Flash Flood Warning 45, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
434 PM CDT WED MAY 13 2015

.DISCUSSION...
THE MAIN UPDATE WITH THE FORECAST PACKAGE THIS AFTERNOON IS THE
EXTENSION OF THE ONGOING FLASH FLOOD WATCH TO 1 AM CDT THURSDAY.
SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO INCREASE WEST OF
INTERSTATE 45 THIS AFTERNOON AS AN APPROACHING TROUGH PUSHES A
THUNDERSTORM COMPLEX INTO THE REGION. BECOMING INCREASINGLY
CONCERNED WITH THE ORIENTATION OF THIS ACTIVITY /SOUTHWEST TO
NORTHEAST/ AS IT WILL ALLOW THUNDERSTORMS TO TRAIN... OR MOVE
REPEATEDLY OVER THE SAME AREA. THE 12Z SOUNDING FROM CORPUS
CHRISTI REPORTED OVER 1.9 INCHES OF PRECIPITABLE WATER... AND WITH
SOUTHERLY TO SOUTHEASTERLY WINDS DRAWING IN ADDITIONAL MOISTURE AS
AN EFFECTIVE WARM FRONT LIFTS NORTH... AMPLE MOISTURE CONTINUES TO
RESIDE ACROSS THE REGION.

THIS... COUPLED WITH SOME WEAKER 850-300 MB MEAN WINDS /SOUTHEAST 10
TO 20 KNOTS/... WILL ALLOW FOR SOME SLOW MOVING AND HEAVY RAIN
PRODUCING STORMS. SEVERAL FLASH FLOOD WARNINGS HAVE ALREADY BEEN
ISSUED THIS AFTERNOON WITH RADAR ESTIMATED RAIN RATES BETWEEN 1
AND 2 INCHES OVER ALREADY SATURATED GROUNDS PROMOTING ADDITIONAL
FLOODING CONCERNS FOR PARTS OF THE REGION. THUNDERSTORM ACTIVITY
CONTINUES TO BUILD THIS AFTERNOON AS INCREASING FORCING FROM THE
LEADING EDGE OF THE APPROACHING TROUGH REACHES THE REGION. HI-
RESOLUTION GUIDANCE SHOWS THAT THIS ACTIVITY WILL CONTINUE TO
SWING NORTHEAST ACROSS THE REGION THIS EVENING... EFFECTIVELY
CLEARING THE REGION BETWEEN 9 PM AND MIDNIGHT. HIGHLIGHTING THE
GREATEST POTENTIAL FOR HEAVY RAIN ALONG AND NORTH OF HIGHWAY 59
TONIGHT... BUT CANNOT RULE OUT ISOLATED CELLS CAPABLE OF PRODUCING
HEAVY RAIN FARTHER SOUTH OF THIS AREA.

SUBSIDENCE BEHIND TONIGHT/S SHORTWAVE TROUGH MAY HELP PUT A BRIEF
END TO RAIN CHANCES EARLY THURSDAY MORNING... BUT DIURNALLY DRIVEN
THUNDERSTORMS WILL BE POSSIBLE WITH PEAK HEATING ACROSS THE REGION
TOMORROW AFTERNOON. OTHERWISE... INTERMITTENT PERIODS OF SHOWERS
AND THUNDERSTORMS EXPECTED TO CONTINUE IN THE EXTENDED WITH
TEMPERATURES NEAR SEASONAL NORMALS.

HUFFMAN

&&

.MARINE...

MODERATE ONSHORE FLOW WILL CONTINUE THROUGH TUESDAY. SHOWERS AND
THUNDERSTORMS MAY SKIRT THROUGH THE BAYS AND NEARSHORE WATERS
TONIGHT. UPPER RIDGING BUILDS SLIGHTLY TO THE EAST AND SOUTHEAST
WHICH MAY LIMIT RAINS TO MORE OF SHOWERS. WINDS SHOULD INCREASE LATE
FRIDAY AND INTO SATURDAY AND WILL PROBABLY REQUIRE SCA.

45

&&

.AVIATION...

STORMS MOVING THROUGH UTS/CXO TERMINALS AND TAIL END OF THE LINE
COULD REACH IAH/HOU 22-23Z. WINDS SOUTHEASTERLY TO SOUTH THE
REMAINDER OF THE AFTERNOON AND OVERNIGHT. MVFR CIGS SHOULD FORM IN
THE WAKE OF THE SYSTEM BLANKETING MOST SITES.

45

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      69  85  72  83  71 /  50  40  20  50  30
HOUSTON (IAH)              72  85  72  84  72 /  40  40  20  50  20
GALVESTON (GLS)            75  82  75  81  76 /  30  30  20  40  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH UNTIL 1 AM CDT THURSDAY FOR THE FOLLOWING
     ZONES: 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.

GM...NONE.
&&

DISCUSSION...14

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
350 PM CDT WED MAY 13 2015

TXZ163-164-176>179-195>200-210>214-226-227-235>238-142100-
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-
350 PM CDT WED MAY 13 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SEVERAL INCHES OF RAIN HAS FALLEN OVER THE PAST FEW DAYS AND THE
REGION WILL BE MORE SUSCEPTIBLE TO REPEAT FLOODING WHEN RAIN
RETURNS. ALTHOUGH EXTREME RAINFALL IS DIFFICULT TO FORECAST...THE
SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE REGION TONIGHT...WITH
A CHANCE FOR ACCUMULATIONS OF GREATER THAN AN INCH. THE GREATEST
THREAT FOR HEAVY RAIN LEADING TO FLOODING POTENTIAL WILL RESIDE
ALONG AND NORTH OF THE HIGHWAY 59 CORRIDOR. ADDITIONAL RAINFALL
WILL ALSO AGGRAVATE ONGOING RIVER FLOODING CONCERNS.

ADDITIONALLY... AN ISOLATED TORNADO THREAT WILL EXIST THIS EVENING
PRIMARILY ALONG THE UPPER TEXAS COAST.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS REMAIN IN THE FORECAST INTO NEXT WEEK. ADDITIONAL
RAINFALL MAY AGGRAVATE ANY ONGOING FLOODING CONCERNS.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS MAY BE NEEDED THROUGH THE WEEK.

GMZ330-335-350-355-370-375-142100-
GALVESTON BAY-MATAGORDA BAY-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM-
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM-
WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM-
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM-
350 PM CDT WED MAY 13 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ALONG THE COAST WITH A
LOW POSSIBILITY FOR WATERSPOUTS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS WILL BE POSSIBLE OVER THE COASTAL WATERS OVER THE
NEXT SEVERAL DAYS.

..SPOTTER INFORMATION STATEMENT...
MARINERS ARE ENOURAGED TO REPORT ANY WATERSPOUTS OR FUNNEL CLOUDS
THEY OBSERVER.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
338 PM CDT WED MAY 13 2015

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

0324 PM     FUNNEL CLOUD     4 WSW GANADO            29.03N  96.57W
05/13/2015                   JACKSON            TX   TRAINED SPOTTER

            FUNNEL CLOUD OVER LAKE TEXANA...BETWEEN EDNA AND
            GANADO.

&&

EVENT NUMBER HGX1500239

DCH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
407 PM CDT WED MAY 13 2015

TXZ235-132145-
JACKSON TX-
407 PM CDT WED MAY 13 2015

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL JACKSON COUNTY UNTIL 445
PM CDT...

AT 405 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM
NEAR INEZ...OR 10 MILES SOUTHWEST OF EDNA...MOVING NORTH AT 10 MPH.

WINDS IN EXCESS OF 40 MPH AND FUNNEL CLOUDS ARE POSSIBLE WITH THIS
STORM.

LOCATIONS IMPACTED INCLUDE...
EDNA...VANDERBILT...AND LAKE TEXANA.

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.

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.

IF ON OR NEAR LAKE TEXANA...GET OUT OF THE WATER AND MOVE TO SAFE
SHELTER IMMEDIATELY. IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH
TO BE STRUCK BY LIGHTNING. IN ADDITION...STRONG THUNDERSTORMS CAN
PRODUCE LARGE CAPSIZING WAVES...EVEN ON SMALL BODIES OF WATER. MOVE
INTO DOCK AND SEEK SAFE SHELTER NOW. DON'T BE CAUGHT ON THE WATER IN
A THUNDERSTORM.

&&

LAT...LON 2906 9682 2899 9652 2875 9664 2876 9667
      2877 9668 2878 9670 2880 9670 2880 9671
      2882 9671 2882 9672 2885 9670 2886 9672
      2889 9673 2890 9676 2893 9680 2897 9681
      2900 9682
TIME...MOT...LOC 2105Z 193DEG 7KT 2885 9673

40