Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 310440
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1140 PM CDT WED JUL 30 2014

.DISCUSSION...
SEE AVIATION FOR 6Z TAF ISSUANCE.

&&

.AVIATION...
CONFIDENCE HAS STARTED TO GROW THAT SHOWERS AND THUNDERSTORMS WILL
BE POSSIBLE TOMORROW AS A FRONT SAGS TO THE SOUTH. THE FRONT WILL
BE THROUGH COLLEGE STATION BY 6 PM WITH SHOWERS AND THUNDERSTORMS
STARTING EARLY AFTERNOON AT OUR NORTHERN TAF SITES. LATE AFTERNOON
INTO EVENING THESE SHOWERS AND THUNDERSTORMS SHOULD CONTINUE TO
PUSH SOUTH. GLOBAL MODELS CONTINUE TO AGREE ON SHOWERS AND
THUNDERSTORMS FIRING WITH THE TEXAS TECH WRF NOW ALSO COMING ON
BOARD (THE TTWRF DID INITIALIZE POORLY THOUGH). GIVEN THE BOUNDARY
ACROSS THE AREA AND HIGH MOISTURE VALUES (PWAT VALUES ~2.00") RAIN
LOOKS POSSIBLE. CONFIDENCE IS NOT HIGH ON THE STORMS MAKING IT TO
KGLS THOUGH. THE BOUNDARY WILL LIKELY NOT MAKE IT TO KGLS THURSDAY
NIGHT INTO FRIDAY MORNING. HOW FAR THE BOUNDARY MAKES IT WILL
LIKELY DETERMINE IF KGLS GETS RAIN. THESE STORMS WILL ALSO LIKELY
NOT BE MOVING FAST. 23

&&

.PREV DISCUSSION... /ISSUED 944 PM CDT WED JUL 30 2014/

DISCUSSION...
SHORT TERM UPDATE FOR INCREASING CIN AND CLOUD COVER. HAVE LOWERED
POPS TONIGHT BASED ON THE HIGH RES MODELS AND SYNOPTIC MODELS FOR
THAT MATTER SHOWING DECREASING COVERAGE OF THE STORMS ALONG THE
FRONTAL BOUNDARY. LEAD S/W CAN BE SEEN ON WV MOVING THROUGH OK AND
HELPED WITH INITIATION OF STORMS IN CENTRAL OK AND TRAILING BACK
ALONG THE FRONTAL BOUNDARY. THIS S/W TRACKS ESE AND LOOKS TO BE
RAPIDLY OUTRUNNING THE LL FOCUS. SPEED MAX THAT SHOULD HELP AID
DEVELOPMENT TOMORROW MAY BE FAR ENOUGH TO THE NORTHEAST TO HAVE
LESS IMPACT BUT STILL ENOUGH WITH FRONTAL CONVERGENCE FOR
OVERCOMING THE CAP AND PRODUCING SCATTERED SHOWERS AND
THUNDERSTORMS IN THE MORNING UP NORTH AND INLAND AREAS IN THE
AFTERNOON. SATELLITE AND SREF DO HAVE THE AREA UNDERNEATH THE
MOIST AXIS SO CONFIDENCE IS STILL PRETTY HIGH THAT THE REGION WILL
SEE THE SCATTERED STORMS AND POPS MAY NEED BUMPING UP. SOME
DOUBTS ABOUT HOW FAR SOUTH IT WILL MOVE AS OUTFLOW MAY BE THE BEST
MEANS TO GET IT TO THE COAST AND THE BEST DCAPE IS IN THE MID
AFTERNOON HOURS.
45

PREV DISCUSSION... /ISSUED 646 PM CDT WED JUL 30 2014/

DISCUSSION...
SEE AVIATION FOR 0Z TAF ISSUANCE.

AVIATION...
ALL SITES VFR THIS AFTERNOON AS NEXT STORM SYSTEM TO AFFECT
SOUTHEAST TEXAS IS CURRENTLY LOCATED IN OKLAHOMA. LAST NIGHT SOME
SITES BRIEFLY WENT MVFR AND THINK THERE WILL BE ANOTHER SLIGHT
CHANCE TONIGHT BUT ANY SITES THAT DO GO MVFR SHOULD QUICKLY
BOUNCE BACK TO VFR AS THE SUNRISES. TOMORROW AFTERNOON A SURFACE
COLD FRONT CURRENTLY LOCATED IN OKLAHOMA WILL MOVE SOUTHWARDS AND
APPROACH THE AREA. GFS AND NAM BOTH SHOW PRECIP STARTING AT KCLL
AROUND 1 PM. RAIN CHANCES THEN MOVE INTO THE CITY AROUND 5 PM.
GLOBAL MODELS CONTINUE TO SHOW PRETTY GOOD COVERAGE IN THE QPF
FIELDS WHILE THE HIGH RES MODELS SHOW COVERAGE QUICKLY DISSIPATING
AS RAIN MOVES INTO SOUTHEAST TEXAS. FORECAST SOUNDINGS SHOW A CAP
IN PLACE TOMORROW THAT QUICKLY DISSIPATES AS THE SHORTWAVE
APPROACHES. OVERALL HAVE LEANED TOWARDS THE GLOBAL MODELS DUE TO
THE BOUNDARY REMAINING IN CLOSE PROXIMITY TO THE AREA WITH AMPLE
MOISTURE. FUTURE TAF PACKAGES WILL CONTINUE TO REFINE THE COVERAGE
AND TIMING OF POTENTIAL PRECIPITATION. 23

PREV DISCUSSION... /ISSUED 317 PM CDT WED JUL 30 2014/

DISCUSSION...
THE MODELS KEEP A NORTHWESTERLY FLOW OVER SE TX THROUGH THE
UPCOMING WEEKEND. THIS WILL HELP DRIVE A WEAK COLD FRONT INTO THE
FORECAST AREA LATE ON THURSDAY OR EARLY FRIDAY. BOTH THE GFS AND
ECMWF HANG THE FRONT UP ALONG OR OFF THE COAST THROUGH THE
WEEKEND. DURING THE EARLY PART OF NEXT WEEK BOTH MODELS DO APPEAR
TO TRY AND BUILD THE UPPER RIDGE BACK OVERHEAD...BUT BOTH DO KEEP
A WEAKNESS IN THE RIDGE OVER THE LOWER MISSISSIPPI VALLEY AND THE
NORTHWESTERN GULF OF MEXICO. BOTH MODELS DO PUSH THE WEAK FRONT
BACK INLAND MONDAY AND TUESDAY.

THE MAIN FORECAST CHALLENGE IS THUNDERSTORM CHANCES AND COVERAGE
LATE THURSDAY INTO FRIDAY. ALSO CONCERNED ABOUT THE POSSIBILITY
OF LOCALLY HEAVY RAINFALL. A DECENT SHORTWAVE TROUGH WILL
ACCOMPANY THE COLD FRONT INTO SE TX. AT THE SAME TIME...THE UPPER
LEVELS SHOW A GOOD DIFFLUENT FLOW. EVEN THOUGH THE MODEL GUIDANCE
KEEPS THE POPS GENERALLY BETWEEN 30 AND 40 PERCENT...THE FORECAST
SOUNDINGS SHOW PW/S UP TO AROUND 2.3 INCHES AND CAPE VALUES
BETWEEN 2000 AND 3000. WILL MONITOR THE MODEL TRENDS OVER THE NEXT
24 HOURS IN ORDER TO PINPOINT THE BEST CHANCES AND COVERAGE OF THE
RAINFALL THREAT.

THE MODELS KEEP BEST RAINFALL CHANCES ALONG OR OFF THE COAST FROM
LATE FRIDAY THROUGH MONDAY. AFTER THE FRONTAL BOUNDARY MOVES
INLAND...ISOLATED CHANCES STILL LOOK POSSIBLE TUESDAY AND
WEDNESDAY.

40

MARINE...
LIGHT...MAINLY ONSHORE FLOW WILL PERSIST THRU THURS NIGHT. A COOL
FRONT WILL APPROACH THE COAST FRIDAY. THIS BOUNDARY WILL MEANDER
BACK AND FORTH NEAR THE COASTLINE THRU THE WEEKEND AND SHOULD
SERVE AS A FOCUS FOR SHOWERS AND THUNDERSTORMS. LIGHT/VARIABLE
WINDS SHOULD PERSIST WITH LOW SEAS - EXCEPTION BEING IN AND NEAR
STORMS WHICH COULD BE STRONG AT TIMES. MORE PREVALENT ONSHORE FLOW
SHOULD RESUME EARLY NEXT WEEK...BUT WINDS/SEAS STILL DON`T LOOK
VERY IMPRESSIVE. 47

PREV DISCUSSION... /ISSUED 1217 PM CDT WED JUL 30 2014/

AVIATION...
SHOULD SEE A FAIRLY QUIET 18-24 HOURS WITH MAINLY VFR CONDITIONS
PERSISTING. MAY SEE SOME ISOLATED AFTN TSTM CELLS POP UP...SO WILL
KEEP AN EYE ON THINGS. BUT CHANCES LOOK TOO LOW TO MENTION IN
INDIVIDUAL TAFS ATTM. SIMILAR CONDITIONS TONIGHT AS LAST NIGHT
WITH JUST SOME BRIEF & PATCHY MVFR CIGS/VIS LATE. TSTM CHANCES
INCREASE THURS AFTN AS COOL FRONT MOVES CLOSER TO SE TX. THIS
BOUNDARY ALONG W/ SEABREEZE WILL PROVIDE A FOCUSING MECHANISM.
POTENTIAL EXISTS FOR SOME LOCALIZED STRONG CELLS. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      74  93  72  91  71 /  10  30  30  20  10
HOUSTON (IAH)              74  94  75  90  72 /  10  20  40  40  30
GALVESTON (GLS)            81  91  80  88  79 /  10  20  30  40  30

&&

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

$$

AVIATION/MARINE...23


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