Area Forecast Discussion
Issued by NWS Brownsville, TX
FXUS64 KBRO 280557
Area Forecast Discussion
National Weather Service BROWNSVILLE TX
1257 AM CDT Wed Sep 28 2016
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...A NE-SW oriented coastal trough/stationary front is
currently positioned from the offshore waters down through near
BRO. This will be the main driver of any aviation weather concerns
for the next 24 hours. For the near-term, radar indicating a
linear band of showers/light rain positioned along or parallel to the
front, with intermittent -RA being reported at BRO. Though this
activity is expected to continue for the next several hours, trend
has been for intensity and coverage of showers to decrease over
land, so will cover with VCSH at BRO and leave out mention at HRL.
Short-term model guidance in good agreement that aforementioned
trough will finally progress back inland a bit today...most likely
around 16-18Z. This should bring periods of SHRA to BRO and HRL
with TEMPO MFVR ceilings, along with a modest wind shift from N to
NNE. Leaving SHRA out of MFE for now as it`s doubtful that precip
associated with the trough will make it that far inland.
After sunset, winds go slack with VFR prevailing through the
evening hours. With the light winds and possible wet ground in
spots, may have to consider mention of BR later at night, but more
on that in the 12Z edition...
.PREV DISCUSSION... /issued 650 PM CDT Tue Sep 27 2016/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...MVFR is prevailing at MFE while BRO and HRL are both
VFR. Convection should remain over the adjacent coastal waters
tonight while light offshore winds prevail. Tomorrow, veering and
increasing winds will occur with a surface disturbance shifting
west and allowing showers to move onshore during the afternoon
PREV DISCUSSION... /issued 231 PM CDT Tue Sep 27 2016/
SHORT TERM (Now through Wednesday night): A weak coastal trough
lies offshore, still triggering isolated convection, but coverage is
on the decrease over land as north winds and lower dew points take
hold. Have trimmed back pops for tonight through Wednesday night,
and gone with scattered or less showers through the short term,
which is a lot less than a model consensus was advertising, probably
trying to bring the coastal trough onshore. Cooler, drier air is
filtering in and essentially turning a convective situation into an
overrunning one, however, and a weak one at that. As a result, may
still see light precip through tomorrow, with forecast PWAT values
still remaining well above two inches in a saturated lwr atmosphere,
but cloud cover will tend to erode through the day, relegating most
residual shower activity to the Gulf (see marine discussion below).
Temperatures will be slightly cooler, in the lower to middle 70s at
night, with some upper 60s possible in the upper valley. High temps
on Wednesday will be mainly in the 80s, possibly touching 90 inland.
LONG TERM (Thursday through Tuesday): Not many changes to the
long term forecast today. Lingering moisture due to the coastal
trough will still be in place early on Thursday and have left low-
end rainfall chances generally over portions of the lower RGV.
However...a large area of surface high pressure will slide south
across the Central and Southern Plains. Meanwhile...a ridge of
high pressure build across Texas in response to a deepening storm
system that will be centered around the Great Lakes region.
The high pressure systems and northerly flow will help drive any
remnant rainfall south of the the RGV and generally bring a much
drier air mass to the Deep South Texas. Temperatures will begin to
warm up to near or even above normal values once again.
However... with the dry air in place...the heat indices will not
be nearly as oppressive as noted the last few weeks.
Now through Wednesday night...North winds have picked up through
the day, and are almost at SCEC criteria offshore. Will leave it
to the oncoming shift to make that call with respect to the
afternoon CWF issuance. In the mean time, disorganized showers and
thunderstorms over the Southwest Gulf lie along a surface trough
extending north into the lower Texas coastal waters, meaning some
convection may continue offshore in the short term. Otherwise,
looking for mainly light north to northeast winds and low to mdt
seas after tonight.
Thursday through Sunday...Light to moderate N to NE winds will
generally be on place through the period as surface high pressure
dominates the weather through the weekend. Seas will be be in the
2 to 3 feet range.
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