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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 201958

Area Forecast Discussion
National Weather Service Brownsville TX
258 PM CDT Tue Aug 20 2019

.SHORT TERM (Now through Wednesday night): Satellite and radar 
images indicate isolated showers continue to develop along the 
seabreeze front across the coastal counties of deep south Texas this 
afternoon. GOES-16 total precipitable water value satellite images 
indicate the PW values are not as high across the northwest Gulf of 
Mexico compared to yesterday but we are still seeing some convection 
developing and moving across the coastal sections of deep south 
Texas and northeast Mexico. The good news is that some weakness will 
develop in the 500mb subtropical ridge across deep south Texas and 
northeast Mexico tonight into Wednesday as a 500mb inverted trough 
moves across the Bay of Campeche Wed afternoon. Will mention 
isolated showers and thunderstorms across the coastal sections of 
deep south Texas Wed afternoon as the seabreeze front provides low 
level convergence across the area. Temperatures will continue to be 
near normal to above normal tonight through Wed night. No heat 
advisories or record high temperatures are expected Wed afternoon 
but it will still be hot. 

.LONG TERM (Thursday through Tuesday): An inverted trough will
continue to move over the northwest Gulf of Mexico while pushing 
the prevailing 500 mb ridge further north into the Southern Plains
and the Four Corners region on Thursday. This mid level feature 
will allow deeper moisture to increase across the region Thursday 
into the first of half of the weekend. The best rain chances are 
expected to remain across the eastern portions of the CWA and over
the Gulf waters Thursday through Saturday. Lingering moisture 
should support a slight chance or chance of showers and 
thunderstorms through early next week. The increase in cloud cover
and rain chances should keep high temperatures a bit lower 
through much of the period. 


.MARINE (Now through Wednesday night): Seas were near 3.6 feet with 
southeast winds near 7.8 knots at buoy020 early this afternoon. 
Light to moderate southeast winds will prevail across the coastal 
waters tonight with weak surface high pressure across the eastern 
Gulf of Mexico. The pressure gradient will remain weak across the 
lower Texas coast Wednesday and light southeast winds will prevail 
across the Laguna Madre and offshore waters with slightly higher 
winds across the bay waters Wed afternoon. Winds will increase 
slightly offshore the lower Texas coast Wed night.

Thursday through Saturday Night...Light to moderate southeast winds 
and low seas will continue Thursday and Thursday night. The pressure 
gradient is expected to increase on Friday which will allow winds 
and seas to become moderate through Saturday night. Showers and 
thunderstorms will be possible at times across the coastal waters 
through the period. 


.FIRE WEATHER...Relative humidity values will be slightly higher Wed 
afternoon compared to today and 20 foot winds will be slightly lower 
Wed afternoon compared to today so a fire danger statement may not 
be needed tomorrow except for the extreme western portions of the 


BAYVIEW/PORT ISABEL  79  95  78  92 /  10  20  20  30 
BROWNSVILLE          78  96  77  95 /  10  20  10  30 
HARLINGEN            76  99  76  97 /  10  20  10  30 
MCALLEN              79 101  78  98 /  10  20  10  20 
RIO GRANDE CITY      79 103  77 102 /  10  10  10  20 
SOUTH PADRE ISLAND   81  91  79  86 /  10  20  20  40 




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