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

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FXUS64 KEWX 161126
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
626 AM CDT Wed Aug 16 2017

.UPDATE...
12Z Aviation Update Below.

&&

.AVIATION...
BKN MVFR stratus has developed along the edge of the Escarpment into
the Hill Country, including AUS and SAT. The stratus remains just off
to the south and east of DRT, but there is a slight chance it could
work into the DRT area over the next couple of hours. Due to confidence
have left a SCT group at DRT. The stratus should will mix out 15Z-17Z
with VFR conditions and southeast winds gusting at times to around
20 kts through the afternoon. Isolated SHRAs and TSTMs are possible
along the Rio Grande and western Hill Country today. Have left this
mention out of the DRT TAF due to expected coverage and lower
confidence in timing.

&&

.PREV DISCUSSION... /ISSUED 343 AM CDT Wed Aug 16 2017/

SHORT TERM (Today through Thursday)...
Another afternoon of near Heat Advisory criteria to consider. A
factor that could impact heat indices is a weak disturbance
currently producing shower activity over the Hill Country. This
disturbance is loosely tied to a larger/stronger disturbance over the
Central Plains which have collectively suppressed ridging aloft over
TX and enhanced the low level pressure gradients. Thus as this ill-
defined weakness lifts and shears apart northward today, low level
winds may ease up, leaving an air-mass that does not mix as it did on
Tuesday. Residual high clouds spilling south from this weakening
disturbance could also reduce mixing, but also could reduce ambient
temperatures. Given the expected borderline values, some model
tendencies to under-forecast the amount of mixing, and the
expectation of another gusty wind afternoon, will punt the idea of a
Heat Advy to the day shift and issue another SPS.

Will expect a near persistence day for most areas, but may need to
update and lower max temps over northern counties if the stratiform
precip area this morning doesn`t dissipate soon. Residual moisture
over the north, some early morning cloud streets showing up on
radar over the far SE, and isolated activity suggested by rapid
refresh models have us going slightly less stable with two areas of
isolated thunderstorm chances today.

Consensus of synoptic models show the mid to upper level ridge axis
sharpening and lifting northward today into tonight, so expect a
drier picture and possibly higher ambient temperatures with lower dew
points for Thursday.

LONG TERM (Thursday Night through Tuesday)...
The ridge axis aloft remains oriented mostly E-W across TX with near
persistence heat and dry weather to continue through the weekend. On
Monday, a TUTT low over the Gulf approaches the TX coast and could
send enough of a moisture surge for some isolated Coastal Prairie
convection Monday and Tuesday. The low appears to be driving west
into an upper ridge that is strengthening over the Swrn US over the
weekend, so will remain conservative this pattern and only consider
a slight chance of rain for the Sern counties.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              99  78  99  77 100 /  -   -   -   -   -
Austin Bergstrom Intl Airport  99  77  98  76 100 /  10  -   -    0  -
New Braunfels Muni Airport     99  76  99  75 100 /  -    0  -    0  -
Burnet Muni Airport            95  75  96  74  98 /  10  10  10  -   -
Del Rio Intl Airport           98  80 100  79 100 /  30  10  10   0  -
Georgetown Muni Airport        96  77  97  76  98 /  10  10  10  10  -
Hondo Muni Airport             99  76  99  75 101 /  10  -    0   0  -
San Marcos Muni Airport        99  77  98  76 100 /  -   -   -    0  -
La Grange - Fayette Regional   97  78  98  76  99 /  10  -   -   -   10
San Antonio Intl Airport       98  78  98  77 100 /  -   -   -    0  -
Stinson Muni Airport          100  77 100  77 100 /  -    0  -    0  10

&&

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

$$

Mesoscale/Aviation...Runyen
Synoptic/Grids...Oaks



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