FXUS64 KBMX 142351
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
550 PM CST MON DEC 14 2009
.UPDATE...FOR AVIATION.
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.SHORT TERM...TONIGHT AND TUESDAY.
SURFACE WARM FRONT WAS LOCATED ACROSS THE SOUTHERN PART OF CENTRAL
ALABAMA THIS AFTERNOON. SURFACE BASED INSTABILITY WAS LIMITED TO
AREAS SOUTH OF THE FRONT...GENERALLY FROM LIVINGSTON TO EUFAULA.
THIS SURFACE BASED INSTABILITY AXIS/WARM FRONT WILL PUSH SLOWLY
NORTHWARD OVERNIGHT BUT SHOULD REMAIN GENERALLY SOUTH OF
INTERSTATE 20. SURFACE DEW POINTS HAVE INCREASED EVEN NORTH OF THE
WARM FRONT INTO THE UPPER 50S NORTH OF INTERSTATE 20. SOME
ELEVATED INSTABILITY EXISTS NORTH OF THE PREVIOUSLY DESCRIBED
BOUNDARY...THEREFORE WILL MENTION THUNDER POSSIBLE AT ALL
LOCATIONS OVERNIGHT. A COLD FRONT ENTERS CENTRAL ALABAMA FROM THE
NORTHWEST LATE TONIGHT...ONLY ENHANCING MOISTURE CONVERGENCE AND
RAIN POTENTIAL.
A FEW STRONG STORMS ARE POSSIBLE IN THE SURFACE BASED INSTABILITY
ZONE SOUTH. THE MAIN THREAT APPEARS TO BE LOCALLY HEAVY RAINFALL...
WHERE THE PRECIP WATER VALUES ARE OVER 1.5 INCHES WHICH IS SEVERAL
STANDARD DEVIATIONS ABOVE NORMAL...OR NEAR 200% OF NORMAL. A FEW
THUNDERSTORM WIND GUSTS MAY ALSO OCCUR...BUT THE MOISTURE LEVELS
PRESENT WILL MINIMIZE THEIR OCCURRENCE. A FLASH FLOOD WATCH HAS
BEEN POSTED FOR AREAS SOUTH AND SOUTHEAST THROUGH TUESDAY. IT
APPEARS THAT THE HEAVIEST RAINFALL WILL OCCUR THE REMAINDER OF
THIS AFTERNOON THROUGH NOON TUESDAY...AN ADDITIONAL 3 TO 4 INCHES
MAY FALL. THIS ALSO HAPPENS TO BE WHERE THE HEAVIEST RAIN
OCCURRED OVER THE PAST 48 HOURS OR SO.
SATURATED BOUNDARY LAYER CONDITIONS WILL PREVAIL DURING THE
OVERNIGHT HOURS WITH THE POTENTIAL OF COOLING AS A COLD FRONT
APPROACHES FROM THE NORTHWEST. MODEL SOUNDINGS INDICATE THE
COMBINATION OF VERY LOW CLOUD COVER AND FOG. WILL RE-ISSUE THE DENSE
FOG ADVISORY UNTIL 10 AM TUESDAY MORNING AREAWIDE WITH SOME
IMPROVEMENT EXPECTED FROM NORTHWEST TO SOUTHEAST TUESDAY MORNING.
THE FRONT THAT PUSHES IN ON TUESDAY APPEARS TO BE QUITE STRONG. HIGH
TEMPERATURES WILL BE SOME 10 DEGREES LOWER THAN TODAY...GENERALLY IN
THE 50S. THIS FRONT DROPS THINGS CLOSER TO NORMAL FOR MID
DECEMBER.
.LONG TERM...WEDNESDAY THROUGH SUNDAY.
RATHER QUIET PERIOD EXPECTED AS HIGH PRESSURE REMAINS IN PLACE
THROUGH THE WORK WEEK AND A DRY COLD FRONT BRINGS A RE-ENFORCING
SHOT OF COOLER AIR ACROSS THE AREA DURING THE WEEKEND. OVER-ALL
TEMPERATURES WILL BE CLOSE TO SEASONAL NORMALS(50S/30S) THROUGH THE
WEEK...THEN SLIGHTLY COLDER DURING THE WEEKEND.
50
&&
.AVIATION...00Z TAF DISCUSSION.
SHOWERS AND STORMS FOR THE SOUTH AND LOW CLOUDS AND DRIZZLE FOR THE
NORTHERN SITES. THERE WAS SOME ANTICIPATION OF MINOR CLEARING
PREVIOUSLY FOR THE NORTH...BUT CEILINGS HAVE ALREADY DROPPED AT
TCL...BHM...AND EET. WILL CONTINUE IFR AND LIFR THROUGH 19 TO 21Z
THIS AFTERNOON.
EXPECTING FOR THE HEAVIER RAIN SHOWERS TO ONLY AFFECT THE SOUTHERN
TAF SITES. WILL ADJUST THE FORECAST IF NEEDED IF IT APPEARS
OTHERWISE SINCE COMPUTER MODELS ARE CONFIDENT THAT THE HEAVY RAIN
WILL REMAIN SOUTHWARD.
A COLD FRONT WILL THEN BEGIN TO MOVE IN FROM THE NORTH AFTER 00Z
TONIGHT. EXPECT A WIND SHIFT TO THE NORTH AFTER THE FRONT MOVES
THROUGH...BUT NOT EXPECTING CEILINGS TO LIFT. FINALLY EXPECTING
CLEARING...AT LEAST LOWER CEILINGS FOR THE NORTH AFTER 21Z. LOWER
CEILINGS IMPROVE TO MVFR FOR THE SOUTH AFTER 21Z. IMPROVEMENT HERE
IS EXPECTED AFTER 00Z TOMORROW.
16
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY FOR ALL OF CENTRAL AL THROUGH 10 AM CST TUESDAY.
FLASH FLOOD WATCH FOR TALLAPOOSA...CHAMBERS...DALLAS...AUTAUGA...
LOWNDES...ELMORE...MONTGOMERY...MACON...BULLOCK...LEE...RUSSELL...
PIKE...AND BARBOUR UNTIL NOON CST TUESDAY.
&&
$$
