Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 210235 AAC
AFDCRP

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
935 PM CDT Sun May 20 2018

.DISCUSSION...

Updated forecast based on radar trends and expected convection
overnight. Not expecting much overnight maybe closer to the coast.
Most of the activity well west of the Rio Grande should stay west
or move south of the area overnight. Still did keep a low chance
or slight chance after midnight to account for this. All forecast
parameters for tonight and portions of Monday have been updated.
Products are out. Made some adjustments to the marine forecast.
That will be issued by 10 PM.

&&

.PREVIOUS DISCUSSION... /Issued 659 PM CDT Sun May 20 2018/

DISCUSSION...

Convective line stretches from Whitsett southward to George West
with a broken line of storms extending southwestward to near
Laredo. Some of these storms may be strong to possibly severe with
strong to damaging winds being the primary threat. This threat
should continue into the evening for a few more hours. Main reason
for the update was to align pops closer to radar trends and
expected movement of the storms during the evening hours.
Additional updates will likely be needed.

PREVIOUS DISCUSSION... /Issued 630 PM CDT Sun May 20 2018/

DISCUSSION...

There will be an update coming out shortly on the evening package
based on the current radar/radar trends and expected convective
progress this evening and overnight. Also adjusting some other
parameters as-needed to fall more in line with the observations.
Update will be out shortly.

See .AVIATION discussion for 00Z TAFs.

AVIATION...

Main issue is the convection and this set of terminals is based in
part on radar and surface forcing trends (LAPS convergence),
along with meso-model "trends" (meso models cannot be relied on
for exact location of convection just that convection will likely
be around some areas). Given that, am expecting convection to move
more to the south during the evening, especially KLRD and KALI
terminals, but also possibly into the KVCT terminal. Lots of
surface moisture divergence near KCRP terminal at this time
(thus against rain), and that is the tricky terminal but given
that the models have been consistent on possibly having something
proximate to the terminal this evening did also include
convection here (weaker however). Best shot for convection is
between 02Z and 07Z at KALI, 03Z and 08Z at KCRP, 01Z to 07Z at
KLRD (possibly longer), and 01Z to 05Z at KVCT. Strongest storms
(gusts greater than 30 knots likely at all but KCRP (but not that
KCRP cannot get higher winds...cannot base on worst case
situation). After the convection, should have MVFR CIGS develop
all terminals, with some showers possibly in the vicinity of KCRP
overnight. CIGS improve to VFR before by 17Z with potential for
some convection during the afternoon again. For now, put in VCTS
at KALI and KLRD during the afternoon with much uncertainty
elsewhere. Less winds and more easterly in the forecast for
tonight and Monday outside of convection.

PREVIOUS DISCUSSION... /Issued 401 PM CDT Sun May 20 2018/

SHORT TERM (Tonight through Monday night)...

Main forecast concern is thunderstorm potential this afternoon and
evening. Convection associated with outflow boundary to the north
will slowly approach the northwest and northern parts of the region
over the next several hours. HRRR runs over the last few hours
support this, and actually bring this area of showers and storms
near the coast later this evening. MLCAPE values remain around
2000 J/kj at this time with little to no capping across South
Texas. Strong storms will be possible as this activity moves into
the area late this afternoon and early evening with primary
threats of gusty winds and small hail. An isolated severe storm or
two is not completely out of the question either. Some moderate
to heavy rains may also occur with PW values around 1.7 to 1.8
inches.

This area of showers and storms should slowly moves to the
south and east tonight. Confidence is not that great of any
redevelopment, but sufficient moisture lingering around will
warrant low pops through 12z. Overnight lows will generally be in
the lower to middle 70s inland with upper 70s along the coast.

Any remnant boundaries coupled with an approaching upper level
disturbance may result in isolated to scattered storms on Monday.
Will continue with 30 to 40 pops, with best chances along the Rio
Grande and western Brush Country. Highs tomorrow will be in the
upper 80s to low 90s.

LONG TERM (Tuesday through Sunday)...

Ridging pattern will develop overhead on Tuesday. Sufficient moisture
along the coast may allow for isolated showers or storms to develop
and stream onshore throughout the day on Tuesday.  Drier air will
then push into the region Wednesday, with below normal moisture and
dry conditions persisting into late in the week as mid/upper level
ridging remains set overhead.  A warming trend will continue through
the week, with highs back near 100 degrees across the Brush Country
and in the mid to upper 90s to the east by the end of the week. Over
the weekend the upper level ridge will shift further to the west as
a trough axis develops to the east of the region.  Slightly higher
moisture creeping into the coastal areas and less suppressive
conditions aloft may allow for some isolated coastal convection to
pop up again by the weekend.  However, most locations will remain
dry at the time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    74  88  73  90  73  /  60  30  10  20  10
Victoria          72  90  70  91  70  /  50  30  10  20  10
Laredo            75  92  74  94  74  /  20  40  10  10  10
Alice             73  91  71  93  71  /  60  30  10  10  10
Rockport          77  86  76  88  76  /  50  30  10  20  10
Cotulla           71  92  71  94  72  /  20  40  10  10  10
Kingsville        74  92  72  93  73  /  70  30  10  20  10
Navy Corpus       78  86  78  88  77  /  40  30  10  20  10

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.

&&

$$

GW/86...SHORT TERM


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