Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 171714
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1214 PM CDT WED SEP 17 2014

.DISCUSSION...
SEE 18Z AVIATION DISCUSSION.

&&

.AVIATION...
CONVECTIVE TEMPS ARE BETWEEN 82-86 DEGREES AND PW VALUES REMAIN
BETWEEN 2.1-2.3 INCHES. IT WON`T TAKE MUCH LIFT TO GET CONVECTION
TO REFIRE THIS AFTN BUT THE FIRST LINE THAT ROLLED THROUGH THE
AREA WILL KEEP THINGS STABLE FOR A BIT EARLY THIS AFTN. HEATING
WILL ALLOW SHRA/TSRA TO DEVELOP NEAR KCLL/KUTS THIS AFTN. AVIATION
INTERESTS SHOULD BE PREPARED FOR POOR FLYING CONDITIONS BEGINNING
AS EARLY 09Z THURS AS A STRONG S/WV DIVES SE IN THE UPPER FLOW.
CONCERNED THAT CONVECTION WILL FIRE BEFORE SUNRISE AND AFFECT
AREAS FROM KCLL TO KIAH BY 12Z. ACTIVITY WILL PERSIST THROUGH MUCH
OF THE DAY. COULD HAVE USED TEMPO ALL DAY BUT PREFER TO WAIT AND
SEE HOW THE OVERNIGHT SYSTEM EVOLVES. 43

&&

.PREV DISCUSSION... /ISSUED 1107 AM CDT WED SEP 17 2014/

UPDATE...
AFTER MORNING COLLABORATION WITH WPC...THERE HAS BEEN AN ONGOING
ADJUSTMENT OF OUR POPS/WX/QPF GRIDS. THE MAIN THEME IS FOR THE
THREAT OF MORE AREA-WIDE HEAVY RAINFALL LEADING TO FLOODING. THE
CLUSTERS THAT HAVE PASSED ACROSS NORTH-NORTHWEST HARRIS COUNTY HAVE
DROPPED LARGE AMOUNTS OF RAIN IN A SHORT AMOUNT OF TIME...WITH AN
EXAMPLE OF AN INCH WITHIN 15 MINUTES AT THE CYPRESS CREEK AT FM
249 HCFCD RAIN GAUGE. CLUSTERS OF SLOW-MOVING SHOWERS AND STORMS
FORMING WITHIN A HIGHLY MOIST TROPICAL-IN-NATURE AIR MASS HAVE THE
POTENTIAL OF PUTTING DOWN HIGH RAINFALL AMOUNTS/RATES OVER THE
NEXT 24 TO 36 HOURS. FFG HAS HOURLY RATES OF TWO TO THREE INCHES
LEADING TO FLOODING CONCERNS...THREE TO FOUR INCH AMOUNTS OVER 3
TO 6 HOURS WILL SIGNIFICANTLY HEIGHTEN THE FLOOD THREAT...AS WELL.
IN GENERAL...RECENT HIGH RAINFALL RATES/HIGHER RELATIVE-VOLUMETRIC
SOIL CONTENT VALUES RESIDE OVER THOSE COUNTIES EAST AND SOUTHWEST
OF THE CITY SO...ALONG WITH HOUSTON METRO/SUBURBS...THESE WILL BE
THE AREAS THAT WILL MOST LIKELY EXPERIENCE FLOODING ISSUES. POINTS
SURROUNDING THESE LOCATIONS CAN HANDLE MORE RAINFALL...BUT WITH
THESE RECENTLY HIGH HOURLY RAINFALL RATES OF BETWEEN A HALF OF AN
INCH TO NEAR NEAR TWO INCHES...ANY COMMUNITY COULD BE IN THE HAT
IN DEALING WITH (FLASH) FLOODING. THE REST OF THE FORECAST WILL
REMAIN UNCHANGED...OVERCAST WITH AFTERNOON TEMPERATURE EXTREMA IN
THE MID TO UPPER 80S WITH MORNING READINGS FALLING INTO THE MIDDLE
70S. 31

PREV DISCUSSION... /ISSUED 446 AM CDT WED SEP 17 2014/

DISCUSSION...
NOT A LOT OF CHANGES WITH THE GOING FCST OF CONTINUED RAINS FOR
TODAY/TOMORROW. VERY HIGH PW`S NOTED OVER THE REGION (~2.3") AND
NOT EXPECTING THAT WE WILL NEED A LOT OF HEATING FOR PCPN
DEVELOPMENT TO START AGAIN LATER THIS MORNING/AFTN. AS THIS
MOISTURE LINGERS INTO TOMORROW WE MAY HAVE THE REMNANTS OF ODILE
TO DEAL WITH AS WELL. WILL LIKELY KEEP WITH AVG RAINFALL TOTALS
FROM .5 TO 1`... ISO 3-4" TODAY THROUGH TONIGHT.

RAIN CHANCES TO DECREASE SOME BY FRI (ON INTO THE WEEKEND) WITH
WEAK UPPER RIDGING BUILDING IN BEHIND THE UPPER TROF (ODILE REMNANTS).
HOWEVER WILL BE KEEPING ISO/SCT POPS IN FOR THIS PERIOD AS THE DEEP
TROPICAL MOISTURE LINGERS OVER THE AREA. LONG RANGE MODELS KEEPING
WITH THE PASSAGE OF THE COLD FRONT AOA MON...BUT WITH VARYING DEGREES
OF STRENGTH. ECMWF KEEPING ITS FROPA A BIT MORE ROBUST THAN GFS ATTM...
BUT GIVEN THE MORE CONSISTENT PROGS OF A FAIRLY DEEP N/NWLY FLOW
ALOFT WILL BE LEANING MORE TOWARDS THE ECMWF FOR THIS TIME FRAME.

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      89  75  86  72  90 /  70  60  70  20  40
HOUSTON (IAH)              88  75  86  73  89 /  80  40  80  30  50
GALVESTON (GLS)            86  79  84  78  87 /  60  60  70  40  50

&&

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

$$

DISCUSSION...31
AVIATION/MARINE...43


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