Number 18...Retransmitted NWS National Hurricane Center Miami FL EP032018 900 PM MDT Wed Jun 13 2018 After steadily weakening today, Bud's intensity appears to have leveled off for now. The cloud pattern of the tropical storm has generally changed little during the past several hours, with deep convection mostly confined to a curved band that wraps around the eastern half of the circulation. Earlier ASCAT data indicated that the maximum winds were around 45 kt, and since the system has generally changed little in structure since that time, the initial intensity is held at that value. This intensity estimate is also in agreement with an average of the Dvorak T- and CI-numbers from TAFB and SAB. Bud is moving north-northwestward at 6 kt on the southwestern side of a mid-level ridge over Mexico and the southwestern U.S. This general motion is expected during the next 24 hours or so, and that should take Bud across the southern portion of Baja California Sur by late Thursday. After that time, a trough approaching the tropical storm should cause the system to accelerate to the north and north-northeast across the Gulf of California and over mainland Mexico. The models are in very good agreement, and only small adjustments were made to the previous track forecast. Gradual weakening is expected to resume soon as Bud moves over cooler SSTs and into a more stable air mass on its approach to Baja California Sur. Once Bud moves inland over mainland Mexico, the surface circulation will likely dissipate and even though a 72-h position is provided below, it is unlikely that Bud will survive that long due to the rugged terrain. The NHC intensity forecast follows the trend in the model guidance, and is generally an update of the previous one. Bud's remnant moisture plume is expected to spread northward and northeastward into northwestern Mexico and the U.S. Desert Southwest on Friday and Saturday, resulting in significant rainfall and possible flash flooding across those areas. For further information on the heavy rainfall threat, please see products issued by your local weather service office. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 20.5N 109.1W 45 KT 50 MPH 12H 14/1200Z 21.4N 109.5W 40 KT 45 MPH 24H 15/0000Z 22.6N 109.9W 35 KT 40 MPH 36H 15/1200Z 24.3N 110.0W 30 KT 35 MPH 48H 16/0000Z 26.8N 109.8W 30 KT 35 MPH...INLAND 72H 17/0000Z 33.0N 108.0W 20 KT 25 MPH...POST-TROP/INLAND 96H 18/0000Z...DISSIPATED $$ Forecaster Cangialosi

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