Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 011522
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1022 AM CDT TUE SEP 1 2015

.DISCUSSION...
LOCALLY HEAVY RAINFALL HAS BEEN FALLING SO FAR THIS MORNING GENERALLY
TO THE SOUTH OF HIGHWAY 59 AND ESPECIALLY ACROSS PORTIONS OF GALVESTON
AND BRAZORIA COUNTIES (BETWEEN THE SOUTH HOUSTON AREA AND GALVESTON
ISLAND) WHERE AN ESTIMATED 1 TO 3 INCHES HAS OCCURRED. AT 10 AM...A
LARGE CLUSTER OF STORMS FROM THE RICHMOND-ROSENBERG AREA TO GALVESTON
ISLAND LINES UP WELL WITH THE COLDEST CLOUD TOPS ON IR SATELLITE IMAGES...
AND THIS IS WHERE LOCALLY HEAVY RAINFALL CONTINUES TO FALL. RECENT HIGH
RESOLUTION MODELS KEEP THIS ACTIVITY GOING ON FOR A COUPLE MORE HOURS...
THEN SPREAD OUTFLOWS WITH MORE ISOLATED SHOWER AND THUNDERSTORM COVERAGE
NORTHWARD ACROSS THE REST OF OUR AREA AS THE AFTERNOON PROGRESSES. NOT
REAL CONFIDENT ON HOW MUCH LONGER THESE STORMS WILL LAST OR HOW FAR
INLAND THEY WILL GET AS THE DAY PROGRESSES...SO WILL LEAVE THE FORECAST
AS IS FOR NOW (HIGHEST RAIN CHANCES NEAR THE COAST AND LOWEST CHANCES
UP NORTH) AND DO SOME UPDATES AS NEEDED.  42
&&

.PREV DISCUSSION...

DISCUSSION...
WHILE WE ARE SEEING SOME PCPN DEVELOPMENT NEAR THE COAST OVERNIGHT
THIS ACTIVITY HAS NOT LASTED TOO LONG. OF GREATER CONCERN LOOKS TO
BE THE MORE ORGANIZED ACTIVITY DOWN THE TX COAST...WHICH IS EXPECT-
ED TO HEAD THIS WAY TODAY. LOCALLY HEAVY RAINFALL POSSIBLE AS THIS
LARGE AREA OF PCPN MOVES ACROSS SE TX...WITH THE BEST CHANCES NEAR
THE COAST (WHERE DEEPER MOISTURE/BEST LIFT WILL BE LOCATED). NOT A
LOT OF CHANGE FROM EARLIER THINKING OF AVG RAINFALL TOTALS OF 1/2"
TO 1" NORTH OF I-10... AND 2"-4" SOUTH OF THE INTERSTATE.

THIS PATTERN (IN SOME FORM) WILL LIKELY BE REPEATED TOMORROW GIVEN
THE NEARLY STATIONARY UPPER LOW/TROF OVER SOUTH TX. TIMING OF S/WV
ENERGY ASSOCIATED WITH THIS SYSTEM LOOKS TO BE THE MAIN ISSUE LOOK-
ING FORWARD. ECMWF/NAM REMAIN THE FAVORED MODELS AS THEY APPEAR TO
BE INITIALIZING/VERIFYING BEST. 41

MARINE...
SMALL BAND OF SHOWERS/THUNDERSTORMS MOVED THROUGH GALVESTON BAY
EARLIER THIS MORNING BUT S/W CAN BE SEEN ON WATER VAPOR IMAGERY
NEARING CRP AT 09Z AND WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE
FORMED OVER THE LOWER AND MIDDLE TEXAS COASTAL WATERS. THIS S/W
SHOULD ROTATE EAST AND NORTHEAST AND HELP TO ENHANCE DEVELOPMENT
LATER THIS MORNING OVER THE UPPER TEXAS COASTAL WATERS. WIND
PROFILE IS RELAXING OVER THE COASTAL WATERS AND MAY GET A WINDOW
OF A FEW HOURS WITH AN ELEVATED WATERSPOUT THREAT AFTER 9 AM
BEFORE DEVELOPMENT INLAND GETS GOING. LULL IN STORMS SHOULD OCCUR
BY 3 PM OVER THE GULF WATERS. REPEAT EXPECTED WEDNESDAY MORNING
THEN AS UPPER SHEAR AXIS/LOW MOVES EAST THE COVERAGE SHOULD SLOWLY
DECREASE AND RETURN TO THE MORE NORMAL DIURNAL PATTERN. WINDS
REMAIN AT 15 KNOTS OR LESS THROUGH THE PERIOD WITH PLENTY OF 5-10
KNOT PERIODS THROWN IN THERE WITH THE DEPARTURE OF THE UPPER
TROUGH TO THE EAST BY SATURDAY AND STRENGTHENING OF THE UPPER
RIDGING OVER TEXAS.
45

AVIATION...
COVERAGE FROM FIRST IMPULSE THIS MORNING NEAR GLS HAS DIMINISHED
BUT EXPECT COVERAGE TO INCREASE AROUND SUNRISE IN THE GULF AND HOP
INLAND BY 15Z. HAVE TRIED TO NARROW DOWN THE MOST FAVORABLE PERIOD
FOR SHRA/TSRA TRAVERSING THE IAH/HOU TERMINALS AS 16-19Z...THOUGH
VCNTY SHRA/TSRA MAY LINGER TIL MID AFTERNOON. BY LATE AFTERNOON
EXPECT COVERAGE TO DECREASE DRAMATICALLY BUT AFTER 09Z EXPECT MORE
STORMS TO FORM OVER THE GULF AND AGAIN MARCH INLAND TOMORROW
MORNING.
45

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      91  72  91  73  94 /  40  20  30  20  30
HOUSTON (IAH)              88  72  88  72  92 /  60  40  50  30  40
GALVESTON (GLS)            87  78  87  79  88 /  60  50  50  40  50

&&

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

$$

DISCUSSION...42
AVIATION/MARINE...14



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