Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 141009

Area Forecast Discussion
National Weather Service Brownsville TX
409 AM CST Wed Feb 14 2018

.SHORT TERM (Now through Thursday): Surface observations indicate
that widespread fog is affecting Deep South Texas and the Rio Grande
Valley, with visibilities generally between 1/2 and 2 miles. A Dense
Fog Advisory is in effect for Cameron, Willacy, and Hidalgo Counties
right now and has been extended until mid-morning today, as the fog
is expected to persist until that time. Surface observations will
continue to be monitored closely to determine if the Advisory needs
to be expanded in areal coverage. Otherwise, a stationary front
along the Lower Texas Coast will transition to a warm front and move
north during the period, allowing an onshore flow to redevelop and
prevail for a majority of the period. Dry weather is expected as 500
mb high pressure noses-in from the east and prevails over the BRO
CWFA. Rapidly moderating temperatures are expected courtesy of the
redeveloping and intensifying onshore flow. Fog will once again be a
concern late tonight into the early morning hours of Thursday, but
surface winds will likely be strong enough to prevent the fog from
becoming dense.

.LONG TERM (Thursday night through Tuesday): Starting at the end
of the week, the synoptic pattern will favor warm and dry
conditions as a dome of high pressure in the mid-levels positions
itself over the central Gulf of Mexico. This will suppress rain
chances as strong subsidence remains above 850mb. At the surface,
moderate southeast flow will lead to breezy conditions in the
afternoon with dew points in the mid 60s across the area. Have
kept the mention of fog, mainly in the marine areas, as warm and
moist air advects over still-cooler waters.

The forecast this weekend is a bit tricky as models diverge on
the potential of a frontal passage. NAM guidance brings the front
through Deep South Texas Friday night. The main global models,
however, persistently stall the front just to our north and slowly
bring it through on Sunday. Decided to go with the stalling
solution as the main surface high will likely not gain much
southward extent, but rather quickly scoot off to the east.
Therefore, temperatures were nudged up just a couple degrees with
MOS guidance bringing upper 70s to low 80s for highs on Saturday.
Also cut but the PoPs just a smidgen, but kept an area of 30%
coverage as uncertainty remains with the front`s progression.
After the front moves into South Texas, surface high pressure in
the Central U.S. will quickly move eastward with southeast flow
continuing through mid week. The mid-level high pressure system
will have moved into the eastern Gulf with southwest flow over our
region, maintaining at least slight chances of precipitation each


.MARINE (Now through Thursday): Buoy 42019 reported southeast
winds around 14 knots gusting to around 16 knots with seas
slightly under 4 feet with a period of 8 seconds at 02 CST/08 UTC.
A stationary front along the Lower Texas Coast will transition to
a warm front and move north during the period, allowing high
pressure to resume over the western Gulf of Mexico. Light to
moderate winds and low to moderate seas are anticipated for the
Lower Texas coastal waters, but wind speeds over the Laguna Madre
may be high enough to warrant a Small Craft Exercise Caution there
on Thursday. Dense fog will be an additional concern for today,
mainly over the Laguna Madre and nearshore Gulf of Mexico waters.

Thursday night through Monday: Southeast winds at the surface will
continue through at least early Saturday with a cold front moving
into South Texas during the day. Models are still in disagreement
with the progression of the front, but it will likely stall just
to the north with possibly a easterly wind shift late in the day.
Brief northeast winds will be possible if the front can make it
this far south, but high pressure will quickly move eastward and
shift winds back to the southeast through early next week.
Moderate winds and seas building to 4 to 6 feet can be expected.


BAYVIEW/PORT ISABEL  67  64  79  65 /   0   0   0   0
BROWNSVILLE          69  66  81  66 /   0   0   0  10
HARLINGEN            69  64  83  64 /   0   0   0   0
MCALLEN              70  66  85  65 /   0   0   0   0
RIO GRANDE CITY      72  64  87  64 /   0   0   0  10
SOUTH PADRE ISLAND   65  65  74  65 /   0   0   0  10


TX...Dense Fog Advisory until 9 AM CST this morning for TXZ253>257.

GM...Dense Fog Advisory until noon CST today for GMZ130-132-135-150-



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