Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 222337
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
637 PM CDT WED APR 22 2015

.UPDATE...
FOR 00Z AVIATION.

&&

.DISCUSSION...

IT`S BEEN ANOTHER NICE DAY ACROSS CENTRAL ALABAMA WITH MOSTLY
SUNNY SKIES AND TEMPS RISING INTO THE MID 70S TO LOW 80S. A WEAK
FRONTAL BOUNDARY HAS BEEN SLOWLY SLIDING SOUTHWARD TOWARD THE
TENNESSEE VALLEY TODAY AND WILL CONTINUE ITS SOUTHWARD PROGRESS
INTO CENTRAL ALABAMA TONIGHT INTO THURSDAY. SCATTERED SHOWERS AND
A FEW THUNDERSTORMS WILL BE POSSIBLE NEAR THE FRONT THIS EVENING
AND TONIGHT. THE FRONT SHOULD BE NEAR THE GULF COAST BY THURSDAY
NIGHT WHICH SHOULD ALLOW SOME DRIER AIR TO FILTER INTO NORTHERN
AL...BUT IT WON`T LAST LONG.

MOISTURE INCREASES ONCE AGAIN ON FRIDAY AS THE NEXT SYSTEM
APPROACHES. THE OLD FRONTAL BOUNDARY ALONG THE COAST WILL PUSH
BACK TO THE NORTH AS A WARM FRONT LATE FRIDAY NIGHT IN RESPONSE TO
RETURNED SOUTHERLY FLOW AHEAD OF A SFC LOW PRESSURE SYSTEM IN THE
PLAINS. OVERRUNNING PRECIP NORTH OF THE WARM FRONT WILL OVERSPREAD
THE CWA FROM SW TO NE FRIDAY NIGHT. THERE ARE STILL SOME QUESTIONS
IN REGARDS TO WHAT WILL HAPPEN ON SATURDAY ONCE WE ARE FIRMLY IN
THE WARM SECTOR. MODELS SHOW THE BEST UPPER LEVEL ENERGY AND MEAN
MOISTURE PUSHING EAST OF THE AREA BY AFTERNOON.
HOWEVER...INSTABILITIES INCREASE TO AROUND 2500 J/KG AND A
SECONDARY LLJ DEVELOPS OVER THE TN VALLEY. SHEAR IS ALSO
PRESENT...MORE SPEED VS DIRECTIONAL BY AFTERNOON THOUGH. IF ENOUGH
MOISTURE REMAINS AND ENOUGH LIFT IS PRESENT THEN SEVERE STORMS
WOULD DEFINITELY BE IN THE CARDS. EVEN THOUGH SOME QUESTIONS
REMAIN WILL CONTINUE TO MENTION SEVERE POSSIBILITIES FOR SATURDAY
AFTERNOON. IT`S IMPORTANT TO NOTE THAT PW VALUES DO INCREASE TO
1.5-2.0 INCHES WITH THIS SYSTEM. THEREFORE HEAVY RAINFALL IS
LIKELY AT TIMES. THE GOOD NEWS IS THAT FFG VALUES HAVE HAD A
CHANCE TO REBOUND SINCE THE LAST RAINS. BASED ON THIS...WIDESPREAD
FLASH FLOODING DOES NOT APPEAR LIKELY ATTM...BUT LOCALIZED
FLOODING MAY BE POSSIBLE.

WE SHOULD GET A BRIEF REPRIEVE BEFORE THE NEXT SYSTEM ARRIVES
SOMETIME EARLY NEXT WEEK. MODELS STILL SHOW QUITE A BIT OF
VARIABILITY WITH THE SYSTEM AND HAVE SLOWED IT DOWN UNTIL THE
TUESDAY/WEDNESDAY TIMEFRAME. EVEN THOUGH THE OPERATIONAL GFS HAS
TRENDED SLIGHTLY FARTHER SOUTH WITH IT`S SFC LOW PLACEMENT/TRACK
IT IS STILL MUCH FARTHER NORTH AS COMPARED TO THE COASTAL TRACK OF
THE ECMWF. WHAT`S INTERESTING TO NOTE IS THAT THE GFS ENSEMBLE
MEAN IS FAIRLY SIMILAR TO THE ECMWF. DUE TO THE SLOWER AND STILL
DIVERSE SOLUTIONS HAVE DECIDED TO REMOVE THE SEVERE MENTION FOR
MONDAY. HOWEVER THE SYSTEM STILL BEARS WATCHING AND SOMETHING MAY
NEED TO BE ADDED BACK IN LATER IF MODELS CAN FINALLY COME INTO
BETTER AGREEMENT.

19


&&

.AVIATION...
00Z TAF DISCUSSION.

VFR CONDITIONS CURRENTLY ACROSS THE TERMINALS AND EXPECT THESE
CONDITIONS WILL CONTINUE THROUGHOUT THE TAF CYCLE. A COLD FRONT IS
CURRENTLY MOVING ACROSS THE TENNESSE VALLEY AND A LINE OF SHOWERS
AND STORMS HAVE DEVELOPED ALONG THIS BOUNDARY. EXPECT THIS
ACTIVITY WILL WEAKEN AFTER SUNSET AND COULD SEE A FEW SHOWERS AND
STORMS AT KANB AND KASN BUT CONFIDENCE IS NOT HIGH ENOUGH TO
INCLUDE IN THE TAFS AT THIS TIME. WILL MAKE AMENDMENTS FOR SHOWERS
AND STORMS IF NECESSARY.

05/MA

&&

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

$$



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