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Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

                            
000
FXUS64 KBRO 221959
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
259 PM CDT Wed May 22 2019

.SHORT TERM (Now through Thursday night): The main forecast issue in 
the short term will be heat, with mid 70s to near 80 degrees at 
night, and 90s to near the century mark on Thursday. Heat index 
values will stay in the 80s to lower 90s until late in the 
evening, while values on Thursday afternoon will reach the 102 to 
107 degree range for a few hours in the afternoon for portions of 
deep South Texas and the RGV. The elevated heat index values will 
be supported by dew points well into the 70s for most of the area.

On the large scale, stable mid level ridging over the lower 
Southeast United States extends west into portions of East Texas. 
High pressure over the Gulf will provide continued moist, low 
level southeast flow, along with moderate to breezy southeast 
winds. If anything, downstream mid level ridging will build 
slightly farther west to over the North Central Gulf in the short 
term. The stable conditions will favor haze, as particulate matter
from burning in Mexico continues to move north on the prevailing 
winds. A mix of clouds and sun will prevail on Thursday, though 
the extra morning cloudiness will scatter out to some extent by 
afternoon. Rain chances will remain muted in the short term.


.LONG TERM (Friday through Wednesday): Hot and breezy conditions
will be the story in the long term as we finish off the week and
head into the weekend. In the midst of an amplified upper-level 
flow, high pressure will broaden across the Southeastern U.S., 
extending westward into the Western Gulf and across Deep South 
Texas. Models are in fair agreement through much of the long term 
period, therefore, few changes were needed in this forecast 
update. Daily high temperatures will be a few degrees above normal
with elevated dew points, maintaining heat index values of 105 or
greater at times. Model time-heights show very shallow moisture 
with RH values below 25% above 850mb. The only notable chance of a
shower or storms is on Friday with a bit deeper moisture 
available near the coast. Breezy conditions along the coastal 
counties may hinder seabreeze development, so have kept silent 10%
PoP for now.

&&

.MARINE (Now through Thursday night): Moderate to strong 
southeast winds and moderate to high seas will persist through the
forecast. A broad and strong surface high pressure area will 
remain anchored in place over the Gulf of Mexico, supporting a 
tighter pressure gradient and the related higher winds and seas. 
Small craft advisory conditions will persist in the short term, 
with wave heights in addition to winds meeting criteria on the 
Gulf, and choppy to rough conditions on the Bay.

Friday through Wednesday: Adverse marine conditions will be
possible each day as a series of surface lows develop and move
through the Central Plains, tightening the pressure gradient
across the Western Gulf. Periodic Small Craft Advisories will
likely be needed for at least hazardous seas. The gradient should
relax a bit early next week, though Small Craft Exercise Caution
conditions can be expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  79  88  79  91 /   0   0   0  10 
BROWNSVILLE          80  90  80  93 /   0  10   0  10 
HARLINGEN            79  93  78  94 /   0  10   0  10 
MCALLEN              79  93  79  95 /   0   0   0  10 
RIO GRANDE CITY      79  95  78  98 /   0   0   0  10 
SOUTH PADRE ISLAND   80  83  79  82 /   0   0   0  10 

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 6 PM CDT this evening for TXZ248-252-253.

GM...Small Craft Advisory for winds until 7 AM CDT Thursday for 
     GMZ130-132-135.

     Small Craft Advisory until 7 AM CDT Thursday for GMZ150-155-170-
     175.

&&

$$

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