Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 170250 AAB

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
850 PM CST Mon Jan 16 2017


Just made some very minor changes to the dew point and wind grids
for the first period. Otherwise, GFE Forecast Monitor shows nearly
all green fields (winds are a bit high) but hopefully update with
combination of forecast, GFSLAMP and RUC will help lower the
differences which were not big anyway (it just did). PFM and AFM
have been updated. An update to the ZFP is not needed at this
time. Marine forecast looks good at this time as well. Still a
small chance for possible showers along the boundary overnight.


.PREVIOUS DISCUSSION... /Issued 539 PM CST Mon Jan 16 2017/


See Aviation Discussion for 0Z TAFS.


Front will slowly creep southward on Tuesday, which will provide
the main focus for thunderstorms on Tuesday afternoon. Before 18Z
do not expect much in convection although there could be a few
weak showers near KLRD toward 12Z with weak upslope flow. AOA have TEMPO or PROB30 for all sites, as could have some
wind gusts 30 knots or more and feel relatively confident (given
model data) that thunder will be around. See the four terminal
forecasts for more information.

Before that, as usual we will see lowering of winds/CIGS and in
some locations (KALI and KVCT) VSBYS starting mainly AOB 06Z and
continuing through about 16Z. With rich moisture and low winds due
to proximity of front, will probably develop IFR/LIFR conditions
east of KLRD terminal before 12Z. Winds on Tuesday mainly SE to
start (weak in KLRD), then backing more toward the east during the
day as the front approaches.

PREVIOUS DISCUSSION... /Issued 358 PM CST Mon Jan 16 2017/

SHORT TERM (Tonight through Tuesday Night)...

Weak boundary/front is analyzed to be draped from just west of
Beeville to just west of Orange just east of
Alive...extending southward to just west of Kingsville /also
currently evident on WSR 88d 0.5 reflectivity/. Much of short
term forecast is strongly dependent upon placement of front
through the period. Guidance is struggling with its
handling/placement of the boundary and thus forecast certainty is
lower than normal with this forecast package.

Front/boundary is prog to push west this evening...but is
currently farther east than any guidance indicates. As such...I
am hesitant to forecast the front going overly far to the west.
Regardless...the front should at least push west some tonight
which will result in SSE low level flow persisting across the
eastern half of the CWA. H85 moisture levels /which have been
decreasing this afternoon/ are prog to increase again tonight
which may become sufficient for showers to develop in isolated
convergence bands within the low level flow/. Accounting for
such...I have included 20 POPs for the N Coastal Bend and Victoria
area for late tonight. By late in the night...a H5 vort max is
prog to advect towards the area...a 90 to 100 kt h25 jet is prog
to shift farther to the east...and moisture depth is prog to
increase. Combination of these factors /especially the increase in
large scale lift/ should result in a few showers or even an
isolated thunderstorm developing by late in the night across the
NW Brush Country where boundary is currently expected to push
westward towards.

Boundary is prog to slowly push back south and east across the CWA
during the day Tuesday with scattered showers and a few
thunderstorms developing as a result. Again...placement of the
boundary will be critical regarding placement of highest POPs. For
now...I have highest POPs across the N and W CWA for the morning
with chances expanding elsewhere through the afternoon. If
boundary shifts far enough N and W tonight...then much of the
Coastal Plains may remain dry for much of Tuesday.

By late Tuesday afternoon /and especially into the evening
hours/...thermodynamics are prog to become more favorable for
thunderstorm development. Bulk shear values are prog to increase
to roughly 30 to 40 kts...with guidance indicating a marginally
to moderately unstable airmass in place...while upper level
divergence is prog to increase significantly across S TX Wed
evening as a 130kt H25 jet streaks NE across Del Rio and a 100kt
streak shoots across BRO`s CWA. Combination of all these
factors...along with a continued unseasonably high moisture depth
/PWATs prog to be around 1.60"...which is roughly +2 sigma for
mid January/. Result should be the development of scattered to
numerous showers and thunderstorms during the evening. Given the
aforementioned synoptic and thermodynamic features in play...a few
thunderstorms may become strong to severe /especially across the
Coastal Plains where moisture depth and instability are prog to be
the greatest/. A few damaging wind gusts will be possible with
the strongest activity...but with hodographs prog to become
increasingly curved across the Coastal isolated
tornado will also be possible. Isolated flooding may also occur
with any cells that begin to train overnight /greatest chances for
isolated flooding currently appear to be across the Victoria
area/...but the overall flooding threat for S TX is currently
expected to be low.

Min temps will continue to be unseasonably warm tonight with max
temps on Tuesday strongly contingent upon amount of precip and
and placement of boundary. Cooler conditions expected by late
Tuesday night as boundary pushes through and rain cooled air
settles in.

LONG TERM...(Wednesday through Monday)...

Frontal boundary will remain draped across the Coastal Bend into
Wednesday. Deep moisture will be located along and ahead of the
boundary with PW values about 1.5 inches. As a result, decent
chances of showers and thunderstorms will continue on Wednesday with
favored locations across from the Brush Country into the Coastal
Bend. Both the GFS and European bring the upper low into the
Panhandle of Texas Wednesday night into Thursday morning, with
trough extending back to the southwest into Mexico. Increased lift
from the trough and upper jet to the north will result in another
round of convection Wednesday night into Thursday. Trough axis will
finally push through South Texas by Thurday night, with quickly
diminishing rain chances from west to east.

Progressive pattern will persist through the end of the forecast
period. Another upper level trough will approach and move through he
region on Friday. However, concerns over moisture availability will
preclude mentioning any chances of rain. A potent system will then
move out of the Southwest US on Saturday into Saturday night, with
the corresponding front moving through Saturday night/Sunday
morning. This system will have the potential to bring some much
stronger winds to South Texas for Sunday.

Temperatures on Wednesday will be tricky depending on evolution
frontal boundary, but 60s across the west and low 70s near the coast
seem reasonable.  Then a warming trend will commence Thursday
through Saturday with above normal temperatures (70s and low 80s)
across the region. Only a slight setback in temps are expected
behind the pacific front on Sunday.


Corpus Christi    69  78  63  73  58  /  10  40  80  50  40
Victoria          66  75  59  70  57  /  30  60  90  70  50
Laredo            64  75  57  67  56  /  20  50  60  20  20
Alice             65  80  61  70  57  /  10  50  80  50  30
Rockport          67  77  63  69  59  /  10  50  80  60  50
Cotulla           62  68  55  65  53  /  30  60  70  30  20
Kingsville        66  81  62  73  58  /  10  40  70  40  40
Navy Corpus       68  76  63  70  59  /  10  40  70  50  50





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