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

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571
FXUS64 KEWX 241150
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
650 AM CDT SUN JUL 24 2016

.AVIATION.../12Z TAFS/
Scattered to broken MVFR ceilings should continue along the I-35
corridor through 14Z before lifting to VFR for the rest of today.
Considering these broken MVFR ceilings should be intermittent,
have chosen to handle them with a TEMPO group while prevailing
scattered cloud decks for the I-35 TAF sites. Southerly winds will
become more southeasterly this afternoon sustained to 10 knots
with gusts up to 20 knots. Isolated showers and thunderstorms will
remain well east of I-35, but an upper level disturbance from the
east will increase rain chances for the I-35 TAF sites just beyond
the end of the period tomorrow afternoon.


&&

.PREV DISCUSSION... /ISSUED 358 AM CDT SUN JUL 24 2016/

SHORT TERM (Today through Monday)...
An earlier and more widespread return of stratus early this
morning indicates slowly increasing moisture across South Central
Texas. With the Subtropical Ridge nearby, similar high
temperatures as Saturday are expected. Dewpoints will not mix out
as efficiently making heat indices a degree or so higher. Values
of 105 to 108 are expected along and east of I-35, as well as in
few spots along the Rio Grande. A few spots near the Coastal
Plains will flirt with Heat Advisory Criteria with values of 108
to 110 for an hour or two. Will issue a Special Weather Statement
to cover this. Due to the increasing moisture, the seabreeze will
become more active with isolated showers and thunderstorms late
this afternoon into early evening near the Coastal Plains.

A significant change in the pattern develops on Monday as the
Subtropical Ridge erodes to the west allowing a weak upper level
trough currently over the lower Mississippi Valley to drift to the
southwest across Eastern Texas. An outflow boundary generated by
early in the day showers and thunderstorms will push into South
Central Texas during the afternoon. This boundary and solar
heating will interact with an increasingly moist airmass with PWS
approaching 2 inches to generate isolated to scattered showers and
thunderstorms across the Hill Country to along and east of US
Highway 281 as the afternoon progresses. The rains and increased
clouds will "cool" high temperatures slightly, except across the
Rio Grande Plains. Some heat indices in the 105 to 107 range are
still expected east of I-35 and across the Rio Grange Plains.

LONG TERM (Monday Night through Saturday)...
The former Mississippi Valley trough and the surface boundary
will drift across Central Texas into Mexico Monday Night into
Tuesday while an upper level trough currently over Florida moves
across the Gulf of Mexico and across Texas Tuesday night into
Wednesday. Moisture levels increase further with PWS in the 2 to
2.3 inch range. Expect most showers and thunderstorms to be driven
by additional surface boundaries, an enhanced seabreeze, and solar
heating with greatest areal coverage during the daytime hours of
Tuesday and Wednesday. Due to the higher PWS, some locally heavy
rains are expected with isolated rainfall amounts of 2 to 3 inches
possible. Weak shear and minor CAPE could allow for gusty winds
with the strongest storms. The showers and thunderstorms should
wane with loss of solar heating allowing coverage to become more
isolated at night. However, the ECMWF maintains upward forcing at
night as a weak upper level jet passes over our area and the low
level jet strengthens. For now, will side with the model consensus
and only go with slight chances, although the ECMWF would result
in higher chances at night. The former Florida trough moves off to
the west by Thursday with an upper level shear axis lingering over
Central Texas late this week into next weekend. Will introduce
slight chance POPS for Thursday and these may have to extended
into Friday and Saturday as the ECWMF keeps the trough in the
vicinity of the Big Bend while maintaining deeper moisture than
the model consensus. Daytime temperatures will actually be below
normal for most areas Tuesday and Wednesday due to clouds and
rain. The last time they were below normal was in early June.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry             101  79  99  76  93 /  -   -   30  20  50
Austin Bergstrom Intl Airport 100  77  98  75  92 /  -   -   30  20  50
New Braunfels Muni Airport    101  77  98  75  93 /   0  -   20  20  50
Burnet Muni Airport            99  76  96  75  90 /   0  -   30  20  50
Del Rio Intl Airport          103  80 102  79  95 /   0   0  10  20  40
Georgetown Muni Airport       100  78  96  75  91 /  -   -   30  20  50
Hondo Muni Airport            101  76 100  76  94 /   0   0  10  20  50
San Marcos Muni Airport       100  77  98  75  91 /  -   -   30  20  50
La Grange - Fayette Regional  100  77  97  76  93 /  10  10  40  20  50
San Antonio Intl Airport       99  78  98  77  93 /   0  -   20  20  50
Stinson Muni Airport          102  78 100  77  95 /   0  -   20  20  50

&&

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

$$

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



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