Special Weather Statement, NWS Austin/San Antonio, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
645 PM CDT FRI OCT 30 2015

.UPDATE...
ROUND TWO OF STORMS IS BEGINNING TO DEVELOP ACROSS VAL VERDE
COUNTY AT THE PRESENT TIME. ONE SEVERE STORM IS ALREADY ONGOING
AND A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR LOCATIONS WEST
OF A KERRVILLE TO PEARSALL LINE. THESE THUNDERSTORMS ARE
DEVELOPING EAST OF A SURFACE LOW CENTERED JUST WEST OF THE RIO
GRANDE. THE ENVIRONMENT IS SUPPORTIVE FOR SEVERE CONVECTION WITH
SBCAPES APPROACHING 2500 J/KG AND EFFECTIVE BULK SHEAR VALUES
APPROACHING 55-70 KNOTS. A PACIFIC FRONT OR DRYLINE WILL SERVE AS
THE SURFACE FOCUS FOR CONVECTION AS THIS BOUNDARY SHOULD MOVE
EAST THIS EVENING.

A COLD FRONT WAS LOCATED IN THE TEXAS PANHANDLE BUT SHOULD NOT
MOVE INTO OUR REGION UNTIL AFTER DAY BREAK. HIGH-RES MODEL OUTPUT
SHOWS THE PACIFIC FRONT MOVING THROUGH THE AREA BY 14Z TOMORROW
MORNING WITH WEST WINDS AND DRIER CONDITIONS BEHIND THE FRONT
CLEARING THINGS OUT. WITH AN ACTUAL BOUNDARY PUSHING THROUGH THE
AREA...ANY ONE LOCATION SHOULD NOT RECEIVE FURTHER PROLONGED
CONVECTION. THE LATEST HRRR RUN SUPPORTS OUR CURRENT FORECAST OF
1-2 INCHES WITH AN ISOLATED 5 INCH TOTAL. EVEN THOUGH THESE TOTALS
ARE NOT HIGH...1-2 INCHES WILL LEAD TO FURTHER QUICK RISES OF
AREA CREEKS WHICH ALREADY RECEIVED EXTREME RAINFALL TODAY.
THEREFORE...THE FLASH FLOOD WATCH WILL CONTINUE.

&&

.PREV DISCUSSION... /ISSUED 628 PM CDT FRI OCT 30 2015/

AVIATION...
/00Z TAFS/
MVFR CONDITIONS ARE EXPECTED ACROSS AREA SITES THIS EVENING
WITH PERIODS OF IFR AND EVEN LIFR OVERNIGHT AND EARLY SATURDAY.
A COLD FRONT IS EXPECTED TO PUSH ACROSS THE AREA LATE THIS EVENING
INTO THE OVERNIGHT HOURS COUPLED WITH AN UPPER LEVEL DISTURBANCE
PUSHING FROM WEST TEXAS TOWARDS SOUTH CENTRAL TEXAS. WITH THIS
SCENARIO IN PLACE...EXPECT SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS. SOME OF THESE STORMS MAY BE STRONG TO SEVERE
CAPABLE OF PRODUCING DAMAGING WINDS UP TO 52 KNOTS. DURING THESE
STORMS CIGS AND VBSYS WITH LOWER SIGNIFICANTLY. AS THE COLD FRONT
PUSHES THROUGH THE AREA...A WIND SHIFT IS EXPECTED FIRST ACROSS
THE SOUTHERN EDWARDS PLATEAU WITH WIND SHIFTING TO THE NORTH
ALONG THE I-35 TERMINALS AROUND MID MORNING (16Z) SATURDAY.
WEATHER CONDITIONS WILL IMPROVE FROM WEST TO EAST ON SATURDAY WITH
SHOWERS AND STORMS MAINLY AFFECTING THE THE EASTERN
COUNTIES...AWAY FROM AREA TERMINALS.

PREV DISCUSSION... /ISSUED 440 PM CDT FRI OCT 30 2015/

SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
A RELATIVE LULL IN OUR HISTORIC HEAVY RAINFALL EVENT IS EXPECTED
THROUGH THE EARLY EVENING HOURS OVER MOST OF SOUTH CENTRAL TEXAS
AS MOST OF THE REGION REMAINS IN THE WARM SECTOR OF THE PACIFIC
MIDLATITUDE CYCLONE NOW THAT THE WARM FRONT HAS MOVED NORTH OF OUR
CWA. ISOLATED TO SCATTERED SHOWERS AND POSSIBLY A THUNDERSTORM WILL
CONTINUE MAINLY NORTH OF INTERSTATE 10 AND EAST OF HIGHWAY 281.
ALTHOUGH CAPE IS CURRENTLY FAIRLY LIMITED NORTH OF AN AUSTIN TO LA
GRANGE LINE...EFFECTIVE STORM RELATIVE HELICITY VALUES APPROACHING
300 M^2/S^2 AND BULK SHEAR VALUES OF 40-45 KTS WILL ALLOW ANY
STRONGER CELLS TO ROTATE SHOULD ANY DEVELOP. THUS...HAVE ALLOWED
THE TORNADO WATCH FOR OUR NORTHWESTERN MOST SIX COUNTIES TO
CONTINUE THROUGH 7PM CDT AFTER COORDINATING WITH SPC OUT OF AN
ABUNDANCE OF CAUTION SHOULD CAPE RECOVER MORE QUICKLY THAN
EXPECTED. ASIDE FROM THAT...THE MAIN CONCERN THROUGH THE EARLY
EVENING HOURS FOR THE I-35 CORRIDOR WILL BE SIGNIFICANT RIVER
FLOODING ISSUES AS THE LAST FLASH FLOOD EMERGENCY FOR ONION CREEK
HAS EXPIRED BEFORE TWO SEPARATE POTENTIAL ROUNDS OF STORMS MOVE
THROUGH THE AREA TONIGHT.

ATTENTION FOR OUR FIRST ROUND OF STRONG TO SEVERE STORMS EXPECTED
LATER TONIGHT FOR THE I-35 CORRIDOR...HILL COUNTRY...AND EDWARDS
PLATEAU TURNS OUT WEST WHERE CONVECTION IS TRYING TO DEVELOP
ALONG A PRE-FRONTAL TROUGH OR PSEUDO DRYLINE THAT IS MOVING INTO
WESTERN VAL VERDE COUNTY. ISOLATED CONVECTION HAS BEGUN TO FIRE IN
MEXICO ALONG THE SERRENIAS DEL BURRO MOUNTAINS WITH A LINE OF
CONVECTION IN THE NE PART OF SAN ANGELOS CWA ASSOCIATED WITH THIS
FEATURE...WITH SOME AGITATED CU IN BETWEEN THE TWO AREAS. THE LAST
SEVERAL RUNS OF THE HRRR AND 12Z TX TECH WRF HAVE HANDLED THE
TIMING OF THIS INITIATION RELATIVELY WELL COMPARED TO MOST OTHER
GLOBAL MODELS AND HI-RES GUIDANCE...SO TRUST THAT AT LEAST A FEW
CONVECTIVE CELLS WILL DEVELOP AND MOVE EAST INTO THE EVENING
HOURS...REACHING THE I-35 CORRIDOR AROUND 9-10 PM CDT. FAVORABLE
HELICITY AND SHEAR VALUES WILL SUPPORT ROTATING UPDRAFTS SHOULD
THESE CELLS DEVELOP AND REMAIN FAIRLY DISCRETE...SO STRAIGHT LINE
WIND DAMAGE...SEVERE HAIL...AND ISOLATED TORNADOES WILL BE
POSSIBLE.

A SECOND ROUND OF STRONG TO SEVERE STORMS IS EXPECTED TO DEVELOP
WITH THE MAIN COLD FRONT OVERNIGHT...WHICH THE MOST RECENT RUN OF
THE HRRR AND TX TECH WRF INDICATE WILL REACH THE I-35 CORRIDOR
AROUND 3-5 AM CDT SATURDAY MORNING. THESE STORMS SHOULD INCLUDE A
STRAIGHT-LINE WIND THREAT IN ADDITION TO THE FLASH FLOOD THREAT.
GIVEN THE 5-10 INCHES AND ISOLATED 12-16 INCH TOTALS THAT HAVE
FALLEN ALONG THE I-35 CORRIDOR FROM A SWATH FROM FAR NW BEXAR
COUNTY TO WIMBERLEY TO EAST AUSTIN TO ELGIN...ANY ADDITIONAL
RAINFALL THAT FALLS WILL DIRECTLY RUNOFF RESULTING IN FLASH
FLOODING AND FURTHER COMPLICATING ONGOING RIVER FLOODING ISSUES.
THE FAST PROGRESSION OF THIS SYSTEM SHOULD KEEP AVERAGE RAINFALL
TOTALS TO 1 TO 2 INCHES WITH ISOLATED SPOTS UP TO 4 INCHES. SOME
RUNS OF THE HRRR SUGGEST THIS MAY BE A BROKEN LINE OF CONVECTION
WHILE THE TX TECH WRF SHOWS IT WILL BE CONTINUOUS...SO HOPEFULLY
THE BROKEN LINE MATERIALIZES TO HELP MITIGATE SOME OF THESE ISSUES
OR THE RAINFALL TOTALS ARE EVENLY DISTRIBUTED. RAIN CHANCES WILL
END FROM WEST TO EAST BY SATURDAY AFTERNOON AS DRIER AIR AND
CLEARER SKIES MOVE IN BEHIND THE COLD FRONT TO CAUSE A COOL AND
DRY HALLOWEEN NIGHT FOR TRICK OR TREATING.

LONG TERM (SUNDAY THROUGH FRIDAY)...
DRY WEATHER WILL CONTINUE THROUGH TUESDAY AS MOISTURE DOES NOT
BEGIN TO RETURN WITH SOUTHERLY FLOW UNTIL MONDAY EVENING. RAIN
CHANCES WILL BEGIN TO INCREASE BY LATE TUESDAY INTO WEDNESDAY
AHEAD OF OUR NEXT UPPER LEVEL DISTURBANCE. THESE RAIN CHANCES ARE
EXPECTED TO PERSIST THROUGH AT LEAST FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              66  79  57  77  50 /  70  40  10  -   -
AUSTIN BERGSTROM INTL AIRPORT  67  80  57  77  48 /  70  40  10  -   -
NEW BRAUNFELS MUNI AIRPORT     68  83  57  78  51 /  70  40  -    0   0
BURNET MUNI AIRPORT            63  75  54  75  51 /  80  30  10  -    0
DEL RIO INTL AIRPORT           62  79  53  82  51 /  60  10   0   0   0
GEORGETOWN MUNI AIRPORT        65  77  55  75  51 /  80  40  10  10  -
HONDO MUNI AIRPORT             65  82  54  80  50 /  60  10  -    0   0
SAN MARCOS MUNI AIRPORT        68  80  57  77  51 /  70  40  -    0   0
LA GRANGE - FAYETTE REGIONAL   70  81  59  76  53 /  80  60  10  10  -
SAN ANTONIO INTL AIRPORT       67  83  56  78  51 /  70  20  -    0   0
STINSON MUNI AIRPORT           68  84  57  79  51 /  70  20  -    0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SATURDAY MORNING FOR THE FOLLOWING
COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...
CALDWELL...COMAL...DE WITT...FAYETTE...GILLESPIE...GONZALES...
GUADALUPE...HAYS...KARNES...KENDALL...KERR...LAVACA...LEE...LLANO...
MEDINA...TRAVIS...WILLIAMSON...WILSON.

&&

MESOSCALE/AVIATION...HAMPSHIRE
SYNOPTIC/GRIDS...04

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
632 PM CDT FRI OCT 30 2015

TXZ171>173-183>194-202>209-217>225-228-312345-
LLANO-BURNET-WILLIAMSON-VAL VERDE-EDWARDS-REAL-KERR-BANDERA-
GILLESPIE-KENDALL-BLANCO-HAYS-TRAVIS-BASTROP-LEE-KINNEY-UVALDE-
MEDINA-BEXAR-COMAL-GUADALUPE-CALDWELL-FAYETTE-MAVERICK-ZAVALA-
FRIO-ATASCOSA-WILSON-KARNES-GONZALES-DE WITT-LAVACA-DIMMIT-
632 PM CDT FRI OCT 30 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TONIGHT.

A SLIGHT RISK OF SEVERE STORMS CAPABLE OF PRODUCING DAMAGING
WINDS...ISOLATED TORNADOES...AND LOCALLY HEAVY RAINFALL CAPABLE OF
PRODUCING FLASH FLOODING IS POSSIBLE THROUGH TONIGHT. ANOTHER
ROUND OF CONVECTION IS EXPECTED TO MOVE THROUGH THE AREA THIS
EVENING AND OVERNIGHT. 1-2 INCHES OF RAIN WITH ISOLATED LOCATIONS
REACHING 5 INCHES WILL CAUSE ADDITIONAL FLASH FLOODING FOR
LOCATIONS WHICH ALREADY RECEIVED EXTREME RAINFALL TODAY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

CHANCES OF LOCALLY HEAVY RAINFALL AND ISOLATED STRONG TO SEVERE
THUNDERSTORMS WILL CONTINUE THROUGH SATURDAY MORNING. A FLASH
FLOOD WATCH IS IN EFFECT UNTIL 10 AM SATURDAY MORNING ALONG AND
EAST OF A LINE FROM KERRVILLE TO PEARSALL. HEAVY RAINFALL
RESULTING IN LOCALIZED FLASH FLOODING WILL BE THE PRIMARY THREAT
BUT DAMAGING WINDS AND FREQUENTLY LIGHTNING WILL ALSO EXIST WITH
THIS SYSTEM AS IT MOVES THROUGH BY THE AFTERNOON WHEN SKIES CLEAR
OUT BEHIND THE FRONT. A STORM SYSTEM PRODUCING SHOWERS AND
THUNDERSTORMS WILL APPROACH BY WEDNESDAY BUT NO WIDESPREAD
HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE TONIGHT THROUGH SATURDAY
MORNING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
931 PM CDT FRI OCT 30 2015

TXZ183-310300-
VAL VERDE TX-
931 PM CDT FRI OCT 30 2015

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL VAL VERDE COUNTY
UNTIL 1000 PM CDT...

AT 931 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
COMSTOCK...MOVING NORTHEAST AT 15 MPH.

NICKEL SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
COMSTOCK AND DEVILS RIVER STATE NATURAL AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM.
LIGHTNING CAN STRIKE 10 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

&&

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 200 AM CDT FOR
SOUTH CENTRAL TEXAS.

LAT...LON 2965 10124 2980 10134 3005 10089 2976 10076
TIME...MOT...LOC 0231Z 247DEG 11KT 2976 10121

CP

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