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Tropical Storm BUD


Tropical Storm Bud Discussion Number  16
NWS National Hurricane Center Miami FL       EP032018
900 AM MDT Wed Jun 13 2018

Bud has continued to rapidly weaken due to significant upwelling of
colder water beneath the cyclone, resulting in a pronounced erosion
of the deep convection in the inner-core region. Sea-surface
temperature data from U-Miami RSMAS indicate that Bud has churned
up a cold wake that is least 3 deg C cooler than the surrounding
ocean temperatures. The initial intensity of 55 kt is based on
average of T- and CI-numbers from TAFB and SAB.

Bud has been wobbling slowly about a north-northwestward track of
about 340/04 kt for the past 12 h, and that is the motion used for
this advisory.  A deep-layer ridge located over the southwestern
United States that has been partly blocking Bud's poleward trek is
expected to slowly weaken and shift eastward during the next 72 h,
giving way to an approaching mid-latitude trough. The increasing
southerly flow between the ridge and the approaching trough will
gradually induce a more northward component of motion by Thursday,
followed by a turn toward the north-northeast on Friday. No change
has been made to the previous NHC track forecast, and the new
advisory is similar to the previous one and lies along the eastern
edge of the model guidance envelope.

Now that Bud has weakened to a tropical storm, significant upwelling
beneath the cyclone should abate somewhat. However, Bud will be
moving over sub-26C SSTs within the next 6-12 h, which will act to
keep the atmosphere only marginally conducive for the formation of
significant convection despite the vertical wind shear remaining
quite favorable at only around 5 kt. A gradual spin down of Bud's
circulation is expected until landfall occurs on southern Baja
California Sur, followed by more significant erosion of the wind
field on Friday due to cyclone interacting with the mountainous
terrain of Baja California Sur and northwestern Mexico. The new
intensity forecast is similar to the previous advisory and the
Decay-SHIPS intensity model, and is slightly below the intensity
consensus models. Despite Bud's expected weakening, the cyclone is
still anticipated to be a tropical storm when it reaches southern
Baja California Sur in 36-48 hours.

Bud's remnant moisture plume is expected to spread northward and
northeastward into northwestern Mexico and the U.S. Desert Southwest
over the weekend, 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.


INIT  13/1500Z 19.4N 108.8W   55 KT  65 MPH
 12H  14/0000Z 20.1N 109.0W   45 KT  50 MPH
 24H  14/1200Z 21.1N 109.4W   40 KT  45 MPH
 36H  15/0000Z 22.4N 109.7W   35 KT  40 MPH
 48H  15/1200Z 24.2N 109.9W   35 KT  40 MPH
 72H  16/1200Z 29.3N 109.4W   25 KT  30 MPH...POST-TROP/INLAND
 96H  17/1200Z 35.5N 106.0W   20 KT  25 MPH...POST-TROP/INLAND
120H  18/1200Z...DISSIPATED

Forecaster Stewart