Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 181739
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1239 PM CDT THU SEP 18 2014

.DISCUSSION...
SEE 18Z AVIATION DISCUSSION.

&&

.AVIATION...
AVIATION CONDITIONS WILL BRIEFLY IMPROVE AT KIAH AND KHOU THROUGH
THE EVENING BUT AM EXPECTING CONDS TO DETERIORATE AT KCLL/KUTS AND
KGLS THROUGH THE AFTERNOON AS CONVECTION MOVES TOWARD THE
PERIPHERY OF THE HGX CWA. LEANED TOWARD A HRRR/NAM12 AND RAP BLEND
WHICH SETS UP LOW LEVEL CONVERGENCE WITH EAST WINDS OVER LAND AND
SE WINDS OVER THE WATER. SHRA SHOULD REDEVELOP SOUTH OF I-10
BETWEEN 08-11Z FRIDAY AND EXPAND INLAND. GFS LOOKS TO BE TOO
AGGRESSIVE WITH DRYING FRI MORNING. 43

&&

.PREV DISCUSSION... /ISSUED 1042 AM CDT THU SEP 18 2014/

UPDATE...
ANOTHER DAY OF SLOW-MOVING CLUSTERS OF MODERATE TO HEAVY RAIN
CELLS...WITH EMBEDDED THUNDERSTORMS...THAT HAVE PRODUCED NUISANCE
FLOODING AROUND HOUSTON METRO. COMMUNITIES OF WESTERN HARRIS...
SOUTHEASTERN MONTGOMERY...AND SOUTHERN SAN JACINTO COUNTIES HAVE
RECEIVED THE HIGHEST RAINFALL THIS MORNING. UPPER LAYER SOIL
SATURATION INDICATES THAT THE SOUTHEASTERN CWA ARE THE COUNTIES
THAT CAN PICK UP THE LEAST AMOUNT OF RAINFALL BEFORE DEALING WITH
FLOODING ISSUES. THE CORE RAINS ARE MOVING A LITTLE FASTER OFF TO
THE NORTHEAST AT 15 TO 20 MPH...AND THIS IS THE GOOD NEWS. THE
LESS GOOD NEWS IS THAT THERE IS WESTERN COUNTY PRECIPITATION RE-
DEVELOPMENT...WITH AN APPROACHING NORTH CENTRAL TEXAS SHORTWAVE
DISTURBANCE EMBEDDED WITHIN THE MID-LEVEL SOUTHEASTERLY STEERING
FLOW. THE AIR MASS REMAINS UNCHANGED AND...OTHER THAN SOME BRIEF
MOMENTS OF RESPITE AFTER PASSING RAIN AS THE ATMOSPHERE QUICKLY
RE-CHARGES...THE SITUATION WILL BE OF RETURNING PRECIPITATION. IT
ALL DEPENDS UPON THE NEAR TERM AREAL EXTENT AND IMPACT OF AFTERNOON
RAIN/STORM ACTIVITY OVER THE NEXT 6 HOURS IN DETERMINING WHETHER
THE FLOOD WATCH NEEDS TO BE EXTENDED INTO FRIDAY. RAIN AND OVERCAST
EQUATE TO MANY ONLY ACHIEVING THE MID 80S FOR MAXIMUM TEMPERATURES.
AS OF NOW...IT APPEARS THAT FRIDAY WILL BE A TRANSITION DAY TO
RELATIVELY DRIER WEEKEND CONDITIONS. HIGHER RAIN CHANCES SHOULD BE
FOCUSED ALONG THE COAST AND POINTS SOUTHWESTWARD...OR WHERE THE
HIGHER MOISTURE RESIDES. THIS ASSUMPTION IS BASED UPON A DRIER AIR
AIR MASS OVER THE SABINE REGION MODELED TO PUSH INTO THE EASTERN
CWA BEHIND A VERY WEAK NORTHEASTERN BOUNDARY PASSAGE EARLY FRIDAY
MORNING. 31

PREV DISCUSSION... /ISSUED 455 AM CDT THU SEP 18 2014/

DISCUSSION...
WET FCST TO CONTINUE TODAY BUT WITH A CONTINUED THREAT OF FLOODING.
GROUNDS WET FROM RAINS THE PREVIOUS FEW DAYS ALONG WITH THE POTENTIAL
OF ADDITIONAL RAINS TODAY WILL KEEP THE FLOOD WATCH IN PLACE THROUGH
THIS EVENING.

ALREADY SEEING DEVELOPMENT OVER THE NEARSHORE WATERS THIS MORNING
AS THE CONTINUED WAA FLOW COLLIDES WITH THE MORE S/SE MOVING DISTURBANCE
COMING OUT OF SOUTH CENTRAL TX. ALSO SEEING HINTS OF YET ANOTHER
DISTURBANCE TRYING TO DIVE DOWN FROM NORTH TX. THESE SYSTEMS COMBINED
WITH THIS STILL VERY MOIST/TROPICAL AIR MASS ALREADY IN PLACE SHOULD
PRODUCE WIDESPREAD CONVECTION ACROSS THE CWA THRU THIS AFTN/EVE.

PER THE LATEST MODEL RUNS...THE REST OF THE WEEK/WEEKEND FORECAST SHOULD
SEE SOME DRYING BUT CONSENSUS NOT AS STRONG WITH THIS NEXT COLD FRONT
EARLY NEXT WEEK. PROGS APPEAR TO BE HAVING ISSUES WITH THE HANDLING
OF THE REMNANTS OF ODILE AND MAY BE EXAGGERATING ITS IMPACT ON THE
MAIN UPPER FLOW/PATTERN. AS SUCH WILL NOT BE CHANGING THE EXTENDED
FCSTS (TOO MUCH) OF FROPA MON (ALONG WITH COOLER AND DRIER CONDTIONS
NEXT WEEK). 41

MARINE...
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS MORNING
AND MAY HAVE A CLUSTER MOVE INTO THE COASTAL WATERS THIS AFTERNOON
WITH GUSTY WINDS. SOUTHEAST WINDS WILL BECOME MORE EASTERLY ON
FRIDAY...AND INCREASE FRIDAY NIGHT AND SATURDAY. WEAK HIGH
PRESSURE SETTLES OVER SETX/LA AND WINDS SHOULD SLOWLY RELAX ON
MONDAY. A COLD FRONT SHOULD (IF THE ECMWF IS CORRECT-FAVORING IT
ATTM) MOVE INTO THE COASTAL WATERS ON TUESDAY OF COURSE DEPENDING
ON HOW WELL THE MODELS HANDLE ODILE AND THE NEXT TROUGH THROUGH
THE EASTERN U.S.. 45

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      71  88  71  91  73 /  60  50  20  30  20
HOUSTON (IAH)              71  88  72  90  74 /  60  70  20  30  20
GALVESTON (GLS)            77  86  79  88  79 /  60  60  30  30  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES:
     AUSTIN...BRAZORIA...BRAZOS...BURLESON...CHAMBERS...
     COLORADO...FORT BEND...GALVESTON...GRIMES...HARRIS...
     HOUSTON...JACKSON...LIBERTY...MADISON...MATAGORDA...
     MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER...
     WALLER...WASHINGTON...WHARTON.

GM...NONE.
&&

$$

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



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