FXUS64 KBMX 142133
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
333 PM CST MON DEC 14 2009
.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...18Z TAF DISCUSSION.
POOR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS ALL SITES FOR THE
ENTIRE 24 HOUR FORECAST PERIOD. VISIBILITIES COULD IMPROVE SOME
ACROSS THE NORTHERN TAF SITES THIS AFTERNOON...BUT BY EVENING THEY
ARE EXPECTED TO BACK DOWN.
A SHORT PERIOD OF CLEARING COULD OCCUR ACROSS TCL THROUGH 21Z WHICH
IS NOT REFLECTED ON THE TAF FORECAST. A SMALL AREA OF CLEAR SKIES
ACROSS NORTHERN MISSISSIPPI COULD MAKE ITS WAY TOWARDS TCL.
HOWEVER...IF THIS OCCURS IT WILL BE VERY SHORT LIVED AND I AM NOT
COMPLETELY CONFIDENT THAT IT WOULD EVEN LAST MORE THAN 30 MINUTES.
RAIN HAS NOW BEGAN MOVING NORTH AFFECTING THE SOUTHERN TAF SITES. ON
AND OFF SHOWERS AND THUNDERSTORMS ARE EXPECTED AT THROUGH THE NEXT
24 HOURS. RAIN COULD BE VERY HEAVY AT TIMES AND COULD BRIEFLY REDUCE
VISIBILITIES BACK DOWN TO AT LEAST IFR.
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 A WHOLE LOT
UNFORTUNATELY.
10/ARM
&&
.PRELIMINARY POINT TEMPS/POPS...
GADSDEN 65 51 52 33 55 / 30 70 30 10 10
ANNISTON 63 53 54 34 57 / 40 90 50 10 10
BIRMINGHAM 67 49 53 33 56 / 40 90 50 10 10
TUSCALOOSA 66 48 55 33 57 / 60 90 60 10 10
CALERA 64 52 54 35 56 / 70 90 60 10 10
AUBURN 64 55 60 37 57 / 100 100 80 10 10
MONTGOMERY 68 58 58 39 60 / 100 100 90 10 10
TROY 71 60 62 40 59 / 100 100 100 20 10
&&
.BMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
