Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 310434
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1134 PM CDT THU JUL 30 2015

.DISCUSSION...
SEE 06Z AVIATION DISCUSSION.

&&

.AVIATION...
PRECIPITATION LASTED A BIT LONGER THAN EXPECTED BUT IS IN THE
PROCESS OF DISSIPATING. AN ISOLATED SHOWER CAN NOT BE RULED OUT AT
ANY TIME OVERNIGHT AS PW VALUES REMAIN ABOVE 2.00 INCHES. NAM12
AND THE GFS DIFFER WITH PW VALUES ON FRIDAY WITH THE NAM MORE
AGGRESSIVE WITH MOISTURE. THE RAP HAS BACKED OFF SIGNIFICANTLY
WITH MORNING PRECIP AND IS NOW WAITING ON HEATING TO TRIGGER
SHRA/TSRA. WILL LEAN TOWARD A RAP/HRRR/GFS BLEND WHICH FOCUSES
MUCH OF THE PRECIP ON FRI OVER THE SW HALF OF THE CWA. WILL CARRY
VCSH FOR KLBX...KSGR...KHOU AND KGLS. DRY AIR WILL FILTER INTO
THE AREA FROM THE NE LATE FRIDAY AFTN AND WILL END PRECIP FROM NE
TO SW TOWARD EVENING. NUMEROUS OUTFLOW BOUNDARIES AND A WEAK
PRESSURE GRADIENT MAKES FCSTING WIND DIRECTION DIFFICULT. 43

&&

.PREV DISCUSSION... /ISSUED 912 PM CDT THU JUL 30 2015/

DISCUSSION...
SHOWERS AND THUNDERSTORMS STILL DRIFTING DOWN INTO NE ZONES AT
THIS HOUR. ANOTHER IMPORTANT FEATURE...RADAR SHOWING OUTFLOW FROM
LOUISIANA CONVECTION MOVING IN FROM THE EAST. THIS OUTFLOW TO
BRING SOME GUSTY EAST AND NORTHEAST WINDS SHORTLY TO GALVESTON BAY
AND EASTERN COASTAL GULF WATERS. WIND GUSTS WERE AS HIGH AS 40
KNOTS OVER COASTAL LOUISIANA...LIKELY 30 KNOTS OR SO FOR SOME
AREAS NOW. HAVE ISSUED A MARINE WEATHER STATEMENT TO GIVE A HEADS
UP FOR THIS FEATURE AND ADJUSTED WIND GRIDS AS WELL.

OVERNIGHT...EXPECT A CONTINUED SLOW WEAKENING TREND IN SHOWER AND
THUNDERSTORM ACTIVITY OVER LAND...BUT CANT RULE OUT AN ISOLATED
SHOWER OR THUNDERSTORM ANYWHERE GIVEN THE AIRMASS CATEGORIZED BY
DEEPER MOISTURE. FOR COASTAL AREAS WILL LIKELY SEE SQUALL LINE
BRUSH AT LEAST OUTER WATERS...BUT OUTFLOW WILL MOVE FROM NE TO SW
ALONG THE COAST WITH SOME ADDITIONAL DEVELOPMENT POSSIBLE. HAVE
BUMPED UP POPS FOR COASTAL WATERS TO COVER THIS. HIGH RESOLUTION
RAPID REFRESH SUPPORTS THIS SCENARIO. 46

PREV DISCUSSION... /ISSUED 304 PM CDT THU JUL 30 2015/

DISCUSSION...

SCT CONVECTION IS OCCURRING ACROSS NORTHERN AND EASTERN AREAS THIS
AFTERNOON. THIS ACTIVITY IS MOVING SOUTHWEST...SO CENTRAL AREAS
WILL LIKELY SEE SCT CONVECTION AS WELL LATER THIS AFTERNOON AND
EVENING. NORTHERN AND EASTERN AREAS ARE MOIST AND UNSTABLE...SO
ISOLATED STRONG STORMS ARE POSSIBLE. MAX TEMPS ARE AROUND 100
ACROSS FAR INLAND AREAS...UPPER 90S CENTRAL AREAS...AND LOWER TO
MID 90S COAST. HEAT INDICES REMAIN IN THE 100 TO 107 DEGREE RANGE
THIS AFTERNOON.

THE FRONTAL BOUNDARY IS NEAR THE RED RIVER AND IN SW ARK. THIS
BOUNDARY WILL MOVE SOUTHWEST INTO NE PORTIONS OF SE TEXAS LATE
TONIGHT/EARLY FRIDAY MORNING. BEHIND THE BOUNDARY WE WILL SEE A
DRIER AIRMASS ADVECT INTO THE REGION. THE LOCATION OF BOUNDARY WILL
DETERMINE WHERE THE BEST RAIN CHCS ARE TOMORROW. SOUTH OF THE
BOUNDARY EXPECT SCT CONVECTION AGAIN WHERE PW VALUES ARE JUST
OVER 2 INCHES. WILL TAPER POPS UPWARD FROM THE NE TO SW AREAS OF
SE TX....BASED ON THE PRECIPITABLE WATER GRADIENT EXPECTATIONS
ON FRI. BY SAT MORNING THE DEEP MOISTURE WILL BE OFFSHORE AND SW
OF SE TX...SO RAIN CHCS WILL BE VERY SMALL AGAIN FROM SAT
THROUGH MID-WEEK.

NOT MUCH CHG EXPECTED IN MAX TEMPS...SOME VARIATIONS THE NEXT
COUPLE OF DAYS DUE TO DIFFERENCES IN LAYER MOISTURE LEVELS. FAR
INLAND AREAS ON SAT COULD SEE WIDESPREAD TEMPS OVR 100 DUE TO THE
VERY DRY AIRMASS THAT WILL BE IN PLACE.

MARINE...A WEAK BACKDOOR FRONT NORTH OF THE AREA WILL EFFECT THE
COAST LATE THURSDAY INTO FRIDAY. HOWEVER...THE WINDS ASSOCIATED
WITH THE FRONT SHOULD BE LIGHT ENOUGH TO BE INFLUENCED BY THE SEA
BREEZE ON FRIDAY THROUGH THE WEEKEND.

AN OFFSHORE FLOW DURING THE EARLY MORNING HOURS WILL RELAX AND
BECOME ONSHORE DURING PEAK HEATING IN THE AFTERNOON BEFORE BECOMING
SOUTHWESTERLY IN THE EVENING. RAIN CHANCES WILL BE ON THE INCREASE
TONIGHT AND FRIDAY AS POOL OF MOISTURE OVER LA AND GULF SLIDES
WESTWARD INTO THE UPPER TEXAS COASTAL WATERS.

FORECAST MODELS BUILD THE HIGH PRESSURE RIDGE BACK OVER THE COASTAL
WATERS LATE IN THE WEEKEND AND EARLY NEXT WEEK. 44

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      78  99  75 101  76 /  20  30  20  10  10
HOUSTON (IAH)              79  99  77 100  76 /  30  30  10  10  10
GALVESTON (GLS)            82  92  82  94  82 /  30  30  10  10  10

&&

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

$$

DISCUSSION...46
AVIATION/MARINE...40



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