Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 011200
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
600 AM CST SUN MAR 1 2015

.UPDATE...
FOR 12Z AVIATION.

&&

.DISCUSSION...

FLOW ACROSS THE SOUTHERN U.S. THIS MORNING IS RATHER ZONAL...WITH A
CLOSED LOW SLOWLY DROPPING SOUTHWARD ALONG THE SOUTHERN CALIFORNIA
COAST AND A TROUGH MOVING INTO THE MIDWEST FROM CENTRAL CANADA. AT
THE SURFACE...HIGH PRESSURE EXTENDS SOUTHWARD ACROSS THE CAROLINAS
AND GEORGIA...WITH A WEAK WEDGE EXTENDING INTO EAST CENTRAL
ALABAMA. A WEAK FRONT IS MOVING ACROSS THE OHIO RIVER VALLEY AHEAD
OF THE TROUGH MOVING OUT OF CANADA. ACROSS CENTRAL ALABAMA...LOW
LEVEL LIFT HAS ALLOWED CLOUDS TO SPREAD NORTHWARD THIS
MORNING...WHICH HAS KEPT TEMPERATURES IN THE LOWER 40S TO LOWER
50S. WITHIN THIS LIFT...A FEW SHOWERS ARE MOVING NORTHWARD ALONG
THE GEORGIA STATE LINE. WITH LOW LEVEL LIFT CONTINUING THROUGH THE
DAY...CLOUD COVER WILL REMAIN ACROSS THE AREA AND SCATTERED
SHOWERS WILL BE POSSIBLE. WILL ALSO BE LOOKING TO THE NORTHWEST AS
THE FRONT SINKS SOUTHWARD TOWARD THE AREA. THINK THE BETTER
MOISTURE POOLING AND RAIN CHANCES WILL REMAIN TO OUR NORTHWEST
TODAY AS MID LEVEL HEIGHTS INCREASE SLIGHTLY. TEMPERATURES WILL BE
SIMILAR TO YESTERDAY...HIGHS IN THE LOWER 50S TO LOWER 60S.

TONIGHT AND MONDAY...THE FRONT DOES SLIDE INTO THE AREA...QUICKLY
GETTING CAUGHT IN ZONAL FLOW AND WEAKENING. WILL CARRY LIKELY POPS
ACROSS THE NORTHWEST GIVEN THE HIGH MOISTURE CONTENT. FOG WILL BE
POSSIBLE SOUTH OF THE FRONT TONIGHT. WINDS DO SHIFT TO THE NORTH
BEHIND THE FRONT... BUT DO NOT EXPECT A SIGNIFICANT COOL DAY WITH
THIS SYSTEM. LOWS TONIGHT WILL BE IN THE 40S TO LOWER 50S...AND
HIGHS TOMORROW IN THE UPPER 40S FAR NORTHEAST TO NEAR 70 IN THE
SOUTHEAST. BY TUESDAY...ENERGY IN THE DESERT SOUTHWEST WILL EJECT
EASTWARD AS A SECOND TROUGH DROPS OUT OF CANADA AND INTO THE
CENTRAL PLAINS. A SURFACE LOW WILL DEVELOP LEE OF THE ROCKIES AND
THE NEARBY STALLED FRONT WILL LIFT BACK NORTHWARD AS THIS LOW
MOVES TOWARD THE MIDWEST...LEAVING THE LOCAL AREA IN THE WARM
SECTOR. WITH SOUTHERLY FLOW AND MID LEVEL HEIGHTS INCREASING
ACROSS CENTRAL ALABAMA...HIGHS WILL PUSH INTO THE UPPER 70S ACROSS
THE SOUTH. SCATTERED THUNDERSTORMS ARE POSSIBLE...BUT FORCING IS
RATHER DISORGANIZED AND INSTABILITY TOO LOW TO MENTION A CONCERN
OF SEVERE STORMS AT THIS TIME. WOULD NOT BE SURPRISED TO SEE 80
DEGREES SOMEWHERE ACROSS SOUTH CENTRAL ALABAMA IF A FEW BREAKS IN
THE CLOUDS HAPPEN EARLY ENOUGH IN THE DAY.

THE SOUTHERN AND NORTHERN STREAMS PHASE OVER THE CENTRAL PLAINS
AND A UPPER JET STRENGTHENS OVER THE OHIO RIVER VALLEY TO 180KTS
AS THE SURFACE LOW MOVES THROUGH THE OHIO RIVER VALLEY TUESDAY
NIGHT AND WEDNESDAY. A COLD FRONT DROPS SOUTHWARD INTO THE
TENNESSEE VALLEY AND THEN CENTRAL ALABAMA EARLY WEDNESDAY MORNING.
WITH THE JET POSITIONED TO OUR NORTH AND FORCING MAXIMIZED BEHIND
THE FRONT...MOST OF RAINFALL WILL OCCUR POST FRONTAL...WHICH ALONG
WITH LOW LEVEL SOUTHWESTERLY WINDS...WILL LIMIT ANY SEVERE
POTENTIAL. AS A STRONG ARCTIC DIVES SOUTHWARD BEHIND THE
FRONT...COLD AIR WILL SURGE SOUTHWARD AND A TRANSITION TO A WINTRY
MIX IS EXPECTED ACROSS THE NORTH WEDNESDAY NIGHT.

MODELS MAINTAIN A SLIGHT TIMING DIFFERENCE ON THE FRONT AND COLD
AIR ARRIVAL. THE ECMWF IS MORE CONSERVATIVE...AND MATCHES UP
BETTER WITH THE CMC...AND IS NOT SO BULLISH ON THE COLD AIR
QUICKLY PUSHING SOUTHWARD...AS THE GFS DOES. WILL HOPE FOR BETTER
CONSISTENCY OVER THE NEXT COUPLE DAYS. EITHER WAY...AS COLD AIR
UNDERCUTS WARM AIR ALOFT...RAIN WILL TRANSITION TO FREEZING RAIN
ACROSS LOCATIONS NORTH OF I-20. MODELS CONTINUE TO SHOW QUITE A
BIT OF QPF BEHIND THE FRONT...WHICH IS CAUSE FOR CONCERN GIVEN THE
TEMP PROFILES. AS THE COLUMN COOLS...THERE IS A CHANCE OF A BRIEF
SNOW/SLEET MIX AS PRECIP ENDS...BUT THE MAIN IMPACT WOULD BE
FREEZING RAIN AND ICE ACCUMULATION. CONFIDENCE WILL NEED TO
INCREASE REGARDING WHEN THE COLD AIR ARRIVES AND HOW FAR SOUTH
IT PUSHES WHILE RAIN IS STILL FALLING...BEFORE WE TALK ICE
ACCUMULATION AMOUNTS. CONTINUE TO MONITOR FORECAST UPDATES FOR
CHANGES...AS THIS COULD BE A SIGNIFICANT EVENT FOR PORTIONS OF
CENTRAL ALABAMA.

14

&&

.AVIATION...
12Z TAF DISCUSSION.

IFR TO LOW-END MVFR CIGS WILL CONTINUE TO IMPACT ALL TERMINALS
THROUGH THE FORECAST PERIOD. EVEN THOUGH CIGS MAY RISE SOME THIS
AFTERNOON...THEY SHOULD NOT RISE ABOVE 2K FEET AT ANY POINT.
ISOLATED TO SCATTERED SHOWERS WILL BE POSSIBLE THROUGH THE
DAY...BUT HAVE NOT INCLUDED ANY PREVAILING SHRA IN THE FORECAST AT
THIS TIME. OVERNIGHT TONIGHT...PATCHY FOG WILL CONTINUE TO BE
POSSIBLE ESPECIALLY ACROSS THE SOUTHERN TERMINALS BUT HAVE NOT
REDUCED ANY VIS BELOW 6SM AT THIS TIME. SURFACE WINDS WILL PREVAIL
FROM THE EAST THIS AFTERNOON AND REMAIN LIGHT.

56/GDG

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     54  44  54  47  70 /  30  60  60  40  40
ANNISTON    55  45  58  50  72 /  30  40  60  40  30
BIRMINGHAM  58  48  56  51  73 /  30  60  70  40  30
TUSCALOOSA  61  49  57  50  75 /  20  60  70  30  30
CALERA      58  49  58  53  74 /  20  40  60  30  30
AUBURN      55  46  64  54  74 /  30  30  40  30  30
MONTGOMERY  60  50  66  56  77 /  20  30  50  20  20
TROY        60  49  68  56  77 /  20  20  30  20  20

&&

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

&&

$$








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