Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 041053
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
453 AM CST WED MAR 4 2015

.DISCUSSION...
YESTERDAY`S WARM FRONT IS NORTH OF THE CWA WITH ANY INTERIOR DENSE
FOG FORMING ALONG ITS NORTHERN PERIPHERY. A VERY WARM AND MOIST
ENVIRONMENT OUT THERE THIS MORNING WITH AVERAGE REGIONAL TEMPERATURES
AND DEW POINTS IN THE UPPER 60S. THESE VERY WARM AND MORE HUMID
WEDNESDAY CONDITIONS WILL ULTIMATELY PLAY A CRITICAL ROLE IN THE
POST-FRONTAL OF WHAT WILL LIKELY NOT BE MUCH UP NORTH CONCERNING
THE LACK OF ANY SIG IMPACTS FROM A POSSIBLE RAIN/SLEET WINTRY MIX.
HOUSTON`S 80 F MAX TEMP TIED A RECORD MAX TEMP RECORD FROM 2008.
TODAY`S FORECAST OF 80 F WILL BE WITHIN A DEGREE OF ANOTHER RECORD
OF 81 F HELD SINCE 1957. LOW POPS TODAY FOR ONLY DRIZZLE/MIST OR
VERY LIGHT SHORT-LIVED SHOWERS. A 40 KT LLJ (35 KT JUST-OFF-THE-SURFACE
WINDS ON KHGX`S VAD WIND PROFILE) HAS INHIBITED INLAND FOG FORMATION.
DIFFERENT STORY OVER THE WATERS AS HIGH NEAR 70 F DEW POINT AIR
OVER COOL SHELF WATERS IN THE LOWER 50S HAS KEPT AREAS OF DENSE
FOG IN PLACE...THIS TYPE OF FOG WILL REMAIN THROUGH LATE MORNING
WITH AFTERNOON IMPROVEMENT TO JUST AREAS OF 3 TO 5 MILE FOG. AS
WINDS BEGIN TO WEAKEN JUST DOWNSTREAM OF AN APPROACHING CENTRAL
TEXAS COLD FRONT...COASTAL AREA/MARITIME FOG MAY THICKEN UP AFTER
TONIGHT`S SUNSET. THINNING AFTERNOON CLOUD COVER...DUE TO MODERATE
ONSHORE MIXING WINDS AND THE REMNANTS OF THE EVER-WEAKENING LLJ...
WILL HAVE AFTERNOON TEMPERATURES AGAIN WARMING INTO THE MIDDLE
70S UP NORTH TO AROUND 80 F OVER THE SOUTHERN THIRD OF THE CWA.
ENJOY THIS LAST DAY OF `SPRING`.

THE MUCH ADVERTISED COLD FRONT WILL ENTER OUR FAR NW FA AROUND
SUNSET...THIS BOUNDARY TO SWING LIGHT VRB BREEZES AROUND TO N-NW
IN THE CITY AROUND 9 PM...STRONG NORTHERLIES AT THE COAST FROM
MIDNIGHT ONWARD. WESTERN AND COASTAL COUNTY WIND ADVISORIES WILL
BE LIKELY TONIGHT INTO THURSDAY MORNING FOR GREATER THAN 25 MPH
WINDS. THE FOLLOWING AIR MASS IS FRIGID/DRY...CURRENT CENTRAL
PLAINS TEMPERATURES OF LOW TEENS/SINGLE DIGIT DEW POINTS...TRANSLATES
TO STRONG COLD AIR ADVECTION. FROM TEE SHIRTS TO COATS WITHIN A
DAY AS THERE WILL BE AROUND A 35 TO 40 DEGREE 24 HOUR TEMPERATURE
DIFFERENTIAL. THE COLUMN WILL CERTAINLY COOL TO NEAR FREEZING
ACROSS THE NORTH...BUT TIMING MAY BE DELAYED. THIS DELAY MAY PLACE
THE COLDEST TEMPERATURES OVER DIMINISHING PRECIPITATION. COOLING
DOES OCCUR DURING THE THURSDAY MORNING POST-FRONTAL PERIOD OF MORE
OF AN OVERRUNNING PRECIPITATION EVENT...THE FAR NORTHERN COUNTY
PROFILE HAS A NEAR 2,500 FOOT BELOW FREEZING LOWER 900 MB LAYER.
AS MENTIONED EARLIER...THE GROUND AND SURROUNDING (ELEVATED)
ROADWAYS/BRIDGES WILL LIKELY BE TOO WARM SO HAVE EXCLUDED ANY
MENTION OF -FZRA. WITH THE PRECEDENT WARM CONDITIONS...ALONG WITH
A PROFILE THAT SUPPORTS A RAIN/SLEET MIX...ANY ACCUMULATIONS LEADING
TO ANY SIGNIFICANT TRAVEL IMPACTS IS VERY LOW AT THIS POINT IN
TIME. THE LATEST NWP MODEL RUNS HAVE NORTHERN COUNTY THURSDAY 12Z
SURFACE TEMPERATURES IN THE MID TO UPPER 30S (RAW/MOS). HIGHER REZ
WRF IS SPLIT ON THE ONSET OF FREEZING SFC TEMPS WITH THE ARW/NMM
CORES A TOUCH FASTER THAN THE NCEP SOLUTION. BOTTOM LINE IS THAT
THE MAJORITY OF SOLUTIONS ARE COMING IN WITH ABOVE FREEZING 2M
TEMPERATURES DURING THE HIGHEST CHANCE FOR PRECIPITATION....A
RAIN/SLEET EVENT WITH LITTLE TO MINOR IMPACTS. THERE MAY BE SOME
RUMBLES OF THUNDER LATE WEDNESDAY/EARLY THURSDAY AS MID-LEVEL
COOLING AND LIFT FROM THE BOUNDARY ITSELF (WITHIN A GT 1.5 INCH
PWAT AIR MASS) MAY PROVIDE JUST ENOUGH LL INSTABILITY TO GENERATE
ISOLATED LIGHTNING.

ALL INLAND PRECIPITATION COMES TO AN END BY FRIDAY MORNING...WEAKENING
NORTHERLIES UNDER CLEARING SKIES WILL ALLOW THERMOMETERS TO PLUMMENT
INTO AN AREAWIDE FREEZE. THE FREEZING LINE WILL LIKELY REACH THE
COASTAL COUNTIES...AVERAGE UPPER 20S NORTH OF THE CITY TO AROUND
FREEZING ELSEWHERE/MID 30S AT IMMEDIATE COAST. MAY WANT TO MAKE
THE PREPARATIONS NOW TO PROTECT YOUR 3 P`S FOR A MINOR FREEZE
(PEOPLE PETS AND PLANTS). A DEVELOPING SOUTHWESTERN CONUS/NORTHERN
MEXICO 5H TROUGH SET-UP THROUGH THE UPCOMING WEEKEND INTO EARLY
WEEK. A SERIES OF WEAK DISTURBANCE PASSING UP AHEAD OF THIS BROAD
TROUGH WILL INCREASE POPS (FOR MAINLY SHOWERS) TO HIGH CHANCES SUNDAY
INTO EARLY MONDAY. SOLUTIONS DIVERGE FROM DAY 7 ON WITH THE MORE
WET GFS DEVELOPING A WESTERN GULF SURFACE TROUGH...THE LESS AGGRESSIVE
EURO PLACING HIGHER QPF FURTHER SOUTH AND OFFSHORE. TEMPERATURES
WILL SUBSEQUENTLY WARM BACK INTO THE 60S BY EARLY WEEK...MORNINGS
REMAIN IN THE CHILLY 40S. 31

&&

.MARINE...
ALTHOUGH THERE COULD BE INTERMITTENT IMPROVEMENTS IN VISIBILITIES AT
TIMES...THE THREAT OF SEA FOG WILL PERSIST INTO THE EVENING HOURS. A
STRONG COLD FRONT IS EXPECTED TO MOVE OFF THE COAST LATE THIS
EVENING...PROBABLY RIGHT AROUND MIDNIGHT (SLIGHTLY BEFORE THAT IN
THE BAYS). STRONG NORTH WINDS ARE EXPECTED BEHIND THE FRONT...WITH
FREQUENT GUSTS TO GALE FORCE LIKELY INTO THURSDAY AFTERNOON. NEXT
SHIFT WILL LIKELY NEED TO UPGRADE THE GALE WATCH TO A WARNING ONCE
TIMING IS FURTHER NAILED DOWN. STRONG OFFSHORE FLOW WILL ALSO
TRANSPORT SOME WATER OUT OF THE BAYS SO WILL NEED TO MONITOR
POTENTIAL FOR LOW WATER ADVISORY ON THURS. WIND SPEEDS WILL VERY
SLOWLY DIMINISH BEGINNING THURSDAY NIGHT AND BECOME NORTHEAST INTO
THE WEEKEND AS A COASTAL TROF DEVELOPS OFFSHORE. 47

&&

.AVIATION... THINK WE`RE GOING TO SEE IFR CIGS CONTINUE TO
TRANSITION INTO MVFR TERRITORY BY MID TO LATE MORNING AND VFR FOR
MANY AREAS DURING THE AFTN. COLD FRONT AND ASSOCIATED SHRA WILL
APPROACH CLL AROUND 4PM, IAH 9 PM AND COAST MIDNIGHT. MUCH STRONGER
WINDS...700-1500FT CIGS AND POST FRONTAL PRECIP WILL CONTINUE
OVERNIGHT. CANNOT COMPLETELY RULE OUT SOME RAIN/SLEET MIX AT CLL/UTS
AFTER MIDNIGHT BUT GROUNDS SHOULD >32 SO NO SIGNIFICANT SFC IMPACTS
EXPECTED.   47

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      76  33  36  27  47 /  70  90  20  10  10
HOUSTON (IAH)              80  38  40  29  49 /  50  80  50  10  10
GALVESTON (GLS)            71  42  42  35  47 /  20  60  50  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...DENSE FOG ADVISORY UNTIL 4 AM CST EARLY THIS MORNING FOR THE
     FOLLOWING ZONES: GALVESTON.

GM...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES:
     GALVESTON BAY...MATAGORDA BAY...WATERS FROM FREEPORT TO THE
     MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
     TO FREEPORT OUT 20 NM.

     GALE WATCH FROM THIS EVENING THROUGH THURSDAY MORNING FOR THE
     FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.

     GALE WATCH FROM LATE TONIGHT THROUGH THURSDAY AFTERNOON FOR THE
     FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
     CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
     MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
     TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO
     FREEPORT OUT 20 NM.

&&

$$

DISCUSSION...31



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