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

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FXUS64 KEWX 191525
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1025 AM CDT Fri Jul 19 2019

.UPDATE...
Visible satellite has shown low clouds lifting and scattering this
morning with cloud streets having formed east of Interstate 35.
Current forecast appears largely on track, but have added a mention
of isolated rain showers to the Coastal Plains counties this
afternoon where slightly lower convective temperatures should allow
for a shower or two to develop mid to late afternoon. Heat will
continue to be the main hazard today with peak values topping out
between 105 and 110 this afternoon.

&&

.PREV DISCUSSION... /ISSUED 643 AM CDT Fri Jul 19 2019/

UPDATE...
Please see the 12Z aviation forecast discussion below.

AVIATION...
Low clouds continue to develop along the I-35 corridor this morning.
Cigs are primarily MVFR, although some IFR conditions will continue
at AUS through 13Z. Improvement is in store by mid morning as cigs
scatter/lift back to VFR around 14Z as SAT/SSF to around 15Z at AUS.
Will continue to only mention SCT clouds at DRT for a few hours this
morning as confidence is not high enough to go with any MVFR cigs.
Gusty south to southeast winds are in store for all sites during the
mid-morning through early evening hours. Another round of low clouds
are in store early Saturday morning.

PREV DISCUSSION... /ISSUED 343 AM CDT Fri Jul 19 2019/

SHORT TERM (Today through Saturday)...
The current weather pattern across the CONUS is characterized by very
weak mid level flow across the southern two thirds of the country,
with a large subtropical high parked over the region. A band of very
strong (abnormally strong for mid to late July) zonal west to east
flow at 500 mb is present from the Pacific NW all the way toward the
Great Lakes and into Ontario/Quebec.

Currently across the region, temperatures range from the mid 70s to
the mid 80s (DRT still at 85 as of 3 am) with southeasterly winds
and generally clear skies. A stratus deck is expected to develop in
the usual locations a bit later this morning before mixing out by mid
morning. Another hot afternoon is in store for South Central Texas
today, with highs ranging from the upper 90s to low 100s for most of
the region. Heat indices will max out in the 102 to 107 range this
afternoon. Breezy southeasterly winds are expected once more today,
with sustained winds up to 15 mph and gusts up to 25 mph this
afternoon. Tonight will again be a repeat of the previous night. Another
hot and dry day is expected for Saturday as the ridge of high
pressure continues overhead.

LONG TERM (Sunday through Thursday)...
The center of the subtropical high shifts toward the Four Corners
region on Sunday, which will amplify the mid level ridge across the
western CONUS. This will cause a few subtle changes for Sunday and
Monday, with high temperatures and heat indices perhaps a degree or
so cooler. This also may allow for an isolated sea breeze shower or
thunderstorm to develop across the far southeastern counties across
the Coastal Plains on Sunday and Monday afternoons.

A strong mid/upper level low will be centered over northern Quebec by
Monday, with an accompanying mid level trough in place from
Quebec/Ontario all the way south into the Ohio Valley. This trough
is expected to dig as far south as the LA/MS/AL Gulf Coast by
Tuesday, and will help drive a cold front into the region. Fairly
significant differences still remain between the GFS and the ECMWF in
how they handle the front and the effects thereof. The 00z GFS is
more progressive with the front, and indicates showers and
thunderstorms along and ahead of the front beginning on Tuesday
morning and ending precip rather quickly by Tuesday night as the
front makes it through to the Texas Gulf Coast and South Texas. The
00z ECMWF shows a slower progression of the front through the area,
with chances for showers/storms from Tuesday morning through
Wednesday night. Thus, the ECMWF is a bit more bullish on total
rainfall amounts compared to the GFS. However, the 00z ECMWF shows
considerably less rainfall accumulations than previous runs. The
ECMWF suggests anywhere from a quarter of an inch across Austin and
the Hill Country to up to an inch or so across the Coastal Plains.
The GFS maxes out at about half an inch for the Coastal Plains. It is
worth mentioning that the operational run of the 00z GFS is much
lower with QPF than the other members (and the ensemble mean) of the
GFS ensembles. Both models do develop an inverted trough type feature
by middle of next week, but keep it focused to the Texas Gulf Coast,
with the heaviest rainfall occurring along and just off the coast
from Corpus to Houston. For this forecast package, generally broad
brush chance PoPs (30 to 40 percent) from Tuesday morning through
Wednesday afternoon before tapering off to slight chance PoPs (20
percent) by Wednesday night and into Thursday, with the highest
chances of rain for areas along and east of the Interstate 35/37
corridor. Stay tuned as hopefully models will come to a better
consensus as we approach Monday/Tuesday. One thing that the models
do generally agree upon is considerably cooler than normal high
temperatures for the middle of next week, with highs likely hanging
around 90 degrees compared to the normal highs of the mid to upper
90s.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry             100  75  99  75  99 /  -    0   0   0   0
Austin Bergstrom Intl Airport  98  75  98  74  98 /  -    0   0   0  -
New Braunfels Muni Airport     98  74  98  73  97 /  -    0   0   0   0
Burnet Muni Airport            96  73  97  73  96 /   0   0   0   0   0
Del Rio Intl Airport          102  76 101  75 100 /   0   0   0   0   0
Georgetown Muni Airport        99  75  97  74  97 /  -    0   0   0   0
Hondo Muni Airport            102  73 101  73 100 /   0   0   0   0   0
San Marcos Muni Airport        99  74  98  74  98 /  10   0   0   0   0
La Grange - Fayette Regional   96  77  96  76  96 /  10   0  -    0  10
San Antonio Intl Airport       99  75  98  74  97 /  -    0   0   0   0
Stinson Muni Airport           99  75 100  74  99 /  -    0   0   0   0

&&

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

$$

Aviation...Oaks
Short-Term/Long-Term...Huffman



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