Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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461
FXUS64 KCRP 191122 AAA
AFDCRP

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
522 AM CST Mon Feb 19 2018

.DISCUSSION...Update for 12z Aviation.

&&

.AVIATION...MVFR CIGs xpctd early in the TAF period (brief window
of IFR at KCRP/KVCT) with a transition to VFR xpctd thru the day.
Low CIGs should eventually mix out today as strong diurnal mixing
occurs. Main aerodrome wx impact for much of the day will be
strong SSErly winds as a strong Srly LLJ of near 50 kts mixes
down. Strongest sfc winds (sustained 20 to 30 kts) xpctd to occur
from KCRP to KVCT from late mrng thru late aftn as core of LLJ
drapes across that area. Low CIGs to redvlp tonight as moisture
pools under a thermal inversion. LLJ also expands/dvlps Wwrd
tonight with sfc winds remaining sustained around 15 kts.

&&

.PREVIOUS DISCUSSION... /Issued 417 AM CST Mon Feb 19 2018/

SHORT TERM (Today through Wednesday)...

A spring-like weather pattern will prevail across S TX through
the short term period with wind being the primary weather impact.
A strong southerly LLJ exists across S TX early this morning with
the PBL failing to decouple so far (as of writing). Windy
conditions should prevail through the day as the LLJ strengthens
further (925mb flow prog to increase to near 50 kts across the
Coastal Plains). The strongest winds are expected to occur from
mid/late morning through late afternoon when diurnal mixing is
maximized. Given the strength of the LLJ and expected mixing
(maximum momentum transfer output is indicating potential for
frequent gusts of 40 to 45 mph), I have opted to go with a Wind
Advisory for the southern three coastal counties. Areal coverage
of the advisory may be a little conservative with future updates
potentially needing to expand the advisory farther north towards
Victoria.

Max temps should warm well into the 80s today for most inland
areas as WAA persists and a very warm H9 to H7 thermal layer
mixes downward. A few 90s are expected across the western Brush
Country.

Strong winds and mixing in the lower levels should preclude any
showers from being able to develop today.

The LLJ is prog to rapidly redevelop/expand westward tonight and
remain strong. Much like early this morning, the PBL is not
expected to decouple until very late tonight with strong WAA
preventing temps from falling much lower than 70 degrees for
overnight lows. Strong mixing should once again preclude precip
from developing. However, an increase in large scale lift may
become sufficient enough by late in the night for an isolated
shower to develop...but chances are too low to include in the
forecast at this time.

Breezy conditions will continue into Tuesday, but overall wind
speeds should be lower than today`s values as the LLJ is prog to
weaken through the day. A few showers may occur across the N
Coastal Bend/Victoria area during the morning hours as moisture
pools under a thermal inversion. The inversion will have a harder
time mixing out on Tuesday, which should keep a greater amount of
cloud cover around. However, a strong H25 jet is prog to approach
the region with ripples of H5 vorticity advecting towards the area
at times. This enhancement of synoptic lift may be sufficient for
isolated convection to develop across inland areas by late Tuesday
afternoon (mainly inland Northern Coastal Bend and the NE Brush
Country). Otherwise, continued unseasonably warm conditions will
occur.

LONG TERM...(Tuesday night through Sunday)...

GFS/ECMWF deterministic output generally consistent with respect to
the upper pattern, with an upper disturbance moving rapidly/lifting
across the Plains Wednesday, while another system meanders over the
WRN CONUS Wednesday through Friday, then becomes progressive and
moves across the Plains Saturday. The timing/position of the
foregoing upper pattern appears to contribute to the stalling of the
front near the TX coast Wednesday night. Expect the combination of
copious moisture (PWAT values well above normal) and frontal
convergence to result in at least scattered convection Wednesday
through Thursday. Anticipate that the combination of sufficient
moisture and upper jet dynamics (associated with the second system)
Saturday/Sunday will contribute to isolated/scattered convection
Friday through Sunday.

MARINE...SSE flow expected to strengthen today with Small Craft
Advisories in effect for much of the area. Strongest winds are
expected to occur across the Offshore waters where SSTs are the
warmest (allowing for better mixing of the atmosphere). However,
wind speeds and seas across waters off Padre and Mustang Islands
may still reach Advisory levels. Farther north (Matagorda Island
and vicinity) the SSTs are cooler and as such wind speeds should
be a little lower. The stronger southerly flow should preclude
dense fog from occurring, but areas of haze and high moisture
values will likely reduce visibilities to 4 to 6 miles at times
today and Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    83  69  80  67  78  /  10  10  10  40  60
Victoria          82  68  79  66  76  /  10  10  30  60  70
Laredo            91  69  86  68  82  /  10  10  10  40  50
Alice             88  69  85  67  81  /  10  10  20  40  50
Rockport          78  68  76  66  73  /  10  10  10  50  60
Cotulla           90  69  85  65  79  /  10  10  10  60  60
Kingsville        88  70  85  68  82  /  10  10  10  40  50
Navy Corpus       79  68  77  66  74  /  10  10  10  40  50

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Wind Advisory from 10 AM this morning to 5 PM CST this afternoon
     For the following zones: Kleberg...Nueces...San Patricio.

GM...Small Craft Advisory until 10 AM CST Tuesday For the following
     zones: 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 from 10 AM this morning to 8 PM CST this
     evening For the following zones: Bays and Waterways from
     Baffin Bay to Port Aransas...Coastal waters from Baffin Bay
     to Port Aransas out 20 NM.

&&

$$

RH/79...AVIATION



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