Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 150416

Area Forecast Discussion
National Weather Service Corpus Christi TX
1016 PM CST Thu Dec 14 2017


A few adjustments to the forecast late this evening, mostly to
increase PoPs farther northwest into the CWA and also across the
south. We continue the SCA for all the Middle Texas Coastal waters
though there could still be an occasional gale force gust, mostly
over the southern waters by daybreak. Still think the frequency of
the occurrence is short lived to exclude a Gale Warning. We will
continue to watch how the winds and subsequent gusts respond
behind the cold front.


.PREVIOUS DISCUSSION... /Issued 613 PM CST Thu Dec 14 2017/


Update for 00Z aviation cycle.


Tonight...Mostly VFR. Cold front continues to move towards the
south but lies just north of the region. Winds for the most part
have already shifted to the north-northeast and they will become
stronger and quite gusty through the overnight hours behind the
front. Areas of rain, mostly light with little in the way of
impacts, has already started falling at KLRD/KCRP as we expect
more activity tonight. A few pockets of MVFR cigs may develop
along the frontal boundary and with some of the overnight showers.
Medium confidence.

Friday...VFR. Gusty northerly winds expected to decrease
throughout the day. Rain will also be on the downward trend as
cigs remain around 4-6kft. High confidence.

PREVIOUS DISCUSSION... /Issued 354 PM CST Thu Dec 14 2017/

SHORT TERM (Tonight through Friday night)...

Satellite imagery shows the short wave trough moving into the
central plains while the upper trough near northern Baja
California is deepening as energy dives southward through the
Great Basin. This will lead to an upper low forming over northwest
Mexico tonight that digs south toward southern Baja California.
Stream of mid and high level moisture from the southern Baja
California through Mexico into south Texas will continue tonight.
KCRP radar showed light returns moving across the southern part of
the area late this afternoon with LRD reporting light rain. It
will take some time this evening to overcome the drier air in the
lower levels for precipitation to reach the surface. PoPs will be
in the 20-30 percent range this evening.

Cold front moving south through central Texas will reach the
area this evening but the colder air will be lagging a bit. Winds
will increase overnight over the coastal areas as gradient
strengthens. Isentropic lift will increase in the 300-310K layer
behind the front as a strong upper level jet moves out of central
Texas. South Texas will be in the favorable right entrance region
for large scale lift late tonight into Friday morning. GFS/ECMWF
along with hi-res models indicated a large area of precipitation
will develop overnight and spread across the southern and central
portions of the forecast area into the coastal waters. NAM is a
little drier bringing in a deeper layer of dry air in the lower
levels behind the front. Will lean toward the wetter solutions but
will show drying/lower rain chances moving across the region
north to south during the day Friday. Drier air will be in place
Friday evening but low level warm air advection will increase
along the Rio Grande overnight as a short wave trough moves
northeast into the area ahead of the upper low that forms over
northern Mexico.

MARINE (Tonight through Friday)...

Cold front will move into the coastal waters late this evening.
Winds expected to increase quickly overnight as colder air moves
into the waters and as the pressure gradient increases. The strong
offshore flow will occur late tonight through Friday morning with a
brief period around daybreak when wind gusts could be near or
slightly above gale force over the Gulf waters. Wind speeds will
diminish by Friday afternoon with seas slow to subside. Made no
changes to current SCA in effect. SCA will begin at 07Z for all
marine waters and expire at 18Z Friday for the bays and 00Z
Saturday for the Gulf waters. Isolated thunderstorms will be
possible late tonight behind the front within area of showers.

LONG TERM (Saturday through Thursday)...

An active pattern continues in the long term period. Initially, an
upper level disturbance will linger over the region Saturday into
Sunday behind the Friday cold front. This will continue high rain
chances Saturday and Saturday night as a stream of Pacific moisture
flows over South Texas and a coastal trough develops. As the upper
disturbance pulls out of the region Sunday drier air moves in, but
the next upper disturbance is already digging into the southwest
states. This will push another cold front through the region Monday
or Monday night. Guidance is pretty progressive with getting the
upper level energy associated with this system out rather quickly on
Tuesday...though ECMWF does lag behind a bit into Tuesday night.
Moisture availability is in question for any precipitation
associated with this front. Current guidance would indicate most of
the rain chance will remain in marine areas as the front pushes
through before a substantial moisture return is possible. ECMWF a
little wetter for the Coastal Bend. Will just stick with a slight
chance pop for the this area and better chances offshore for now.

Expect well below normal temperatures Saturday with substantial
cloud cover. A few breaks on Sunday and temperatures back to around
normal. Cloudy skies expected once again Monday/Tuesday, with
temperatures near to slightly above normal.


Corpus Christi    50  56  45  57  48  /  70  70  20  60  50
Victoria          46  58  43  57  47  /  40  30  10  60  70
Laredo            48  54  43  51  43  /  80  60  40  70  50
Alice             48  55  44  56  46  /  70  70  20  60  50
Rockport          50  56  46  59  50  /  60  70  10  60  60
Cotulla           48  59  43  52  42  /  50  30  10  70  50
Kingsville        49  56  45  56  47  /  80  80  20  60  50
Navy Corpus       52  56  47  60  51  /  70  80  20  60  50


GM...Small Craft Advisory until 6 PM CST Friday For the following
     zones: Coastal waters from Baffin Bay to Port Aransas out
     20 NM...Coastal waters from Port Aransas to Matagorda Ship
     Channel out 20 NM...Waters from Baffin Bay to Port Aransas
     from 20 to 60 NM...Waters from Port Aransas to Matagorda
     Ship Channel from 20 to 60 NM.

     Small Craft Advisory until noon CST Friday For the following
     zones: Bays and Waterways from Baffin Bay to Port Aransas...
     Bays and Waterways from Port Aransas to Port O`Connor.



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