Area Forecast Discussion
Issued by NWS Corpus Christi, TX

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000
FXUS64 KCRP 211724
AFDCRP

Area Forecast Discussion
National Weather Service Corpus Christi TX
1224 PM CDT Sat Apr 21 2018

.DISCUSSION...

See aviation discussion below for the 18Z TAFs.

&&

.AVIATION...

A mix of VFR and MVFR cigs can be expected through this afternoon,
then becoming more predominantly MVFR this evening. The exception
is LRD where cigs are expected to be mostly VFR through the TAF
period. Isolated to scattered showers and a few thunderstorms will
be possible across S TX this afternoon, mainly east of highway 16
with the best chc across the VCT area. Sfc winds will be light and
variable across the LRD area this afternoon as an inverted
trough moves eastward into the area. Farther east, winds will
remain S to SE with gusts up to around 25kt, especially closer to
the coast. A cold front is expected to move south through the area
overnight bringing another round of light showers and shifting
winds to the north and strengthening to mod levels. VFR condtiions
are expected across S TX in the wake of the front by mid morning
Sunday.

&&

.PREVIOUS DISCUSSION... /Issued 852 AM CDT Sat Apr 21 2018/

DISCUSSION...

See marine discussion below for latest updates.

MARINE...

Have expanded the slight chance of TSRA`s across the waters for
this morning. Ongoing TSRA`s are moving toward the waters and
meso-scale models show this area of rain moving northeast toward
HGX`s area through the remainder of the morning hours.

PREVIOUS DISCUSSION... /Issued 643 AM CDT Sat Apr 21 2018/

DISCUSSION...As of 1130z, elevated convection persists across the
Brush Country. DPVA associated with a rather potent H5 s/w trough
advecting across Coahuila MX is aiding in convective development
this morning...with the ongoing convection located in an area of
high MUCAPE (latest NAM progs MUCAPE values around 1500 j/kg) as
well as being located on the eastern edge of an area of higher
sfc-6km and especially sfc-8km deep layer shear values.
Convection should gradually diminish over the next couple of hours
as it moves into an area of lower MUCAPE and as the
aforementioned mid level disturbance shifts a little NNErly. Have
increased POPs slightly for this morning across the Brush Country
with this update.

PREVIOUS DISCUSSION... /Issued 608 AM CDT Sat Apr 21 2018/

DISCUSSION...Update for 12z Aviation.

AVIATION...Convection vcnty of KLRD (as of writing) should shift
east early in the TAF period and may diminish or dissipate before
reaching KALI. Aside from brief period of early mrng
convection...iso to sct SHRA and additional iso TSRA will be
possible today across S TX. MVFR CIGs will prevail for much of the
day...though KLRD may clear out some this aftn. Period of low end
MVFR/upper end IFR and reductions in VSBYs possible this evening
and overnight across KCRP/KVCT/KALI as sfc winds calm ahead of a
cold front. FROPA xpctd to occur from N to S late in the night
with a thin band of SHRA/Iso TSRA possible across KVCT and KCRP.
ESErly sfc winds today become breezy at times across KCRP to KVCT.

PREVIOUS DISCUSSION... /Issued 518 AM CDT Sat Apr 21 2018/

DISCUSSION...Will be increasing POPs for rest of tonight and
early Saturday for the W Brush Country. Convection has rapidly
developed just west of Laredo over the last hour. Mesoanalysis
indicates an H5 s/w trough advecting east across Coahuila MX with
an axis of deeper moisture draped along the Rio Grande.
Combination of these factors are leading to some elevated
convection along the Rio Grande...which may persist for a few
hours. Only guidance that seems to be picking up on this is the
06z NAM. Will lean near term forecast towards that guidance suite.

PREVIOUS DISCUSSION... /Issued 424 AM CDT Sat Apr 21 2018/

SHORT TERM (Today through Sunday)...

WAA has been trying to strengthen overnight...but pooling of LLVL
moisture may still be lacking some. The KCRP WSR 88D VAD wind
profile is indicating a southerly LLJ of 40 to 45 kts...but this
may be overestimating a bit as the radar may be detecting the
spring avian migration (per reflectivity imagery as of writing).
Regardless...the llvl flow aloft is rather southerly and we need
it to become SSE or SErly to get better llvl moisture advection.

For this morning...it`s currently appearing less and less likely
that we will see much in the way of precip. Guidance continues to
insist that we will see a notable increase in moisture levels in
the sfc-H7 layer this morning...which may still happen. However,
the LLJ is prog to maintain itself across the Coastal Plains for
much of the day which should result in too much in the way of
diurnal mixing/breezy conditions to allow much in the way of
showers to develop/maintain themselves. Have lowered POPs for this
morning, as a result. While an isolated shower may still occur
today...slightly better chances may exist across the western
Coastal Plains where the LLJ will be weaker...and across the
Victoria area where moisture depth will be the greatest. Even
there...chances are not all that great. For the afternoon, shower
activity may increase slightly across the NE Brush Country and
towards Beeville and Goliad...to perhaps Victoria...as a modest
increase in instability occurs. However...a strong EML around H7
should preclude much, if any, thunderstorms from occurring.
Caveat to this is if more sunshine than expected occurs this
afternoon across S TX...which would result in greater instability
and better chances of lifting parcels above the EML. Only the 00z
ECMWF is indicating this potential (and to an extent, the CMC).
Aside from precip chances...breezy conditions are likely across
the eastern third of the CWA where the core of the LLJ is prog to
exist...while light winds occur across the Brush Country as a sfc
dryline tries to shift east out of MX. Cloud cover should keep
temps at or slightly below normal today across much of the area
(except along the Rio Grande).

Most areas should be dry this evening (aside from a lingering
shower across the Victoria area). Significantly drier air aloft is
prog to spread across the region by mid to late evening as a
strong mid level trough to our north shifts east. With drier air
spreading over the moist lower levels, some fog may occur by
mid/late evening across inland areas...if sfc winds can decrease
enough. Overnight...a cold front will approach the area from the
north. Guidance indicates a vort max may wrap around the
aforementioned trough/low late in the night which may aid in a
thin band of showers and isolated thunderstorms to develop along
the front as it pushes across the Victoria area and down the
coast. Most areas tonight, however, will still remain dry.

A drier airmass will spread south across the region on Sunday
with northerly flow prevailing. Despite northerly flow...the drier
air will allow for stronger warming and thus max temps on Sunday
may be a few degrees warmer than today`s max temps.

LONG TERM...(Sunday night through Friday)...

Progressive pattern will continue for much of next week with a
series of upper troughs moving across the central part of the
country. To begin the period, upper low will slowly shift into the
Mid-South, leaving weak ridging to zonal flow across South Texas
Monday into Tuesday. Another upper level system will then dive
southeast of the northern and central Plains heading into Wednesday.
The associated cold front will be approaching the region Wednesday
evening. However, models have been inconsistent with precip chances
with this boundary. For consistency sake, will keep pops below
mentionable levels for now. A potentially stronger front may move
through South Texas at the end of the forecast period. Latest
guidance has come in wetter for the end of the week, but confidence
is not high enough to mention showers and storms just yet. If these
trends continue, then rain chances will likely need to be introduced
for Friday.

Regarding temperatures, it will be warm throughout the week under
partly to mostly cloudy skies. Highs will primarily be in the upper
70s over the northern Coastal Bend with 80s for the remainder of the
area. The warmest days of the week will be Tuesday into Wednesday as
highs may approach 90 degrees over the Rio Grande Plains.

&&

.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi    81  66  84  60  82  /  20  20  10  10   0
Victoria          78  61  80  55  81  /  40  30   0   0   0
Laredo            86  65  87  64  86  /  30  10   0  10  10
Alice             81  64  86  59  85  /  20  10  10  10  10
Rockport          79  65  80  62  79  /  20  30   0   0   0
Cotulla           83  59  83  58  86  /  20  10   0   0  10
Kingsville        82  67  86  60  84  /  10  10  10  10  10
Navy Corpus       79  68  81  65  78  /  20  20  10  10   0

&&

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

&&

$$

TE/81...AVIATION



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