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000
FXUS64 KBMX 131744
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1244 PM CDT THU JUN 13 2013

.UPDATE...
FOR 18Z AVIATION.

&&

.DISCUSSION...

ACTIVE AFTERNOON AND EVENING STILL IN THE CARDS HERE ACROSS CENTRAL
ALABAMA AS A FRONTAL BOUNDARY PUSHES SOUTHWARD ACROSS THE REGION
BRINGING POSSIBLE SEVERE STORMS TO THE AREA.

LOOKING AT THE CURRENT BIG PICTURE...SFC LOW PRESSURE CENTER IS NOW
NEAR PENNSYLVANIA WITH THE TRAILING COLD FRONT STRETCHING
SOUTHEASTWARD THRU THE MISSOURI BOOTHILL AND INTO EXTREME NORTHERN
ARKANSAS. SATELLITE ALSO INDICATES A NARROW CLOUD LINE ACROSS
NORTHERN AL/MS IN ASSOCIATION WITH WHAT APPEARS TO BE A WEAKNESS
IN THE MID LEVELS. BETWEEN THESE TWO FEATURES (FRONT/CLOUD LINE)
ARE SEVERAL OUTFLOW BOUNDARIES FROM PREVIOUS/ONGOING CONVECTION
AND AREAS OF WEAK CONVERGENCE SEEN ACROSS KY/TN. AS OF THIS
WRITING...RADAR INDICATES LITTLE TO NO CONVECTION JUST TO THE
NORTH OF ALABAMA...OTHER THAN A COUPLE SMALL RETURNS NEAR THE
TN/KY LINE.

CLOSER TO HOME...SFC RIDGING CONTINUES TO WEAKEN AS THE
TROUGH/FRONT APPROACH FROM THE NORTH. TEMPS ARE ALREADY IN THE
MID/UPPER 80S WITH HIGHS EXPECTED TO BE IN THE LOW/MID 90S. DEW
POINTS ARE STILL IN THE LOW 70S ACROSS THE BOARD. AFTER SOME
MESOSCALE ANALYSIS OVER OUR AREA...NO BOUNDARIES COULD BE DETECTED
ACROSS THE CWA. WITH NO LIFTING MECHANISM CURRENTLY IN THE
VICINITY STILL DO NOT EXPECT CONVECTIVE INITIATION UNTIL THE
FRONTAL BOUNDARY MOVES NEARER/INTO THE AREA.

AS FAR AS THE SETUP FOR THIS AFTERNOON/EVENING IS CONCERNED...NOT
MUCH HAS CHANGED. WITH RATHER LITTLE NEW GUIDANCE TO CONSIDER AT
THIS JUNCTURE HAVE NOT MADE ANY MAJOR CHANGES TO POP/WX GRIDS FOR
THE SYSTEM. TIMING STILL LOOKS GOOD FOR NOW...GENERALLY 3 PM NORTH
TO 10 PM SOUTH...GIVE OR TAKE AN HR. QUESTIONS REMAIN WITH REGARDS
TO THE OVERALL COVERAGE OF STORMS AHEAD OF THE FRONT. WILL STORMS
BE MORE SCATTERED AND IN CLUSTERS...OR WILL THEY EVENTUALLY CONGEAL
INTO A SOLID LINEAR FEATURE? IT LOOKS LIKE ONLY TIME WILL
TELL...UNFORTUNATELY.

SEVERE WEATHER PARAMETERS REMAIN ABOUT THE SAME. SOUNDING PROFILES
STILL INDICATE PLENTY OF INSTABILITY...DRY AIR ALOFT...AND STEEP
LOW LEVEL LAPSE RATES. DOWNDRAFT CAPES ARE ALSO RATHER HIGH.
THEREFORE DAMAGING WINDS WILL REMAIN THE HIGHEST THREAT...FOLLOWED
BY LARGE HAIL AND FREQUENT CLOUD-TO-GROUND LIGHTNING.
HOWEVER...THERE ARE A COUPLE OF OTHER THINGS TO CONSIDER THAT
COULD HINDER ORGANIZED DEVELOPMENT. FIRST...MEAN MOISTURE REMAINS ON THE
LOW SIDE...WITH ALL MOISTURE RESIDING IN THE LOWEST LEVELS.
SECOND...CONVERGENCE JUST AHEAD OF THE FRONT DOESN`T LOOK VERY
STRONG THANKS TO WESTERLY SFC WINDS AND NW WINDS ALOFT. WE ARE PLANNING
ON DOING A SPECIAL BALLOON RELEASE AROUND 20Z THIS AFTERNOON TO
BETTER SAMPLE THE ATMOSPHERE JUST PRIOR TO THE ARRIVAL OF THE
SYSTEM. LOOK FOR ADDITIONAL UPDATES AS WE MOVE INTO THE AFTERNOON
HOURS.

ONE MORE THING TO TALK ABOUT FOR TODAY...HEAT. THE ONGOING HOT AND
HUMID CONDITIONS COULD RESULT IN HEAT INDEX VALUES AROUND 105
DEGREES FOR UP TO A COUPLE HOURS IN THE WEST. THEREFORE A HEAT
ADVISORY REMAINED IN EFFECT UNTIL 6 PM FOR COUNTIES GENERALLY ALONG
AND WEST OF INTERSTATE 65.

19


&&

.AVIATION...
18Z TAF DISCUSSION.

NO MAJOR CHANGES MADE TO THE ONGOING AVIATION FORECAST. STORMS
HAVE NOW BEGUN TO DEVELOP AHEAD OF THE COLD FRONT ACROSS TN AND
WILL PUSH SOUTHWARD THRU THE DAY. WITH THE STORMS STILL NORTH OF
THE STATE AND IN THE DEVELOPMENT STAGE...WILL NOT MAKE ANY ADJUSTMENTS
TO TSRA TIMING UNTIL THEY AT LEAST ENTER NORTH AL WHEN A BETTER
MOTION/SPEED CAN BE ATTAINED. LOOK FOR TS TO AFFECT MOST...IF NOT
ALL...TERMINALS AT SOME POINT DURING THE LATE AFTN AND EVNG.
STRONG WINDS AND HAIL MAY ACCOMPANY SOME STORMS...WHILE BRIEF
HEAVY RAINFALL AND FREQUENT CLOUD-TO-GROUND LIGHTNING WILL BE
MORE PREVALENT.

ACTIVITY WILL COME TO AN END FROM NORTH TO SOUTH AS THE FRONT
PASSES THRU. CIGS SHOULD REMAIN VFR THRU THE PERIOD...WITH REDUCED
VIS WITHIN TSTORMS. WINDS WILL BE OUT OF THE WEST PRIOR TO FRONTAL
PASSAGE...WITH WINDS SHIFTING TO THE NW AFTERWARD. SPEEDS OF
10-15 KTS WITH HIGHER GUSTS WILL BE COMMON AT EACH TERMINAL UNTIL
THE STORMS/FRONT PASS THRU. PATCHY FOG MAY BE POSSIBLE OVERNIGHT
IF WINDS BECOME LIGHT ENOUGH.

19

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     67  86  62  90  65 /  20   0   0   0   0
ANNISTON    68  88  63  90  67 /  30   0   0   0   0
BIRMINGHAM  68  88  66  91  69 /  20   0   0   0   0
TUSCALOOSA  70  90  66  93  70 /  30   0   0   0   0
CALERA      70  89  66  91  69 /  30   0   0   0   0
AUBURN      72  87  68  90  68 /  60   0   0   0   0
MONTGOMERY  74  92  67  94  70 /  60   0   0   0   0
TROY        74  91  68  92  69 /  60   0   0   0   0

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR THE FOLLOWING
COUNTIES: BIBB...FAYETTE...GREENE...HALE...JEFFERSON...LAMAR...
MARENGO...MARION...PERRY...PICKENS...SHELBY...SUMTER...
TUSCALOOSA...WALKER...WINSTON.

&&

$$