Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 282347
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
647 PM CDT SAT MAR 28 2015



.AVIATION...
VFR. SSW WINDS GRADUALLY RELAXING EARLY THIS EVENING. VERY DRY
PROFILE AND MOISTURE RETURN HAS BEEN PRETTY MEAGER AND MIXED
THROUGH A DEEP LAYER. DON`T EXPECT ANY LARGE AREAS OF ST OR FOG.
PERHAPS A BIT OF MIFG AT CXO BUT THINK IT IS TOO DRY. NAM AND GFS
SEEM FAR TO OVERDONE WITH VLIFR CONDITIONS FORECAST. OVERNIGHT
WINDS BECOME MORE SOUTHERLY THEN INCREASE TOMORROW TO AROUND 15
KNOTS AND GUSTY PRIMARILY FROM 180-190. SHALLOW MOISTURE RETURN
SUNDAY WITH GULF SKIES THAT ARE CLEAR NOW SO AM ONLY EXPECTING
FEW/SCT 2000-2500FT LATE IN THE MORNING.
45

&&

.PREV DISCUSSION... /ISSUED 257 PM CDT SAT MAR 28 2015/

DISCUSSION...
AT 2 PM...SURFACE HIGH PRESSURE WAS LOCATED OVER THE OHIO VALLEY
AND STRONG LOW PRESSURE WAS LOCATED OVER THE NORTHERN PLAINS. THE
GRADIENT BETWEEN THESE TWO SYSTEMS WILL KEEP MODERATE TO
OCCASIONALLY STRONG WINDS IN PLACE THIS EVENING. IT WILL ALSO
BRING A SLOW INCREASE IN LOW LEVEL MOISTURE. SURFACE WINDS WILL
DECOUPLE AFTER MIDNIGHT BUT WINDS JUST OFF THE SURFACE WILL REMAIN
STRONG. AS THE TEMPERATURES COOL OVERNIGHT...FEEL THE AIR WILL
SATURATE AND CLOUDS WILL EVENTUALLY FORM TOWARD SUNRISE. BOTH THE
NAM AND GFS HINT AT CLOUD COVER FOR A BRIEF WINDOW BETWEEN 10-15Z
SUNDAY. THE GRADIENT WILL REMAIN TIGHT ON SUNDAY AND ANOTHER
BREEZY DAY IS IN STORE FOR THE REGION. 850 TEMPS WARM A BIT ON
SUNDAY AND COUPLED WITH THE WARMER START TO THE DAY SHOULD ALLOW
TEMPS TO WARM INTO THE MID 80S. ANY MORNING CLOUD COVER WILL
ERODE AS DRIER AIR ALOFT MIXES TOWARD THE SURFACE. CLOUDS RETURN
AGAIN SUNDAY NIGHT AND WILL LINGER MONDAY AS A WEAK DISTURBANCE
MOVES ACROSS SE TX. FCST SOUNDINGS SHOW A STOUT CAP IN PLACE ON
MONDAY BUT ALSO SHOW A SATURATED LAYER BENEATH THE CAP. CAN`T RULE
OUT SOME WEAK SHOWERS ON MONDAY...ESPECIALLY OVER THE NW HALF
CLOSER TO THE DISTURBANCE. TUESDAY STILL LOOKS TOO DRY WITH PW
VALUES ONLY REACHING 1.10 INCHES. CAPPING LOOKS WEAKER BUT THE
MEAGER MOISTURE LEVELS AND VERY DRY LAYER ABOVE 850 MB SHOULD
LIMIT COVERAGE AND WILL ONLY CARRY 20 POPS FOR NOW.

ANOTHER SHORT WAVE WILL APPROACH SE TX ON TUESDAY NIGHT AND
WEDNESDAY. MODELS DIVERGE A BIT ON TIMING AND INTENSITY OF THIS
SYSTEM. THE CANADIAN AND ECMWF ARE SIMILAR WITH TIMING AND QPF
OUTPUT WHILE THE GFS IS FASTER...DRIER AND OVERALL JUST MORE
BENIGN. THE ECMWF HAS MUCH BETTER JET DYNAMICS WITH SE TX LYING IN
A LFQ WHILE THE GFS PLACES SE TX IN A SUBSIDENT REGION OF THE JET.
PW VALUES ALSO DIFFER WITH THE GFS PW VALUES AT 1.3O INCHES WHILE
THE ECMWF SHOWS VALUES REACHING 1.60 INCHES. THE ECMWF SOUNDINGS
ALSO SHOW A SATURATED PROFILE FROM THE SFC TO 500 MB WHILE THE
GFS DOES NOT. HAVE LEANED TOWARD THE EC SINCE THE CANADIAN NOW
SUPPORTS THE ECMWF AND THE EC HAS BEEN VERY CONSISTENT OVER THE
LAST 3-4 DAYS. BUMPED POPS TO LIKELY FOR WEDNESDAY.

THE FLOW ALOFT ON THU/FRI WILL BE W-SW BECOMING MORE SW WITH TIME.
THIS TYPE OF FLOW USUALLY KEEPS THINGS CLOUDY WITH SCT SHRA AS
WEAK UPPER LEVEL DISTURBANCES TRAVERSE THE AREA. YET FCST SOUNDINGS
SHOW A CAP IN PLACE AND MEAGER PWATS. HAVE KEPT POPS OUT OF THE
GRIDS FOR THU/FRI BUT THE FLOW ALOFT WOULD SUGGEST THAT MAYBE
LOWISH POPS ARE NEEDED. ANOTHER COLD FRONT WILL CROSS SE TX NEXT
SATURDAY. THE FRONT WILL BRING A CHANCE OF SHOWERS AND COOLER
TEMPERATURES. 43

MARINE...
THE ONSHORE PRESSURE GRADIENT BETWEEN EASTERN U.S. HIGH PRESSURE AND
WESTERN TEXAS TROUGHING WILL MAINTAIN A LIGHT...TO OCCASIONALLY
MODERATE...SOUTHERLY WIND PATTERN OVER THE NEXT SEVERAL DAYS. THE
EXTENDED DURATION OF GENERALLY 10-15 KT ONSHORE WINDS WILL INCREASE
FURTHER OFFSHORE SEAS BY ANOTHER COUPLE OF FEET THROUGH EARLY
MONDAY. THE GRADIENT SHOULD BE TIGHT ENOUGH OVER THE FAR WESTERN
OFFSHORE WATERS TO MENTION A DECENT CHANCE FOR A SHORT FUSE CAUTION
LATE SUNDAY NIGHT INTO EARLY MONDAY. INCREASING SHOWERS AND STORM
CHANCES LATE TUESDAY THROUGH WEDNESDAY AS A SHORTWAVE DISTURBANCE
PASSES EAST ACROSS THE MARITIME. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      56  82  62  79  62 /   0   0  10  20  10
HOUSTON (IAH)              58  82  63  81  63 /   0   0  10  20  10
GALVESTON (GLS)            63  77  66  77  66 /   0   0  10   0  10

&&

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

$$

DISCUSSION...41
AVIATION/MARINE...45



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