Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 292337
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
637 PM CDT FRI APR 29 2016

.AVIATION...
LOW TO MODERATE CONFIDENCE FORECAST. MOISTURE AXIS FROM MATAGORDA
BAY TO KCLL TO MADISON COUNTY SHOULD SLOWLY MOVE EASTWARD THROUGH
THE NIGHT. SHOWERS AND THUNDERSTORMS WERE DEVELOPING WITHIN THE
MOIST AXIS. MODEL SOLUTIONS DIFFERED...HOWEVER THERE WAS ENOUGH
CONSENSUS BETWEEN THE GFS/NAM12/RAP13 TO TRY AND TIME THE EVENT
TONIGHT AND SATURDAY. TERMINALS WERE BASED ON THE NAM12 AND RAP13
AND THE PREVIOUS PACKAGE.

40

&&

.PREV DISCUSSION... /ISSUED 341 PM CDT FRI APR 29 2016/

DISCUSSION...
..FLASH FLOOD WATCH EXPANDED IN AREA TO INCLUDE LIBERTY/CHAMBERS
GALVESTON/BRAZORIA COUNTIES. SEVERE THREAT SLIGHT TO ENHANCED
ACROSS THE REGION THIS AFTERNOON AND TONIGHT...

INGREDIENTS ALL IN PLACE NOW ACROSS THE REGION. PW 1.25-1.5 AND
CLIMBING. TEMPERATURES HAVE SOARED TO 85-88 DEGREES ACROSS THE
NORTH AND WINDS HAVE BEGUN TO INCREASE AND GET GUSTY. SETX IS
GOING TO BE UNDER THE GUN TONIGHT FOR SEVERE AND VERY HEAVY
RAINFALL.

SEVERE POTENTIAL SHOULD START OUT AS TORNADO/HAIL THREAT IN THE
WEST AND THEN SHIFT EASTWARD THROUGHOUT THE EVENING. AS WE GET
INTO THE EVENING THE THREAT SHOULD ALSO INCLUDE DAMAGING WINDS
ACROSS THE REGION...WET GROUND WILL ALLOW FOR TREE FALL AT LOWER
WIND SPEEDS THAN NORMAL.

FLOODING THREAT FOR MANY RUNS OF THE HRRR/NAM POINT TO AN EAST
WEST BOUNDARY ACROSS SETX...LOCATION MAY BE WELL NORTH OF THE
HOUSTON METRO AREA OR FURTHER SOUTH INTO THE METRO AREA. THIS
COULD BE A VERY DANGEROUS SITUATION IF THIS SETS UP ALONG THE
SPRING CREEK TO I-10 CORRIDOR. RAINFALL RATES OF 2-4 INCHES WILL
BE EASY TO ACHIEVE IN THIS PRECIPITATION EFFICIENT ENVIRONMENT
GIVEN THE VERY STRONG LL INFLOW AND LL SATURATION. EVENTUALLY
THIS STORM COMPLEX SLIDES EAST AND SHOULD BE MOVING OUT OF THE
AREA AROUND NOON SATURDAY OR PERHAPS EARLIER IF THE COLD POOL CAN
GET MORE DOMINANT BUT THROUGH 3 AM THIS SEEMS UNLIKELY THAT IT
COULD SURGE EAST OUT OF THE REGION. THE COLD FRONT PUSHES DOWN
ACROSS THE AREA LATE SATURDAY AND BRINGS IN DRYING AT LEAST OVER
THE NW 2/3RDS OF THE AREA.

BEYOND SATURDAY THE STATIONARY BOUNDARY REMAINS IN PLAY ACROSS
THE SOUTHERN PORTIONS OF THE AREA OR NEARSHORE WATERS AND THEN AS
NEXT TROUGH DROPS IN OVER THE WESTERN U.S. THE FRONT ACTIVATES
AGAIN SUNDAY AND PROBABLY MORE LIKELY MONDAY AND TUESDAY AS NEXT
UPPER LOW EJECTS OUT OF THE MEAN UPPER TROUGH. THE `GOOD` NEWS IS
THAT STRONG LL INFLOW IS NOT NEARLY AS STRONG WITH THE SUNDAY-
TUESDAY TIMEFRAME SO STORMS WILL PROBABLY MORE SCATTERED AND NOT
AS FOCUSED.

PERSONS ACROSS SETX LATE THIS AFTERNOON AND OVERNIGHT SHOULD BE
PREPARED FOR A VERY ROUGH NIGHT OF WEATHER.

45

MARINE...
MODERATE TO STRONG ONSHORE WINDS AND ELEVATED SEAS WILL PERSIST
THROUGH SATURDAY. CAUTION FLAGS ARE UP THE BAYS AND NEARSHORE
WATERS...AND ADVISORIES ARE IN EFFECT FOR THE OFFSHORE WATERS.
THE COASTAL FLOOD ADVISORY REMAINS IN EFFECT FOR BEACHES/
INTERCOASTAL WATERWAYS DOWN THE BRAZORIA COUNTY COASTLINE.
ONSHORE WINDS WILL HELP TO PILE UP WATER ONTO ROADWAYS/LOW-LYING
AREAS IN THESE AREAS DURING HIGH TIDE...ESPECIALLY CLOSE TO THE

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      72  84  69  82  66 / 100  50  40  50  50
HOUSTON (IAH)              73  82  71  82  70 / 100  60  40  50  60
GALVESTON (GLS)            75  80  74  80  73 /  60  60  30  40  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING
     ZONES: AUSTIN...BRAZORIA...BRAZOS...BURLESON...CHAMBERS...
     COLORADO...FORT BEND...GALVESTON...GRIMES...HARRIS...
     HOUSTON...LIBERTY...MADISON...MONTGOMERY...POLK...SAN
     JACINTO...TRINITY...WALKER...WALLER...WASHINGTON...WHARTON.

     COASTAL FLOOD ADVISORY UNTIL 6 PM CDT SATURDAY FOR THE FOLLOWING
     ZONES: BRAZORIA...CHAMBERS...GALVESTON.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 6 AM CDT SATURDAY FOR
     THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...WATERS
     FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...
     WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.

     SMALL CRAFT ADVISORY UNTIL 6 AM CDT SATURDAY FOR THE FOLLOWING
     ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
     20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
     60 NM.

&&

$$

DISCUSSION...48
AVIATION/MARINE...40


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