Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 131759 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1159 AM CST Mon Feb 13 2017

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


.AVIATION...Breezy south southeast winds are pumping moisture in
from the Gulf, supporting sct to bkn low clouds. A mid level low
with leading diffluence is moving from North Central Mexico toward
West Texas. Isolated to scattered convection is developing over
the Rio Grande Plains...roughly along a stalled surface front
running from west to east across South Texas. Much of the upper
energy will remain north of the CWA as it moves west to east over
the next 24 hours, but the tail end of the surface front will
move through the local area Tuesday morning. The wind shift will
arrive in the lower valley late Tuesday morning, by about noon.
MVFR ceilings will develop late tonight and will continue until
after frontal passage as gulf moisture pools ahead of the
boundary. Scattered showers with isolated embedded thunderstorms
will be possible with the front, with modest forecast convective
parameters. By mid Tuesday afternoon, however, the front will be
offshore with clearing skies and moderate to breezy northwest
winds at the local TAF sites.


.PREV DISCUSSION... /issued 529 AM CST Mon Feb 13 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Southeast breezes overnight have remained a bit more
elevated than expected, which has kept fog from developing for
most areas. Some very light fog is still expected around sunrise,
but will be brief and mix out quickly after sunrise. Breezy
conditions return later this morning, with southeast winds
expected to reach 15 to 20 knots with some higher gusts during
the afternoon. Winds will remain elevated overnight as the next
front approaches. The front itself will not reach local airports
until just after sunrise Tuesday. Shower activity will be on the
increase after midnight, but will more affect flights corridors to
the north until the front arrives.

PREV DISCUSSION... /issued 355 AM CST Mon Feb 13 2017/

SHORT TERM (Today through Tuesday):Well advertised arrival of the
cold front still on track for Tuesday as the H5 trough sweeps across
North Texas. Near term models show the development of some streamer
showers as moisture pours northward toward the front. Activity will
not be widespread, as main midlevel support is still well away from
the region. Most shower activity will be this morning, but can`t
quite rule out a few showers across the northern Ranchlands this

Models show the surface low beginning to wrap up in the vicinity of
the Texas Big Bend, as sweeping eastward across the state during the
ensuing 24 hours. This will bring the front through Deep South Texas
during the later morning hours on Tuesday. Since the front won`t
arrive until after sunrise, the capping inversion will likely
prohibit the formation of shower activity locally overnight tonight.
But the  arrival of the surface forcing with the front during the
morning, along with the passage of the H5 trough through North
Texas, will bring a good shot for showers and a few thunderstorms.
Precipitation will likely be offshore by mid-afternoon, with
drier air surging in from the west later in the afternoon.

LONG TERM (Tuesday Night through Sunday):Latest GFS/ECMWF
remain in the good model to model consistency exhibiting a high
amplitude fairly progressive split flow pattern. The active
ridge-trough pattern will bring about a roller coaster of
changes...albeit slow.

Flat ridging takes shape over Texas Wednesday in wake of
Tuesday`s cold front. Fair and cool conditions are expected
Tuesday night through Friday morning with temperatures finally
near to slightly below normal. A shortwave trough in the
southern stream tracks across Texas Friday bringing with it
moderate scale ascent, deepening moisture and increasing
instability as temperatures warm above normal. This should lead to
at least a chance of showers and thunderstorms. GFS is a bit
higher on pops then ECMWF and slight disconnect on timing which
could have a factor if thunderstorms are more prevalent. Will
continue the general blend with plenty of time to adjust as this
time period gets closer. Shortwave ridge builds in behind the
departing trough with a fair cool Friday night and a fair warm
Saturday in advance of the next upstream large trough. This deeper
high amplitude trough could should allow for rapid influx of
moisture and warm tempeatures and bring about the next chance of
rain as early as Sunday and probably Monday as well all depending
on its forward speed.

MARINE:Now through Tuesday: Southeast flow continues during the
day today due to the front stalled in central Texas. Winds will
remain in the 10 to 15 knot range, keeping seas steady around 4
feet. Low pressure begins to develop and move eastward Monday
night, and will draw the cold front southward through the marine
areas Tuesday afternoon. Winds ahead of the front will increase to
around 20 knots, while southeasterly swells increase to 5 to 7
feet. Winds will shift to the southwest around noon, with a
gradual continued turn to the northwest through the afternoon.
Winds will not increase with the initial wind shift, but will wait
until after sunset. Showers and thunderstorms are expected Most
of the day Tuesday, with a considerable threat for thunder and
gusty winds.

Tuesday night through Friday...The longer term marine forecast
will start under adverse conditions as Fresh northwest winds and
building seas are anticipated Tuesday night and Wednesday in wake
of a cold front. Small craft advisories are likely for all or
portions of the coastal waters anytime through Wednesday. Weak
high pressure builds into the region Wednesday night and Thursday
with winds and seas rapidly lowering with very good conditions.
Next storm system advances into Texas Friday with southeast winds
and seas on the increase.




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