Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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FXUS64 KCRP 230510
AFDCRP

Area Forecast Discussion
National Weather Service Corpus Christi TX
1110 PM CST Thu Feb 22 2018

.DISCUSSION...

Warm front sitting off the Middle Texas Coast but has moved into
Matagorda County. Areas of fog continue to be a concern over the
nearshore waters and northern bays as visibilities remain less
than one-mile. Stalled front south of Matagorda County may start
to move towards our coastline as a warm front over the next few
hours but may take most of the night to see onshore winds develop
closer to the coast.

Farther west across the Rio Grande Plains a mid-level shortwave
trough of low pressure is moving through. Showers and
thunderstorms are developing ahead of this impulse tapping into
elevated instability. We continue the isolated thunderstorm
wording tonight across this region as the area of storms will
should continue to move northeastward through the Brush Country.
Mostly a fog/drizzle overnight period is expected across the
Coastal Plains and Coastal Bend.

Update for 06Z aviation cycle below.

&&

.AVIATION...

Overall, very little change from the previous TAF cycle.

Tonight...IFR/LIFR. Conditions will remain pretty much unchanged
from where they are currently. Some patchy fog and drizzle will
keep VSBYS lower tonight under light northerly winds. An area of
showers is expected to move out of Mexico later this evening and
could impact KLRD. High confidence overall.

Friday...Improving to MVFR late day. Will still have to contend
with LIFR/IFR for much of the morning and possibly early afternoon
before CIGS gradually lift towards MVFR late in the cycle. Warm
front is expected to shift through the region but could get hung
up to the east of KLRD. Southeasterly winds will develop behind
the front and conditions should gradually improve to MVFR.
Expecting conditions to worsen back to IFR by late evening. Medium
to high confidence overall.

&&

PREVIOUS DISCUSSION... /Issued 402 PM CST Thu Feb 22 2018/

SHORT TERM (Tonight through Friday night)...

Satellite imagery shows the front stationary over the coastal
waters from 20 nm southeast of Port o`Connor to about 50 nm east
of Baffin Bay. Still prefer the NAM/ARW handling of the front and
the shallow cold air mass in place. Expect the frontal boundary
will begin drifting back toward the coast later tonight and should
be near the coast around 15Z Friday. Areas of fog will occur over
the coastal plains this evening and push inland into the Brush
Country overnight. The warm front will quickly move inland
through the coastal plains during the morning but may have a
difficult time retreating through all of the Brush Country. NAM
continues to show the warm front not reaching I-35 with highs only
in the lower 60s. Will show the front passing through Laredo and
Cotulla similar to the ARW.

An upper level disturbance was moving northeast over central
Mexico where thunderstorms have formed over southern Coahuila.
This short wave trough will move northeast through the Brush
Country tonight. Expect shower activity will increase during the
evening hours as this short wave trough approaches and low level
warm air advection strengthens. Mid level instability associated
with this feature will lead to a chance of thunderstorms over the
Brush Country later tonight.

Isentropic lift will keep a threat of showers during the morning
hours over the Brush Country but rain chances will diminish by the
afternoon as the warm front moves inland. A weaker short wave
trough should move northeast out of Mexico into the Brush Country
Friday night to provide another chance for showers.

MARINE...Will continue the Dense Fog Advisory for the near shore
waters and the bays north of Port Aransas through 12Z Friday.
Could possibly have issued it for the southern offshore waters as
the front has pushed a little more offshore. But expect the front
will begin to drift back toward the coast and out of this marine
zone.

LONG TERM (Saturday through Thursday)...

Warm front will be pushing west on Saturday but there remains some
question how far into Webb/LaSalle counties it gets before next cool
front pushes back in.  The NAM, which has handled this arctic
airmass far better than other guidance, suggests the warm surge
stops near or even east of I-35.  This seems reasonable, and after
coordination with EWX have lowered highs considerable far west.
Otherwise the CWA will spend most of Saturday in the warm sector and
isolated convection should dvlp north as boundary pushes thru later
in the aftn.

Cool front pushes east Saturday Night.  The post-frontal airmass
will really just be a modified version of the cool airmass currently
over the region.  This means Sunday will likely be another cool
cloudy day and as post-frontal isentropic lift kicks in we should
see decent cvrg of light rain over the east.  Will cap PoPs at 50%
now but these may need raised later.  A slow warmup will then begin
through mid-week as southerly flow returns.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    54  76  68  84  61  /  20  10  10  10  30
Victoria          51  77  67  82  56  /  30  20  20  20  30
Laredo            53  72  66  79  59  /  70  30  30  10  20
Alice             54  78  67  88  61  /  30  20  10  10  30
Rockport          55  71  68  78  60  /  20  10  10  20  30
Cotulla           51  69  63  71  53  /  70  40  40  10  10
Kingsville        54  77  68  87  62  /  20  10  10  10  30
Navy Corpus       56  71  69  81  61  /  20  10  10  10  30

&&

.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Dense Fog Advisory until 6 AM CST Friday For the following
     zones: 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.

&&

$$

GH/77...AVIATION



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