FXUS64 KBMX 231143
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
545 AM CST WED DEC 23 2009
.UPDATE...AVIATION DISCUSSION.
&&
.DISCUSSION...
UPPER LOW SPINNING THROUGH THE FOUR CORNERS REGION THIS MORNING...AS
A SURFACE LOW IN CENTRAL TX BEGINS TO DEEPEN. LIGHT RAIN DEVELOPING
IN NORTH MS THIS MORNING...IN RESPONSE TO A SHORT WAVE CROSSING THE
SOUTHERN MS RIVER VALLEY AHEAD OF THE MAIN UPPER LOW. THIS ACTIVITY
WILL LIKELY SKIRT NORTHWEST CENTRAL ALABAMA...BEFORE WEAKENING AND
PUSHING NORTH OF THE TN VALLEY. WEDGING OF DRY AIR AROUND THE
SOUTHERN APPALACHIANS WILL PREVENT ACTIVITY FROM PUSHING TOO FAR
EAST TODAY. IN RESPONSE TO THE STRENGTHENING SYSTEM TO OUR
WEST...SOUTHEASTERLY WINDS WILL INCREASE...BUT WITH CLOUD COVER
SPREADING INTO THE AREA...TEMPERATURES WILL BE WARM BUT NOT QUITE AS
HIGH AS YESTERDAY. EXPECTING LOW 60S IN THE SOUTH AND UPPER 50S IN
THE NORTH.
WITH MODELS REMAINING IN GOOD AGREEMENT WITH THE PROGRESSION OF THE
STORM SYSTEM...NO BIG CHANGES TO THE FORECAST OVER THE NEXT COUPLE
DAYS. AS THE SFC LOW DEEPENS AND MOVES NORTHWARD UP THE MS RIVER
VALLEY...IT WILL PUSH A COLD FRONT THROUGH CENTRAL ALABAMA THURS
NIGHT. AHEAD OF THE FRONT...EXPECT SHOWERS TO BEGIN SPREADING INTO
WEST CENTRAL ALABAMA AS EARLY AS THIS AFTERNOON...GRADUALLY BECOMING
MORE WIDESPREAD OVERNIGHT AND TOMORROW MORNING. DRY AIR WEDGING INTO
EAST CENTRAL ALABAMA WILL LIKELY KEEP ACTIVITY CONFINED TO WESTERN
PORTIONS OF THE FORECAST AREA UNTIL AFTER MIDNIGHT TONIGHT. SURFACE
INSTABILITY WILL BE VERY WEAK WITH THIS SYSTEM...AND CONTINUE TO
EXPECT A VIRTUALLY NO CAPE/HIGH SHEAR SET UP. AS A SQUALL LINE
DEVELOPS TO OUR WEST AND MOVES INTO CENTRAL ALABAMA THURS AFTN...THE
BETTER UPPER LEVEL DYNAMICS AND STRONG LLJ WILL BE LIFTING AWAY FROM
THE AREA. STILL...STRONG STORMS WILL BE POSSIBLE...MAINLY IN THE
SOUTHWEST PORTION OF THE AREA...WITH DAMAGING WINDS BEING THE MAIN
THREAT.
BEGINNING TONIGHT THROUGH THURS...AHEAD OF THE SYSTEM STRONG
GRADIENT WINDS WILL BE POSSIBLE...WITH GUSTS UP TO 35-40 MPH. TEMPS
WILL AGAIN BE IN THE UPPER 50S TO LOW 60S ON THURS. HEAVIER
RAIN/TSTMS WILL END FROM WEST TO EAST THURS NIGHT. ALTHOUGH A PERIOD
OF LIGHT RAIN IS POSSIBLE BEFORE MOISTURE LIFTS NORTH OF THE
AREA...AND WILL LEAVE SMALL POPS IN FOR FRIDAY MORNING.
THE CLOSED UPPER LOW/TROUGH WILL MEANDER AROUND THE MIDWEST THROUGH
THE WEEKEND...SENDING WEAK UPPER LEVEL ENERGY ACROSS CENTRAL
ALABAMA. THIS WILL MAINTAIN AT LEAST PARTLY CLOUDY...BUT
DRY...CONDITIONS INTO NEXT WEEK. LATEST GUIDANCE HAS TRENDED COOLER
WITH TEMPERATURES OVER THE WEEKEND AND INTO NEXT WEEK. POSSIBLY A
RESULT OF THE EXPECTED SNOW PACK FROM THIS STORM SYSTEM ACROSS A
LARGE PORTION OF THE NORTHERN CENTRAL PLAINS AND MIDWEST? WILL TREND
TEMPS DOWN SOME EACH PERIOD...WITH THE HIGHS IN THE MID 40S TO LOW
50S AND OVERNIGHT LOWS IN THE MID 20S TO LOW 30S.
A MODERATING TREND TAKES PLACE AS ANOTHER SYSTEM BEGINS TO DEVELOP
TO OUR WEST BY THE MIDDLE OF NEXT WEEK...AND WILL MAINTAIN LOW POPS
BEGINNING TUESDAY.
14
&&
.AVIATION...12Z TAF DISCUSSION.
VFR CONDS WILL PERSIST THRU 06Z. RAIN OVER NORTHERN MISSISSIPPI WILL
TRACK NORTHEAST AND STAY NORTH OF TAF SITES. CLOUDS WITH CIGS AROUND
5000 FEET AGL HAVE DEVELOPED ACROSS NORTH ALABAMA DUE TO INCREASING
WARM AIR ADVECTION...BUT THESE CLOUDS WILL NOT LIKELY PERSIST AS
MIXING OCCURS TODAY. LOWER CLOUDS WITH CIGS 1500-2500 FEET WILL
LIKELY FORM AFTER 06Z DUE TO INCREASING MOISTURE. RAIN WILL LIKELY
HOLD OFF UNTIL AFTER 12Z. SOUTHEAST WINDS WILL ALSO INCREASE AFTER
06Z WITH SUSTAINED SPEEDS 10-15 KNOTS. THE THRESHOLD FOR LOW LEVEL
WIND SHEAR MAY NOT BE MEET DUE TO INCREASING SPEEDS THROUGHOUT THE
LOWEST 2000 FEET ABOVE SURFACE...BUT SPEEDS WILL APPROACH 40 KNOTS
AT 2000 FEET AGL BY 09Z.
58/ROSE
&&
.PRELIMINARY POINT TEMPS/POPS...
GADSDEN 57 43 56 44 51 / 20 20 70 100 20
ANNISTON 57 46 56 47 53 / 10 20 70 100 20
BIRMINGHAM 58 51 56 43 51 / 20 30 80 100 20
TUSCALOOSA 60 52 61 43 54 / 30 40 100 90 10
CALERA 59 51 59 44 52 / 20 30 90 100 20
AUBURN 60 45 56 46 55 / 10 20 70 100 10
MONTGOMERY 63 51 63 46 57 / 10 20 80 100 10
TROY 63 50 63 46 57 / 10 20 70 100 10
&&
.BMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
