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

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FXUS64 KEWX 211416
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
916 AM CDT THU AUG 21 2014

.UPDATE...HEAT ADVISORY ISSUED FOR SOUTHEAST COUNTIES FOR THIS
AFTERNOON AND EARLY EVENING. THE MOST LIKELY LOCATIONS TO SEE
105-110 DEG HEAT INDEX IS ALONG AND SOUTH OF A LA GRANGE TO
GONZALES TO FLORESVILLE LINE. NORTH OF THIS LINE TO THE I-35
CORRIDOR 103-105 DEG HEAT INDEX EXPECTED. WITH THE EXCEPTION OF
THE HILL COUNTRY...MOST LOCATIONS ACROSS SOUTH-CENTRAL TEXAS
REMAINED NEAR OR ABOVE 80 DEGS FOR LOWS THIS MORNING...COMPOUNDING
HEAT EXHAUSTION POTENTIAL. MINOR TWEAKS UP IN ACTUAL TEMP FORECAST
ALSO MADE BASED ON HIGHS FROM YESTERDAY...STARTING TEMPS FOR
TODAY...AND RIDGE BUILDING TOWARDS THE AREA.

ALSO...AND ELEVATED FIRE DANGER IS POSSIBLE THIS AFTERNOON AND
EVENING ALONG THE RIO GRANDE...WHERE MIN RH VALUES DIP TO AROUND
25 PERCENT AND GUSTY WINDS OCCUR.

JR

&&

.PREV DISCUSSION... /ISSUED 626 AM CDT THU AUG 21 2014/

AVIATION...
THE I-35 TAF SITES HAVE BEEN ALTERNATING BETWEEN VFR AND MVFR THIS
MORNING DUE TO PATCHY STRATUS ACROSS SOUTH CENTRAL TEXAS. EXPECT
THE STATUS TO STICK AROUND THROUGH 15Z CAUSING PERIODS OF MVFR
CIGS ALONG THE I-35 TERMINALS. DEL RIO COULD ALSO SEE PERIODS OF MVFR
CIGS...SIMILAR TO THE LAST TWO MORNINGS...SO HAVE CONTINUED TO
CARRY THE TEMPO GROUP FROM 13 TO 15Z. VFR CONDITIONS THIS
AFTERNOON UNDER PARTLY CLOUDY TO MOSTLY SUNNY SKIES. STRATUS WILL
ONCE AGAIN DEVELOP TONIGHT...BUILDING OVER THE I-35 TERMINALS
BETWEEN 07Z/08Z AND AT DRT AROUND 11Z FRIDAY MORNING THEN BURNING
OFF BY 16Z.

WINDS WILL CONTINUE TO BE STRONG AND GUSTY TODAY OUT OF THE SOUTH
(AUS/SAT/SSF) AND SOUTHEAST (DRT). THE HIGHEST WIND SPEEDS ARE
EXPECTED TO BE THIS AFTERNOON WHEN WE COULD SEE SUSTAINED WINDS
BETWEEN 10-15 KNOTS AND GUSTS AS HIGH AS 25 KNOTS. WINDS WEAKEN TO
AROUND 10 KNOTS TONIGHT.

PREV DISCUSSION... /ISSUED 342 AM CDT THU AUG 21 2014/

SHORT TERM (TODAY THROUGH FRIDAY)...
A COUPLE OF WEAK SHOWERS CONTINUE FROM STORMS THAT MOVED INTO THE
WESTERN ZONES LATE THIS EVENING. THESE SHOULD CONTINUE TO WEAKEN
AS THEY PROGRESS NORTH OVER THE NEXT FEW HOURS. OTHERWISE...TODAY
WILL BE HOT AND DRY FOR MUCH OF SOUTH CENTRAL TEXAS. CANT
COMPLETELY RULE OUT A STRAY SHOWER THIS AFTERNOON BUT MOISTURE
LEVELS ARE TOO LOW TO WARRANT ANY MENTION OF ACTIVITY IN THE
OFFICIAL FORECAST AT THIS TIME. PW VALUES REMAIN AROUND 1.5
INCHES OR LESS ON FRIDAY AND WILL KEEP THE FORECAST DRY. THE
DRYING OF THE ATMOSPHERE IS IN RESPONSE TO A BUILDING HIGH MOVING
IN FROM THE EAST. THE SUBSEQUENT SUBSIDENCE IS THEREFORE DRYING
OUT THE ATMOSPHERE AND ENDING RAIN CHANCES FOR THE AREA. LOW-LEVEL
THERMAL PROFILES ARE NOT EXPECTED TO CHANGE TOO MUCH AND HIGH
TEMPERATURES SHOULD BE PERSISTENT...AROUND THE MIDDLE 90S TO NEAR
100 DEGREES.

LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...
THE UPPER HIGH IS FORECAST TO WEAKEN AND LIFT NORTH BY SUNDAY.
THIS IS IN RESPONSE TO A LOW PRESSURE SYSTEM MOVING INTO THE
NORTHERN PLAINS. THIS SHOULD ALLOW MOISTURE VALUES TO SLOWLY
INCREASE AGAIN WITH AFTERNOON SHOWER AND THUNDERSTORM ACTIVITY
RETURNING TO THE FORECAST ON WEDNESDAY. THE RETURN OF PRECIP COULD
BE A BIT SOONER THAN THAT DEPENDING ON THE RATE OF THE MOISTURE
RETURN...BUT OPTED TO LEAVE THE FORECAST DRY UNTIL WEDNESDAY FOR
NOW. JUST BEYOND THE CURRENT PACKAGE...THE GFS IS FORECASTING A
FAIRLY PROGRESSIVE TROUGH MOVING THROUGH THE PLAINS THURSDAY WHICH
WOULD SEND A FRONTAL BOUNDARY INTO TEXAS THURSDAY/FRIDAY BRINGING
RAIN CHANCES FOR MUCH OF THE FORECAST AREA. THE ECMWF IS MUCH
SLOWER WITH ITS HANDLING OF THE UPPER TROUGH AND KEEPS HIGH
PRESSURE PERSISTENT OVER THE SOUTHERN PLAINS. THE MORE PROGRESSIVE
PATTERN OF THE THE OPERATIONAL GFS IS SUPPORTED BY MOST OF THE
GFSENSEMBLE MEMBERS AS WELL AS THE CANADIAN SO IT DOES BEAR
WATCHING.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY             101  78  99  75  99 /  -   -    0   0  -
AUSTIN BERGSTROM INTL AIRPORT 101  76  99  73  98 /  -   -    0   0  -
NEW BRAUNFELS MUNI AIRPORT    102  75 100  72  99 /  -   -    0   0  -
BURNET MUNI AIRPORT            98  75  96  73  96 /  -   -    0   0  -
DEL RIO INTL AIRPORT           98  78  98  75  97 /  10   0   0   0  -
GEORGETOWN MUNI AIRPORT        99  79  97  74  96 /  -   -    0   0  -
HONDO MUNI AIRPORT             99  75  98  72  97 /  -    0   0   0  -
SAN MARCOS MUNI AIRPORT       100  77  99  73  97 /  -   -    0   0  -
LA GRANGE - FAYETTE REGIONAL  102  79  99  76  99 /  -   -   -   -   10
SAN ANTONIO INTL AIRPORT      100  80  99  76  98 /  -   -    0   0  -
STINSON MUNI AIRPORT          102  78 100  75  99 /  -   -    0   0  -

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM CDT THIS EVENING FOR
THE FOLLOWING COUNTIES: DE WITT...FAYETTE...GONZALES...KARNES...
LAVACA...WILSON.

&&

$$

MESOSCALE/AVIATION...07
SYNOPTIC/GRIDS...76
PUBLIC SERVICE/DATA COLLECTION...33





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