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

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625
FXUS64 KEWX 230552
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1252 AM CDT Fri Jun 23 2017

.AVIATION...
Lower level moisture with MVFR, possibly IFR, CIGs returns to eastern
areas and KAUS, KSAT, KSSF by Friday morning (09Z-12Z), then mixes
out by mid morning (13Z-15Z). Lower level moisture deepens a little
Friday night with MVFR/IFR CIGs after 24/06Z. Otherwise, VFR skies
prevail overnight through Friday evening. ISOLD SHRA/TSRA will move
into the Hill Country late Friday night as a weak cold front
approaches. Impacts to TAF sites are expected on Saturday as the
front drifts further south. S to SE winds 5 to 10 KTs increase to 10
to 20 KTs and gusty on Friday.

&&

.PREV DISCUSSION... /ISSUED 309 PM CDT Thu Jun 22 2017/

SHORT TERM (Tonight through Friday Night)...
12Z sounding data shows quite the contrast in atmospheric moisture in
place across the southern portion of Texas with precipitable water
values around 1 inch at DRT to near 2.5 inches in far southeast
Texas. Satellite-derived precipitable water values are near 2 inches
along and east of the Highway 77 corridor this afternoon. With
daytime heating, we could see an isolated shower or storm develop
through early evening and will continue to mention a 20% chance in
the forecast. Any activity that manages to develop should dissipate
with the loss of daytime heating. Dry weather is in store overnight
across south central Texas as southeasterly winds gradually bring an
increase in low-level moisture. Temperatures on Friday are set to
increase as subsidence associated with the subtropical ridge axis
builds in from the west. In addition, the low-level thermal ridge
will amplify across western and central Texas ahead of a cold front
moving into southern Oklahoma. This will result in high temperatures
ranging from the mid to upper 90s across the Hill Country, near 100
along the I-35 corridor with readings near 105 along the Rio Grande.
The combination of heat and humidity will likely result in elevated
heat index values across all areas. A Heat Advisory may very well be
needed on Friday, especially across the Rio Grande plains and areas
along and east of the I-35 corridor. For Friday night, we will need
to monitor an area of convection expected to develop across west
central Texas during the evening hours. Some of this activity could
move down into the Hill Country or southern Edwards Plateau beginning
late evening. For now, we will keep rain chances fairly low, but
have opted to mention a 20-30% chance for showers and storms for the
above mentioned areas Friday night. Should these storms maintain
intensity, we could see a strong storm or two, mainly north of a
Langtry to Llano line. For now, we will not mention this in the
Hazardous Weather Outlook as any storms would likely be moving in
after peak heating hours.

LONG TERM (Saturday through Thursday)...
The forecast for the upcoming weekend still appears to offer up some
rain chances across south central Texas as a weak cold front will
slowly migrate southward. The exact progress of this cold front
remains in question as much will likely depend on the amount of
convection that develops along and behind the front. So while our
confidence in the placement of this front is low, it does appear we
will see enough moisture, lift and instability to result in scattered
showers and thunderstorms across the region for the upcoming
weekend. Best guess for now is the cold front will stay north of our
region on Saturday, but could move in on Sunday and help increase
rain chances slightly. While the frontal boundary will likely become
increasingly diffuse early next week, a fairly active northwest flow
aloft will contribute to our rain chances on Monday and Tuesday. We
should see enough influence from the subtropical ridge to keep most
areas dry on Wednesday and Thursday. The exception will be near the
coastal plains, where some afternoon showers and storms may develop
along the sea breeze.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              77  92  73  91  72 /  10  40  30  40  30
Austin Bergstrom Intl Airport  76  92  73  90  72 /  10  40  30  40  30
New Braunfels Muni Airport     76  92  73  91  72 /  10  40  30  40  30
Burnet Muni Airport            74  89  71  88  70 /  20  40  20  40  30
Del Rio Intl Airport           79  96  75  94  75 /  10  20  20  20  10
Georgetown Muni Airport        75  90  72  89  71 /  20  40  30  40  30
Hondo Muni Airport             77  95  73  93  73 /  10  30  20  30  20
San Marcos Muni Airport        77  92  73  91  72 /  10  40  30  40  30
La Grange - Fayette Regional   77  91  74  91  73 /  20  40  30  50  30
San Antonio Intl Airport       78  93  75  92  74 /  10  40  30  40  30
Stinson Muni Airport           78  93  75  92  74 /  10  40  30  40  30

&&

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

$$

Mesoscale/Aviation...04
Synoptic/Grids...05



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