Special Weather Statement, NWS Austin/San Antonio, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1128 AM CDT FRI OCT 30 2015

.UPDATE...
ANOTHER HISTORICAL OCTOBER FLOOD EVENT IS ONGOING ACROSS PORTIONS
OF SOUTH CENTRAL TEXAS...WITH A SWATH OF 6 TO 12 INCH RAINFALL
TOTALS...AND AT LEAST 16 INCHES 5 MILES SW OF KYLE...OBSERVED
ALONG THE ESCARPMENT FROM JUST NORTHWEST OF SAN ANTONIO THROUGH
WIMBERLEY AND KYLE TO SOUTHEAST SIDES OF AUSTIN. BACKBUILDING
CELLS CONTINUE TO DEVELOP AND TRAIN ALONG A QUASI-STATIONARY AND
CONVECTIVELY REINFORCED WARM FRONTAL BOUNDARY WHERE SIGNIFICANT
CELL TRAINING CONTINUES TO OCCUR. THIS...COUPLED WITH A 50 KT
SOUTHERLY LLJ...STRONG ISENTROPIC ASCENT...AND OROGRAPHIC LIFTING
ALONG THE ESCARPMENT...CONTINUES TO GENERATE CONVECTION.
ALTHOUGH CONVECTION IS SLIGHTLY LESS DEEP THAN IT WAS A FEW HOURS
AGO WHEN UP TO 6 INCH/HR RAIN RATES WERE OBSERVED...THIS TRAINING
WILL CONTINUE A SIGNIFICANT LOCALLY HEAVY RAINFALL THREAT
PRIMARILY ALONG A LINE ORIENTED FROM SAN MARCOS TO ELGIN TO
LEXINGTON. FLASH FLOOD EMERGENCIES HAVE ALREADY BEEN ISSUED FOR
FAR NW BEXAR...MOST OF COMAL AND HAYS...AND THE ONION CREEK BASIN
IN SOUTHEAST TRAVIS COUNTIES. ADDITIONAL SIGNIFICANT FLASH
FLOODING IS ALSO VERY LIKELY TO EXPAND INTO BASTROP...LEE...EASTERN
TRAVIS...AND POSSIBLY FAR EASTERN WILLIAMSON COUNTIES IN THE NEXT
FEW HOURS AS CELLS CONTINUE MOVING INTO THESE AREAS. ISOLATED RAIN
TOTALS IN EXCESS OF 20 INCHES ARE NOT OUT OF THE QUESTION.

A THREAT FOR ISOLATED TORNADOES ALONG AND EAST OF THE ESCARPMENT ALSO
EXISTS FOR AT LEAST THE NEXT FEW HOURS WITH SHEAR VALUES IN
EXCESS OF 55 KTS AND HELICITY VALUES ABOVE 300 M^2/S^2. ALTHOUGH
THIS THREAT IS WINDING DOWN TO SOME EXTEND DUE TO A RELATIVE LACK
OF DISCRETE CELLS...ANY NEW CELL DEVELOPMENT SOUTHWEST OF THIS
LINE AND INTO THE TRAINING LINE MAY HAVE THE POSSIBILITY OF
PRODUCING A TORNADO. HOWEVER...THE PRIMARY THREAT BY FAR FOR THIS
EVENT IS SIGNIFINCANT FLASH AND SUBSEQUENT RIVER FLOODING.

THE AFTERNOON AFD WILL COVER MORE ABOUT HOW THIS SYSTEM WILL
EVOLVE TONIGHT...BUT HI-RES MODELS CONTINUE TO INDICATE SCATTERED
TO WIDESPREAD CELLS WILL DEVELOP THROUGH THE AFTERNOON...THOUGH
IT WILL SEEM LIKE A LULL COMPARED TO THIS MORNINGS RAINFALL. HI-
RES AND MODEL GUIDANCE HAVE GENERALLY NOT HANDLED THIS EVENT VERY
WELL...BUT THE CURRENT RAP AND HRRR MODEL RUNS DO INDICATE THIS AS
WELL...THOUGH THINKING IT WILL NOT BE QUITE AS PROGRESSIVE AS THEY
SUGGEST. AFTER A RELATIVE LULL THIS AFTERNOON...EXPECT CELLS TO
REDEVELOP TONIGHT ALONG A PRE-FRONTAL TROUGH AFTER 20-21Z THIS
AFTERNOON IN THE EDWARDS PLATEAU AND RIO GRANDE PLAINS BEFORE
MOVING INTO THE I-35 CORRIDOR LATER THIS EVENING AFTER 1-3Z. THIS
RAINFALL SHOULD BE MUCH MORE PROGRESSIVE...BUT STILL THINKING 1 TO
2 INCHES OF RAINFALL TONIGHT WITH ISOLATED TOTALS TO 4 INCHES WILL
BE POSSIBLE. THE HRRR ALSO SUGGESTS THE AREA THAT RECEIVED THE
HEAVIEST RAINFALL MAY BE TOO WORKED OVER FROM AN INSTABILITY
STANDPOINT TO ALLOW FOR ADDITIONAL CONVECTION TONIGHT.
HOWEVER...GIVEN THE FOCUSED AREA AND STRONG SYNOPTIC FORCING
TONIGHT...FEEL THE HRRR IS PROBABLY TOO AGRESSIVE ON THAT AT THE
MOMENT. THERE IS LITTLE DOUBT THAT WE WILL SEE SOME STORM EVENT
TOTALS IN EXCESS OF 18-20 INCHES BY SATURDAY MORNING.

&&

.PREV DISCUSSION... /ISSUED 704 AM CDT FRI OCT 30 2015/

AVIATION.../12Z TAFS/
WIDESPREAD SHOWERS AND THUNDERSTORMS CONTINUE TO AFFECT THE I-35
TAF SITES ALONG AND NORTH OF A NW-SE ORIENTED WARM FRONT. THIS
FRONTAL BOUNDARY SHOULD MOVE NORTH OF SAT/SSF WITHIN THE NEXT FEW
HOURS TO END TSRA BY 13-14Z...WHILE TSRA SHOULD PERSIST THROUGH
16Z AT AUS WHERE THE BOUNDARY WILL TAKE LONGER TO MOVE THROUGH.
CIGS SHOULD GENERALLY REMAIN MVFR AT SAT/SSF FOR THE REST OF THE
DAY...BUT CIGS AND VSBYS WILL BE MORE VARIABLE AT AUS THROUGH 16Z
ALLOWING FOR TEMPORARY IFR CONDITIONS TO MIX BEFORE THEN. TSRA ARE
NOT EXPECTED AT DRT THROUGH MID TO LATE AFTERNOON...BUT MVFR CIGS
WILL CONTINUE TO AFFECT THE SITE.

A RELATIVE LULL IN THE THUNDERSTORM ACTIVITY IS EXPECTED THIS
AFTERNOON AS SOUTH CENTRAL TEXAS REMAINS IN THE WARM SECTOR OF
THIS PACIFIC MIDLATITUDE CYCLONE...BUT ISOLATED TSRA WILL BE
POSSIBLE...ESPECIALLY AFTER 21-22 AT SAT/SSF. BASED ON HI-RES
MODEL TRENDS AND A GENERALLY FASTER PROGRESSION OF THIS SYSTEM...A
LINE OF TSRA IS EXPECTED LATER THIS EVENING AFTER 23Z AT DRT AND
3-4Z AT THE I-35 TAF SITES. OBSERVATIONAL TRENDS AND FUTURE MODEL
RUNS SHOULD HELP REFINE THESE TIMES WITH THE NEXT AFD. RAPID
CLEARING BEHIND A WEAK COLD FRONT SHOULD END TSRA CHANCES BY
SUNRISE WITH NW WINDS FOR SATURDAY.

PREV DISCUSSION... /ISSUED 329 AM CDT FRI OCT 30 2015/

SHORT TERM (TODAY THROUGH SATURDAY)...
ANOTHER SOUTHERN STREAM UPPER TROUGH WILL BRING HIGH CHANCES OF
RAIN TODAY THROUGH SATURDAY. THE FIRST ROUND OF RAINS ARE WELL
UNDERWAY AND WILL BE IMPACTING THE METRO CITIES DURING THE MORNING
COMMUTE. PWAT VALUES AROUND 2 INCHES STACKING UP OVER THE I-35
CORRIDOR THIS MORNING MEANS THAT SOME OF THE CONVECTION WILL
BECOME VERY EFFICIENT RAIN PRODUCERS. NEGATING FACTOR IS THAT THE
FIRST ROUND OF CONVECTION IS CRUISING AT 30 MPH TO THE NORTHEAST
WITH ONLY MINIMAL AREAS OF TRAINING EXPECTED. CURRENTLY EXPECT 1
TO 2 INCHES OF RAIN TO PASS ACROSS THE AREA EARLY TODAY WITH
ANOTHER ROUND EXPECTED TO FIRE OVER THE EDWARDS PLATEAU AND HILL
COUNTRY FOR THIS EVENING INTO TONIGHT. HOWEVER...A SECONDARY ROUND
OF HEAVY RAIN COULD FORM IN AN UPSTREAM PROPAGATION REGION BY
DAYBREAK AND LEAD TO HEAVY RAINFALL AMOUNTS SUFFICIENT FOR A FLASH
FLOOD THREAT. WILL WANT TO MONITOR RADAR TRENDS FOR ANOTHER COUPLE
HOURS BEFORE CONSIDERING A FFA. STORM TOTAL EXPECTED AMOUNTS FOR
NOW REMAIN AT 2-4...ISOLATED 6...WITH SOME OF THE RAIN FALLING
EARLY THIS MORNING AND OUTSIDE THE EFFECTIVE FORECAST PERIOD.

IN TERMS OF THE MARGINAL TO SLIGHT RISK SEVERE THREAT...THE
MORNING ACTIVITY HAS THE LOOK OF HEAVY DOWNPOURS BASED ON ELEVATED
DYNAMICS AND LOW LEVEL JET WITHOUT MUCH INFLUENCE FROM SURFACE
FEATURES. HOWEVER...LOW LEVEL HELICITY VALUES ARE HIGH THIS
MORNING...AND SOME ROTATING STORMS HAVE ALREADY BEEN NOTED OVER
THE RIO GRANDE PLAINS. EXPECT THE BULK OF THE SEVERE THREAT TO
OCCUR TOWARD MIDDAY THROUGH LATE TONIGHT AS BULK SHEAR INCREASES
40-55 KNOTS AND CAPES EXCEED 1000 J/KG.

THE HEAVY RAIN THREAT SHOULD CLEAR TO THE EAST OF THE AREA TOWARD
SATURDAY MORNING...ALTHOUGH POPS REMAIN FAIRLY HIGH OVER OUR FAR
EASTERN COUNTIES IN THE DAYTIME SATURDAY. TYPICALLY THIS PATTERN
WOULD FAVOR AN MCS THAT WILL PUSH EAST OF I-35 IN THE LATE NIGHT
HOURS WITH THE COOL OUTFLOW SURGING THE CONVECTIVE LINE EAST INTO
SOUTHEAST TX BY DAYBREAK. THUS PRIMARY CONCERNS FOR FLOODING IN
OUR FORECAST AREA ARE EXPECTED TO END AT AROUND DAYBREAK.

LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)...
THE DEPARTING SOUTHERN STREAM UPPER TROUGH LEAVES ANOTHER COUPLE
OF MILD AND DRY DAYS TO RECOVER...BUT BY LATE TUESDAY MOISTURE
BEGINS RACING ONSHORE IN ADVANCE OF ANOTHER PACIFIC TROUGH. THIS
SYSTEM WILL ALSO CONTAIN THE POTENTIAL FOR HEAVY DOWNPOURS...BUT
IS CURRENTLY FORECAST TO PASS FARTHER NORTH OVER THE SOUTHERN
PLAINS. WILL TAKE THE HIGH PWAT VALUES SHOWN BY THE GFS WITH SOME
DEGREE OF SKEPTICISM...BUT CONTINUE TO RUN SEVERAL PERIODS OF
CHANCE TO LIKELY POPS FOR WEDNESDAY INTO NEXT FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              77  66  78  57  77 / 100  90  40  10  -
AUSTIN BERGSTROM INTL AIRPORT  78  66  79  54  77 / 100  90  40  10  -
NEW BRAUNFELS MUNI AIRPORT     79  67  82  56  79 /  90  90  40  10  -
BURNET MUNI AIRPORT            75  62  74  54  75 /  90  90  30  10  -
DEL RIO INTL AIRPORT           81  61  79  53  82 /  70  70  20  -    0
GEORGETOWN MUNI AIRPORT        76  65  76  54  75 /  90  90  40  10  -
HONDO MUNI AIRPORT             80  65  83  54  80 /  90  80  30  -    0
SAN MARCOS MUNI AIRPORT        78  67  80  57  77 / 100  90  40  10  -
LA GRANGE - FAYETTE REGIONAL   79  70  80  58  76 /  90  80  70  20  10
SAN ANTONIO INTL AIRPORT       80  67  82  57  80 /  90  90  30  -   -
STINSON MUNI AIRPORT           81  68  84  58  80 /  80  80  30  -   -

&&

.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...17
SYNOPTIC/GRIDS...LH
PUBLIC SERVICE/DATA COLLECTION...TREADWAY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
811 AM CDT FRI OCT 30 2015

TXZ171>173-183>194-202>209-217>225-228-311315-
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-
811 AM CDT FRI OCT 30 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TODAY AND 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 TODAY FOR MOST OF SOUTH
CENTRAL TEXAS. THE FIRST ROUND OF THUNDERSTORMS IS OCCURRING THIS
MORNING...AND A TORNADO WATCH IS IN EFFECT UNTIL NOON LOCAL TIME
ALONG AND EAST OF KERRVILLE TO PEARSALL. A SECOND ROUND OF
THUNDERSTORMS IS EXPECTED LATER THIS AFTERNOON AND TONIGHT...AND
A FLASH FLOOD WATCH IS IN EFFECT ALONG AND EAST OF A LINE FROM
KERRVILLE TO PEARSALL. RAINFALL AMOUNTS WILL AVERAGE BETWEEN 2-4
INCHES WITH ISOLATED TOTALS UP TO 6 INCHES.

.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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1148 AM CDT FRI OCT 30 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1115 AM     FLASH FLOOD      2 NNE MENDOZA           30.03N  97.67W
10/30/2015                   CALDWELL           TX   LAW ENFORCEMENT

            HIGH WATER AND ROAD CLOSED AT FM1854 AND HWY 21...ALSO
            THERE ARE REPORTS OF VEHICLES STALLED IN HIGH WATER ON
            OTHER POINTS OF HWY 21 AND SH130

&&

EVENT NUMBER EWX1500833

SBS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1151 AM CDT FRI OCT 30 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1050 AM     HEAVY RAIN       5 SW KYLE               29.94N  97.93W
10/30/2015  M16.00 INCH      HAYS               TX   COCORAHS

            THIS IS A STORM TOTAL REPORT THUS FAR...

&&

EVENT NUMBER EWX1500834

SBS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1158 AM CDT FRI OCT 30 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1054 AM     FLASH FLOOD      6 N SAN MARCOS          29.96N  97.93W
10/30/2015                   HAYS               TX   COCORAHS

            STORM TOTAL THUS FAR WITH 7.36 INCHES REPORTED IN THE
            PAST HOUR AND A HALF...BRIDGE NEAR THE OBSERVERS HOUSE
            APPEARS TO BE GONE AND ROAD APPEARED TO BE FLOATING IN
            ONE PIECE

&&

EVENT NUMBER EWX1500835

SBS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1205 PM CDT FRI OCT 30 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1155 AM     FLASH FLOOD      ELGIN                   30.35N  97.37W
10/30/2015                   BASTROP            TX   BROADCAST MEDIA

            ONGOING RESCUES OF PEOPLE IN VEHICLES STRANDED IN HIGH
            WATER

&&

EVENT NUMBER EWX1500836

SBS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1219 PM CDT FRI OCT 30 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0820 AM     HEAVY RAIN       6 SSE SPRING BRANCH     29.79N  98.36W
10/30/2015  M7.50 INCH       COMAL              TX   COCORAHS

            STORM TOTAL THUS FAR...

&&

EVENT NUMBER EWX1500837

SBS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1221 PM CDT FRI OCT 30 2015

TXZ173-192-301800-
WILLIAMSON TX-TRAVIS TX-
1221 PM CDT FRI OCT 30 2015

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL WILLIAMSON AND CENTRAL
TRAVIS COUNTIES UNTIL 100 PM CDT...

AT 1221 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM
NEAR ANDERSON MILL...MOVING NORTHEAST AT 35 MPH.

WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
AUSTIN...ROUND ROCK...CEDAR PARK...GEORGETOWN...PFLUGERVILLE...
TAYLOR...GRANGER...WINDEMERE...ANDERSON MILL...SERENADA...HUTTO...
BARTLETT...THRALL...WEIR...GEORGETOWN DAM...COUPLAND...GRANGER DAM...
HUDSON BEND...SANDOVAL AND RICES CROSSING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...WITH ONGOING
FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED ROADWAYS.

&&

A TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM CDT FOR SOUTH CENTRAL
TEXAS.

LAT...LON 3079 9741 3068 9725 3066 9724 3044 9739
      3028 9776 3041 9791 3085 9757
TIME...MOT...LOC 1721Z 228DEG 32KT 3042 9774