Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 301735
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1235 PM CDT MON MAR 30 2015

.AVIATION...
THE GENERAL THEME WILL BE VFR THROUGH TONIGHT...AREAWIDE MVFR
DECKS FILLING BACK IN LATE MONDAY INTO EARLY TUESDAY. PM SOUTHWEST
TO SOUTH WINDS AOA 10 KTS. AN AFTERNOON SEA BREEZE MAY BACK 8-12KT
WINDS AND SCT SKIES OUT ACROSS MORE COASTAL TERMINALS. LOWER LEVEL
MOISTURE TRAPPED UNDER A NEAR 5K FT INVERSION SHOULD MAINTAIN AT
LEAST A SCT CEILING THROUGH THE AFTERNOON...COOLING AFTER SUNSET
WILL ALLOW AN OVERCAST DECK TO FILL IN AT MVFR CAT. ENOUGH OF A
LOW LEVEL WIND TO KEEP THE STRATUS IN PLACE...ALTHOUGH MORE RURAL
SITES COULD EXPERIENCE TEMPO IFR CATS IN BOTH CEILING AND VISBYS
FROM 09-14Z. 31

&&

.PREV DISCUSSION... /ISSUED 1040 AM CDT MON MAR 30 2015/

UPDATE...
SEE MORNING UPDATE.

DISCUSSION...
AT 8 AM...A WEAK AND RATHER DIFFUSE LOOKING COLD FRONT EXTENDED
FROM ABOUT TEXARKANA TO FORT WORTH TO ABOUT DEL RIO. THIS BOUNDARY
WON`T MAKE MUCH MORE PROGRESS SOUTHEAST. 12Z SOUNDINGS SHOW QUITE
A BIT OF DRY AIR AT 850 MB AND PW VALUES LESS THAN AN INCH. CRP
SOUNDING IS STRONGLY CAPPED WHILE SHV SHOWS CONSIDERABLY LESS
CAPPING...PWATS AT 1.15 INCHES AND A SLIGHTLY DEEPER SATURATED
LAYER FROM THE SFC TO 700 MB. SHORT TERM GUIDANCE DOES NOT SUPPORT
MUCH IN THE WAY OF RAINFALL THIS AFTN BUT FEEL THE LESS CAPPED SHV
SOUNDING JUSTIFIES ISOLATED SHOWERS OVER THE EXTREME NORTH THIS
AFTN. TEMPS ARE ALREADY IN THE LOWER 70S AT 10 AM SO WILL LEAN
TOWARD THE WARMER ECMWF GUIDANCE FOR MAX TEMPS THIS AFTN. WILL
BUMP CURRENT MAX TEMPS UP A FEW DEGREES OVER THE W-SW ZONES. NEW
ZONES OUT BY 1100 AM. 43

&&

PREV DISCUSSION... /ISSUED 356 AM CDT MON MAR 30 2015/

DISCUSSION...
A WEST-NORTHWEST FLOW ALOFT WILL FLATTEN OUT OVER THE NEXT FEW
DAYS BEFORE AMPLIFYING OVER THE WEEKEND. A SHORTWAVE TROUGH
APPROACHING THE BAJA CA COAST EARLY THIS MORNING WILL SHEAR OUT
AS IT MOVES ACROSS THE AREA ON TUESDAY NIGHT AND WEDNESDAY. A
DEEPER UPPER TROUGH WILL HELP PUSH A COLD FRONT THROUGH ON FRIDAY
NIGHT AND SATURDAY MORNING.

THE MODELS DIFFERED A BIT ON THE STRENGTH OF THE SYSTEM THAT WILL
MOVE OVERHEAD DURING MID WEEK PERIOD. THE ECMWF AND NAM12 WERE
STRONGER AND GENERATED A MORE MOIST AIRMASS THAN DID THE GFS. EVEN
WITH THE DIFFERENCES...ALL THREE MODELS APPEARED TO CONTINUE THEIR
RUN-TO-RUN CONSISTENCY. BOTH THE GFS AND ECMWF KEPT A FAIRLY LARGE
850 MB HIGH PRESSURE AREA OVER THE CENTRAL AND EASTERN GULF
THROUGH LATE TUESDAY. HOWEVER...THE GFS KEPT THE HIGH IN PLACE ON
WEDNESDAY WHILE THE ECMWF PUSHED THE RIDGE EASTWARD. THINK THAT
THE ECMWF MAY BE A BIT TOO AGGRESSIVE WITH THE UPPER LEVEL
FEATURE AND DECIDED TO PARE BACK THE RAIN CHANCES ON WEDNESDAY A
BIT.

THERE WERE STILL DIFFERENCES IN THE FRONTAL PASSAGE TIMING BETWEEN
THE GFS AND ECMWF FRIDAY NIGHT AND SATURDAY MORNING. STAYED WITH A
COMPROMISE BETWEEN THE MODELS. ISENTROPIC LIFT BEHIND THE FRONT
WILL HELP BRING BETTER RAIN CHANCES ACROSS SOUTHEAST TEXAS OVER
THE WEEKEND. 40

&&

MARINE...
A WEAKER PRESSURE GRADIENT WILL BRING LOWER WINDS AND SEAS TO THE
AREA TODAY...AND THIS QUIETER PATTERN WILL PERSIST FOR MUCH OF
THE WEEK WITH SEAS RUNNING AROUND 2 TO 4 FEET NEARSHORE AND AROUND
3 TO 5 FEET OFFSHORE. SOUTH WINDS SHOULD REMAIN IN A 5 TO 15 KNOT
RANGE. THE WATERS COULD SEE SOME SHOWERS/THUNDERSTORMS TUESDAY
NIGHT/WEDNESDAY AS A DISTURBANCE MOVES EASTWARD ACROSS THE AREA.
WILL STILL SHOW A FAST MOVING COLD FRONT RACING OFF THE COAST AND
THROUGH THE COASTAL WATERS LATE FRIDAY NIGHT THROUGH EARLY
SATURDAY MORNING WITH MODERATE NORTHEAST WINDS AND BUILDING SEAS
IN ITS WAKE. CAUTION FLAGS ARE PROBABLY GOING TO BE NEEDED. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      62  81  63  79  63 /  10  10  30  50  20
HOUSTON (IAH)              61  82  64  80  65 /  10  10  20  50  20
GALVESTON (GLS)            64  77  66  74  68 /  10  10  30  50  20

&&

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

$$

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



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