Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 251554
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1054 AM CDT SAT APR 25 2015

.UPDATE...
MESOSCALE UPDATE.

&&

.DISCUSSION...

THE FIRST WAVE OF CONVECTION HAS PUSHED EASTWARD INTO GEORGIA AND
CENTRAL ALABAMA IS CURRENTLY RAIN FREE DUE TO SUBSIDENCE IN WAKE
OF MORNING ACTIVITY. SURFACE DEWPOINTS ARE CLIMBING QUICKLY WITH
MIDDLE 60S AS FAR NORTH OF I-20. AS SURFACE TEMPERATURES WARM INTO
THE LOWER 80S THIS AFTERNOON ACROSS THE SOUTHERN HALF OF THE AREA
...CAPE VALUES WILL CLIMB TO BETWEEN 2500 AND 3000 J/KG WITH 0-6KM
BULK SHEAR OF 60-70 KNOTS. ATMOSPHERE WILL CERTAINLY HAVE TIME TO
RECOVER AND SUPPORT SEVERE STORMS. THE NEXT UPSTREAM MCS IS
CURRENTLY OVER SOUTHERN LOUISIANA. THIS SYSTEM IS TAKING AN
EASTERLY TRACK AND HIGH RESOLUTION FORECAST MODELS ARE ALSO
KEEPING THIS SYSTEM ALONG THE GULF COAST. THE BETTER THUNDERSTORM
CHANCES WILL BE ACROSS THE SOUTHERN COUNTIES OF CENTRAL ALABAMA
THIS AFTERNOON...WITH MORE ISOLATED ACTIVITY NORTH OF I-20. WITH
SURFACE WINDS VEERING TO A SOUTHWEST DIRECTION THIS AFTERNOON...
WIND FLOW BECOMES UNI-DIRECTIONAL AND TORNADO THREAT APPEARS TO
LOW TO KEEP IN FORECAST PRODUCTS. WILL ALSO REMOVE SEVERE THREAT
FOR AREAS NORTH OF OF I-20.

58/ROSE

&&

.AVIATION...
12Z TAF DISCUSSION.

AT 12Z...FIRST WAVE OF TSRA WILL CONTINUE TO MOVE ACROSS EAST AL AND
KMGM AND KTOI THROUGH 1430Z. BEHIND THIS SYSTEM...LINGERING MVFR
CIGS WILL OCCUR THROUGH 18Z...WITH BRIEF PERIODS OF IFR CIGS ABOVE
GROUND LEVEL IN HIGHER TERRAIN SITES LIKE KANB AND KASN. BY
14Z...SOUTHWEST SFC WINDS WILL PICK UP IN INTENSITY...ALONG WITH
SLOWING BREAKS IN CLOUDS WHICH WILL LEAD TO MIXING AND CIGS RISING
TO VFR CONDITIONS AROUND 18Z.  WITH MAIN FRONT STILL FAR TO THE
WEST...AND APPROACHING UPPER LEVEL DYNAMICS...THERE IS THE POTENTIAL
FOR TSRA REDEVELOPMENT AFTER 18Z.  HOWEVER...CURRENT THINKING IS
THAT ACTIVITY WILL BE TOO ISOLATED TO PINPOINT AT ANY TAF SITE OTHER
THAN VCTS. STEFKOVICH


&&

.PREV DISCUSSION...
/ISSUED 655 AM CDT SAT APR 25 2015/

SHORT DISCUSSION THIS MORNING TO ONLY HANDLE THE SHORT TERM.
LINE OF CONVECTION MOVING INTO WESTERN ALABAMA IS MOVING INTO A
SLIGHTLY MORE STABLE AIRMASS. DEWPOINTS IN WESTERN ALABAMA NEAR
THE STATE LINE JUST NOW REACHING THE LOWER 60S WITH A DROP OFF
INTO THE MID 50S AT TCL. SURFACE BASED CAPE STILL NON-EXISTENT
WITH MU CAPE BETWEEN 100 TO 250 J/KG. THE REALLY MOISTURE RICH AIR
IS STILL JUST TO THE SOUTHWEST OF THE CWA. SHEAR VALUES ARE
PLENTIFUL TO SUPPORT SEVERE WEATHER HOWEVER...WITH 0-1KM HELICITY
OF 450+ AND 0-6KM BULK SHEAR AROUND 70 KTS.

OVER THE NEXT 1 TO 3 HOURS...A VERY STRONG MID LEVEL
JET FROM THE SOUTHWEST IS FORECAST TO MOVE INTO WESTERN ALABAMA
BY THE HRRR. WE SHOULD SEE AN INCREASING IN PRECIPITABLE WATER
WITH DEWPOINTS RISING INTO THE MID AND UPPER 60S AND AN INCREASE
IN THE POTENTIAL FOR SURFACE BASED CONVECTION.

STILL A LOT OF UNCERTAINTY WITH THE POTENTIAL RE-DEVELOPMENT LATER
THIS AFTERNOON. LOOKS LIKE THERE MIGHT BE A SECONDARY MID LEVEL
SPEED MAX TO DEVELOP OVER THE CWA BY AFTERNOON. HI-RES MODELS DO
RESPOND WITH SOME REDEVELOPMENT IN THE AREA SO THE POTENTIAL FOR A
SECOND ROUND OF SEVERE WEATHER STILL POSSIBLE. WILL SEE HOW THE
CURRENT CONVECTION EVOLVES THROUGH THE EARLY TO MID MORNING AND
UPDATE LATER FOR ANY CHANGES.

88

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     79  62  79  51  72 /  20  30  10  10   0
ANNISTON    81  64  81  54  73 /  20  30  10  10   0
BIRMINGHAM  81  65  82  55  73 /  20  20  10  10   0
TUSCALOOSA  83  65  84  56  75 /  20  10  10  10  10
CALERA      82  65  83  56  74 /  20  20  10  10  10
AUBURN      78  65  83  57  75 /  40  30  10  10  10
MONTGOMERY  84  67  87  60  78 /  50  20  10  10  10
TROY        83  67  87  61  79 /  60  20  10  10  10

&&

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

$$



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