Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 022137
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
337 PM CST MON MAR 2 2015

.DISCUSSION...
FRONTAL BOUNDARY HAS REMAINED IN THE GULF OF MEXICO TODAY
ALLOWING FOR COOL DAMP CONDITIONS MOST OF THE DAY. TEMPS HAVE NOT
RISEN MUCH BUT WITH THIN ENOUGH CLOUD COVER A FEW AREAS HAVE
REACHED THE UPPER 50S TO LOW 60S ALONG THE COAST. AREAS FROM KCLL
TO KUTS REMAIN IN THE 40S. KCLL HAS NOT REACHED THE 50S SINCE
HAVING A HIGH OF 50F ON FEB 25. BEFORE THAT IT WAS FEB 22. WATER
VAPOR IMAGERY DOES SHOW STRONG SHORT WAVE TROUGH OVER THE DESERT
SW WHICH SHOULD PUSH INTO THE C PLAINS BY 12Z TUE. THIS SHOULD
ALLOW FOR SFC CYCLOGENESIS IN THE HIGH PLAINS AND FOR SOUTHERLY
WINDS TO DEVELOP. FRONAL BOUNDARY SHOULD MOVE NORTH AS A WARM
FRONT BRINGING BACK TEMPS IN THE 70S AND DEWPOINTS IN THE 60S.
FORECAST WILL KEEP A CHANCE OF SHOWERS AND MAYBE AN ISO
THUNDERSTORM. FORECAST SOUNDING STILL SHOW A DECENT CAP AND
LIMITED INSTABILITY SO AN ISO STORM MAYBE A STRETCH.

THE MAIN FORECAST CHALLENGE WILL BE THE CHANGES IN THE WEATEHR
WED INTO THUR. FORECAST MODELS ARE IN DECENT AGREEMENT WITH STRONG
TROUGH PULLING THROUGH THE PLAINS WEDNESDAY WITH AN UPPER LOW OVER
CALIFORNIA MOVING EAST ACROSS MEXICO AND S ROCKIES PHASING WITH
THIS SYSTEM. A STRONG COLD FRONT IS EXPECTED TO PUSH INTO THE AREA
WED BUT THE NAM/GFS/ECMWF ALL HAVE DIFFERENT TIMING. FORECAST
LEANED MORE ON THE FASTER GFS AND EVEN ABOUT 3 HRS FASTER THAN
THAT. THERE IS GOOD SUPPORT FOR A FASTER FRONTAL MOVEMENT GIVEN
THE DEEP TROUGH OVER THE PLAINS. THE ONLY PROBLEM IS THAT THE
PHASING TROUGH MAY KEEP JET STREAM FLOW SW AND HELP STALL THE
FRONT. THAT SAID...JUST LOOKS LIKE THERE WILL BE A COLD ENOUGH
AIRMASS TO KEEP IT PUSHING THROUGH.

THE RACE IS THEN ON BETWEEN FREEZING TEMPS AND PRECIP FALLING FOR
WED NIGHT INTO THUR. SYNOPTICALLY JET STREAM BECOMES FAVORABLE
WITH LIFT DUE TO RIGHT ENTRANCE REGION POSITIONED OVER MUCH OF C
AND E TX. FRONTOGENETIC LIFT INCREASES IN 850-700MB OVER THE AREA.
MODEL SOUNDINGS AT KCLL/KUTS SHOW A NICE MIX OF PRECIP FROM
RA/FRZRA TO SLEET. IF THE COLD AIR DEEPENS ENOUGH AND
SATURATES...COULD GET MORE SLEET TO FALL. MAIN AREAS OF CONCERN
WILL BE FOR COLLEGE STATION TO LIVINGSTON NORTHWARD. THIS ALSO
HINGES ON TIMING OF FREEZING TEMPS AND IF PRECIP WILL BE FALLING
THROUGH THAT AIR. PRECIP IS EXPECTED TO DECREASE THROUGH THE
MORNING AS LIFT EXITS THE REGION AND SUBSIDENCE BEGINS TO TAKE
OVER. ICE/SLEET AMOUNTS WILL BE DIFFICULT TO DETERMINE SINCE THERE
WILL BE TIMING ISSUES WITH THE COLD SUB FREEZING AIR AND PRECIP
FALLING INTO IT. ISSUED A SPECIAL WEATHER STATEMENT TO HIGHLIGHT
MAIN THINKING ON WHAT WHEN AND WHERE WITH IMPACTS.

EXTENDED FORECAST IS STILL QUITE UNCERTAIN FOR THE WEEKEND AND
INTO EARLY NEXT WEEK. GFS/ECMWF BOTH BRING ANOTHER UPPER LOW
TOWARDS TEXAS SATURDAY INTO SUNDAY. FORECAST WILL KEEP SOME RAIN
CHANCES GOING TO ACCOUNT FOR THIS WAVE BUT STILL LOTS OF TIMING
ISSUES. BOTH MODELS HAVE RUN TO RUN CONSISTENCY BUT NOT WITH EACH
OTHER.

39

&&

.MARINE...
THIS BREAK IN THE SEA FOG EXPECTED TO BE BRIEF WITH THE RETURN OF ON-
SHORE SFC WINDS THIS EVENING/OVERNIGHT. THE LIMITED/LOWERED VISIBILI-
TIES WITH THE FOG SHOULD LINGER FOR MOST OF TOMORROW AND WEDS...EVEN
WITH THE ONSHORE WINDS STRENGTHENING/DEEPENING OUT AHEAD OF THE NEXT
COLD FRONT. MODELS STILL BRINGING THIS FRONT INTO THE BAYS LATE WEDS
AFTN AND INTO THE COASTAL WATERS WEDS EVENING. TIGHT GRADIENT IN THE
WAKE OF THE FRONT WILL PRODUCE VERY STRONG/GUSTY N/NE WINDS FOR WEDS
NIGHT ON THROUGH MOST OF THURS. WIND GUSTS MAY EXCEED GALE FORCE BUT
THE PROGGED SUSTAINED FLOW WILL LIKELY KEEP US IN THE SMALL CRAFT AD-
VISORY CATEGORY FOR THAT TIME FRAME. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      50  72  61  63  30 /  30  30  30  70  70
HOUSTON (IAH)              56  76  64  70  34 /  20  20  20  50  70
GALVESTON (GLS)            57  72  61  66  37 /  20  20  20  30  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL 10 PM CST THIS EVENING FOR THE
     FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...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...39
AVIATION/MARINE...41


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