Severe Thunderstorm Warning 41, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
718 PM CDT THU JUN 12 2014

.DISCUSSION...
SEE 00Z DISCUSSION.

&&

.AVIATION...
THUNDERSTORMS HAVE RAPIDLY DEVELOPED ALONG AN OUTFLOW BOUNDARY
BETWEEN IAH AND CXO THIS EVENING. THESE THUNDERSTORMS MAY BRIEFLY
REDUCE CIGS AND VSBYS TO MVFR LEVELS...HOWEVER BY FAR THE BIGGEST
IMPACT TO THE TERMINALS COULD BE STRONG GUSTY WINDS AND THE
POSSIBILITY FOR SMALL HAIL. THESE STORMS SHOULD MOVE OUT OF THE
VCNTY OF THESE TERMINALS BY 02Z.

ANOTHER LINE OF THUNDERSTORMS IS POSSIBLE BETWEEN 04Z AT THE
NORTHERN TERMINALS AND 08Z AT THE COAST AS AN UPPER LEVEL
DISTURBANCE MOVES ACROSS THE AREA. THESE STORMS MAY BE A LITTLE
MORE LESS SEVERE IN NATURE AS THE ATMOSPHERE WILL HAVE BEEN
WORKED OVER BY EARLIER CONVECTION. MESO MODELS SUGGEST THAT THE
CONVECTIVE ACTIVITY MAY WEAKEN SIGNIFICANTLY AS IT APPROACHES THE
COAST.

AM CONCERNED ABOUT THE INCREASED POSSIBILITY OF MVFR CIGS/VSBYS AT
UTS...CXO...AND IAH LATE TONIGHT SHOULD SKIES CLEAR OUT DURING
PREDAWN HOURS.

ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE BY FRIDAY AFTERNOON AS
THE MAIN TROF ACCESS ROTATES ACROSS THE FORECAST AREA.  44

&&

.PREV DISCUSSION... /ISSUED 335 PM CDT THU JUN 12 2014/

..SLIGHT RISK OF SEVERE STORMS TONIGHT...

DISCUSSION...
THIS FORECAST UPDATE FOCUSED MAINLY ON THE POTENTIAL FOR SEVERE
WEATHER TONIGHT INTO FRIDAY MORNING. LATEST VIS SATELLITE AND SFC
OBS SHOW OUTFLOW BOUNDARY FROM BASICALLY JASPER TX TO STEPHENVILLE
TX THIS AFTERNOON. STORMS STARTING TO DEVELOP JUST NORTH OF THE
BOUNDARY OVER TX SHOULD BE ABLE TO TAP STRONG INSTABILITY TO
ITSELF AS OUTFLOW BOUNDARY DISSIPATES. SPC RAP MESO ANALYSIS SHOWS
QUITE A BIT OF INSTABILITY OVER THE SEVERE WEATHER RISK AREA.
WATER VAPOR IMAGERY SHOWS DRY SLOT AND SHORTWAVE TROUGH AXIS ALSO
PUSHING OVER THE REGION. ALSO MAY SEE AN AREA OF ENHANCED JET
STREAM WINDS OVER THIS REGION AS WELL. THIS SHOULD FURTHER HELP
SUPPORT CONVECTIVE INITIATION THE NEXT SEVERAL HRS. OVERALL THE
ENVIRONMENT LOOKS FAVORABLE FOR ORGANIZED CONVECTION THIS EVENING
AND TONIGHT ACROSS MUCH OF TX.

MESO MODELS OF HRRR/WRF-ARW/NMM AND WRF RUN BY TX TECH ALL SHOW A
LINE OF STORMS MOVING INTO SE TX AROUND 01-04Z THIS EVENING. THE
12Z NAM ALSO HINTS AT THIS WITH THE OTHER SYNOPTIC MODELS SHOWING
HIGH QPF OVER C TX INTO SE TX INDICATIVE OF CONVECTION. GIVEN ALL
THIS AGREEMENT ADDED 70 POPS TO THE FORECAST WITH MENTION OF
SEVERE STORMS FOR TONIGHT. LIKE TIMING OF REACHING NORTHERN THIRD
OF THE FORECAST AREA FROM 00Z-04Z AND THEN HOUSTON AREA AROUND
03Z-07Z. DEPENDING ON HOW CONVECTION EVOLVES...SQUALL LINE COULD
BE SLOWER IF IT TAKES MORE TIME TO DEVELOP. INSTABILITY AND SHEAR
PARAMETERS SUPPORT BOWING SEGMENTS WITH THE SQUALL LINE. WRF-ARW
REALLY SHOWS THIS STRUCTURE WELL AT 03Z TONIGHT. THINK DAMAGING
WIND/HAIL THREAT WILL BE MAIN CONCERN. SHOULD BOW ECHOES
FORM...HIGHER CHANCE FOR WIND DAMAGE AND POWER OUTAGES ACROSS THE
AREA. MODELS DO SHOW SQUALL LINE WEAKENING AS IT MOVES INTO THE
HOUSTON AREA SO IMPACTS MAY BE LESS FARTHER SOUTH THAN BRAZOS
VALLEY INTO EAST TEXAS. STILL LOW CHANCES OF THE LINE MAKING IT TO
THE COAST BUT WILL LARGELY DEPEND ON STRENGTH OF COLD POOL AND CAP
WEAKENING. AS SUCH HAVE TAPERED OFF POPS FOR TONIGHT CLOSER TO THE
COAST SOUTH OF I-10.

FRIDAY MAY STILL HAVE SOME CHANCES OF THUNDERSTORMS. MAIN
SHORTWAVE TROUGH AXIS WILL FINALLY ROTATE THROUGH WITH A BACK
DOOR FRONT APPROACHING THE AREA. GFS/NAM/ECMWF HINT AT SOME
DEVELOPMENT ALONG THIS BOUNDARY WITH PASSING TROUGH AXIS. KEPT
SOME 30 POPS IN THE FORECAST BUT OVERNIGHT SQUALL LINE COULD HAVE
REALLY WORKED OVER THE BOUNDARY LAYER AND DOUBT THERE WILL BE MUCH
RECOVERY. GFS DOES HINT AT PRECIP WATER VALUES AROUND 1.8-2.0
INCHES SO WITH TEMPS IN THE UPPER 80S TO LOW 90S TOMORROW...COULD
SEE STORMS DEVELOP AGAIN ALONG THE BOUNDARY. SEVERE THREAT LOOKS
LOW BUT AGAIN COULD SEE A WIND THREAT WITH BRIEF HEAVY RAINFALL.

REST OF THE FORECAST LOOKS ON TRACK WHEN LOOKING AT GFS/ECMWF DATA
FOR THE EXTENDED. RAIN CHANCES LOOK MINIMAL SAT BUT COULD GET SOME
ISO ACTIVITY SUN/MON. REST OF THE WEEK WILL BE QUESTIONABLE AS TO
THE STRENGTH OF THE RIDGE AND ANY LINGERING DEEP MOISTURE. SUPPOSE
THAT SEA BREEZE COULD DEVELOP TO SUPPORT A STORM OR TWO BUT TOO
FAR OUT TO PINPOINT MESOSCALE FORECAST DETAILS.

39

AVIATION...
KEPT THE MENTION OF VCTS IN FOR THIS AFTN FOR SOME SITES AS ANOTHER
LINE PASSES THROUGH THE AREA. HOWEVER SHORT-TERM MODELS STILL GOING
WITH MORE WIDESPREAD PCPN FOR TONIGHT AS THE MAIN SHORTWAVE MOVES A-
CROSS THE AREA TO THE EAST. 41

MARINE...
ONSHORE WINDS CONTINUING A SLOW UPTICK WITH THE TIGHTENING GRADIENT
(IN RESPONSE TO THE DEEPENING LOW OUT WEST). AS THE SYSTEM MOVES TO
THE EAST FRIDAY...WIND SPEEDS SHOULD DECREASE SLIGHTLY/BRIEFLY THRU
SAT. GRADIENT EXPECTED TIGHTEN ONCE AGAIN LATE SAT WITH ANOTHER LOW
DEVELOPING IN THE LEE OF THE ROCKIES.  MODERATE/OCCASIONALLY STRONG
ONSHORE WINDS TO PREVAIL OVER THE COASTAL WATERS THROUGH EARLY NEXT
WEEK. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      75  91  74  91  74 /  70  30  20  10  10
HOUSTON (IAH)              75  91  74  91  74 /  50  30  20  10  10
GALVESTON (GLS)            79  88  79  88  79 /  30  30  10  10  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

DISCUSSION...42
AVIATION/MARINE...44

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
351 PM CDT THU JUN 12 2014

TXZ163-164-176>179-195>200-210>214-226-227-235>238-132100-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
351 PM CDT THU JUN 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

...SLIGHT RISK OF SEVERE STORMS AND HEAVY RAINFALL...

.DAY ONE...THIS AFTERNOON AND TONIGHT

TONIGHT INTO FRIDAY A LINE OF THUNDERSTORMS MAY MOVE INTO THE
AREA FROM NORTH TEXAS AS AN UPPER LEVEL DISTURBANCE AND FRONTAL
BOUNDARY MOVE INTO THE REGION. THIS LINE OF STORMS COULD MOVE
INTO AREAS NORTH OF INTERSTATE 10 AND THEN WEAKEN AS THEY MOVE
SOUTHWARD. THERE ARE STILL SOME TIMING ISSUES OF WHEN THE LINE OF
STORMS COULD MOVE INTO THE AREA. LATEST FORECAST DATA SUGGESTS A
LINE OF STORMS MOVING INTO THE CROCKETT TO COLLEGE STATION AREAS
AROUND 7-9PM. THE LINE WILL LIKELY WEAKEN AS IT MOVES INTO THE
HOUSTON AREA AROUND 11PM TO 1AM TONIGHT. REGARDLESS THESE STORMS
MAY BE SEVERE WITH HAIL AND DAMAGING WINDS AS THE MAIN THREATS.
SHOULD THE LINE OF STORMS SHOW BOWING SEGMENTS...STRONGER DAMAGING
WINDS CAN BE EXPECTED.

A SECONDARY CONCERN MAY BE HEAVY RAINFALL IF STORMS BECOME
ORGANIZED IN A SQUALL LINE. POSSIBLE THAT WITH DEEP MOISTURE IN
PLACE AND ROBUST UPDRAFTS IN THE LINE COULD SUPPORT 1 TO 2 INCHES
OF RAINFALL AN HOUR. STORM MOTIONS MAY BE NEAR 30 MPH TO START BUT
COULD SLOW DOWN TO WHERE HEAVY RAINFALL COULD OCCUR OVER LOCALIZED
AREAS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

IT IS POSSIBLE ANOTHER ROUND OF STORMS COULD FORM FRIDAY
AFTERNOON BEFORE THE THE UPPER LEVEL DISTURBANCE EXITS THE REGION.
SOME OF THESE STORMS COULD BE STRONG.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THURSDAY NIGHT INTO FRIDAY
MORNING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
503 PM CDT THU JUN 12 2014

TXZ200-122245-
LIBERTY TX-
503 PM CDT THU JUN 12 2014

...SPECIAL WEATHER STATEMENT...

AT 501 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 5
MILES NORTHEAST OF DEVERS...DRIFTING SOUTHEAST AT 5 MPH THOUGH
ADDITIONAL STORMS MAY FORM UPSTREAM TO THE NORTHWEST AND MOVE OVER
THE SAME AREA.

HALF INCH HAIL AND WINDS IN EXCESS OF 30 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
DEVERS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

HEAVY 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 15 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.

&&

LAT...LON 2992 9445 3006 9464 3012 9459 3011 9445
      2994 9444
TIME...MOT...LOC 2201Z 301DEG 5KT 3002 9445

!KP!

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
617 PM CDT THU JUN 12 2014

TXZ178-179-199-200-213-130015-
HARRIS TX-SAN JACINTO TX-POLK TX-LIBERTY TX-MONTGOMERY TX-
617 PM CDT THU JUN 12 2014

...SPECIAL WEATHER STATEMENT...

AT 613 PM CDT...DOPPLER RADAR WAS TRACKING SEVERAL NEARLY STATIONARY
STRONG THUNDERSTORMS FROM ALDINE TO WOODLOCH TO THE WILLIS AREA TO
BETWEEN GOODRICH AND SHEPHERD. THESE STORMS WERE NEARLY STATIONARY.

BRIEF VERY HEAVY RAINFALL...POSSIBLY APPROACHING 1 TO 2 INCHES IN A
SHORT PERIOD OF TIME...AND WIND GUSTS IN EXCESS OF 30 MPH WILL BE
POSSIBLE WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
CONROE...HUMBLE...CLEVELAND...WILLIS...NORTHSIDE / NORTHLINE...
ALDINE...KINGWOOD...SPRING...GREATER GREENSPOINT...THE WOODLANDS...
NEAR NORTHSIDE HOUSTON...GREATER FIFTH WARD...OAK RIDGE NORTH...
SHEPHERD...PANORAMA VILLAGE...SHENANDOAH...SPLENDORA...PATTON
VILLAGE...ROMAN FOREST AND WOODBRANCH.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

VERY HEAVY RAINFALL IS POSSIBLE. DO NOT DRIVE YOUR VEHICLE THROUGH
FLOODED ROADWAYS.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
OFFICE IN LEAGUE CITY .

&&

LAT...LON 3048 9474 2979 9534 3016 9562 3045 9554
      3060 9502
TIME...MOT...LOC 2313Z 127DEG 1KT 3021 9543

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
705 PM CDT THU JUN 12 2014

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

0635 PM     HAIL             WOODLOCH                30.22N  95.41W
06/12/2014  M1.50 INCH       MONTGOMERY         TX   PUBLIC

            1.00 TO 1.50 INCH HAIL IN THE WOODLOCH AREA. RECEIVED
            FROM TWITTER.

&&

EVENT NUMBER HGX1400127

42

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