FXUS64 KBMX 212327
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
527 PM CST MON DEC 21 2009
.UPDATE...AVIATION DISCUSSION.
&&
.DISCUSSION...
CONDITIONS TO REMAIN FAIRLY TRANQUIL OVER THE NEXT FEW DAYS ACROSS
THE AREA. WITH TEMPERATURES SLOWLY MODIFYING EACH DAY. LOOK FOR THE
COLDEST NIGHT OF THE PERIOD TO BE TONIGHT AS WE WILL BE UNDER THE
INFLUENCE OF HIGH PRESSURE AND FAIRLY CALM WINDS. TUESDAY
NIGHT...SOUTHEASTERLY FLOW WILL INCREASE AHEAD OF THE NEXT STORM
SYSTEM. WITH MOISTURE AND CLOUD COVER INCREASING...LOWS WILL BE IN
THE MID 30S TO MID 40S.
A STRONG UPPER LEVEL TROUGH WILL DROP INTO THE DESERT SOUTHWEST
TUESDAY...AND MOVE INTO THE SOUTHERN PLAINS WEDNESDAY. A SURFACE LOW
WILL DEEPEN AHEAD OF THIS SYSTEM...MOVE UP THE MISSISSIPPI RIVER
VALLEY...AND DRAG A COLD FRONT THROUGH CENTRAL ALABAMA THURSDAY.
MODELS ARE AGREEING EVEN MORE ON THE OVERALL TIMING FOR THIS EVENT
AND CONFIDENCE IS GROWING SOMEWHAT. THE OVERALL TIMING DIFFERENCE OF
THE SQUALL LINE IS NOW LESS THAN 6 HOURS...WITH THE SLOWER NAM AND
EURO BRINGING THE SQUALL LINE INTO THE AREA BY THURSDAY EVENING AND
INTO THE OVERNIGHT. THE GFS IS BRINGING THE FRONT THROUGH LATE
THURSDAY AFTERNOON/THURSDAY NIGHT. WHILE THESE DIFFERENCES ARE MUCH
SMALLER THAN PREVIOUS...THERE IS STILL A LARGE BIT OF DIFFERENCE IN
THE MODELS IN REGARDS TO SEVERE WEATHER.
THE OVERALL SCENARIO FOR THE WEDNESDAY THROUGH THURSDAY TIME-FRAME
WILL BE AS FOLLOWS. COLD AIR WEDGE WILL BE IN PLACE ACROSS THE EAST
FROM TONIGHT THROUGH WEDNESDAY. AS A WARM FRONT TRIES TO LIFT NORTH
WEDNESDAY NIGHT/THURSDAY MORNING...IT WILL HAVE A HARD TIME ERODING
THIS WEDGE...ESPECIALLY IF IT IS ENHANCED WITH THE SNOW PACK FROM
THE PREVIOUS STORM.
WITH THAT SAID WE MAY SEE A RISE IN DEWPOINTS WITH THE WARM FRONT
WEDNESDAY AFTERNOON...BUT THE JUICIEST AIRMASS SHOULD REMAIN SOUTH OF
THE AREA...AT LEAST UNTIL THE COLD FRONT ITSELF WORKS CLOSER TO THE
AREA. RAIN WILL SPREAD INTO CENTRAL ALABAMA WEDNESDAY AFTERNOON...
BECOMING MORE WIDESPREAD DURING THE EVENING. THE COLD FRONT WILL
MOVE THROUGH THE AREA ON THURSDAY. AS FOR SEVERE THREATS...WILL
CONTINUE WITH THE MENTION OF SEVERE WITH A LOW CONFIDENCE WITH THE
COLD FRONT. WHILE THE TIME FRAME FOR SEVERE WEATHER WILL BE
SMALL...WE WILL NEED TO WATCH ANY DEVELOPMENT TO OUR WEST ALONG THE
COLD FRONT. MODELS CONTINUE TO INDICATE THAT THE MAIN DYNAMICS WILL
BE LIFTING NORTH AND WEST OF THE AREA...BUT ANY CONVECTION THAT GETS
GOING TO THE WEST...COULD CREATE ITS OWN ENVIRONMENT AND CONTINUE
THE SEVERE THREAT FOR WESTERN ALABAMA. QUESTION HERE WILL BE HOW FAR
NORTH WILL THE HIGHER DEWPOINTS ACTUALLY GO BEFORE THE DYNAMICS
BEGIN TO LIFT OUT OF THE AREA.
LOOK FOR THE RAIN/STORMS TO END THURSDAY NIGHT. MAY SEE SOME DRIZZLE
THROUGH THE EARLY EVENING...BUT MODELS CONTINUE TO INDICATE THE
MOISTURE WILL LIFT NORTH OF THE AREA BEFORE THE COLD AIR MAKES IT
INTO THE AREA...ELIMINATING ANY CHANCE FOR WINTRY PRECIP. BEHIND
THIS SYSTEM...TEMPERATURES CHRISTMAS DAY WILL BE IN THE MID 40S IN
THE NORTH TO LOW 50S IN THE SOUTH.
GENERALLY CLOUDY CONDITIONS WILL CONTINUE ACROSS THE AREA NEXT
WEEKEND AS A COUPLE SHORT WAVES BRUSH THE AREA. TEMPERATURES WILL BE
IN THE MID 40S TO LOW 50S EACH AFTERNOON WITH OVERNIGHT LOWS IN THE
MID 20S TO LOW 30S.
NEXT SYSTEM APPROACHES TOWARD THE MIDDLE OF NEXT WEEK...WITH
NUMEROUS TIMING ISSUES TO WATCH OVER THE NEXT FEW RUNS.
16
&&
.AVIATION...00Z TAF DISCUSSION.
ON FIRST INSPECTION...IT WOULD SEEM THAT THERE WOULD BE NO AVIATION
WEATHER CONCERNS OVER THE NEXT 24 HOUR TAF CYCLE. BUT LOOKING AT
OBSERVATIONS THIS AFTERNOON (DEWPOINTS IN THE LOWER 30S)...AND
EXPECTED LOW TEMPERATURES TONIGHT (UPPER 20S TO NEAR 30 IN MANY
AREAS)...UPS THEORY WOULD LEAD ONE TO BELIEVE THAT FOG FORMTION
COULD BECOME A PROBLEM. I HIT THE FOG POTENTIAL HARDEST AT
TCL...ANB...AND TOI BASED MAINLY ON PERSISTENCE FROM THE PREVIOUS
NIGHT. JUST BE AWARE THAT ANY TAF LOCATION LATE TONIGHT COULD SEE
AREAS OF FOG THAT COULD REDUCE VISIBILITIES BELOW A MILE FOR A TIME.
OTHER THAN THAT...VFR CONDITIONS TO CONTINUE.
/61/
&&
.PRELIMINARY POINT TEMPS/POPS...
GADSDEN 26 58 37 58 43 / 0 0 10 20 40
ANNISTON 29 60 35 59 43 / 0 0 10 10 30
BIRMINGHAM 33 60 39 58 44 / 0 0 10 20 50
TUSCALOOSA 31 63 42 60 48 / 0 0 10 40 50
CALERA 31 61 40 59 45 / 0 0 10 20 50
AUBURN 33 58 35 60 42 / 0 0 10 10 20
MONTGOMERY 29 64 41 63 49 / 0 0 10 10 30
TROY 27 62 39 63 47 / 0 10 10 10 20
&&
.BMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
