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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 161800 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
100 PM CDT Thu Aug 16 2018

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


.AVIATION...High pressure at the surface and aloft will provide
very dry atmospheric conditions to maintain VFR conditions the
next 24 hours. A very limited cumulus field today dissipates
this evening before the limited cloud field redevelops Friday
mid-late morning possibly reaching as far as KMFE. South to
Southeast winds gusting to around 25 knots diminish through the
evening with lighter winds and lower gusts Friday as surface high
pressure builds into the region weakening the gradient. 


.PREV DISCUSSION... /issued 640 AM CDT Thu Aug 16 2018/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...IR satl imagery and surface obs indicate VFR
conditions in place over the RGV. The VFR conditions around the
region will persist throughout the next 24 hours as 500 mb ridging
strengthens. Some MVFR ceilings will be briefly possible tonight
through sunrise Fri. But will not mention this potential cld cover
in the 06z TAF issuance. The SE low level winds will become 
somewhat gusty after sunrise today as the stronger winds aloft 
mix down to the surface. Some brief isold conv will be possible 
today, but will not mention in the current TAF issuance. 

PREV DISCUSSION... /issued 353 AM CDT Thu Aug 16 2018/ 

SHORT TERM (Now through Friday): 500 mb ridging will persist over 
TX and will build steadily west throughout today and Friday. This 
will maintain temps above climo for mid August with pretty low conv 
chcs due to the increasing stability across the area. The afternoon 
sea breeze effect in addition to the daytime heating may produce 
some very isold conv Thur and Fri afternoon. However will maintain 
only some silent 10 % pops due to the strengthening 500 mb 
ridging limiting the conv. 

The ridging over the RGV will tend to hold the max temps generally 
above climo and a little above numerical guidance through Fri. 
Numerical guidance has been underperforming the observed max temps 
over the last few days. The ECMWF appears to be the warmest of the 
three short term model sets. Will be going a couple of degrees 
warmer than this for maxes on Thur and Fri. 

Heat index numbers throughout the short term will remain somewhat 
elevated maxing out in the 105 to 110 range for portions of the 
region today and tomorrow. At this time they do not appear hot 
enough to require any heat advisories. 

LONG TERM (Friday Night through Wednesday): Hot and generally 
rain free conditions will continue through the period with high 
pressure aloft and at the surface. Rain chances will remain low 
through the long term but can't rule isolated sea breeze 
convection by midweek as slightly deeper moisture arrives. 
Temperatures are expected to remain above normal through Wednesday.
High temperatures each day will generally range from the low to 
mid 90s in the lower Valley to the upper 90s to the triple digits 
in the mid to upper Valley with overnight lows in the 70s to 
around 80 degrees. Heat index values will generally range between 
105-109 degrees each afternoon across much of the deep south 

MARINE (Now through Friday): Broad surface ridging will remain in 
place over the western Atlantic and the Gulf of Mex through Fri. 
This surface ridge will maintain a relatively decent PGF over the 
Laguna Madre keeping the surface winds up close to SCEC crit through 

Friday night through Monday Night: Surface high pressure across 
the Gulf and lower pressure inland will support light to moderate
winds and moderate seas through period. The gradient will increase
slightly by late in the weekend with small craft exercise caution
conditions likely on the Laguna Madre and possibly across the Gulf
of Mexico waters on Sunday and Monday.




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