Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 212349 AAA

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
649 PM CDT Thu Sep 21 2017

.DISCUSSION...Isolated convection persists across the Victoria
Crossroads and parts of the Brush Country. Will keep slight chance
PoPs going for a couple of hours this evening before activity
diminishes. See Aviation section for 00Z TAFs.


.AVIATION...Isolated thunderstorms linger in the VCT area and are
in the vicinity of LRD. This activity should diminish with loss of
heating by 02Z. Storms will be capable of producing MVFR/IFR vsbys
in brief heavy rain. Mid and high level cloudiness associated with
the convection will remain over the region into the overnight
hours. If higher cloud deck decreases enough, could see patchy fog
over the inland coastal plains from 10-14Z Friday with MVFR vsbys.
Streamer showers along the coast by daybreak will move into the
coastal counties possibly affecting CRP and VCT Friday morning.
Expect MVFR ceilings will be prevalent for the coastal plains
Friday morning with VFR ceilings expected in the afternoon.
Isolated to scattered convection will be possible with the sea
breeze boundary in the afternoon with better chance in the VCT
area. For LRD area, expect MVFR ceilings to occur by 10Z and
remain through the morning hours, then give way to VFR in the


.PREVIOUS DISCUSSION... /Issued 327 PM CDT Thu Sep 21 2017/

SHORT TERM (Tonight through Friday night)...

Main forecast challenge will be the rain chances on Friday. Models
are showing convection on Friday with varying scenarios, and
feeling is that the convection may be a tad overdone. Reasoning is
that the upper ridge tries to build back in a bit more on Friday
and the moisture is a bit lower. However, moisture will be
adequate and the winds are not going to be very strong. As a
result, am going with a sea-breeze/climatology scenario for rain
chances on Friday, with low chance POPs over the northeastern CWFA
and slight chances farther south and west. Rain will as-usual in
this scenario will have a chance to begin with some coastal
showers (how much is uncertain as there could be some mid level
drier air coming in) increasing with daytime heating and moving
farther inland in the afternoon. Rain should taper off rapidly by
evening, and another slight chance for rain overnight mainly over
the gulf waters toward daybreak with the coastal convergence and
lack of cap.

Otherwise, should be a slight decrease in temperatures (and I do
mean slight), given that the boundary layer/850 mb temperatures
fall a degree or so each period and this is followed by lower 2
meter temperatures. Thus, generally followed that trend from
observed temperatures through Friday night. Other than the
temperatures and the rain chances, generally went with a consensus
forecast (including some bias-corrected for dew points) on most
other sensible weather parameters.

MARINE (Tonight through Friday night)...

No real issues with the marine package. Generally isolated to
possibly scattered convection Friday morning diminishing in the
mid to late afternoon with the sea-breeze, then the potential for
some isolated activity overnight Friday night. Generally weak to
moderate onshore flow continues.

LONG TERM (Friday Night through Wednesday)...

Upper level trough will be digging into the western US at onset of
longterm period while ridge lifts northeastward. Moisture remains
moderate through the period with PWATs generally between 1.5 and 2
inches increasing later in the period. Saturday and
Sunday looks like mainly low end pops continue...20s and a few 30s
with mainly an enhanced sea breeze pattern expected. By Monday...and
more into Tuesday and Wednesday, upper level disturbances rounding
the base of the trough could start to have an influence on precip
activity. Monday energy is mainly north of the area...but will keep
a 40 pop in northeast. Tuesday through Thursday have chance pops
area wide with energy much closer to the area and moisture
increases. Most model guidance showing a reinforcing surge of
moisture into the area by Tuesday, but there are variations in
location and extent of the moisture. Regardless, this combined with
the upper disturbances should bring a fair chance for convection.

Temperatures remain slightly above normal early in the period, but
slide just a bit with the increased moisture and cloud cover by mid-
week...closer to normal values.  Muggy overnight conditions will
certainly not improve through the extended period with mid 70s dpts
continuing. Lows will be mainly in the mid and upper 70s through the


Corpus Christi    77  92  77  91  75  /  20  20  20  20  20
Victoria          76  91  75  91  72  /  20  30  10  20  10
Laredo            79  98  79  97  75  /  20  10  10  10  10
Alice             75  95  75  94  73  /  10  20  10  20  10
Rockport          82  91  81  90  79  /  20  30  20  20  20
Cotulla           78  97  77  96  74  /  20  10  10  20  10
Kingsville        78  94  77  93  74  /  10  20  10  20  20
Navy Corpus       82  91  81  90  78  /  20  20  20  20  20





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