Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 221205
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
705 AM CDT TUE JUL 22 2014

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

&&

.AVIATION...
NOT MUCH CHANGE IN THE PREVIOUS THINKING. EXPECT THERE TO BE VERY
LITTLE TSRA COVERAGE IF ANY. HI RES MESOSCALE MODELS HINT AT
CONVECTION E/NE OF KIAH AND KHOU. PREVIOUS TAFS HAD VCTS AND SO
KEPT THAT IN CURRENT TAFS. SEEMS LIKE STORMS COULD AFFECT THESE
TERMINALS WITH STORM MOTIONS FROM THE NE. TIMING LOOKS TO STILL BE
20-23Z. WILL NOT MENTION CONVECTION ANYWHERE ELSE AT THIS TIME.

39

&&

.PREV DISCUSSION... /ISSUED 506 AM CDT TUE JUL 22 2014/

DISCUSSION...
A NORTHERLY UPPER LEVEL PATTERN WAS IN PLACE OVER SE TX EARLY THIS
MORNING. THIS WAS DUE TO AN UPPER LEVEL HIGH OVER THE PLAINS
INTERACTING WITH A DEVELOPING UPPER LOW NEAR THE GA...AL...AND FL
BORDER. THERE WAS ALSO A WEAKENING FRONTAL BOUNDARY EXTENDING
FROM NEAR BPT TO SOMEWHERE BETWEEN UTS AND LFK. THIS MAY LEAD TO
ISOLATED SHOWERS THIS MORNING IN THE EASTERN COUNTIES ALONG THE
COAST. LATER THIS AFTERNOON...THE MODELS ARE AGREEING THAT THE
SEABREEZE MAY HELP GENERATE ISOLATED SHOWERS OR THUNDERSTORMS.

THE MODEL CONSENSUS IS FOR THE UPPER LOW TO SLOWLY MOVE WESTWARD
THE NEXT FEW DAYS SO THAT BY THURSDAY THE LOW SHOULD BE SHEARING
OUT ALONG OR JUST OFF THE UPPER TEXAS COAST. THE NAM12 AND ECWMF
BOTH INDICATE THE RESULTING UPPER TROUGH WILL MOVE INTO SE TX...
WHILE THE CANADIAN AND GFS BOTH KEEP THE TROUGH OFF THE COAST.
HOWEVER...THE GFS ENSEMBLE PRECIPITATION DOES PICK UP THE RAIN
CHANCES ON THURSDAY. BECAUSE OF THE NAM12 AND GFS ENSEMBLE...
DECIDED TO TWEAK THE RAIN CHANCES UP A BIT ON THURSDAY.
OTHERWISE...THE RAIN FORECAST IS ESSENTIALLY THE SAME AS THE
PREVIOUS FORECAST PACKAGE.

BESIDES THE RAIN CHANCES...THE BIG ITEM OF NOTE FOR TODAY AND
WEDNESDAY WILL BE THE AFTERNOON HEAT INDEX. BECAUSE OF THE VERY
MOIST AIRMASS COMBINING WITH HIGH TEMPERATURES IN THE MID 90S...
THE HEAT INDEX WILL PROBABLY REACH TO BETWEEN 102 AND 107 THIS
AFTERNOON. SOME LOCATIONS MAY BRIEFLY REACH 108 TO 110. BECAUSE
THE CRITERIA FOR AN EXCESSIVE HEAT ADVISORY IS TWO CONSECUTIVE
DAYS OF A HEAT INDEX OF 108 OR MORE...WILL PAY CLOSE ATTENTION TO
WHAT OCCURS TODAY. VALUES ON WEDNESDAY MAY REACH CLOSE TO WHAT
OCCURS TODAY.

AFTER THE RAIN CHANCES ON THURSDAY...THE RIDGE OVER THE CENTRAL
AND SOUTHERN PLAINS IS FORECAST TO SHIFT TO OVER AZ...NM...AND
WEST TEXAS OVER THE END OF THE WEEK...AND THEN INTO THE FOUR-
CORNERS REGION OF UT...CO...NM...AND AZ EARLY NEXT WEEK. THIS WILL
PUT A VERY WARM AIRMASS OVER SE TX OVER THE WEEKEND INTO MONDAY.
BY TUESDAY THE GFS TRIES TO WORK ANOTHER UPPER LEVEL WEAKNESS OVER
THE FORECAST AREA...ALTHOUGH THE ECMWF EXTENDS THE RIDGE OVER SE
TX INTO LOUISIANA. DAYTIME HIGHS OVER THE WEEKEND SHOULD REACH
INTO THE UPPER 90S AND THE 100 DEGREE MARK MAY BE REACHED BY
MONDAY. IF THE GFS IS CORRECT...SLIGHT CHANCES FOR RAIN WILL
RETURN BY TUESDAY.

40

MARINE...
UPPER LEVEL HIGH PRESSURE WILL BE THE MAIN WEATHER FEATURE TO
DOMINATE CONDITIONS THE NEXT FEW DAYS. THIS WILL ALLOW FOR TYPICAL
SUMMER TIME HEAT WITH ONSHORE WINDS FOR MUCH OF THE WEEK. ONSHORE
WINDS WILL DEVELOP MAINLY IN THE AFTERNOON WITH THE SEA BREEZE.
WINDS TURN OFFSHORE BRIEFLY IN THE MORNING HOURS AS LAND BREEZE
PUSHES OFFSHORE. 39

AVIATION...
TODAY WILL BE ANOTHER TOUGH DAY FORECASTING CONVECTIVE INITIATION
IF ANY DUE TO DAY TIME HEATING. HI RES MESOSCALE MODELS DEPICT
AT LEAST SOME CONVECTION IN/NEAR HOUSTON TERMINALS FOR THE LATE
AFTERNOON HOURS. BEST TIMES FOR CONVECTION WILL LIKELY BE 20-23Z
THIS AFTERNOON BUT CONFIDENCE IS STILL PRETTY LOW. OVERALL SHOULD
HAVE VFR CIGS BUT MIGHT GET SOME MVFR CIGS DUE TO LOW STRATUS AND
FOG. 39

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      97  75  97  75  97 /  10  10  20  10  20
HOUSTON (IAH)              96  77  96  77  94 /  20  20  30  20  30
GALVESTON (GLS)            91  81  91  81  90 /  20  20  20  20  30

&&

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

$$

DISCUSSION...41
AVIATION/MARINE...39


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