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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 181103 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
603 AM CDT Mon Mar 18 2019

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

.AVIATION...No significant changes to the previous suite of TAFs. 
A wide area of light rain continues to stream east out of 
neighboring Mexico, and model guidance suggests this will persist 
through the entire TAF period. VFR cloud decks are anticipated and
a slip into MVFR is not forecast. 

.PREV DISCUSSION... /issued 439 AM CDT Mon Mar 18 2019/ 

SHORT TERM (Today through Tuesday): A wide swath of light rain is 
moving east out of neighboring Mexico and over mainly the southern 
half of Deep South Texas and the Rio Grande Valley. Model guidance 
suggests this will continue until around sunset this evening due to 
the approach and passage of a weak mid-level impulse riding within a 
west-southwest to east-northeast 500 mb flow overhead. In the wake 
of the disturbance, mainly coastal precipitation is expected tonight 
as an inverted surface trough develops along the Lower Texas Coast. 
The threat for rainfall will push westward on Tuesday, and encompass 
the entire BRO CWFA, as the surface trough eases inland and largely 
fades. The persistent threat of rainfall and overcast skies will 
lead to well below normal temperatures for this time of year.  

On the oceanographic side of the short term portion of the forecast, 
the Coastal Flood Statement will be continued until around sunset 
this evening as moderate swells from the east combine with the 
afternoon high tide to produce a minor threat of coastal flooding at 
the local beaches. 

LONG TERM (Tuesday night through Sunday): Weather conditions will 
finally start to recover back closer to normal each day, as surface 
troughing fills and high pressure builds across the Northern Gulf of 
Mexico. An easterly fetch of winds will keep temperatures mild and 
slowly rising Wednesday through Friday, with continued moisture 
advection into the low-levels. This will keep rain chances in with 
PoP of around 30 to 40%, however, mid-level ridging will at least 
allow temperatures to warm into the lower 80s by the weekend. The 
next trough will quickly follow, with models bringing in another 
deep 500mb low in the Four Corners Region. Southwest flow aloft 
across Deep South Texas along with deeper-layer moisture will bring 
the opportunity for thunderstorms Friday into Saturday as a couple 
weak shortwave troughs rotate through the main trough. It appears 
that most of the energy and better diffluence will lift well to our 
north, which would be good news for our Weather Festival on Saturday 
(10 AM to 4 PM). Still too early to tell, but temperatures at least 
look to be comfortable in the low 80s. Going into early next week, 
more zonal flow returns with very dry air moving into the mid-levels 
with strengthening northwest flow aloft. This would bring lowering 
rain chances and temperatures warming up to well above normal.

MARINE (Now through Tuesday): Buoy 42020 reported northeast winds 
around 10 knots gusting to around 14 knots with seas slightly under 
4 feet with a period of 7 seconds at 250 CDT/750 UTC. Deteriorating 
marine conditions are expected along the Lower Texas Coast due to a 
tightening pressure gradient and building swells approaching from 
the east. Small Craft Exercise Caution is likely today and tonight, 
with Small Craft Advisory likely on Tuesday, for the Gulf of Mexico 

Tuesday night through Sunday: Surface high pressure will build 
across the Northern Gulf, allowing for a long fetch of easterly flow 
into the Western Gulf. Overall seas are expected to be improved, 
however, swells may build to 3 to 5 feet along with an increase in 
period. The next storm system developing in the Plains late in the 
week will result in increasing southeast winds across the coastal 
waters, with small craft exercise caution conditions likely this 



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