Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 240927

Area Forecast Discussion
National Weather Service Brownsville TX
427 AM CDT Tue Apr 24 2018

.SHORT TERM (Now through Wednesday): Quiet weather will prevail
through the period with high pressure at the surface and aloft. The
combination of near-surface moisture and light winds may allow some
patchy, shallow fog to develop across mainly eastern portions of the
Rio Grande Valley and northern Ranchlands around sunrise this
morning. Westerly flow aloft and some upper level moisture will
support an increase of high level clouds through late tonight.

Southeast flow returns by this afternoon as surface high pressure
moves east into the Gulf of Mexico. Temperatures today will be warm
with high temperatures ranging from the mid 70s at the beaches, mid
to upper 80s along the I-69E corridor and low 90s far west. Partly
cloudy and mild tonight with low temperatures falling into the mid
to upper 60s. A 500 mb short wave trough will dig south over the
central Plains with the associated weak cold front moving south
across central Texas on Wednesday. Moisture will gradually increase
ahead of the approaching front Wednesday afternoon resulting in a
slight chance of showers, mainly along and west of the I-69C
corridor. High temperatures Wednesday will range from the mid to
upper 70s near the coast to the 80s inland.

.LONG TERM (Wednesday Night through Monday): An increasingly
unsettled weather pattern is anticipated during this portion of
the forecast. A series of 500 mb shortwaves will ride within a
mid-level flow from the northwest, west, and southwest and over
Deep South Texas and the Rio Grande Valley. When coupled with the
approach and passage of a pair of weak cold fronts late in the
week and early in the weekend, isolated to scattered showers and
thunderstorms will result within the BRO CWFA. The best chance for
convection is anticipated to be Wednesday night, when a vigorous
shortwave from the northwest generates a 40 percent chance of
convection across the forecast area. For this time period, the
Storm Prediction Center places all of Deep South Texas and the Rio
Grande Valley in a general risk of thunderstorms. Despite the two
weak cold frontal passages, near normal daytime high and overnight
low temperatures are forecast, aided by significant cloud cover
during a majority of the long term forecast period.

.MARINE (Now through Wednesday): Favorable marine conditions
expected along the lower Texas coastal waters through the period.
Buoy 42020 reported east-southeast winds around 3.9 knots with seas
slightly under 1.6 feet with a period of 4 seconds at 0240 CDT/0740
UTC. Surface high pressure will prevail across the western Gulf of
Mexico through Wednesday. A weak pressure gradient will support
light east to southeast winds and low seas through the period.

Wednesday Night through Monday: Surface high pressure is expected
to be the dominant force for the western Gulf of Mexico during the
forecast period. This will result in light to moderate winds and
low to moderate seas along the Lower Texas Coast, with Small Craft
Exercise Caution and Small Craft Advisory not likely to be needed.

BAYVIEW/PORT ISABEL  82  69  82  68 /  10   0  10  40
BROWNSVILLE          86  68  84  68 /  10  10  20  40
HARLINGEN            87  66  86  67 /  10   0  10  40
MCALLEN              90  70  87  68 /  10  10  20  40
RIO GRANDE CITY      91  69  88  65 /  10   0  30  40
SOUTH PADRE ISLAND   76  72  77  70 /  10   0  10  40



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