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Area Forecast Discussion (AFD)

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

                            
000
FXUS64 KBRO 181125 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
625 AM CDT Tue Jun 18 2019

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

&&

.AVIATION...Light southeast winds and a few passing low cloud 
decks prevail across deep south Texas this morning. MVFR ceilings
will be possible through around 13Z at MFE. Otherwise, generally VFR
conditions are expected for the next 24 hours as high pressure 
builds over the area. Light southeast winds this morning will 
become moderate later this morning into the afternoon. Ample low 
level moisture may support a return of MVFR ceilings late in the 
period, especially at MFE.

&&

.PREV DISCUSSION... /issued 433 AM CDT Tue Jun 18 2019/ 

SHORT TERM (Now through Wednesday): Hot and humid weather with 
above normal temperatures will prevail through the period as mid 
level ridging builds over northern Mexico. Surface high pressure 
across the Gulf of Mexico will bring steady light to moderate 
southeast winds and allow limited low level moisture to move up from 
the south. Some light fog will be possible across ranchlands around 
sunrise. High temperatures today will range from the 80s at the 
beaches, mid to upper 90s inland and triple digit heat across the 
west, mainly west of the I-69C corridor, and will support heat index 
values of 108 to 112 degrees for a couple of hours this afternoon. A 
heat advisory does not appear likely for today due to the duration 
and coverage of the heat indices, but will be closely monitored. 
Another warm and muggy night is on tap for tonight with low 
temperatures falling only into the upper 70s and lower 80s under 
partly cloudy skies. High temperatures on Wednesday should be a 
couple of degrees warmer than today with triple digit high 
temperatures spreading closer to the coast, along the I-69E 
corridor. The combination of the higher temperatures and the 
persistent higher dewpoints will support afternoon heat index values 
of 111 to 116 or higher, on Wednesday. Heat advisories are likely 
for all or portions of the deep south Texas Wednesday afternoon.

LONG TERM (Wednesday Night through Monday): The main issue in this
portion of the forecast continues to be heat. Broad 500 mb high 
pressure centered over the Gulf of Mexico and extended over Deep 
South Texas and the Rio Grande Valley will persist throughout the
period, essentially preventing any precipitation and producing 
limited cloud cover. With well above normal daytime high 
temperatures forecast and a relatively moist and humid atmosphere 
also in place, the potential for a Heat Advisory and/or Excessive 
Heat Warning for portions or all of the BRO CWFA each day is 
high.

MARINE (Now through Wednesday): Favorable marine conditions are 
expected through much of the period as high pressure settles across 
the Gulf. Light to moderate southeast winds with seas of 2 to 4 feet 
will prevail through midweek. Small craft exercise caution 
conditions may be possible on the Laguna Madre by Wednesday 
afternoon.

Wednesday Night through Monday: An enhanced pressure gradient
continues to be anticipated for this period with high pressure 
over the Gulf of Mexico interacting with thermal low pressure over
northern Mexico. A Small Craft Advisory for Winds is likely to be
needed for the Laguna Madre beginning on Thursday, with Small 
Craft Advisory for the Gulf of Mexico waters likely beginning on 
Friday. 

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

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