Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 170917

Area Forecast Discussion
National Weather Service Brownsville TX
417 AM CDT Tue Apr 17 2018

.SHORT TERM (Now through Wednesday):  Another warm and windy day is
in store for the Rio Grande Valley and Deep South Texas.  Strong SSE
winds will develop quickly this morning, as KBRO VWP has been
consistently indicating winds of 45-50KT just off the deck at 2-3
kft. AGL since around midnight.  That being said, will hold off on
any Wind Advisories for today.  Short-term guidance is in pretty
good agreement that winds across the coastal counties of Cameron,
Willacy, and Kenedy will top out just below criteria.  This is also
consistent with a slightly farther north (vs. previous runs) path of
the lee surface cyclone, which is progged to emerge into NE
Colorado/SW Nebraska before swooping through Kansas this evening,
implying that the pressure gradient won`t be quite as tight.  An SPS
will be forthcoming to highlight the expected 25-30mph winds with a
few gusts approaching 40mph.  These strong southerly winds should
also act to hold dewpoints fairly steady across the CWA (upper 50s-
low 60s F), with implications for Fire Weather; see below. Inherited
temps of a couple degrees above normal (and similar to Monday`s
readings) looked good and so were largely retained.

Winds will remain breezy into the evening for the mid-Lower Valley,
before tapering off a bit more after midnight.  Surface moisture
advection into the area will continue, with dewpoints creeping back
up into the mid-60s for all areas by daybreak Wednesday.  This
moisture will remain confined to a few thousand feet of the surface,
though, so nil precip chances continue through the short-term (with
the possible exception of a few "streamer" showers offshore late
tonight).  With the elevated dewpoints and winds, min temps
Wednesday will range from the mid-60s NW to around 70 in Brownsville
and the beaches.

For Wednesday, still a bit breezy but with partly cloudy skies and a
more humid feel.  Temps may edge up another degree or two with warm-
air advection ahead of a front which is progged to stall out across
South-Central Texas.

.LONG TERM (Wednesday Night through Monday): Isolated showers and
thunderstorms will dominate across the BRO CWFA for a majority of
the forecast period. The first batch of isolated precipitation
will be generated by a weak cold front that will stall and then
dissipate just north of Deep South Texas and the Rio Grande Valley.
The next round of rainfall will be sparked by a closed 500 mb low
pressure system and related troughiness moving east through the
Central Plains. The last period of convection will be the result
of the approach and passage of a cold front late Sunday night
through Monday. Persistent cloud cover and no major cold air
advection will lead to generally near normal daytime high and
overnight low temperatures throughout the period. The coolest
temperatures may occur Sunday night and Monday night as a result
of the weak frontal passage.

.MARINE (Now through Wednesday):  Latest observation from Buoy 42020
as of 3:30am CDT shows SSE winds of 21G27KT and seas of 5-6 ft.  A
low-pressure center emerging into the lee of the Rockies today will
continue tightening the pressure gradient and keep strong SSE winds
across all of the Lower Texas Coastal Waters.  A Small Craft
Advisory for Winds is in effect for the Laguna Madre from 8am-10pm
today, and the SCA for the Gulf waters has been extended through 4am
on Wednesday morning.  Small Craft Exercise Caution conditions may
persist through part of Wednesday morning, before winds and seas
subside to more moderate levels as a weakening front stalls north of
the waters, weakening the pressure gradient.

Wednesday Night through Monday: A weak cold front is expected to
dissipate just north of the Lower Texas Coast Wednesday night into
Thursday, with another cold front anticipated to pass through on
Monday. Outside of these frontal approaches/passages, surface high
pressure will prevail. Generally moderate winds and seas are
forecast for the Lower Texas coastal waters throughout the period.
Winds and/or seas may reach Small Craft Exercise Caution criteria
Friday night through Saturday night, and again on Monday.

.FIRE WEATHER...A strong pressure gradient exists across Deep South
Texas. This will provide SSE 20-ft. winds of 15 to 20 knots (17 to
23 mph) across most of the Rio Grande valley Tuesday. Temperatures
will be in the upper 80s to lower 90s across the area this afternoon
and with dewpoints in the upper 50s to lower 60s F, relative
humidity values will fall to 30-35% across most of the CWA.
However, Red Flag Warning Criteria are not expected to be met, as
the stronger winds nearer the coast will not coincide with the
lowest RH values.  Furthermore, the Storm Prediction Center has not
included the area in its "Elevated" outlook area. Hence, after
collaboration with CRP, the Fire Weather Watch has been cancelled. A
Fire Danger Statement will be issued for the entire area instead, as
dry fuels and High to Very High Fire Danger will be in place.


BAYVIEW/PORT ISABEL  86  71  85  71 /   0  10   0  20
BROWNSVILLE          85  70  87  71 /   0   0   0  20
HARLINGEN            88  68  88  69 /   0   0   0  20
MCALLEN              89  70  91  71 /   0   0   0  20
RIO GRANDE CITY      94  68  95  70 /   0   0   0  20
SOUTH PADRE ISLAND   81  71  79  72 /   0  10   0  20

GM...Small Craft Advisory for winds from 8 AM this morning to 10 PM
     CDT this evening for GMZ130-132-135.

     Small Craft Advisory until 4 AM CDT Wednesday for GMZ150-155-170-


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