HAMweather.com Area Forecast Discussion for County Warning Area BMX

Thu, 16 Feb 2012 12:16:09 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
542 AM CST THU FEB 16 2012

.UPDATE...
FOR AVIATION.

.DISCUSSION...

MOST OF THE RAIN HAS DEPARTED THE CWA WITH THE EXCEPTION OF AREAS
ALONG AND SOUTH OF INTERSTATE 85. EXPECT SHOWERS TO SLOWLY MOVE
OUT OF THAT AREA BY NOON. THE WEAK COLD FRONT WILL MOVE THROUGH
TODAY WITH ONLY SOME ISOLATED SHOWER DEVELOPMENT POSSIBLE. THE
PARTIAL CLEARING EXPECTED LATER TODAY AND TONIGHT WILL BE
TEMPORARY AS CYCLOGENESIS BEGINS TO OCCUR ALONG THE TEXAS GULF
COAST IN RESPONSE TO FAIRLY VIGOROUS SHORTWAVE TRACKING NORTHEAST
FROM TEXAS INTO THE MID SOUTH REGION. WIDESPREAD PRECIP SHOULD
ACCOMPANY THIS SYSTEM SO THIS PACKAGE INCLUDES CATEGORICAL POPS ON
SATURDAY DUE TO HIGH CONFIDENCE AND DECENT MODEL AGREEMENT. 

THE THREAT FOR SEVERE STORMS WILL HAVE TO BE MONITORED CLOSELY WITH 
THIS SYSTEM AS IT APPEARS THAT THE SURFACE LOW WILL DEEPEN AS IT 
MOVES FROM THE LOUISIANA COAST INTO ALABAMA. AS THE WARM FRONT LIFTS 
NORTHWARD...DEWPOINTS IN THE 60S ARE LIKELY TO SPREAD ACROSS AT 
LEAST THE SOUTHERN PART OF THE CWA. MODELS ARE DEPICTING A POSSIBLE 
SECONDARY WARM FRONT LIFTING NORTHWARD AS THE SURFACE LOW TRACKS 
ACROSS CENTRAL ALABAMA. IF THIS OCCURS...THE SEVERE THREAT WILL 
INCREASE. EVEN WITH THIS SCENARIO THE MODELS SHOW VERY LIMITED 
INSTABILITY AT THIS TIME. WITH 0-1 KM HELICITY VALUES IN EXCESS OF 
300 M2/S2...ONLY A SLIGHT INCREASE IN INSTABILITY COULD ALLOW FOR A 
THREAT OF ISOLATED TORNADOES MAINLY SOUTH OF INTERSTATE 85...BUT THE 
SPECIFIC DETAILS OF THIS EVENT ARE UNCLEAR AT THIS TIME. THIS SYSTEM 
SHOULD DEPART BY EARLY SUNDAY MORNING LEADING TO COOLER WEATHER FOR 
LATE SUNDAY AND MONDAY AS A SURFACE HIGH BUILDS IN.

THE NEXT TROUGH WILL MOVE INTO THE PLAINS BY TUESDAY AS THE
SURFACE HIGH SHIFTS TO OUR EAST. RETURN FLOW WILL ALLOW FOR
INCREASING MOISTURE SOMETIME TOWARDS MIDWEEK AND THE POSSIBILITY
OF MORE RAIN AND THUNDERSTORMS.

GRANTHAM/87

.AVIATION...

12Z TAF DISCUSSION.

RAIN HAS JUST ABOUT LEFT THE AREA WITH ONLY TOI SEEING ANY RAIN AT 
THIS TIME. STILL WAITING ON THE FRONT TO ACTUALLY PASS THROUGH 
BEFORE THE WIND SHIFT...SO TRIED TO TIME OUT THE PASSAGE WITH THE 
TAFS. THERE MAY BE SOME BRIEF RAIN WITH THE FRONT...BUT LITTLE 
ACCUMULATION IS EXPECTED. THE BIGGEST CONCERN AHEAD AND BEHIND THE 
FRONT WILL BE THE LOW CLOUDS AND HOW LONG THEY HANG ON. WENT SEVERAL 
HOURS LONGER ON CLEARING THE AREA THAN THE MODELS. IN FACT TOI AND 
MGM MAY NOT CLEAR OUT AT HOW IN REGARDS TO LOW CLOUDS. AREAS THAT DO 
CLEAR THE LOW CLOUDS OUT WILL SEE REDEVELOPMENT AGAIN TONIGHT AS 
RETURN FLOW AHEAD OF THE NEXT SYSTEM PROVIDES THE ADDED LIFT FOR 
ADDITIONAL DEVELOPMENT IN ADDITION TO THE ABUNDANT LOW LEVEL 
MOISTURE. 

16

.BMX WATCHES/WARNINGS/ADVISORIES...
NONE.