Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 231035
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
535 AM CDT SAT JUL 23 2016

.AVIATION...
Patchy areas of stratus with MVFR CIGs are expected east of a KCOT
to KUVA to KAQO line early this morning and late tonight into
early Sunday morning. For KAUS/KSAT/KSSF, will go TEMPOs MVFR CIGs
12Z-14Z and 24/10Z-14Z. Otherwise, VFR skies prevail today through
Sunday morning. S to SE winds 4 to 14 KTS prevail with highest
speeds afternoon into evening hours along with gusts up to 24 KTS
possible.

&&

.PREV DISCUSSION... /ISSUED 422 AM CDT SAT JUL 23 2016/

SHORT TERM (Today through Sunday)...
Water vapor imagery shows that the mid-to-upper ridge that has
been centered over Oklahoma for the past few days is beginning to
retrograde back to the west towards New Mexico. However, midlevel
subsidence from this ridge will be enough to suppress any deep
convection from moving into the Coastal Plains this afternoon,
with hi-res models only showing very isolated light showers. Thus,
any mention of thunderstorms has been removed from the forecast
for today with high temperatures being similar to yesterday in
the upper 90s and lower 100s. Heat indices will rise into the 105
to 108 range along and east of I-35 a few hours this afternoon.

The ridge over New Mexico and midlevel inversion over the Coastal
Plains will weaken further on Sunday, which coupled with a more
active sea breeze, will allow isolated showers and thunderstorms
to occur in the Coastal Plains. In addition, a weak meso low at
midlevels (and upper level anticyclone) currently over Western
Tennessee will slide southwest into Louisiana and northeast Texas
by Sunday. Weak PVA from this subtle midlevel feature may provide
additional encouragement for storms to form in the Coastal Plains,
though it should have a greater effect on Monday. Dry, but humid
weather will prevail elsewhere on Sunday which should be the last
day with sweltering heat and widespread lower 100s of the period.
Increasing moisture beneath a capped boundary layer that may take
some time to mix out will cause the highest heat indices of the
period with more widespread 105 to 108 values and perhaps a few
spots in the Coastal Plains above 108 for a few hours.

LONG TERM (Sunday Night through Friday)...
Dynamic and numerical model guidance along with climatological
analogs continue to point towards a wetter first half of next
week. Thus, confidence is increasing that a healthy portion of
South Central Texas may get some measurable rainfall averaging
around a tenth to quarter of an inch with some locally heavier
amounts of 1-2 inches. As the ridge continues to weaken and
retrograde west towards Nevada to remove our subsidence inversion
aloft, two disturbances will help supply some dynamic forcing
while precipitable water values surge towards 2 inches and the sea
breeze provides some surface forcing in the Coastal Plains. The
first of these disturbances will be the aforementioned weak trough
that will move into the region from northeast Texas on Monday.
Isolated to scattered convection should form on Monday afternoon,
with the greatest chances in the Coastal Plains in closer
proximity to surface forcing from the sea breeze.

The second of these disturbances will be a broader inverted
trough currently taking shape off the coast of Georgia in the
Atlantic. This inverted trough is forecast to track west along
the Gulf Coast early in the work week and increase rain chances
across South Central Texas for Tuesday and Wednesday. The ECMWF
has merged towards the GFS in highlighting Tuesday as the day with
the best rain chances as isolated to scattered showers and
thunderstorms will be possible across the entire region due to
dynamic forcing from the trough. Storm coverage should decrease
slightly on Wednesday as the inverted trough continues tracking
towards west Texas, but still support at least isolated storm
coverage across the entire region. Any outflow boundaries and
circulations that are leftover from the previous day`s convection
will also help focus convection on Tuesday and Wednesday. The
coolest temperatures of the month should happen on Tuesday, with
highs in the lower to mid 90s across most of the region.

Rain chances should end by Thursday morning as the inverted
trough exits the region. The forecast past this point is a bit
murky as a subtropical ridge tries to form over the Louisiana Gulf
Coast towards next weekend, but a shortwave over the Midwest tries
to drag a weak front and convection towards Oklahoma. It is still
too early to tell which will win out, but climatology would
suggest that the ridging would be more likely. Thus, the forecast
for Thursday and Friday trends towards dry weather and warmer
temperatures, though not quite as warm as this weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry             101  78 101  78  98 /  -   -   10  10  20
Austin Bergstrom Intl Airport 100  76 100  75  98 /  -   -   10  10  20
New Braunfels Muni Airport    100  76 101  76  98 /  -   -   10  -   20
Burnet Muni Airport            98  76  99  76  96 /  -   -   10  10  20
Del Rio Intl Airport          103  79 103  79 101 /   0   0  -   -   10
Georgetown Muni Airport        99  78  99  78  96 /  -   -   10  10  20
Hondo Muni Airport             99  76 100  76  99 /  -   -   -   -   10
San Marcos Muni Airport        99  76 100  76  98 /  -   -   10  -   20
La Grange - Fayette Regional  100  77 100  77  95 /  10  10  20  10  30
San Antonio Intl Airport       99  78  99  78  97 /  -   -   10  -   20
Stinson Muni Airport          102  78 102  78  99 /  -   -   10  -   20

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Mesoscale/Aviation...04
Synoptic/Grids...LH



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