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

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136
FXUS64 KEWX 221452
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
952 AM CDT FRI MAY 22 2015

.MORNING UPDATE...
SEEING SOME LIGHT RETURNS ALONG THE I35 CORRIDOR THIS MORNING. THE
DEL RIO SOUNDING THIS MORNING SHOWS A STRONG CAPPING INVERSION AT
700 MB. SO NOT EXPECTING MUCH GROWTH TO THESE SHOWERS AT LEAST
THIS MORNING. LOWERED POPS FOR THE REMAINDER OF THE MORNING FOR
DEL RIO. FOG IS SHOWING SIGNS OF LIFTING AT 15Z THIS MORNING.
OTHERWISE...MOSTLY CLOUDY SKIES WILL PREVAIL TODAY.


&&

.PREV DISCUSSION... /ISSUED 616 AM CDT FRI MAY 22 2015/

UPDATE.../UPDATE TO ADD FOG/
PATCHY FOG HAS DROPPED A FEW VSBYS TO 1/4 MILE SO WILL ADD SOME
FOG TO THE FORECAST THROUGH 15Z. THE CHANCE OF THUNDERSTORMS STILL
EXISTS FOR THIS MORNING...ESPECIALLY SOUTH OF HWY 90...BUT MOST
AREAS SHOULD EXPECT TO SEE PATCHY LIGHT RAIN OR DRIZZLE.

PREV DISCUSSION... /ISSUED 615 AM CDT FRI MAY 22 2015/

AVIATION...
LIFR/VLIFR CONDITIONS HAVE DEVELOPED ACROSS THE AREA TERMINALS
THIS MORNING. EXPECT THESE CONDITIONS TO CONTINUE THROUGH MID-LATE
MORNING WITH SOME SLOW IMPROVEMENT. CANT COMPLETELY RULE OUT THE
CHANCE OF A SHOWER OR THUNDERSTORM TODAY BUT PROBABILITY WAS TOO
LOW TO MENTION IN THE TAFS AND WILL HANDLE THIS WITH
AMENDMENTS IF NEEDED. MORE WIDESPREAD SHOWERS AND STORMS ARE
EXPECTED AFTER 06Z TONIGHT BEGINNING OUT WEST AND WILL MENTION THE
ACTIVITY IN TAFDRT. FUTURE SHIFTS WILL LIKELY NEED TO SHIFT THIS
EAST. OTHERWISE...ANOTHER ROUND OF IFR IS EXPECTED TOMORROW
NIGHT.

PREV DISCUSSION... /ISSUED 406 AM CDT FRI MAY 22 2015/

SHORT TERM (TODAY THROUGH SATURDAY)...
A FLASH FLOOD WATCH WILL LIKELY BE ISSUED WITHIN THE NEXT 12 HOURS
OR SO...GIVEN THE STRONG STORM SYSTEM APPROACHING TX. SCATTERED
SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER THE
AREA...BUT THE HEAVIEST RAINFALL POTENTIAL IS NOT EXPECTED TO
BEGIN UNTIL SATURDAY AFTERNOON.

A SHALLOW FRONTAL INVERSION TODAY WILL KEEP COOLER THAN NORMAL
TEMPS AND LIMIT THE POTENTIAL FOR PERSISTENT DEEP CONVECTION. A
FEW THUNDERSTORMS MOVING INLAND FROM THE COASTAL BEND WILL BE IN A
PWAT REGION OF AROUND 1.8 INCHES...SO THERE COULD BE A FEW CELL
CLUSTERS THAT PRODUCE RAINFALL AMOUNTS OVER AN INCH OVER MAINLY
THE COASTAL PRAIRIES. WHILE RUNOFF CONCERNS ARE NOT ANTICIPATED
FOR TODAY...THE RAINS TODAY WILL CONTINUE TO KEEP SOILS NEAR
SATURATION AND ENHANCE CONCERNS FOR THE HEAVY RAIN EVENT THIS
WEEKEND.

SURFACE WINDS SHOULD TURN MORE SOUTHEASTERLY LATE THIS
AFTERNOON...LEADING TO INCREASED POTENTIAL FOR SURFACE BASED
CONVECTION LATE TODAY. HOWEVER...MOST OF THE MODEL DATA SHOW
LIMITED DEEP CONVECTION THROUGH EARLY SATURDAY...WITH THE CANADIAN
BEING ONE EXCEPTION THAT DEVELOPS AN EARLY SATURDAY MORNING
COMPLEX OVER THE EDWARDS PLATEAU. LATE SATURDAY...MORE MODELS COME
INTO ALIGNMENT ON RAMPING UP HIGHER PRECIPITATION AMOUNTS. WITH
THE EVENT ONLY JUST BEGINNING WILL DISCUSS THIS ENVIRONMENT IN
FURTHER DETAIL IN THE LONG TERM SECTION.

LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)...
AFTERNOON HEATING IS EXPECTED TO BE MODEST DUE TO THE NEAR 2 INCH
PWAT VALUES KEEPING CLOUDS ABUNDANT FOR MUCH OF THE DAY. A FEW
PEEKS OF SUNSHINE COULD LATE SATURDAY AFTERNOON COULD PRESENT A
MINOR SEVERE CONCERN THROUGH SATURDAY EVENING...BUT THE
DEVELOPMENT OF A LARGE HEAVY RAIN PRODUCING COMPLEX LATE IN THE
DAY IS EXPECTED TO PRESENT THE HIGHEST IMPACT OVER THE AREA
SATURDAY EVENING INTO EARLY SUNDAY. WITH RECENT MODEL TRENDS
DEVELOPING A SLIGHTLY BROADER UPPER TROUGH JUST WEST OF TX DURING
THIS PERIOD...THE QPF FORECASTS AMONG THE RECENT SYNOPTIC MODEL
RUNS CONTINUE TO BE VARIED ON TIMING AND LOCATION OF THE HIGHER
PRECIPITATION AMOUNTS. WILL HOLD OFF THE FLASH FLOOD WATCH
ISSUANCE AND GIVE THE MODELS ANOTHER SHOT TO COME INTO BETTER
ALIGNMENT BEFORE ADDING BETTER DETAILS ON THE EVENT TIMING.
FORECAST RAINFALL TOTALS REMAIN CENTERED AROUND THIS HIGHER IMPACT
PERIOD FROM SATURDAY AFTERNOON THROUGH EARLY SUNDAY EVENING...AND
WOULD SUGGEST WIDESPREAD 1-3 INCH RAINS WITH ISOLATED 6 INCH
AMOUNTS POSSIBLE.

A WELL-DEVELOPED MCS SWEEPING ACROSS TX WOULD LIKELY HELP PROVIDE
SOME RELATIVE STABILITY FOR LATE SUNDAY...BUT THE QPF PATTERNS IN
THE MOST OF THE SYNOPTIC MODEL FORECASTS DO NOT SUGGEST SUCH A
COMPLEX. SHOULD THERE BE SMALLER...PROGRESSIVE STORM CLUSTERS AS
SUGGESTED...THE ATMOSPHERE WILL RELOAD QUICKLY WITH STRONG TO
SEVERE STORMS IN ADDITION TO THE TRAINING AND HEAVY RAIN THREATS.
CAPES ARE SUGGESTED TO APPROACH 4000 J/KG BY THE GFS SUNDAY WHICH
WOULD COMBINE WITH AMPLE WIND SHEAR FOR AN HP SUPERCELL THREAT.

THE LIFTING OF THE FIRST LOBE EJECTION OF THE UPPER TROUGH LATE
SUNDAY WOULD SUGGEST RELATIVE MINIMA FOR RAIN CHANCES LATE SUNDAY
EVENING INTO EARLY MONDAY. 00Z MODELS ARE SHOWING BETTER
AGREEMENT ON A SECONDARY LOBE TO MOVE INTO NW TX AND INCREASE
STORM POTENTIAL FOR LATE MONDAY INTO EARLY TUESDAY. THE PATTERN
ALOFT IS EXPECTED TO FLATTEN OUT TO OFFER SOME POTENTIAL FOR
REDUCED THUNDERSTORM POTENTIAL FOR THE REMAINDER OF THE FORECAST
PERIOD...BUT A GENERAL CYCLICAL TROUGHING PATTERN REMAINS OVER
THE SWRN US THROUGH AT LEAST THURSDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              78  71  82  70  79 /  40  20  50  70  80
AUSTIN BERGSTROM INTL AIRPORT  79  70  82  70  79 /  40  20  50  70  80
NEW BRAUNFELS MUNI AIRPORT     80  71  82  70  80 /  50  20  50  70  80
BURNET MUNI AIRPORT            76  69  80  68  78 /  30  20  60  70  80
DEL RIO INTL AIRPORT           84  71  82  69  89 /  40  40  60  60  30
GEORGETOWN MUNI AIRPORT        77  70  81  69  78 /  40  20  50  70  80
HONDO MUNI AIRPORT             79  71  81  69  83 /  50  20  50  80  70
SAN MARCOS MUNI AIRPORT        78  71  81  70  79 /  40  20  50  70  80
LA GRANGE - FAYETTE REGIONAL   80  72  83  72  80 /  40  20  50  50  80
SAN ANTONIO INTL AIRPORT       80  72  82  69  81 /  50  20  50  70  70
STINSON MUNI AIRPORT           80  72  83  71  82 /  50  20  50  70  70

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

MESOSCALE/AVIATION...TB3
SYNOPTIC/GRIDS...05
PUBLIC SERVICE/DATA COLLECTION...TREADWAY



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