Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 231202
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
602 AM CST SUN NOV 23 2014

.UPDATE...
FOR 12Z AVIATION.

&&

.DISCUSSION...

THIS MORNING THE SURFACE RIDGE THAT YESTERDAY STRETCHED ALONG THE
EASTERN SEABOARD HAS NOW MOVED OFF INTO THE ATLANTIC OCEAN. ACROSS
CENTRAL ALABAMA WE STILL HAVE A GENERALLY EAST FLOW. IN THE UPPER
LEVELS...A SHORTWAVE WAS SWINGING ACROSS TEXAS. LATEST SATELLITE
DATA INDICATES THAT THE TROUGH HAS STARTED TO TURN TO THE
NORTHEAST AND SHOULD CONTINUE TO THE NORTHEAST TODAY GIVING A
NEGATIVE TILT TO THE UPPER TROUGH AS IT MOVES ACROSS ARKANSAS AND
THEN INTO KENTUCKY/TENNESSEE BY LATE THIS AFTERNOON. AT THE SAME
TIME...A SURFACE LOW HAS DEVELOPED ACROSS SOUTH TEXAS AND HAS
STARTED TO PUSH NORTHEAST AS WELL IN RESPONSE TO THE SHORTWAVE AND
SHOULD MOVE IT INTO NORTH LOUISIANA THIS MORNING AND INTO
MISSOURI/WESTERN KENTUCKY BY THIS EVENING. THIS SURFACE LOW HAS
ALREADY STARTED TO PULL WARMER/MOIST AIR AND RAIN SHOWERS ACROSS
PORTIONS OF ALABAMA AND INTO GEORGIA WELL AHEAD OF THE DRY LINE
BOUNDARY THAT IS EXPECTED TO PUSH THROUGH DURING THE DAY TODAY.
THEN TONIGHT INTO MONDAY MORNING...A COLD FRONT IS EXPECTED TO
SWEEP THROUGH BEHIND IT TO HELP COOL THINGS OFF FOR THE WEEK.

AS FAR AS PRECIPITATION WITH THIS EVENT...WE WILL CONTINUE TO SEE
ELEVATED SHOWERS AND THEN LATER THIS MORNING THUNDERSTORMS WILL
BEGIN TO SPREAD NORTHWARD ACROSS CENTRAL ALABAMA...BUT THIS
ACTIVITY SHOULD REMAIN ELEVATED FOR THE EARLY MORNING WITH STILL
EXPECTED EASTERLY FLOW AT THE SURFACE. WE SHOULD BEGIN
TRANSITIONING DURING THIS TIME FRAME.

AS WE MOVE INTO THE LATER MORNING HOURS ON SUNDAY...THE LATEST
TRENDS IN MODEL DATA ARE FOCUSING IN OUR BEST OPPORTUNITY FOR
INSTABILITY AND SURFACE BASED CONVECTION AS THE DRY LINE MOVES
ACROSS. ALTHOUGH WE ARE STILL TALKING ABOUT A WINDOW OF 7AM TO
4PM...THE BEST CHANCES LOOK TO BE 11AM THROUGH 4PM...CLOSER TO
THE BOUNDARY PASSAGE...BUT SOME STRONG TO SEVERE ACTIVITY BEFORE
THAT IS NOT TOTALLY OUT OF THE QUESTION IF THE WARM FRONT
PROGRESSES NORTHWARD QUICKER AND WE GET CELLS FIRING UP AHEAD OF
THE LINE. THE QUESTION WILL BE HOW LONG BEFORE OUR DRY LINE
ARRIVAL WILL OUR SURFACE FLOW GIVE WAY TO SOUTHERLY FLOW. THIS MAY
MAKE THE DIFFERENCE IN REALIZING OUR INSTABILITY POTENTIAL AND
EXACTLY HOW FAR NORTH THE HIGHER LOW LEVEL INSTABILITY VALUES
REACH. WITH THE HEAT OF THE DAY POTENTIAL FOR ARRIVAL...WE SHOULD
NOT HAVE AS MUCH OF A PROBLEM GETTING THE REQUIRED INSTABILITY.
AGAIN...THINK HEAVY RAIN WILL BE LESS WIDESPREAD AND MORE LOCALLY
STORM INFLUENCED AS THE LINE SHOULD MOVE AND NOT LINGER.

SOME WRAP AROUND PRECIPITATION IS POSSIBLE AS THE SYSTEM PULLS OUT
OF THE AREA THROUGH MONDAY. ALSO...ANOTHER UPPER SHORTWAVE TROUGH
WILL MOVE ACROSS LATE TUESDAY INTO WEDNESDAY THAT COULD BRING A
FEW SHOWERS ACROSS THE SOUTHEAST. HOWEVER...IT IS EXPECTED TO BE
WELL OUT OF THE AREA BY THURSDAY FOR THANKSGIVING DAY...WITH DRY
WEATHER EXPECTED FOR THE REMAINDER OF THE WEEK INTO NEXT WEEKEND.
A DRY FRONT IS EXPECTED TO MOVE IN ON THANKSGIVING. ALTHOUGH STILL
DRY...THE LATEST MODEL RUN IS SHOWING A WEAKER BOUNDARY THAT MAY
STALL AND FIZZLE OUT. NO MAJOR TEMPERATURES CHANGES ARE EXPECTED
WITH THIS SYSTEM FOR NOW.

08/MK


&&

.AVIATION...
12Z TAF DISCUSSION.

A VERY COMPLICATED FORECAST THIS TAF CYCLE WITH IFR CIGS EARLY IN
THE PERIOD...FOLLOWED BY RAPID DESTABILIZATION OF THE AIR MASS BY
18Z AS A WARM FRONT LIFTS NORTHWARD...AND THEN STABILIZES AGAIN
AFTER 00Z WITH MOIST SOUTHWEST FLOW. EASTERLY FLOW THRU 18Z WILL
KEEP THE AIR MASS STABLE...WITH THE WARM FRONT REMAINING NEAR THE
GULF COAST. REMOVED TSTM CHANCES BEFORE 18Z AT ALL TAF SITES AND
EXPECT SCT SHRWS. DUE TO THE EASTERLY SFC FLOW...CIGS WILL LIKELY
STAY BELOW 1000 FEET UNTIL WARM FRONT LIFTS NORTHWARD. BY 18Z...THE
SFC FLOW WILL BECOME SOUTHEAST AND AN UPPER LEVEL IMPULSE WILL
APPROACH THE AREA FROM THE WEST. EXPECT TSTMS TO BECOME MORE
WIDESPREAD DUE TO DAYTIME HEATING AND ENERGY FROM THE UPPER LEVEL
IMPULSE. CIGS SHOULD RISE TO MVFR CATEGORY AFTER 18Z AND REMAIN
IN THIS RANGE FOR THE AFTERNOON HOURS. SFC WINDS WILL VEER
THROUGHOUT THE DAY AND BECOME SOUTHERLY BETWEEN 18Z AND 21Z AT ALL
TAF SITES. AFTER 00Z...SFC WINDS WILL REMAIN FROM THE SOUTH-
SOUTHWEST AT 10-15 KNOTS AS THE MAIN COLD FRONT APPROACHES FROM
THE WEST. THERE WILL BE ENOUGH RESIDUAL LOW LEVEL MOISTURE AHEAD
OF COLD FRONT FOR VCSH AFTER 00Z. FOR NOW KEPT CIGS IN THE MVFR
RANGE AFTER 00Z...BUT THERE IS A POSSIBILITY CIGS COULD FALL BELOW
1000 FEET DURING THE OVERNIGHT HOURS.

58/ROSE

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     63  53  61  35  53 / 100  30  20  10  10
ANNISTON    64  54  63  37  54 / 100  30  20  10  10
BIRMINGHAM  66  55  62  38  54 / 100  30  20   0  10
TUSCALOOSA  68  53  62  37  57 / 100  20  10   0   0
CALERA      67  55  63  38  55 / 100  20  10   0  10
AUBURN      66  59  68  41  56 / 100  30  10   0  10
MONTGOMERY  71  58  69  40  58 / 100  20  10   0  10
TROY        72  57  71  40  57 / 100  20  10   0  20

&&

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

&&

$$






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