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

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FXUS64 KEWX 252355 AAA

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
655 PM CDT Sat Mar 25 2017

/00Z TAFS/
VFR and clear skies will prevail across area airports through late
this evening. Clouds return overnight with cigs lowering to MVFR/IFR
along the I-35 sites around the 09Z/11Z time frame. Both MOS GFS and
NAM guidance bring LIFR to KAUS for the 12Z hour, however, opted out
from that solution at this time. VFR conditions return to the I-35
terminals by 14Z/15Z Sunday. Southerly flow will prevail through the
forecast period with speeds ranging from 3 to 7 knots overnight and
increasing during the day on Sunday 10 to 15 knots with gusts up to
25 knots.

KDRT should remain VFR during the entire forecast period under a
southeasterly flow of 5 to 10 knots.


.PREV DISCUSSION... /ISSUED 242 PM CDT Sat Mar 25 2017/

SHORT TERM (Tonight through Sunday Night)...
Clear skies with dry air in place across South Central Texas today.
The cold front was located along the Mid Texas coast into Deep South
Texas and is stalling. The front will return back through the area as
a warm front late tonight into Sunday morning in response to a
shortwave moving out of the Southern Rockies and into the Southern
Plains. Initially a very shallow moisture return will take place
leading to some patchy fog Sunday morning east of I-35 and the
development of some stratus along the escarpment.

There are some discrepancies with how deep the moisture become
Sunday afternoon and night and the development of a possible cap,
with the GFS a little deeper with the moisture than the NAM.
Forecast soundings from the NAM also indicate a cap developing Sunday
afternoon and night limiting any potential for convection along the
tail end of the shortwave and dry line across our CWA. The GFS and
ECMWF do indicate convective development late Sunday afternoon across
the far northeast Hill Country and then develops it southward into
the Hill Country and portions of the northern I-35 corridor Sunday
night. Should convection develop Sunday afternoon and evening a
tongue of MLCAPE values of around 2000 J/KG and 40-50kt of deep layer
shear could support a risk for hail. In addition, isolated damaging
straight line winds could be possible given drier aloft and DLCAPE
values forecast around 1000 J/KG. SPC Day 2 Convective Outlook does
clip northern areas of the CWA in a Marginal Risk. Have continued
with a less than 20 POP late Sunday afternoon into Sunday night
across the north, accounting for some uncertainty if the moisture
return is less or cap does develop. Will add a mention into the HWO
as well.

LONG TERM (Monday through Saturday)...
As the shortwave departs a weak cold front is forecast to stall
across the Hill Country and Rio Grande Monday morning and wash out
Monday afternoon and evening.

Models are then consistent with another upper level low digging
through Arizona and into New Mexico Tuesday with a rapid moisture
return taking place across South Central Texas ahead of it Tuesday
into Tuesday night. Isolated to scattered showers and storms are
possible during the day on Tuesday, favoring mainly the western third
of the CWA out across the western Hill Country and northern Rio

Models have trended slightly slower with the upper level low beyond
Tuesday. As the upper level moves across New Mexico Tuesday night
western areas of the CWA are place in a more favorable location for
convective development, with a diffluent flow aloft between the
upper level low to the northwest and sub-tropical jet streak just to
the south. As large scale ascent spreads into the area late Tuesday
night through Wednesday morning both the GFS and ECMWF are indicating
showers and storms increasing in coverage through the Hill Country
and possibly organizing into a complex through the I-35 corridor
early Wednesday, then moving northeast of the area Wednesday afternoon.
GFS has trended farther north with the main ingredients for severe
storms and locally heavy rainfall, but due to run to run variations
will continue with a highlight in the HWO.

ECMWF is slightly faster and farther north with the upper level low
ejecting out Thursday and much more robust with dry slotting over
South Central Texas. GFS however initiates re-development of
convection across central and eastern areas of the CWA late Wednesday
night into Thursday along the cold front. Will maintain some low
pops across this region during this time to account for the

Dry conditions on Friday and then both the GFS and ECMWF indicate
another upper level system possibly impacting the CWA sometime next


Austin Camp Mabry              60  87  66  87  67 /  10  10  10  -   10
Austin Bergstrom Intl Airport  56  87  63  87  65 /  10  10  10  -   10
New Braunfels Muni Airport     57  87  63  87  66 /  10  10  10  -   10
Burnet Muni Airport            57  85  61  85  63 /   0  10  10   0  10
Del Rio Intl Airport           60  92  59  91  67 /   0  -    0   0   0
Georgetown Muni Airport        56  85  63  87  64 /   0  10  10  -   10
Hondo Muni Airport             58  90  61  89  66 /   0  -   10   0  10
San Marcos Muni Airport        58  87  64  88  66 /  10  10  10  -   10
La Grange - Fayette Regional   60  86  67  86  68 /  10  -   10  10  10
San Antonio Intl Airport       60  88  64  88  67 /  -   10  10  -   10
Stinson Muni Airport           60  89  64  87  67 /  -   10  10  -   10




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