Post by tamugmidn on Feb 19, 2009 21:59:47 GMT -6
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
754 PM CST THU FEB 19 2009
.UPDATE...
SKIES HAVE CLEARED ACROSS ALL OF SOUTHEAST TEXAS. AT 01Z...SURFACE
HIGH PRESSURE WAS LOCATED NEAR DFW. DRY AIR IN PLACE COUPLED WITH
LIGHT WINDS SHOULD YIELD SOME COLD TEMPERATURES BY MORNING.
PREVIOUS FORECAST IS IN GREAT SHAPE. NO UPDATE NEEDED. 43
&&
.PREV DISCUSSION... /ISSUED 629 PM CST THU FEB 19 2009/
DISCUSSION...
SEE THE AVIATION SECTION BELOW.
AVIATION...
HIGH PRESSURE WILL DRIFT OVERHEAD TONIGHT AND FRIDAY MORNING. VFR
CONDITIONS TO PERSIST AND THE WINDS WILL BECOME SOUTHEAST 10 TO 14
KNOTS FRIDAY AFTERNOON OVER MOST OF THE TERMINAL SITES.
40
PREV DISCUSSION... /ISSUED 341 PM CST THU FEB 19 2009/
FIRE WEATHER...
GUSTY SURFACE WINDS THIS AFTERNOON WITH RELATIVE HUMIDITY VALUES
RUNNING IN THE UPPER TEENS IN OUR EXTREME NORTHERN COUNTIES AND
LOWER 20S EVERYWHERE ELSE. WINDS SHOULD CALM AND GUSTS WILL END
SHORTLY AFTER SUNSET TONIGHT. RED FLAG WARNING THAT WAS ISSUED FOR
JACKSON AND MATAGORDA COUNTIES WILL BE ALLOWED TO EXPIRE AT 6PM.
WINDS WILL SHIFT MORE TO TO SOUTH AND SOUTHEAST ACROSS THE AREA
TOMORROW MORNING BUT STRONG MOISTURE RETURN IS NOT ANTICIPATED.
THUS...WITH DRY CONDITIONS STILL IN PLACE AND WINDS EXPECTED TO
PICK UP AGAIN TOMORROW WILL HAVE TO CONTINUE TO MONITOR FIRE
DANGER SITUATION CLOSELY INTO THE WEEKEND. 38
MARINE...
SCA HAS BEEN ALLOWED TO EXPIRE FOR THE NEARSHORE WATERS THIS
AFTERNOON AND HAS BEEN REPLACED BY CAUTION ACROSS THE 20 TO 6O NM
MARINE ZONES THROUGH AT LEAST MIDNIGHT TONIGHT. SURFACE HIGH
PRESSURE OVER NORTH TEXAS THIS AFTERNOON WILL SHIFT SOUTHEAST
ACROSS THE AREA OVERNIGHT BEFORE EXITING INTO LOUISIANA ON
FRIDAY MORNING. WINDS ACROSS THE MARINE ZONES WILL SHIFT TO THE
SOUTHEAST TOMORROW MORNING ON THE BACKSIDE OF THE HIGH PRESSURE.
ONSHORE WINDS WILL REMAIN UNTIL A COLD FRONTAL PASSAGE EXPECTED
FOR SATURDAY EVENING. THIS FRONT IS STRONGER THAN OUR LAST SYSTEM
AND WILL BRING STRONG OFFSHORE WINDS AND INCREASED WAVE HEIGHTS
FOR THE LATTER HALF OF THE WEEKEND. WAVES WILL BEGIN TO RELAX ON
MONDAY AS RETURN FLOW SETS UP AGAIN EARLY NEXT WEEK. 38
DISCUSSION...
SFC RIDGE OVER N CENTRAL TX HAS KEPT NORTHERLY WINDS IN PLACE. A
DRY AIRMASS BEHIND THE COLD FRONT HAS MOVED INTO SE TX AS WELL
WITH CONDITIONS COMING CLOSE TO MEETING RED FLAG WARNING
CRITERIA. WINDS ARE CLOSER TO 10-15 MPH THAN 15-20MPH ALTHOUGH
THERE ARE SOME GUSTS TO AROUND 20 MPH ACROSS THE AREA. SFC RIDGE
SHOULD BUILD OVER SE TX TONIGHT ALLOWING FOR WINDS TO DIMINISH.
CLEAR SKIES WILL ALLOW FOR PRIME RADIATIONAL COOLING SO TEMPS
SHOULD DROP INTO THE 30S FOR MOST OF THE AREA EXCEPT ALONG THE
COAST.
THE MAIN FORECAST CONCERN WILL BE WITH RAIN CHANCES THIS WEEKEND.
SFC RIDGE SHOULD SLIDE OFF TO THE EAST TOMORROW AND ALLOW FOR SE
RETURN FLOW FRI NIGHT INTO SAT. UPPER LEVEL FLOW REMAINS OUT OF
THE NW WITH A STRONG TROUGH MOVING THROUGH THE MIDWEST AND GREAT
LAKES BY SAT MORNING. A COLD FRONT WITH A POLAR AIRMASS BEHIND IT
SHOULD WORK INTO SE TX DURING THE DAY SAT. MOISTURE RETURN AHEAD
OF THE FRONT LOOKS REALLY MARGINAL AT BEST. SFC DEWPOINTS MAY
REACH THE LOW 60S AHEAD OF THE FRONT BUT BOUNDARY LAYER MOISTURE
LOOKS RATHER SUSPECT GIVEN THE NAM SOLUTION. THE NAM SEEMS TO BE
HANDLING THE MOISTURE RETURN BETTER THAN THE GFS WHICH IS FASTER
WITH MOISTURE RETURN. GIVEN THIS SET UP...THE FRONT SHOULD KICK
OFF A LINE OF SHOWERS BUT GIVEN LIMITED MOISTURE AND INSTABILITY
THERE MAY ONLY BE A CHANCE FOR AN ISOLATED THUNDERSTORM. WINDS IN
THE 850-700MB LAYER WILL BE MORE SW TO W WHICH MAY BRING IN AN
ELEVATED MIXED LAYER TO CAP MOST OF THE COASTAL PLAIN SOUTH OF
I-10. AS SUCH...POPS WERE SCALED BACK DURING THE MORNING TO 20-30
PERCENT FOR A FEW SHOWERS AND THEN KEPT 40 POPS IN THE AFTERNOON.
SHOULD BETTER BOUNDARY LAYER MOISTURE DEVELOP IT IS POSSIBLE TO
GET SOME HIGHER POPS BUT CONFIDENCE IS LOW IN THAT HAPPENING.
FRONTAL PASSAGE LOOKS REASONABLE WITH THE NAM SOLUTION BEING
FASTER THAN THE GFS ESPECIALLY WITH STRONGER SUPPORT ALOFT WITH
NW FLOW. FORECAST WILL KEEP CLOSE TO THE TIMING OF THE NAM FOR
THE FRONTAL PASSAGE.
ANOTHER SFC RIDGE SHOULD BUILD OVER SE TX SAT NIGHT INTO SUN
WHICH WOULD ALLOW FOR ANOTHER COLD MORNING OR TWO FOR THE START
OF NEXT WEEK. THE 12Z GFS/ECMWF AGREE WITH RETURN FLOW RAMPING UP
AGAIN LATE MON INTO TUE. BOTH MODELS KEEP NW FLOW ALOFT OVER MUCH
OF TX WITH A WEAK RIDGE OVER THE SOUTHERN ROCKIES. ECMWF SEEMS TO
BE STRONGER WITH THIS RIDGE THAN THE GFS. MAIN UNCERTAINTY FOR THE
MIDDLE OF NEXT WEEK WILL BE HOW MUCH MOISTURE RETURNS FROM THE
GULF. RIGHT NOW NONE OF THE MODELS REALLY INDICATE PRECIP TO
REALLY PUT ANY CONFIDENCE. THE GFS SHOWS SOME SPOTTY SHOWERS BUT
TOO FAR OUT TO REALLY PUT MUCH STOCK IN THAT. POPS WERE KEPT
AROUND 10 PERCENT BUT COULD SEE POSSIBLY A FEW MORE SHOWERS
DEVELOPING IN ANY MOISTURE AXIS THAT SETS UP. CAPPING ON THE
OTHERHAND SHOULD BE WELL ESTABLISHED WITH SW FLOW BRINGING IN A
MORE STOUT ELEVATED MIXED LAYER. THE ECMWF DOES BRING A FRONT
THROUGH THE AREA AS IT SEEMS TO DIVERGE IN ITS SOLUTION FROM THE
GFS. SEEMS THAT THE GFS HAS BEEN A TAD MORE CONSISTENT SO WILL
KEEP WITH IT AND THE PREVIOUS FORECAST IN THE EXTENDED RANGE.
OVERPECK/39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 38 70 53 63 35 / 0 0 10 30 10
HOUSTON (IAH) 39 69 53 66 40 / 0 0 10 40 10
GALVESTON (GLS) 50 65 59 66 47 / 0 0 10 40 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL MIDNIGHT CST TONIGHT
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT 20 TO 60 NM.
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
754 PM CST THU FEB 19 2009
.UPDATE...
SKIES HAVE CLEARED ACROSS ALL OF SOUTHEAST TEXAS. AT 01Z...SURFACE
HIGH PRESSURE WAS LOCATED NEAR DFW. DRY AIR IN PLACE COUPLED WITH
LIGHT WINDS SHOULD YIELD SOME COLD TEMPERATURES BY MORNING.
PREVIOUS FORECAST IS IN GREAT SHAPE. NO UPDATE NEEDED. 43
&&
.PREV DISCUSSION... /ISSUED 629 PM CST THU FEB 19 2009/
DISCUSSION...
SEE THE AVIATION SECTION BELOW.
AVIATION...
HIGH PRESSURE WILL DRIFT OVERHEAD TONIGHT AND FRIDAY MORNING. VFR
CONDITIONS TO PERSIST AND THE WINDS WILL BECOME SOUTHEAST 10 TO 14
KNOTS FRIDAY AFTERNOON OVER MOST OF THE TERMINAL SITES.
40
PREV DISCUSSION... /ISSUED 341 PM CST THU FEB 19 2009/
FIRE WEATHER...
GUSTY SURFACE WINDS THIS AFTERNOON WITH RELATIVE HUMIDITY VALUES
RUNNING IN THE UPPER TEENS IN OUR EXTREME NORTHERN COUNTIES AND
LOWER 20S EVERYWHERE ELSE. WINDS SHOULD CALM AND GUSTS WILL END
SHORTLY AFTER SUNSET TONIGHT. RED FLAG WARNING THAT WAS ISSUED FOR
JACKSON AND MATAGORDA COUNTIES WILL BE ALLOWED TO EXPIRE AT 6PM.
WINDS WILL SHIFT MORE TO TO SOUTH AND SOUTHEAST ACROSS THE AREA
TOMORROW MORNING BUT STRONG MOISTURE RETURN IS NOT ANTICIPATED.
THUS...WITH DRY CONDITIONS STILL IN PLACE AND WINDS EXPECTED TO
PICK UP AGAIN TOMORROW WILL HAVE TO CONTINUE TO MONITOR FIRE
DANGER SITUATION CLOSELY INTO THE WEEKEND. 38
MARINE...
SCA HAS BEEN ALLOWED TO EXPIRE FOR THE NEARSHORE WATERS THIS
AFTERNOON AND HAS BEEN REPLACED BY CAUTION ACROSS THE 20 TO 6O NM
MARINE ZONES THROUGH AT LEAST MIDNIGHT TONIGHT. SURFACE HIGH
PRESSURE OVER NORTH TEXAS THIS AFTERNOON WILL SHIFT SOUTHEAST
ACROSS THE AREA OVERNIGHT BEFORE EXITING INTO LOUISIANA ON
FRIDAY MORNING. WINDS ACROSS THE MARINE ZONES WILL SHIFT TO THE
SOUTHEAST TOMORROW MORNING ON THE BACKSIDE OF THE HIGH PRESSURE.
ONSHORE WINDS WILL REMAIN UNTIL A COLD FRONTAL PASSAGE EXPECTED
FOR SATURDAY EVENING. THIS FRONT IS STRONGER THAN OUR LAST SYSTEM
AND WILL BRING STRONG OFFSHORE WINDS AND INCREASED WAVE HEIGHTS
FOR THE LATTER HALF OF THE WEEKEND. WAVES WILL BEGIN TO RELAX ON
MONDAY AS RETURN FLOW SETS UP AGAIN EARLY NEXT WEEK. 38
DISCUSSION...
SFC RIDGE OVER N CENTRAL TX HAS KEPT NORTHERLY WINDS IN PLACE. A
DRY AIRMASS BEHIND THE COLD FRONT HAS MOVED INTO SE TX AS WELL
WITH CONDITIONS COMING CLOSE TO MEETING RED FLAG WARNING
CRITERIA. WINDS ARE CLOSER TO 10-15 MPH THAN 15-20MPH ALTHOUGH
THERE ARE SOME GUSTS TO AROUND 20 MPH ACROSS THE AREA. SFC RIDGE
SHOULD BUILD OVER SE TX TONIGHT ALLOWING FOR WINDS TO DIMINISH.
CLEAR SKIES WILL ALLOW FOR PRIME RADIATIONAL COOLING SO TEMPS
SHOULD DROP INTO THE 30S FOR MOST OF THE AREA EXCEPT ALONG THE
COAST.
THE MAIN FORECAST CONCERN WILL BE WITH RAIN CHANCES THIS WEEKEND.
SFC RIDGE SHOULD SLIDE OFF TO THE EAST TOMORROW AND ALLOW FOR SE
RETURN FLOW FRI NIGHT INTO SAT. UPPER LEVEL FLOW REMAINS OUT OF
THE NW WITH A STRONG TROUGH MOVING THROUGH THE MIDWEST AND GREAT
LAKES BY SAT MORNING. A COLD FRONT WITH A POLAR AIRMASS BEHIND IT
SHOULD WORK INTO SE TX DURING THE DAY SAT. MOISTURE RETURN AHEAD
OF THE FRONT LOOKS REALLY MARGINAL AT BEST. SFC DEWPOINTS MAY
REACH THE LOW 60S AHEAD OF THE FRONT BUT BOUNDARY LAYER MOISTURE
LOOKS RATHER SUSPECT GIVEN THE NAM SOLUTION. THE NAM SEEMS TO BE
HANDLING THE MOISTURE RETURN BETTER THAN THE GFS WHICH IS FASTER
WITH MOISTURE RETURN. GIVEN THIS SET UP...THE FRONT SHOULD KICK
OFF A LINE OF SHOWERS BUT GIVEN LIMITED MOISTURE AND INSTABILITY
THERE MAY ONLY BE A CHANCE FOR AN ISOLATED THUNDERSTORM. WINDS IN
THE 850-700MB LAYER WILL BE MORE SW TO W WHICH MAY BRING IN AN
ELEVATED MIXED LAYER TO CAP MOST OF THE COASTAL PLAIN SOUTH OF
I-10. AS SUCH...POPS WERE SCALED BACK DURING THE MORNING TO 20-30
PERCENT FOR A FEW SHOWERS AND THEN KEPT 40 POPS IN THE AFTERNOON.
SHOULD BETTER BOUNDARY LAYER MOISTURE DEVELOP IT IS POSSIBLE TO
GET SOME HIGHER POPS BUT CONFIDENCE IS LOW IN THAT HAPPENING.
FRONTAL PASSAGE LOOKS REASONABLE WITH THE NAM SOLUTION BEING
FASTER THAN THE GFS ESPECIALLY WITH STRONGER SUPPORT ALOFT WITH
NW FLOW. FORECAST WILL KEEP CLOSE TO THE TIMING OF THE NAM FOR
THE FRONTAL PASSAGE.
ANOTHER SFC RIDGE SHOULD BUILD OVER SE TX SAT NIGHT INTO SUN
WHICH WOULD ALLOW FOR ANOTHER COLD MORNING OR TWO FOR THE START
OF NEXT WEEK. THE 12Z GFS/ECMWF AGREE WITH RETURN FLOW RAMPING UP
AGAIN LATE MON INTO TUE. BOTH MODELS KEEP NW FLOW ALOFT OVER MUCH
OF TX WITH A WEAK RIDGE OVER THE SOUTHERN ROCKIES. ECMWF SEEMS TO
BE STRONGER WITH THIS RIDGE THAN THE GFS. MAIN UNCERTAINTY FOR THE
MIDDLE OF NEXT WEEK WILL BE HOW MUCH MOISTURE RETURNS FROM THE
GULF. RIGHT NOW NONE OF THE MODELS REALLY INDICATE PRECIP TO
REALLY PUT ANY CONFIDENCE. THE GFS SHOWS SOME SPOTTY SHOWERS BUT
TOO FAR OUT TO REALLY PUT MUCH STOCK IN THAT. POPS WERE KEPT
AROUND 10 PERCENT BUT COULD SEE POSSIBLY A FEW MORE SHOWERS
DEVELOPING IN ANY MOISTURE AXIS THAT SETS UP. CAPPING ON THE
OTHERHAND SHOULD BE WELL ESTABLISHED WITH SW FLOW BRINGING IN A
MORE STOUT ELEVATED MIXED LAYER. THE ECMWF DOES BRING A FRONT
THROUGH THE AREA AS IT SEEMS TO DIVERGE IN ITS SOLUTION FROM THE
GFS. SEEMS THAT THE GFS HAS BEEN A TAD MORE CONSISTENT SO WILL
KEEP WITH IT AND THE PREVIOUS FORECAST IN THE EXTENDED RANGE.
OVERPECK/39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 38 70 53 63 35 / 0 0 10 30 10
HOUSTON (IAH) 39 69 53 66 40 / 0 0 10 40 10
GALVESTON (GLS) 50 65 59 66 47 / 0 0 10 40 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL MIDNIGHT CST TONIGHT
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT 20 TO 60 NM.
