Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 251136

Area Forecast Discussion
National Weather Service Brownsville TX
636 AM CDT Sat Mar 25 2017

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


.AVIATION...Intermittent MVFR CIG`s and visibilities have been
affecting the terminals overnight. Expect this to continue through
the mid-morning hours before daytime heating and associated
mixing scatter out and lift the cloud bases and burn off any mist.
VFR should take hold from mid-morning onward with winds and
perhaps a few high clouds. Winds may go light and variable at MFE
for around mid-day as a surface trough approaches or possibly
passes, but this is not reflected in the TAF at this time due to
uncertainty. For early Sunday morning, guidance and forecast
soundings suggesting another round of MVFR ceilings will form up
at the base of an inversion around 025. Will again follow the SREF
probabilities for more prevalence of MVFR CIG`s inland at HRL and
MFE vs. BRO.


.PREV DISCUSSION... /issued 436 AM CDT Sat Mar 25 2017/

SHORT TERM (Now through Sunday): No significant changes made to
the short-term portion of the forecast.  Progressive pattern
continues, with short-wave ridging aloft moving into Texas today.
Meanwhile, latest WPC analysis shows a nearly stationary surface
boundary just NW of LRD.  Not much thermal contrast with this
boundary, but there is some drier air behind it.  Model guidance
shows this boundary penetrating eastward roughly through
Brooks/Hidalgo counties this afternoon (though briefly).  Might see
a band of enhanced cloud cover along this boundary (possibly
sharpened by the sea-breeze effect) but the NW flow aloft and lack
of depth to atmospheric moisture will preclude any precip.  Kept
inherited max temps pretty much intact for today, which will range
from the upper 80s at BRO to mid-90s for MFE and portions of the
Upper Valley.

Low-level SSE flow quickly re-establishes this evening as surface
ridging rebounds in the Gulf.  Precipitable water values fall back
to 0.8-0.9" across the area.  Freshened up min temps for Sunday
morning, which had the effect of lowering them a couple of degrees
for most locales, but still will be in the mid-60s except near the

For Sunday, the next vort max moves from the Panhandle region to
Kansas.  Pressure gradient tightens over Deep S. TX again as the
surface cyclone deepens.  Will definitely be a breezy day, though
not as much so as Friday was with the dynamics passing a little bit
farther north this time.  So expect that winds will stay shy of Wind
Advisory criteria.  Cold front associated with the surface low will
still lie to the NW of CWA by late Sunday afternoon.  Some hint in
the NAM/GFS that some moisture pools along a pre-frontal trough in
the afternoon, but once again it looks to be insufficient for any
precip.  Temps will be rather warm once again, though perhaps a
degree or two less than today`s.

LONG TERM (Sunday Night through Friday): Precipitation-wise, the
only hope for rainfall during the forecast period is expected to
be Wednesday night and Thursday courtesy of the approach and
passage of a cold front associated with a 500-mb low pressure
system in the Central Plains. Otherwise, the remainder of the long
term portion of the forecast will be dry either in the wake of the
front or before with a nearly zonal mid-level flow in place over
the BRO CWFA. The frontal passage will also serve to bring
temperatures more in line with near normal values, but ahead of
the front, expect well above normal to prevail.

MARINE (Now through Sunday): Seas remain agitated on the offshore
Gulf waters, with Buoy 020 reporting seas of 7.5 ft. for the past
several hours, along with S winds of 12-14 knots.  Earlier on,
extended the Small Craft Advisory for the waters 20-60nm out through
6am.  SCEC for seas still in effect for the nearshore waters as
well.  These seas should subside through the morning hours today,
with overall better marine conditions in store as high pressure
briefly moves across the northwest Gulf. Winds will remain around 10
knots, which will allow seas to drop to about 4 feet. SE winds
quickly re-establish Saturday night and pick up through the day on
Sunday, reaching SCEC or possibly low-end SCA conditions with seas
building to at least 6 ft. offshore.

Sunday Night through Friday: Small Craft Advisory conditions will
affect the Lower Texas coastal waters through a majority of the
forecast period, first courtesy of an enhanced gradient between
high and low pressure, and afterwards by the passage of a cold
front Thursday night. Even the most favorable marine conditions
will still feature Small Craft Exercise Caution for at least a
portion of the coastal waters of Deep South Texas and the Rio
Grande Valley.


GM...Small Craft Advisory until 9 AM CDT this morning for GMZ170-175.



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