Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 011813
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
113 PM CDT MON SEP 1 2014

.DISCUSSION...
18Z AVIATION DISCUSSION.

&&

.AVIATION...
AFTERNOON CONVECTION BEGINNING TO BLOSSOM OVER VARIOUS METRO
SITES...MORNING SUN ENERGY WITHIN A HUMID AND UNSTABLE AIR MASS
TO KICK ACTIVITY OFF. MORE PRONOUNCED INFLUENCE FROM THE EASTERN
UPPER RIDGE WILL KEEP COVERAGE TO A MINIMUM AS COMPARED TO RECENT
DAYS. PRIMARILY VFR...A FEW HOURS OF NON-METRO OVERNIGHT TUESDAY
MORNING MVFR WITH A RETURN CHANCE FOR AN HOUR (OR TWO) OF IFR
CEILINGS. SIMILAR CONVECTIVE BEHAVIOR TUESDAY WITH A HIGHER CHANCE
OF MORE AREAL EARLY DAY SHRA/EARLY AFTERNOON -TSRA COVERAGE AS A
HIGHER SLUG OF MOISTURE COMES ONSHORE NORTH OF A BAY OF CAMPECHE
TROPICAL WAVE/WEAK CIRCULATION. 31

&&

.PREV DISCUSSION... /ISSUED 1025 AM CDT MON SEP 1 2014/

UPDATE...
SEE MORNING UPDATE.

.DISCUSSION...
12Z SOUNDING DATA SHOWS PW VALUES BETWEEN 2.00 AND 2.10 INCHES AND
CONVECTIVE TEMPS IN THE MID/UPPER 80S. 850MB MOISTURE LEVELS HAVE
DROPPED A LITTLE FROM YESTERDAY BUT IT STILL LOOKS PLENTY MOIST.
AT 700 MB...A WEAK TROUGH EXTENDS FROM TEXARKANA TO SAN ANTONIO
WITH SLIGHTLY DEEPER MOISTURE NOTED AROUND THE ARKLATEX. AT 250
MB...UPPER LEVEL RIDGING LOOKS A BIT STRONGER AND SUBSIDENCE FROM
THE RIDGE IS EDGING EVER CLOSER TO SE TX. WIDELY SCATTERED SHRA/TSRA
WILL BEGIN TO DEVELOP WITH HEATING. PREV FCST HAS ALL THIS COVERED
SO NO UPDATE IS REQUIRED AT THIS TIME. 43

&&

PREV DISCUSSION... /ISSUED 628 AM CDT MON SEP 1 2014/

.DISCUSSION...
SEE AVIATION FOR 12Z TAF DISCUSSION.

.AVIATION...
IFR CIGS HAVE OVERSPREAD THE NORTHERN TAF SITES THIS MORNING BUT
SHOULD BEGIN TO IMPROVE QUICKLY AFTER SUNRISE. LIGHT SHRA OFFSHORE
APPROACHING GLS AND SHOULD GRADUALLY SPREAD INLAND THROUGH THE
MORNING HOURS. LESS MOISTURE TO WORK WITH TODAY BUT COULD STILL
SEE SOME ISOLATED ACTIVITY INLAND. INSTABILITY HIGH ENOUGH TO GO
WITH VCTS THROUGH THE EARLY AFTERNOON FOR METRO AREA TAF SITES.
ANOTHER ROUND OF MVFR/IFR CIGS POSSIBLE AGAIN EARLY TUESDAY. 38

&&

PREV DISCUSSION... /ISSUED 432 AM CDT MON SEP 1 2014/

.DISCUSSION...
LOW PRESSURE IN THE PLAINS SHOULD DEEPEN TODAY AND SUPPORT
STRONGER SE WINDS AT THE SFC. TROPICAL MOISTURE HAS DECREASED SOME
ACROSS THE AREA BUT PRECIP WATER VALUES STILL REMAIN AROUND 1.9-2
INCHES PER SOUNDINGS AND GOES SOUNDER DATA. UPPER LEVEL TROUGH
OVER THE PLAINS WILL PULL TOWARDS THE GREAT LAKES WITH A TRAILING
SHORTWAVE MOVING ACROSS THE C PLAINS BY THIS AFTERNOON. UPPER
LEVEL RIDGE IS IN THE PROCESS OF BECOMING MORE ESTABLISHED OVER
THE AREA AS HEIGHTS SHOULD RISE TODAY. UPPER LEVEL RIDGE SHOULD
REMAIN BROAD AND FLAT ACROSS THE SOUTHERN U.S. INTO TUE/WED.

IR SATELLITE IMAGERY OVER THE CARIBBEAN SHOWS A TROPICAL WAVE
MOVING OVER THE YUCATAN THIS MORNING. THIS WAVE SHOULD EMERGE INTO
THE BAY OF CAMPECHE TONIGHT INTO TUE. THE GFS/ECMWF AGREE WITH
KEEPING THE TROPICAL WAVE AN OPEN WAVE MOVING TOWARDS THE MEXICAN
COAST. THE NAM AND CANADIAN CLOSE OFF A CIRCULATION WITH THE
POSSIBILITY OF A TROPICAL STORM FORMING BEFORE LANDFALL TUE NIGHT
INTO WED. CANADIAN IS MOST AGGRESSIVE. NHC GIVES THE SYSTEM A 60
PERCENT CHANCE OF TROPICAL CYCLONE DEVELOPMENT THE NEXT 48HRS AND
70 PERCENT CHANCE OVER NEXT 5 DAYS. THE ENVIRONMENT IS AT LEAST
LOOKING MORE FAVORABLE FOR DEVELOPMENT. LATEST FORECASTS HAVE ALL
BEEN VERY CONSISTENT WITH BRINGING THE SYSTEM REGARDLESS OF
STRENGTH INTO THE MEXICO COAST. GREATEST IMPACT FROM THIS SYSTEM
ON THE TX COAST WILL BE INCREASING SEAS AND TROPICAL MOISTURE.
WHILE THE UPPER LEVEL RIDGE WILL BE IN PLACE...THERE STILL SHOULD
BE PLENTY OF MOISTURE FOR THUNDERSTORM CHANCES TUE/WED SO WILL
KEEP 30/40 POPS IN THE FORECAST WITH 50 POPS ON TUE. LOCALLY HEAVY
RAINFALL WILL AGAIN BE POSSIBLE WITH INTENSE RAIN RATES IN
STRONGER STORMS.

THE REST OF THE WEEK WILL BE A BATTLE BETWEEN SUBSIDENCE FROM THE
UPPER LEVEL RIDGE AND CONVECTION DEVELOPING DUE TO DAY TIME
HEATING WITH THE TROPICAL MOISTURE. FORECAST WILL AT LEAST KEEP 20
POPS FOR THE OF THE WEEK INTO THE COMING WEEKEND. UPPER LEVEL
RIDGE WILL REMAIN STRETCHED OVER TX WITH WEAKLY AMPLIFIED ALMOST
ZONAL JET STREAM FLOW ACROSS THE NORTHERN HALF OF THE U.S. MAIN
DIFFERENCES IN THE GFS/ECMWF FOR THE EXTENDED FORECAST IS A BACK
DOOR FRONT COMING INTO THE AREA PER THE ECMWF. THIS WILL STILL BE
DIFFICULT TO DO SINCE THE PATTERN IS STILL WEAKLY AMPLIFIED AND
THE RIDGE MAY BE STRONG ENOUGH TO KEEP THE FRONT OUT OF THE AREA.
39

&&

.MARINE...
ISOLATED SHOWERS WILL CONTINUE ACROSS THE COASTAL WATERS TODAY.
EXPECT ONSHORE WINDS TO PERSIST THROUGH MUCH OF THE WEEK WITH
SPEEDS INCREASING BEGINNING LATE TONIGHT AS PRESSURES BEGIN TO
LOWER ACROSS THE BAY OF CAMPECHE. MAY NEED CAUTION FLAGS AS EARLY
AS TONIGHT BUT LIKELY BEGINNING ON TUESDAY. APPROACHING SWELLS
WILL BRING WAVE HEIGHTS UP BY ANOTHER FOOT OR TWO ACROSS THE
OFFSHORE WATERS BY WEDNESDAY. 38

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      77  94  76  94  75 /  10  30  20  20  10
HOUSTON (IAH)              77  91  76  92  76 /  20  50  20  30  10
GALVESTON (GLS)            81  88  81  89  81 /  30  40  20  30  10

&&

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

$$

DISCUSSION...42
AVIATION/MARINE...31


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