Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 211546 AAB
AFDCRP

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
1046 AM CDT Mon Jun 21 2021

.DISCUSSION...Mid level trough axis has moved into the Gulf waters
early this morning with drier air moving into the Brush Country
while high moisture remains along the coast. Subsidence behind the
mid level trough axis will limit convection this afternoon but
will keep slight chance of convection over the Mid-Coast region.
Stratus is lingering a bit over the region this morning especially
over the Brush Country. Adjusted sky cover to reflect more clouds
this morning. Still expect clouds to diminish from west to east
by early this afternoon. Dewpoints from 75-80 degrees across the
area. Still expect heat index values will become excessive for
the inland Coastal Bend to the Brush Country. Made no changes to
the current configuration of Excessive Heat Warning/Heat Advisory.

Will be looking over the 12Z model guidance for convective
forecast for tonight. Convection expected to form along the
frontal boundary from central Texas into the Hill Country this
afternoon will move south and could reach the area late this
evening depicted by the 12Z ARW and HRW NSSL models. With the
amount of instability in place across the region with MLCAPE
values from 2000-3000 J/kg, some of these storms will have the
potential for strong gusty winds. SPC morning outlook has a
Marginal risk of severe storms clipping the northern counties
of the forecast area.

&&

.MARINE...Moderate to strong onshore persists over the Gulf waters
this morning. Extended the SCA for the near shore waters until 18Z
and the offshore waters until 21Z.

&&

.PREV DISCUSSION... /Issued 637 AM CDT Mon Jun 21 2021/

AVIATION...

MVFR conditions across a majority of S TX this morning will
improve to VFR levels by mid to late morning. Mostly VFR
conditions will prevail this afternoon, then begin to lower once
again this evening to MVFR levels. Isolated showers or
thunderstorms continue across the northeast portions of S TX this
morning. Isolated convection will be possible through the day
across the VCT area. The chance for showers and thunderstorms
increase across S TX overnight in response to deep moisture and an
approaching frontal boundary. The convection is expected to become
scattered to numerous by early Tuesday morning. Brief periods of
IFR conditions will be possible in and near the convection.

PREV DISCUSSION... /Issued 417 AM CDT Mon Jun 21 2021/

SHORT TERM (Today through Tuesday)...

Today looks to be hot and humid, especially across the inland
Coastal Plains, Brush Country and Rio Grande Plains where an
Excessive Heat Warning is in effect due to heat indices expected to
be up to 115 degrees. Heat Advisory is in effect for the eastern
coastal counties, northern Coastal Bend and Victoria Crossroads
where heat indices are expected to be around 110. This is due to
dewpoints in the upper 70s to around 80 combined with high temps
this afternoon.

Otherwise, isolated showers and thunderstorms this morning will
continue across the coastal waters and along the coast up to the
Victoria Crossroads off and on through the day. Rain chances
increase through tonight as a weak frontal boundary moves southward
toward S TX and interacts with deep moisture across the area. PWATS
are progged to be around 2-2.2 inches along with CAPE values of 1800-
2600 J/kg. Models have been progging a mid level short wave and
associated MCS to develop over west TX and propagate southeast
along the Rio Grande tonight which could clip the northwest and
west portions of the CWA overnight. Over the remainder of the CWA,
the instability, moisture convergence along the frontal boundary
and a subtle weak upper disturbance will be conducive for
additional sct/num TSRAs overnight into early Tue. Some storms
could become strong with small hail and wind gusts up to 40 mph.

LONG TERM (Tuesday Night through Sunday)...

A weak surface boundary will sink into the area early in the short
term period approaching the coast by mid-day Tuesday. Ahead of the
front expect to see showers and thunderstorms develop within the
very moist airmass that has overtaken the region. PWATs on Sunday
evening sounding had reached 2.55"...nearly 3 standard deviations
above normal. Tuesday morning guidance suggests 2-2.25" PWAT values
over the area. Despite the morning timing, very high dpts and
quickly warming temps could result in sfc cape upwards of 2000 J/KG.
Some indications of higher than that. Winds shift east or northeast,
behind the front, and temps will be several degrees cooler than
today...though still in the 90s for most of the area.

As mid-level ridging builds temperatures will warm again mid to late
week. A few showers and thunderstorms will remain possible Tuesday
night into Wednesday before drier conditions return for the late
half of the week. By the weekend, another unseasonably deep mid-
level trough is forecast to develop. Another surge of moisture will
lead to more showers and thunderstorms for the weekend with a weak
boundary again approaching the area. Model consensus weakens this
boundary as it moves in.  Temperatures generally topping out around
100-103 west with 90s east daily. Heat index values will be 105-109
each day inland.

The potential for minor coastal flooding continues mid-week.

MARINE...

Moderate to strong onshore flow will continue this morning as
surface low pressure deepens over southwest Texas. The combination
of a weak upper level disturbance and copious moisture will
contribute to isolated to scattered showers and thunderstorms today,
then scattered to numerous tonight. The onshore flow will become
weak to moderate tonight as a frontal boundary moves into south-
central Texas and approaches South Texas. The weak frontal
boundary will drift into South Texas Tuesday morning leading to a
weak onshore winds. The onshore flow becomes moderate to strong by
the end of the week as low pressure strengthens in the Southern
Plains. Scattered thunderstorms will be possible Tuesday with
isolated showers and thunderstorms Tuesday night and Wednesday.
Isolated showers will be possible again by the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    94  80  91  78  92  /  20  60  60  20  20
Victoria          92  77  90  76  92  /  30  50  50  20  20
Laredo           104  79  95  78  99  /  10  40  40  20  20
Alice             97  77  92  76  95  /  10  50  60  20  20
Rockport          91  79  90  79  92  /  20  60  60  20  20
Cotulla          103  78  94  78 100  /  10  40  30  10  10
Kingsville        95  78  91  76  93  /  10  50  60  20  20
Navy Corpus       91  81  90  81  90  /  20  60  60  20  20

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening For the following
     zones: Bee...Coastal Kleberg...Coastal Nueces...Coastal
     Refugio...Coastal San Patricio...Goliad...Inland Calhoun...
     Inland Refugio...Inland San Patricio...Victoria.

     Excessive Heat Warning until 7 PM CDT this evening For the
     following zones: Duval...Inland Kleberg...Inland Nueces...
     Jim Wells...La Salle...Live Oak...McMullen...Webb.

GM...Small Craft Advisory until 4 PM CDT this afternoon 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 until 1 PM CDT this afternoon For the
     following zones: Coastal waters from Baffin Bay to Port
     Aransas out 20 NM...Coastal waters from Port Aransas to
     Matagorda Ship Channel out 20 NM.

&&

$$

TMT/89...SHORT TERM


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