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000
FXUS64 KBMX 220514 AAC
AFDBMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1214 AM CDT WED MAY 22 2013

.UPDATE...
FOR AVIATION.

&&

.AVIATION...
06Z TAF DISCUSSION.

FORECAST THINKING HAS NOT CHANGED A WHOLE LOT SINCE 00Z ISSUANCE.
1ST BAND DIED OFF IN NRN MS AS GUST FRONT OUTRAN THE STORM AND IT
DETERIORATED TO THE NE. STILL AGREE WITH MODEL DATA THAT THIS 2ND
LINE WILL DECREASE AS IT MOVES ENE OVER THE NEXT COUPLE OF HOURS.
SO...ONLY HAVE VCTS/VCSH LATER TODAY WITH THE FRONT. WILL BE
CLOSELY MONITORING STORM ACTIVITY ON THE CHANCE THAT STORMS TO NOT
DECREASE AS ANTICIPATED AND THEN AMENDMENTS MAY BE NECESSARY.
THERE WAS A SMALL LINE OF THIN ACTIVITY THAT THE 2ND LINE FED INTO
THAT GAVE IT A BOOST. HOWEVER...WITH THAT DONE...IT SHOULD BEGIN
TO DECREASE SHORTLY. DID BRING CONVECTION UP BY A COUPLE OF HOURS
DURING THE DAY WITH A SLIGHTLY FASTER FRONT...WITH CONVECTION NOW
BY MID MORNING WEST JUST AHEAD OF THE FRONT AND WITH BEST CHANCES
NRN TAFS. SOME MINOR MVFR BR OUT AHEAD OF ACTIVITY THIS MORNING
BUT CIRRUS BLOW OFF COULD CURTAIL SOME OF THIS.

08

&&

.PREV DISCUSSION... /ISSUED 728 PM CDT TUE MAY 21 2013/

DISCUSSION...

EARLY EVENING SURFACE MESO-ANALYSIS SHOWS A PAIR OF (OR THREE)
BIG OUTFLOW BOUNDARIES ACROSS THE SOUTHERN PORTION OF THE
COUNTRY...WITH ACTIVE CONVECTION ALONG THEIR LEADING EDGES. THE
FIRST BOUNDARY WAS IN EASTERN TN...ABOUT TO MOVE ACROSS THE
MOUNTAINS. THE TRAILING SOUTHERN EDGE OF THAT BOUNDARY MAY BE
LINGERING NEAR THE TN/AL STATE LINE. THE OTHER OUTFLOW BOUNDARY
STRETCHED FROM SOUTHERN IL SOUTHWARD...INTERSECTING THE FIRST
BOUNDARY JUST EAST OF MEMPHIS...AND THEN ARCING BACK TO THE
SOUTHWEST NORTHERN LA AND EASTERN TX. THAT LATTER BOUNDARY IS
ACTUALLY A MERGER OF TWO THAT EARLIER WERE A BIT MORE DISCRETE.
EACH BOUNDARY HAD A PRETTY WELL DEFINED MESO-HIGH BEHIND IT
HELPING TO PUSH IT ALONG.

THE BIG QUESTION OF COURSE IS WHETHER THE THUNDERSTORMS ASSOCIATED
WITH THE SECOND BOUNDARY WILL BE ABLE TO CONTINUE. AND IF
SO...THEN HOW FAR AND HOW STRONG? SPC MESOSCALE PARAMETERS STILL
SHOW A GOOD BIT OF INSTABILITY IMMEDIATELY DOWNSTREAM OF THE
ONGOING LINE OF STORMS...IN THE FORM OF 1500-2000 J/KG OF SURFACE
BASED CAPE. LOW LEVEL SHEAR...HOWEVER...REALLY IS LACKING (WITH
0-6 KM BULK SHEAR WELL BELOW 30 KTS...AND 0-1 KM SHEAR LESS THAN
10 KTS). THUS...EVEN IF THE STORMS WERE ABLE TO CONTINUE ON AND
REACH THE WESTERN PORTION OF OUR CWA...THEY SHOULD BE/REMAIN BELOW
SEVERE LEVELS BY THE TIME THEY GET HERE. IF THEY ARE ABLE TO HOLD
TOGETHER...A RULE OF THUMB ANALYSIS PUTS THE LINE OF STORMS AT
MARION COUNTY BETWEEN 10 AND 11 PM.

ASSUMING CONDITIONS DON`T CHANGE DRASTICALLY...FOR THE EVENING
FORECAST UPDATE THE MAIN ADJUSTMENT WILL BE TO BUMP UP THE TIMING
(BY ABOUT 3 HOURS) ON THE CHANCES OF STORMS INTO THE WEST. I THINK
HIGH CHANCE POPS (40-50 PERCENT) ARE STILL JUSTIFIED FOR
NOW...ALTHOUGH I MAY EXPAND THE AREA OF CHANCE POPS EASTWARD JUST
A BIT (PERHAPS AS FAR EAST AS JASPER AND TUSCALOOSA). OTHER
FORECAST ELEMENTS (INCLUDING DEW POINTS) LOOK FINE AT THIS POINT.

/61/

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     63  84  59  78  53 /  40  30  20  10   0
ANNISTON    64  85  60  79  55 /  40  30  20  10   0
BIRMINGHAM  64  85  60  79  56 /  30  30  20  10   0
TUSCALOOSA  63  86  61  82  56 /  30  30  20  10   0
CALERA      65  85  60  81  56 /  40  30  20  10   0
AUBURN      66  85  63  81  58 /  40  30  20  10   0
MONTGOMERY  67  87  65  85  59 /  40  30  20  10   0
TROY        67  86  65  85  59 /  40  30  20  10   0

&&

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

&&

$$

08/61