Severe Thunderstorm Warning 33, NWS Corpus Christi, TX

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
937 PM CDT Fri May 15 2020

.DISCUSSION...

A Severe Thunderstorm Watch has been issued for South Texas until
4 AM CDT Saturday. The atmosphere is unstable and conducive for
severe thunderstorms to develop tonight through early Sat morning.
The storms are expected to move in an easterly as an upper level
low tracks northeast across the region. Damaging wind and large
hail are the primary threats, although a tornado can not be ruled
out. Updates have been issued.

&&

.PREV DISCUSSION... /Issued 703 PM CDT Fri May 15 2020/

DISCUSSION...

Updated for 00Z aviation discussion.

Expect convection to develop and push across the area through the
late evening and overnight hours. Much of the guidance pushes
things rather quickly across the area to the coast by around 12Z
Saturday with some convection lingering along the coast
thereafter. Gusty winds are likely with showers and thunderstorms.
Confidence is lower in what happens during the day tomorrow with
some chance for convection to continue along the coast, but a
majority of guidance will push it through as the upper level
system supporting it moves off to the northeast. VFR conditions
this evening will become MVFR to potentially IFR in thunderstorms
through the night, improving to VFR west during the day Saturday,
but MVFR east.

AVIATION...

PREV DISCUSSION... /Issued 309 PM CDT Fri May 15 2020/

SHORT TERM (Tonight through Saturday night)...

Onshore flow continues to stream moisture into the area this
afternoon. An upper level jet streak over the Brush Country by this
afternoon will provide an area of lift that could result in some
isolated showers and thunderstorms. By this evening, showers and
thunderstorms will become more widespread as a shortwave trough that
is transitioning to a low over west Texas interacts with a dryline
to produce a line of showers and thunderstorms that will push across
the area. Model timing has been inconsistent, but have generally
come into agreement that storms should enter the western portions of
the CWA around 02Z. PWATs of 1.7 to near 2 inches and CAPE values
3000-4000 J/kg will lead to some strong to severe thunderstorms
tonight through tomorrow morning. SPC has an Enhanced risk just
clipping our northwest counties, a Slight risk over the Brush
Country and most of the Coastal Bend, and a Marginal Risk along our
immediate coast. With the dryline activity, we expect cold pools to
form, leading to strong wind gusts. With the high atmospheric
moisture, we can also expect heavy rainfall. WPC has put the Brush
Country in a Slight risk for Excessive Rainfall. Localized flooding
will be possible in any storm.

Severe weather should taper off by morning, with general thunder and
showers continuing, though flash flooding risks will continue
through Saturday afternoon. Another round of showers and
thunderstorms could form Saturday afternoon. Models again differ on
timing and location. Some models, like the TTU-WRF, initiate an
east/west oriented axis of showers and thunderstorms near the
EWX/CRP border, while others (the HRRR, for example) initiate the
storms further south. Flash flood risks on Saturday will be
determined by the development of this second band of showers.

Rain chances will begin to diminish Saturday afternoon and evening
as the associated low pressure moves east into the ArkLaTex area,
with most of the rain moving over the offshore waters.

A HIGH risk for rip currents will continue through Saturday night.

LONG TERM (Sunday through Friday)...

Primary change in the extended was the removal of rain chances for
Monday and Tuesday due to drier model trends and consensus from
neighboring offices. Otherwise, the overall pattern change remains
on track as an upper low departs East TX on Sunday ahead of a stout
upper ridge building throughout the Great Plains Monday and Tuesday.
However, a lingering upper trough behind the low (and perhaps a weak
cold front/light NE wind shift) should serve as another impetus for
additional storms on Sunday before PWATs dry out to 3/4" or less
early next week. By late week, models agree in shifting the ridge
axis northeast of the region which could open up an unsettled
westerly flow regime. How much this transition supports measurable
rain is too uncertain at this time, particularly given PWAT deficits
from earlier in the week, so PoPs were kept silent for now. Temps
meanwhile should hold within a couple degrees of normal most days
throughout the region.

MARINE...

Strengthening onshore flow will continue to cause some building seas
this evening. Seas could reach to 5 to 7 feet by Saturday morning. A
Small Craft Advisory is possible, though have elected to wait on
issuing due to timing issues. Widespread showers and thunderstorms
are expected late tonight and through Saturday, before decreasing
Saturday night. Mariners should use caution if operating in
thunderstorms. Gusty winds, dangerous lightning, and quickly
changing sea states could cause hazardous conditions through
Saturday. Generally weak onshore to occasionally northeast flow
will persist through the middle of next week. Isolated to
scattered showers and storms remain possible on Sunday before high
pressure builds aloft early next week ahead of drier conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    74  84  73  88  71  /  80  80  20  20  10
Victoria          71  81  71  86  70  /  80  80  30  30  10
Laredo            73  91  75  94  73  /  70  30  10  10  10
Alice             72  88  71  91  70  /  80  60  20  20  10
Rockport          74  81  75  86  73  /  90  80  30  30  10
Cotulla           69  90  71  93  71  /  80  30  10  10  10
Kingsville        74  86  72  90  71  /  80  60  20  20  10
Navy Corpus       75  81  75  84  74  /  80  80  30  30  10

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 4 AM CDT Saturday For the following
     zones: Aransas Islands...Calhoun Islands...Kleberg
     Islands...Nueces Islands.

GM...None.

&&

TE/81...SHORT TERM

Hazardous Weather Outlook...UPDATED
National Weather Service Corpus Christi TX
943 PM CDT Fri May 15 2020

TXZ229>234-239>247-342>347-442-443-447-170245-
La Salle-McMullen-Live Oak-Bee-Goliad-Victoria-Webb-Duval-
Jim Wells-Inland Kleberg-Inland Nueces-Inland San Patricio-
Coastal Aransas-Inland Refugio-Inland Calhoun-Coastal Kleberg-
Coastal Nueces-Coastal San Patricio-Aransas Islands-
Coastal Refugio-Coastal Calhoun-Kleberg Islands-Nueces Islands-
Calhoun Islands-
943 PM CDT Fri May 15 2020

This hazardous weather outlook is for South Texas.

.DAY ONE...Tonight

A Severe Thunderstorm Watch has been issued for South Texas until
4 AM CDT.

Scattered to numerous thunderstorms will move across South Texas
tonight. Large hail and damaging wind will be the primary threat,
however a tornado can not be ruled out.

A Slight Risk for excessive rainfall is in place for
northern portions of south Texas tonight.

There is a high risk of rip currents for Gulf-facing beaches
tonight.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

There is a High Risk for rip currents Saturday.

Scattered to numerous thunderstorms are expected Saturday over South
Texas.

Heavy rainfall may occur South Texas tonight and Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to relay reports of severe
weather and flooding while following local, state, and CDC
guidelines. Use hashtags #ccspotter and #txwx

GMZ230-235-250-255-270-275-170245-
Bays and Waterways from Baffin Bay to Port Aransas-
Bays and Waterways from Port Aransas to Port O'Connor-
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-
943 PM CDT Fri May 15 2020

This hazardous weather outlook is for the Middle Texas
Coastal Waters.

.DAY ONE...Tonight

 Severe Thunderstorm Watch has been issued for the bays and
nearshore waters until 4 AM CDT.

Scattered to numerous thunderstorms will move across the region
tonight. Large hail and damaging wind will be the primary threat,
however a tornado or waterspout can not be ruled out.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Scattered to numerous thunderstorms are expected Saturday, with
scattered thunderstorms Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to relay reports of severe
weather while following local, state, and CDC guidelines. Use
hashtags #ccspotter and #txwx

TE