National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

048
FXUS64 KEWX 211516
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1016 AM CDT Wed Aug 21 2019

.UPDATE...
Current forecast remains largely on track with isolated showers and
thunderstorms expected in the Coastal Plains as the sea breeze moves
inland later this afternoon. Coastal convergence has provided some
enhancement in the cumulus field on visible satellite across portions
of Victoria and Jackson Counties this morning and have added an
isolated shower mention for DeWitt and Lavaca as a result. Otherwise,
expect temperatures to reach the mid 90s to low 100s later this
afternoon.

&&

.PREV DISCUSSION... /ISSUED 646 AM CDT Wed Aug 21 2019/

AVIATION...
At KSAT/KSSF, MVFR CIGs mix out mid morning around 21/14Z and return
overnight into Thursday morning 22/08Z-15Z. At KAUS, a southwesterly
component to the lower level flow this morning and overnight into
Thursday morning will keep MVFR level clouds FEW-SCT, though will
monitor for possible updates to mention CIGs. Otherwise, VFR flying
conditions will prevail. At the I-35 sites, southerly winds up to 8
KTs back to southeasterly this afternoon, increase to 9 to 15 KTs
with a few gusts to 22 KTs with the passage of the seabreeze this
evening, then veer to southerly at 4 to 9 KTs tonight. At KDRT,
easterly winds 5 to 10 KTs veer to southeasterly at 10 to 15 KTs with
a few gusts to 22 KTs late morning into afternoon, then back to
easterly at 5 to 10 KTs this evening.

PREV DISCUSSION... /ISSUED 344 AM CDT Wed Aug 21 2019/

SHORT TERM (Today through Thursday)...
The upper level ridge of high pressure which has kept the area hot
and dry for the last several days will begin to break down Wednesday
into Thursday. While the trend of hot and mostly dry weather will
continue temperatures will moderate slightly, with highs one or two
degrees cooler than they have been. This will also mean that rather
than 108-110 afternoon heat index values, heat indices for Wednesday
and Thursday will run more in the 103-106 range. In addition to the
slightly cooler temperature there will be slight chances for showers
and thunderstorms each afternoon east of the Interstate 35 corridor
due to the coastal sea breeze. While coverage should be less than
what was seen on Tuesday, a lucky few should get a brief break from
the heat and some beneficial rain Wednesday and Thursday afternoons.
Overnight lows will continue to run several degrees above normal, in
the mid to upper 70s, while afternoon highs trend closer to normal,
but remain one to two degrees above normal.

LONG TERM (Thursday Night through Tuesday)...
Friday will be similar to Wednesday and Thursday with afternoon highs
in the upper 90s across much of the area, with triple digit heat
closer to the Rio Grande Plains. Models continue to differ with their
solutions for Saturday and beyond. All 3 global models:
GFS/ECMWF/Canadian develop a low pressure system across northern
Mexico Friday night into Saturday morning. The 00z GFS remains the
strongest with this low pressure system, having it catch the tail end
of the trough dropping from the Plains into the SE CONUS Saturday
night into Sunday. The Canadian is similar, but slightly slower than
the GFS in terms of timing. The ECMWF is the weakest with this low
pressure system and leaves it across northern Mexico. The GFS and the
Canadian are wetter solutions as they drag the low pressure across
the Rio Grande and South Texas late in the weekend. The ECMWF is the
drier of the solutions. Despite still maintaining the low pressure
feature the 00z GFS did trend closer to the 00z ECMWF with less QPF.
Will continue to lean towards the drier ECMWF which maintains 20 to
30 percent PoPs for the weekend across much of the area. Regardless
of the rainfall coverage, the weakness of the ridge and potentially
increased cloud cover will keep afternoon highs for Saturday into
early next week close to normal for the latter half of August. While
models do show the ridge strengthening early next week, the center of
the ridge will be over Oklahoma and north Texas rather than South and
West Texas. This keeps slight chance PoPs in the forecast due to
increased moisture and potentially the upper level low still hanging
around South Texas as an inverted trough. While it is good to see
rain chances in the forecast not everyone will see rain over the next
7 days as coverage will generally be isolated.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              99  77  99  77  98 /   0   0   0  -   10
Austin Bergstrom Intl Airport  98  75  98  75  98 /  -   -    0  -   10
New Braunfels Muni Airport     97  74  98  74  98 /   0  -   -   -   10
Burnet Muni Airport            97  74  98  74  97 /   0   0   0   0  -
Del Rio Intl Airport          102  77 101  77 102 /   0   0   0  10  -
Georgetown Muni Airport        99  76 100  76  98 /   0   0   0   0  -
Hondo Muni Airport            101  74 101  75 101 /   0   0   0  10  -
San Marcos Muni Airport        99  75  99  75  98 /  -   -   -   -   10
La Grange - Fayette Regional   99  76  99  76  98 /  10  10  20  -   20
San Antonio Intl Airport       99  77  98  77  98 /   0   0  -   10  -
Stinson Muni Airport           99  77  98  76  99 /   0   0   0  10  10

&&

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

$$

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