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

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FXUS64 KEWX 270643
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
143 AM CDT Mon Mar 27 2017

.AVIATION... /06Z TAFS/
A strong storm moving through Williamson county should remain outside
of the AUS vcnty and should dissipate over the next 1-2 hours. Mvfr
cigs have settled over I-35 terminals and much of the Hill Country
with westward progress slow to occur toward DRT. There is a chance
for LIFR conditions, and the TAFs depict AUS/DRT as the most likely
candidates. IFR conditions should develop any time now over the
higher terrain and descend over to the I-35 terminals in about two
hours. A gradual mixout to VFR skies is expected in the early
afternoon with low clouds expected to return in the last 6 hours of
the 30 hour TAF periods.

&&

.PREV DISCUSSION... /ISSUED 319 PM CDT Sun Mar 26 2017/

SHORT TERM (Tonight through Monday Night)...
Severe weather risk this afternoon remains non-zero but is still
extremely marginal. Currently, satellite imagery is showing some
bubbling cu from Mason County to Fayette County. Latest LAPS
soundings show a weak cap struggling to hold on this afternoon and
RAP forecast soundings keep it holding on through out the afternoon.
Also of note is the presence of about 20-50 J/KG of CIN working
against heated parcels at the surface. If a surface boundary of some
kind were present, concerns would be much higher for the chance for
CI this afternoon, but with surface dewpoints in the 50s west of I-35
and lack of lifting mechanism present east, think its very unlikely
parcels will be able to tap into the ripe conditions aloft. SPC
mesoanalysis shows LFC heights over 4000m thus surface parcels will
need to overcome inhibition, weak surface moisture, and without any
help to lift it to get to that height. Thus, confidence is extremely
low for the chance for storms.

Should one occur though, effective bulk shear, lots of instability,
and strong mid level lapse rates all mean the possibility for strong
to severe storms with large hail and damaging winds.

LONG TERM (Tuesday through Sunday)...
The focus for the short term will be the prospect of severe weather
with our next upper low Tuesday and Wednesday. SPC has already
outlined marginal to slight risk for large hail, damaging winds, and
tornadoes Tuesday and a day 4 area outlined for the Austin area and
northeast Wednesday. Our best timing for severe potential will likely
be late Tuesday night, and maybe as late as early Wednesday morning
(after midnight) as we inherit a mature system that develops near
Abilene. Latest ECMWF shows convection initiating along the dry line
near the Childress area and unzipping southward to Del Rio by
midnight Tuesday night. Overnight, these cells become more
dynamically driven and likely coalesce into a linear system that
pushes across the CWA from the west and impacts the I-35 corridor by
12Z Wednesday morning. While PWAT values over 1.5" have been
advertised thus far, both GFS and ECMWF quickly exit the system after
18Z Wednesday and should limit flash flooding potential. Should this
system indeed become a linear system as advertised, the principle
threat should be damaging straight line winds and hail.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              67  84  67  83  60 /  -   20  40  80  10
Austin Bergstrom Intl Airport  67  84  67  83  59 /  -   20  40  80  10
New Braunfels Muni Airport     67  84  67  84  59 /  -   20  40  80  10
Burnet Muni Airport            63  80  64  80  55 /  -   30  70  80  10
Del Rio Intl Airport           66  87  62  87  57 /  -   30  50  10  -
Georgetown Muni Airport        65  81  65  81  57 /  -   30  50  80  10
Hondo Muni Airport             66  85  66  87  57 /  -   30  40  30  10
San Marcos Muni Airport        66  84  68  84  59 /  -   20  40  80  10
La Grange - Fayette Regional   67  84  69  83  61 /  -   10  30  80  20
San Antonio Intl Airport       68  84  68  85  59 /  -   30  40  70  10
Stinson Muni Airport           67  84  68  85  60 /  -   20  40  70  10

&&

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

$$

Mesoscale/Aviation...Oaks
Synoptic/Grids...04



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