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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 181720 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1220 PM CDT Sat May 18 2019

.DISCUSSION...Updated for latest aviation discussion below.


.AVIATION...Low clouds are plentiful this afternoon with 
continued ample low level moisture and a bit of a stable layer in 
the 850 to 700 mb zone. MVFR ceilings have been dominating, though
with a few breaks. South southeast winds are breezy to strong. 
High pressure will remain in place across the Gulf the next 24 
hours, and MVFR ceilings will continue to dominate, though a brief
lowering to IFR may occur around dawn on Sunday. Winds should 
diminish tonight and should be slightly weaker on Sunday compared 
to today as a low pressure center to the north shifts east. A bit 
of haze is reducing visibility slightly, but not enough to trump 
ceiling impacts. Minor haze/morning mist may persist through 


.PREV DISCUSSION... /issued 622 AM CDT Sat May 18 2019/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Mainly MVFR ceilings and moderate southeast winds 
prevail across deep south Texas this morning. Winds will increase
and become breezy mid to late morning. VFR conditions will 
develop later this morning into the afternoon before MVFR ceilings
return after sunset this evening.

PREV DISCUSSION... /issued 338 AM CDT Sat May 18 2019/ 

LONG TERM (Sunday Night through Friday): Unsettled weather
continues across the Plains through the long term period, with a 
front trying to sweep across the state on Tuesday. Models depict a
slight wind shift on Tuesday afternoon across the western 
counties until southeasterly flow takes back over by Tuesday 
night. Dry and warm flow aloft keeps Deep South Texas capped off 
through the period. The best chance for any isolated showers or 
thunderstorms remains with the seabreeze during mid to late 
afternoon hours, but have kept POPs at 10 percent or less through 
Friday. Due to strengthening pressure gradient, expect breezy to 
windy conditions on Monday into Tuesday, and breezy afternoons 
Wednesday through Friday. 

Heat Index values may top 100 degrees during afternoon hours
across the Rio Grande Valley Monday through Thursday, with Monday
and Wednesday afternoons falling just short of Heat Advisory
criteria across portions of the upper valley, in Starr and Zapata
counties. Mid 90s to near triple digit heat, coupled with
increased low level humidity, could create dangerous conditions
during the heat of the day for those exposed. Typical heat safety
tips messaging would apply this week. Remember to check on your
elderly friends, family, and neighbors. Make sure your pets or
livestock have shade and plenty of water. 

MARINE (Now through Sunday): Strengthening low pressure over the
Plains will support moderate to occasionally strong southeast 
winds and elevated seas across the lower Texas coastal waters 
through the period. Small craft should exercise caution on the 
Laguna Madre and Gulf waters today into tonight, with low end 
small craft advisory conditions possible on the Gulf. Light to
moderate southeast winds and moderate seas will prevail across 
the coastal waters on Sunday as the pressure gradient weakens 
across the western Gulf.

Sunday Night through Friday: As more low pressure works into the
Plains, the pressure gradient strengthens into Monday, increasing
onshore flow along the lower Texas coast and creating hazardous
marine conditions across coastal waters. Moderate to strong
southeasterly winds will continue Monday night into Tuesday, with
occasional gusts to near gale force. Small Craft Advisories will
likely be needed through Tuesday. Small Craft Advisory conditions
may continue Wednesday through Friday across offshore Gulf of
Mexico waters, especially during the afternoon hours. Small Craft
Advisories for Wind are likely Monday and Tuesday across the
Laguna Madre, and may be possible during the afternoon hours of
Wednesday through Friday. 




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