Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 241132
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
632 AM CDT THU JUL 24 2014

.DISCUSSION...
12Z TAF DISCUSSION IN AVIATION SECTION.

&&

.AVIATION...
SQUALL LINE THAT PUSHED INTO THE AREA LATE LAST NIGHT HAS SHED A
STRONG OUTFLOW BOUNDARY THAT INITIATED CONVECTION ALONG IT OVER
THE HOUSTON AREA. THOSE STORMS HAVE SINCE PUSHED INTO THE GULF AND
THE OUTFLOW NOW STRETCHES FROM W OF KCLL TO WEST OF KBYY. THIS HAS
ALLOWED FOR TEMPS TO DROP INTO THE LOW 70S AND DEWPOINTS IN THE
UPPER 60S MAINLY NORTH OF KIAH. THINK OUTFLOW WILL STABILIZE
ATMOSPHERE FOR AWHILE UNTIL DAY TIME HEATING ALLOWS FOR RECOVERY.
WITH DEWPOINTS IN THE LOW 70S ALONG THE COAST AND SEA BREEZE
POSSIBLY DEVELOPING...COULD SEE ISO STORMS BY LATE AFTERNOON. DO
NOT THINK COVERAGE WARRANTS VCTS IN TAFS BUT WILL KEEP IN
KIAH/KHOU/SGR TAFS AS THESE WILL BE AREAS MOST LIKELY TO HAVE TSRA
IN THE AREA. THIS WILL ALSO DEPEND ON UPPER LEVELS OF ATMOSPHERE
BECOMING FOR FAVORABLE FOR CONVECTION WITH ANY VORT MAXES ROTATING
THROUGH THE FLOW. CIGS SHOULD STAY VFR AND EXPECT LIGHT WINDS
AGAIN OVERNIGHT. MAY NEED TO CONSIDER LOWER VSBY TOMORROW MORNING
BUT NOT CONFIDENT ENOUGH TO PUT IN TAFS.

39

&&

.PREV DISCUSSION... /ISSUED 402 AM CDT THU JUL 24 2014/

DISCUSSION...
THE UPPER LOW THAT WAS OVER THE LOUSIANA COAST YESTERDAY HAS
SHEARED OUT EARLY THIS MORNING...WITH THE LEFTOVER TROUGH
STRETCHING FROM EASTERN LOUSIANA TO THE MID TEXAS COAST. A
GENERAL NORTHERLY FLOW WAS IN PLACE ALOFT DUE TO THE WEAKENING
TROUGH AND AN UPPER HIGH CENTERED OVER WESTERN CO AND NM. THE
MODELS GENERALLY BUILD THE HIGH PRESSURE RIDGE OVER EASTERN TEXAS
AND NORTHERN LOUSIANA FRIDAY THROUGH SUNDAY...THEN THEN OVER SE TX
ON MONDAY AS AN UPPER TROUGH BEGINS TO DIG SOUTHWARD FROM THE
GREAT LAKES. AS THIS TROUGH PUSHES INTO THE LOWER MISSISSIPPI
VALLEY DURING THE MID WEEK PERIOD...THE HIGH WILL PUSH WESTWARD
INTO THE DESERT SOUTHWEST AND RETURN A NORTHWESTERLY FLOW OVERHEAD
THE FORECAST AREA.

THE MAIN PROBLEM FOR TODAY CONCERNS THUNDERSTORM CHANCES. THE
SHORT TERM AND HIGH RESOLUTION MODELS AGREE WITH THE BEST RAIN
CHANCES OVER THE SOUTHERN HALF OF THE FORECAST AREA. STORM MOTION
WILL AGAIN BE GENERALLY FROM THE NORTHEAST TO SOUTHWEST...WHILE
MODEL FORECAST SOUNDINGS ALSO INDICATE THE POTENTIAL FOR GUSTY
WINDS AND HEAVY DOWNPOURS IN THE STRONGER STORMS. OF NOTE...THE
NAM BUFR FORECASTS PW/S FROM 1.8 IN THE NORTHWEST TO NEAR 2 INCHES
TOWARD THE COAST...WHILE THE AFTERNOON SOUNDING FORECASTS AN
INVERTED V PROFILE BELOW 850 MB AND DCAPE VALUES OF 700 TO 1100
J/KG.

KEPT THE ISOLATED CHANCES FOR THUNDERSTORMS IN THE FORECAST FOR
FRIDAY AS THE ECWMF IN PARTICULAR KEEPS THE WEAKNESS ALOFT
OVERHEAD AND THE GFS ENSEMBLE FORECASTS SLIGHT CHANCES FOR RAIN.
HOWEVER...THE MAIN FORECAST CHALLENGE FOR FRIDAY THROUGH MONDAY
WILL BE DAYTIME HIGH TEMPERATURES. EVEN THOUGH THE RIDGE WILL
BUILD OVERHEAD...THE GUIDANCE HAS BACKED OFF A BIT ON THE VERY
WARM TEMPERATURES. GIVEN THE OVERALL SOIL MOISTURE CONTENT...
SLIGHTLY COOLER THAN EXPECTED HIGHS ARE LIKELY. HOWEVER...STILL
EXPECT HIGHS OF 96 TO 98 ACROSS THE CENTRAL AND WESTERN COUNTIES.
THE HEAT INDEX WILL ALSO BE WARMEST OVER THE FRIDAY THROUGH
MONDAY...WITH VALUES RANGING FROM 102 TO 106 EACH AFTERNOON.

WITH THE UPPER TROUGH DIGGING SOUTHWARD INTO THE LOWER MISSISSIPPI
VALLEY ON TUESDAY AND WEDNESDAY...BOTH THE GFS AND ECMWF PUSH A
SUMMERTIME COLD FRONT SOUTHWARD INTO EAST AND SOUTHEAST TEXAS.
THERE IS STILL SOME UNCERTAINTY ON HOW FAR SOUTH THE FRONT WILL
BE...BUT FOR NOW IT LOOKS LIKE BOTH DAYS WILL PROBABLY SEE A
RETURN OF THUNDERSTORM CHANCES AND SLIGHTLY COOLER DAYTIME
TEMPERATURES.

40

MARINE...
DO NOT EXPECT MUCH CHANGE IN THE FORECAST FOR THE UPPER TX COAST.
GENERALLY EXPECT SOUTH TO SOUTHWEST WINDS THROUGH THE END OF THE
WEEK AND INTO THE WEEKEND. WINDS MAY INCREASE TO MODERATE LEVELS
OVER THE WEEKEND BUT THEN DECREASE EARLY NEXT WEEK AS A FRONTAL
BOUNDARY APPROACHES EAST TX. LIGHT TO MODERATE WINDS WILL SUPPORT
MAINLY LOW SEAS FOR THE NEXT SEVERAL DAYS. NO MARINE HAZARDS ARE
EXPECTED AT THIS TIME.

39


&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      97  75  98  76  98 /  20  20  10  10  10
HOUSTON (IAH)              96  76  96  76  96 /  40  20  20  10  10
GALVESTON (GLS)            91  79  91  80  91 /  40  10  20  10  10

&&

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

$$

DISCUSSION...40
AVIATION/MARINE...39



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