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Tropical Storm Bud Discussion Number  17
NWS National Hurricane Center Miami FL       EP032018
300 PM MDT Wed Jun 13 2018

Bud has continued to steadily weaken as deep convection has been
non-existent in the inner-core region for more than 6 hours now. A
couple of recent ASCAT overpasses indicated a few 42-kt wind vectors
in the northeastern quadrant.  Even allowing for some undersampling
of the small wind field, those data only support winds of about
45 kt, and that is the intensity used for this advisory.

Bud has been moving in a steadier north-northwestward motion of
about 345/05 kt over the past 6 h. The blocking ridge to the north
of Bud is beginning to weaken and shift slowly eastward. This trend
is expected to continue through the remainder of the forecast period
as a mid-/upper-level trough approaches Baja California from the
northwest. Southerly flow between the ridge and the approaching
trough will gradually increase and induce a northward component of
motion by Thursday, followed by a gradual turn toward the
north-northeast and northeast on Friday. The latest NHC model
guidance remains tightly packed about the previous few forecast
tracks, so significant changes were required on this advisory
package.

Bud will be moving over sub-26C SSTs within the next 6 hours or so,
which will act to inhibit inner-core convection from redeveloping,
resulting in a slow spin down and weakening of the cyclone. However,
there will be enough available instability in outer portion of the
circulation to help maintain a convective banding structure, which
should be sufficient to maintain Bud as a tropical storm until it
reaches Baja California in about 36 hours. After that, interaction
with the mountainous terrain of Baja California Sur and northwestern
Mexico should promote more significant weakening, and Bud is
expected to become a remnant low or dissipate shortly after 72 hours
when the system is inland over northwestern Mexico.

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.

FORECAST POSITIONS AND MAX WINDS

INIT  13/2100Z 19.9N 108.9W   45 KT  50 MPH
 12H  14/0600Z 20.7N 109.2W   40 KT  45 MPH
 24H  14/1800Z 21.8N 109.6W   35 KT  40 MPH
 36H  15/0600Z 23.3N 109.9W   35 KT  40 MPH...INLAND OVER SRN BAJA
 48H  15/1800Z 25.6N 109.9W   30 KT  35 MPH...OVER WATER
 72H  16/1800Z 31.5N 108.5W   20 KT  25 MPH...POST-TROP/INLAND
 96H  17/1800Z...DISSIPATED INLAND

$$
Forecaster Stewart

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