Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 140002

Area Forecast Discussion
National Weather Service Corpus Christi TX
602 PM CST Wed Dec 13 2017


Update for 00Z aviation cycle.



Tonight - Thursday...VFR. More high level clouds stream in
overnight with a few breaks possible. Light and variable surface
flow expected. Thinking ground fog will be hard to come by given
the amount of cloud cover in place, even as low-level moisture
creeps upward. Light easterly flow expected tomorrow ahead of an
approaching cold front which should move through after the current
TAF cycle. We continue the AMD NOT SKED at KLRD as observations
have not been consistently disseminated. High confidence.


.PREVIOUS DISCUSSION... /Issued 354 PM CST Wed Dec 13 2017/

SHORT TERM (Tonight through Thursday night)...

Satellite imagery shows an upper low over northern Baja California
while a strong short wave trough was diving southeast across the
central Rockies. The short wave trough will move through the Four
Corners region tonight while the upper low weakens into a wave as
it drifts southeast. Mid and high level moisture will continue to
stream across South Texas tonight from the southwest. Cloud cover
should limit potential for patchy fog formation along the coast.

The short wave trough over the Rockies will move into the southern
plains on Thursday while a short wave trough moving through the
Great Basin reforms the upper low over central Baja California
into northwest Mexico Thursday night. The first short wave trough
advancing eastward through the plains will send a cold front into
the region Thursday evening. Offshore flow will increase to
moderate to strong levels with SCA conditions expected overnight
Thursday night.

A very strong 25h jet of 150 knots will move out of northern
Mexico into Texas Thursday afternoon and evening. South Texas will
be in the right entrance region of this jet Thursday night. Large
scale lift will increase over the area as the front pushes
through the region. Isentropic lift will increase through the
295-305K layer Thursday night. Precipitable water values will
increase to 1-1.25 inches over the southern part of the forecast
area. Expect a large area of showers to move across South Texas
with the highest chances/categorical across the southern Coastal
Bend into the coastal waters.

LONG TERM (Friday through Wednesday)...

Rain chances will continue through Friday with increased lift aided
by shortwave passing overhead. This is associated with the mid-level
longwave trough moving eastward stretched across the Central Plains
to the Great Lakes. Models continue to cut off a low at the tail end
of the trough and have it pull back toward Baja California
Friday/Friday night. As the main trough pulls to the east and the
low drifts to the west, things are expected to quite down across
South Texas Friday night. Ongoing strong northerly winds will also
gradually weaken through Friday night. The low is then expected to
lift back to the northeast Saturday returning the SW-NE flow aloft,
nudging it into South Texas. Moisture with this system, along with
moisture moving in from the western Gulf will aide in showers for
Saturday. With the mid-level support, did continue mention of
possible thunder, although most activity should remain as showers.
In wake of the late Thursday front, temperatures will not have had
time to recover, so for Saturday, South Texas should experience cold
and rainy conditions, as highs should have a hard time breaking out
of the 50s. By Sunday, models quickly lift the mid-level low
northeast, lifting the bulk of the moisture and rain to the
northeast as well. Models handle early next week differently. The
GFS continues to have moisture lingering nearby while the ECMWF is
much drier. The ECMWF has a reinforcing high move in by Monday while
the GFS holds onto rain chances through Monday with the reinforcing
high moving in by Monday night. For now, will only carry slight
chance on Monday for the waters and coastal regions, but then dry
things by Tuesday.


Corpus Christi    50  73  47  55  46  /   0  20  80  40  20
Victoria          45  71  45  57  41  /   0  10  50  20  10
Laredo            50  68  47  57  45  /   0  10  70  40  20
Alice             48  72  47  56  44  /   0  20  80  40  20
Rockport          52  70  48  56  48  /  10  20  80  40  10
Cotulla           45  70  45  59  44  /   0  10  40  20  10
Kingsville        49  73  47  56  45  /   0  20  80  50  20
Navy Corpus       54  70  49  57  50  /  10  20  80  50  20





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