Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

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

FXUS64 KBRO 251821 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1221 PM CST Sun Feb 25 2018

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


.AVIATION...Models and big picture coming together for a fairly
confident forecast for the next 24 hours. Prior to the passage of
the next somewhat weak front, ceilings have generally lifted to
low VFR and expect this to continue through the remainder of the
afternoon. Gusty south winds at Brownsville will turn
south/southwest and drop off by 2 or 3 PM which has already
happened at McAllen and Harlingen. Been a little concerned about
wind shift line easing into the April-like warm and soupy air mass
(dew points in the lower 70s) but atmosphere itself is relatively
stable and a pretty broad depth of drier air arrives from west to
east (above the eventually slightly cooler low levels) which
should preclude anything more than isolated to scattered showers
this afternoon. Can't rule out a heavier shower with lower
visibility, but for now carried P6SM -SHRA at
Brownsville/Harlingen for more of a sprinkles/light shower
situation overall.

The boundary should reach McAllen by or just before sunset. After
the boundary passes, winds shift to north/northwest but stay
relatively light (8 knots or so) and there may be a window where
ceilings fall but stay just above the IFR line, based on model
soundings and the upcoming precipitation event setting up with
a wave aloft crossing the region. By 1 to 3 AM, that rain should
begin and ceilings will lower to IFR/LIFR soon after, as should
visibility as "cooling" is relative and with temperatures in the
60s and 100% RH expect reductions to 2SM or so in the combination.
Added mention of thunder (PROB30) to the sunrise period as enough
energy exists to produce elevated convection - even some near
surface based lift can't be ruled out.




This product is also available on the web at: