Special Weather Statement, NWS Corpus Christi, TX

Area Forecast Discussion
National Weather Service Corpus Christi TX
625 PM CDT Wed Aug 4 2021

.AVIATION...

/00Z TAFs/ Iso-sct convection to continue through the early
evening before diminishing slightly, mainly impacting LRD-COT but
also briefly at ALI-VCT. Lingering boundaries and sufficient
moisture will lead to on-off rounds of showers/thunderstorms after
midnight through the end of the TAF period. Pinpointing exact
locations will be difficult due to the amount of left-over
boundaries. Light winds are expected through the period ranging
from the NE to SE, but within any showers or storms winds may
become gusty to around 25 KTs. Mostly VFR through the period
except for the potential of MVFR conditions within any
showers/storms.

&&

.PREV DISCUSSION... /Issued 404 PM CDT Wed Aug 4 2021/

SHORT TERM (Tonight through Thursday Night)...

Let's start off with mentioning the high uncertainty in regards to
location of precipitation. The weakening frontal boundary has
meandered over South Texas through the day while interacting with
the afternoon sea breeze and outflow boundaries from showers/storms.
Right now, convection is focused over the Brush Country where LAPS
is showing sufficient surface moisture convergence with CAPE values
well over 3000 J/kg and minimal CINH. Expect scattered convection
development on and off tonight as pop-up thunderstorms stabilize the
near-surface environment with interactions of foreign boundaries
intervene to produce more convection.

Guidances, including CAM models, have not been doing well at
resolving where convection develops, nor the timing. It's important
to note that the ingredients are there; we have some sort of frontal
boundary (decaying or not), moisture convergence, significant
instability, outflow boundaries, greater than 75th percentile PWATs
(2.0-2.4"), and a surface to mid-level trough extending from Mexico
into the Rio Grande Plains. In addition, model soundings still
indicate a heavy rainfall and localized flash flooding threat, with
significant PWATs and slow cloud layer mind wind. The WPC ERO has
most of the CWA in a marginal risk for the rest of today through
Thursday as 1-hr Flash Flood Guidance has lowered to 2.0" to 3.0"
over the western portion of the CWA where soils are already moist
from previous rainfall. Believe the greatest coverage of activity
will take place over the western portion of the CWA tonight, then
expand further over the Coastal Plains and Victoria Crossroads
through Thursday morning.

From the day on Thursday through Thursday night, a deep narrow mid
to upper level trough will pass through Texas, with the axis
extending into South Texas. This feature will support areas of
diffluence aloft and positive vorticity to keep scattered showers
and thunderstorms throughout South Texas all day Thursday. Decreased
coverage to isolated to scattered coverage Thursday night heading
into the long-term period due to a weakening frontal boundary. But
it is worth noting that a few CAM models (although haven't been
performing well) keep the western portion of the CWA rather active.

Seasonal normal lows in the mid to upper 70s are expected tonight
and Thursday night with highs ranging from the upper 80s near the
Victoria Crossroads to the mid 90s south on Thursday. High dewpoints
will cause maximum heat indices to exceed 105 across portions of the
inland Coastal Bend and Coastal Plains. Due to weak winds at the low-
levels, it's worth mentioning the possibility of waterspouts in a
few storms that develop over the Coastal Waters.

LONG TERM (Friday through Wednesday)...

The period begins with the upper level trough exiting the state to
the east and ridging building behind it. Drier conditions will then
be in store for most of the forecast period as high pressure takes
over aloft and at the surface. But, scattered showers and storms
will remain possible on Friday as plentiful moisture stays in place
(PWATs around 2") and with another weak mid-level disturbance
tracking across. By Saturday and through the rest of the period,
convective activity will be isolated and mostly diurnally driven
each day, with the highest rain chances expected across the Victoria
Crossroads where the capping inversion will be weakest. Another weak
upper trough is progged to dip into the region early next week, but
is rapidly taken over by the ridge, therefore not anticipating it
causing much trouble. The drier and relatively quiet overall
conditions expected throughout the long-term will lead to a warming
trend into next week. Heat indices may approach SPS or advisory
levels daily Saturday through Wednesday. Highs will generally be in
the 90s to lower 100s, with overnight lows in the mid 70s to lower
80s area wide.

MARINE...

A weak nearly stationary frontal boundary will combine with copious
moisture and generate scattered showers and thunderstorms tonight
through Thursday night. The boundary is expected to retreat
northward or fizzle out through the day. A weak upper trough of low
pressure will contribute to scattered showers and thunderstorms
Thursday. Winds will generally remain weak out of the south to
southeast tonight through Thursday night. Can't exclude the
possibility of waterspouts with a few storms as winds are relatively
weak through the low-levels. A weak to moderate onshore flow can
be expected Friday through Saturday, becoming moderate Saturday
night and Sunday. Periods of moderate onshore flow will continue
into early next week, with Small Craft Exercise Caution conditions
possible through Monday night. Isolated to scattered showers and
thunderstorms are expected Friday, becoming isolated over the
weekend and into early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    76  91  76  92  77  /  40  50  30  30  10
Victoria          75  88  75  92  76  /  30  60  40  40  10
Laredo            76  93  76  95  77  /  50  40  40  20   0
Alice             75  93  75  94  74  /  40  50  40  30  10
Rockport          78  89  79  90  81  /  40  50  30  40  10
Cotulla           76  91  75  94  76  /  50  50  50  30  10
Kingsville        76  93  76  94  76  /  40  40  40  30   0
Navy Corpus       80  90  81  90  82  /  40  50  30  30  10

&&

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

&&

CB/85...AVIATION

Hazardous Weather Outlook
National Weather Service Corpus Christi TX
1039 AM CDT Wed Aug 4 2021

TXZ229>234-239>247-342>347-442-443-447-051545-
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-
1039 AM CDT Wed Aug 4 2021

This hazardous weather outlook is for South Texas.

.DAY ONE...Today and Tonight

Scattered thunderstorms today and tonight. Locally heavy rainfall
possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Maximum Heat Index values at least 105 to 109 degrees expected
Thursday through the weekend and into next week. Heat Advisory
conditions are possible Saturday through Tuesday across portions of
South Texas as Maximum Heat Index values may exceed 110 degrees.

Scattered thunderstorms are expected Thursday, becoming isolated to
scattered on Friday. Isolated thunderstorms confined to the
northeastern portions of South Texas Saturday through Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

GMZ230-235-250-255-270-275-051545-
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-
1039 AM CDT Wed Aug 4 2021

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

.DAY ONE...Today and Tonight

Scattered thunderstorms today and tonight. Locally heavy rainfall
possible.

Waterspouts are possible through this afternoon over the northern
Coastal Waters.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Scattered thunderstorms expected Thursday, becoming isolated to
scattered on Friday. Isolated thunderstorms Saturday through
Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

EMF

Special Weather Statement
National Weather Service Corpus Christi TX
829 PM CDT Wed Aug 4 2021

TXZ240-050200-
Duval-
829 PM CDT Wed Aug 4 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN DUVAL COUNTY...

At 829 PM CDT, a strong thunderstorm was located over Freer, moving
northeast at 20 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Freer.

This includes US Highway 59 between mile markers 760 and 778.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 2773 9868 2781 9880 2804 9873 2803 9858
      2789 9843
TIME...MOT...LOC 0129Z 219DEG 18KT 2786 9864

CB

Special Weather Statement
National Weather Service Corpus Christi TX
125 AM CDT Thu Aug 5 2021

TXZ239-050700-
Webb-
125 AM CDT Thu Aug 5 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN WEBB COUNTY...

At 125 AM CDT, a strong thunderstorm was located near Chupadera Ranch
Airport, or 26 miles southeast of El Indio, moving northwest at 10
mph.

Winds in excess of 30 mph and half inch hail are possible with this
storm.

Locations impacted include...
Chupadera Ranch Airport.

LAT...LON 2820 10003 2816 10000 2811 10006 2812 10007
      2815 10009 2816 10012 2817 10014 2817 10016
      2819 10018 2819 10021 2820 10021
TIME...MOT...LOC 0625Z 135DEG 11KT 2815 10013

87