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

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FXUS64 KEWX 170025
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
725 PM CDT Tue Oct 16 2018

.AVIATION...
MVFR conditions are expected this evening as the strong post frontal
inversion lingers across South Central Texas with ceilings lowering
to IFR along the I-35 corridor overnight and rising back to MVFR by
mid-morning Wednesday. Lingering isentropic ascent may be able to
produce some light drizzle or rain at all terminals through the
period with high resolution guidance indicating the best window for
AUS/SAT/SSF overnight and DRT after 14-15Z Wednesday. Expect
northerly winds to persist in the 10-15 knot range.

&&

.PREV DISCUSSION... /ISSUED 418 PM CDT Tue Oct 16 2018/

SHORT TERM (Tonight through Wednesday Night)...
Afternoon radar imagery shows persistent rain continuing across
portions of the I-35 corridor, Hill Country and southern Edwards
Plateau. Hourly amounts according to radar and gauge data have been
trending downward this afternoon across the Hill Country and I-35
corridor. However, any additional rainfall falling on saturated
ground will instantly result in runoff.

The latest round of hi-res models suggest the better chance for
precipitation will contract and shift slightly northward this evening
and overnight. This should place the higher rainfall chances along
and north of a Del Rio to Fredericksburg to Burnet line. With models
showing the stronger lift focused along the Rio Grande and southern
Edwards Plateau, we should see the higher rainfall totals through
tonight across Val Verde and Edwards county. However, as mentioned
above, any additional rainfall over the Hill Country into west
central Texas will result in runoff.

On Wednesday, we should see a slight decrease in rainfall chances
across most of the region as the mid-level ridge of high pressure
builds westward across the northern Gulf of Mexico. The exception
will be across portions of the Rio Grande plains and southern Edwards
Plateau where mid-level shortwave activity will move northward from
Coahuila Mexico into the above mentioned areas.

Beginning Wednesday night, an area of higher moisture will begin to
work northward from the western Gulf of Mexico into south Texas. The
latest satellite precipitable water product shows values near 2.5" in
the western Gulf.

LONG TERM (Thursday through Tuesday)...
The above mentioned surge of moisture from the Gulf of Mexico will
continue to spread northward into south central Texas on Thursday.
Models suggest precipitable water values will increase to near 2"
across most of the region. We continue to see a good signal for
rainfall in the model output and have opted to push rain chances much
higher in the forecast for Thursday. Based on the ongoing flooding,
along with another surge of moisture headed our way, we have opted to
extend the Flash Flood Watch through early Thursday evening. If later
model data remains consistent, we will likely have to expand the
coverage of the watch to include counties along the I-35 corridor.
For now, we will forecast an additional 1 to 2 inches with isolated
totals near 4 inches across the watch area.

The active weather pattern is likely to continue Friday and possibly
well into Saturday as another cold front is expected to move in from
the north. We will continue to mention rain chances in the forecast
into early next week, with the better focus likely to remain out west
along the Rio Grande.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              46  54  51  57  52 /  50  40  50  70  70
Austin Bergstrom Intl Airport  51  55  51  57  52 /  40  40  50  70  60
New Braunfels Muni Airport     47  55  51  58  53 /  40  40  60  70  70
Burnet Muni Airport            44  51  48  56  52 /  80  50  40  90  70
Del Rio Intl Airport           44  54  49  57  52 /  80  70  60  60  50
Georgetown Muni Airport        48  53  51  57  52 /  60  40  40  70  70
Hondo Muni Airport             48  57  52  59  54 /  50  50  70 100  80
San Marcos Muni Airport        48  55  51  57  53 /  40  40  60  70  70
La Grange - Fayette Regional   51  58  53  61  56 /  40  40  40  60  50
San Antonio Intl Airport       47  55  51  58  53 /  40  40  70  90  70
Stinson Muni Airport           48  56  52  59  54 /  40  40  70  90  70

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday evening for Bandera-Blanco-
Burnet-Edwards-Gillespie-Kendall-Kerr-Kinney-Llano-Maverick-Medina-
Real-Uvalde-Val Verde-Zavala.

&&

$$

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



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