Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 011830
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
130 PM CDT TUE SEP 1 2015

.UPDATE...
SENT OUT AN UPDATED FORECAST PACKAGE WITH LOWERED POPS AT ALMOST ALL
BUT SOUTHEAST AREAS WHERE LOCALLY HEAVY RAINFALL LINGERS. ALSO TOOK
SEVERAL DEGREES OFF TODAY`S HIGH TEMPERATURES BASED ON CURRENT
OBSERVATION TRENDS AND CLOUD COVER. 42

&&

.AVIATION...
FOR THE 18Z TAFS... MAIN AVIATION CONCERNS CENTER AROUND ONGOING
TSRA/SHRA ACTIVITY AT THE TERMINALS WITH ADDITIONAL DEVELOPMENT
EXPECTED AGAIN ON WEDNESDAY.

SCATTERED TO NUMEROUS THUNDERSTORMS ASSOCIATED WITH A MID TO
UPPER LEVEL DISTURBANCE CONTINUE TO MOVE ACROSS THE TERMINALS THIS
AFTERNOON. BULK OF ACTIVITY IS CONCENTRATED NEAR AND NORTH OF CXO
WITH AN ADDITIONAL BROKEN LINE CLEARING THE HOUSTON TERMINALS AND
SOUTHWARD. STARTING TO SEE ADDITIONAL ACTIVITY DEVELOP OVER THE
GULF AND THIS WILL NEED TO BE MONITORED FOR THE COASTAL SITES THIS
AFTERNOON. HAVE VCTS AT ALL TERMINALS THROUGH 21Z AS ACTIVITY
EXITS THE AREA... WITH ANOTHER ROUND OF SHRA/TSRA POSSIBLE AGAIN
EARLY WEDNESDAY MORNING OVER THE COASTAL WATERS AND SPREADING
NORTH INTO THE TERMINALS THROUGH WEDNESDAY AFTERNOON AS THE
AFOREMENTIONED DISTURBANCE DRAWS CLOSER TO THE REGION.

OTHERWISE... LIGHT AND VARIABLE TO LIGHT AND SOUTHERLY WINDS
EXPECTED FOR THE TERMINALS THROUGH THE PERIOD WITH VFR CONDITIONS
OUTSIDE OF TSRA/SHRA ACTIVITY. SOME STRONGER WIND GUSTS
APPROACHING 20 KNOTS WILL BE POSSIBLE IN CONVECTIVE ACTIVITY AS
WELL AS MVFR VISIBILITIES. COULD SEE A FEW HOURS OF MVFR
VISIBILITIES AT CXO AGAIN WEDNESDAY MORNING AS WELL AT CXO... BUT
ONLY INCLUDING A TEMPO MENTION ATTM.

HUFFMAN

&&

.PREV DISCUSSION...

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

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      72  91  73  94  75 /  20  30  20  30  10
HOUSTON (IAH)              72  88  72  92  74 /  40  50  30  40  20
GALVESTON (GLS)            78  87  79  88  80 /  50  50  40  50  30

&&

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

$$

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



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