Severe Thunderstorm Warning 157, NWS Birmingham, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1205 PM CDT TUE JUN 15 2010

.UPDATE...MORNING UPDATE.

&&

.DISCUSSION...

WENT AHEAD AND RAISED POPS THROUGHOUT THE NORTHWESTERN PORTIONS OF
THE CWA TO REFLECT THE CONVECTIVE DEVELOPMENT AHEAD OF A BOUNDARY
THAT WAS ANALYZED AT 13Z THIS MORNING. ALSO TWEAKED TEMPS A BIT TO
REFLECT CURRENT TEMPERATURES...BUT OVERALL TEMPS LOOK GOOD ACROSS
THE BOARD. ANY STORM THAT DEVELOPS HAS THE POTENTIAL TO PRODUCE VERY
HEAVY DOWNPOURS...AS WELL AS GUSTY WINDS OVER 50 MPH. AN ISOLATED
SEVERE GUST ALSO CANNOT BE RULED OUT. WET MICROBURST POTENTIAL WILL
BE HIGH....WITH CAPES OVER 4000...AND DRIER AIR IN THE MID LEVELS
THAT COULD MIX DOWN TO THE SURFACE WITH EVAPORATIVE COOLING. A FEW
OTHER STATIONARY BOUNDARIES OUT THERE COULD LEAD TO MORE CONVECTIVE
DEVELOPMENT LATER THIS AFTERNOON. UPDATES ARE OUT.

56/GOGGINS

&&

.PREVIOUS DISCUSSION...

EVEN THOUGH WE ARE DEALING WITH A FAIRLY STRONG UPPER RIDGE...IT
APPEARS THAT THE RIDGE WILL NOT BE STRONG ENOUGH OR VERTICALLY
STACKED ENOUGH TO INHIBIT CONVECTION. PER THE LATEST SATELLITE
IMAGERY...THERE ARE SEVERAL MID TO UPPER LEVEL DISTURBANCES
SPINNING IN THE VICINITY OF THE SEUS. THE MODEL SUITE AGREES THAT
MEAN MOISTURE VALUES INCREASE WHILE HIGH TEMPERATURES ARE FORECASTED
TO REACH THE CONVECTIVE TEMPERATURE. THEREFORE...EXPECT A BIT MORE
COVERAGE OF AFTERNOON THUNDERSTORMS THAN THE PREVIOUS FEW DAYS.
MODEL SOUNDINGS ALSO DEPICT THE THREAT OF A FEW WET MICROBURSTS.
YESTERDAY THE MODEL SOUNDINGS WERE NOT ALL THAT IMPRESSIVE AND WE
ACTUALLY DID HAVE A FEW WIND GUSTS OF SEVERE MAGNITUDE. WILL RE-
EVALUATE AFTER THE 12Z SOUNDING COMES IN.

THE GFS DID NOT AGREE WITH THE ECMWF/NAM OR ITS OWN ENSEMBLE
MEMBERS ON POPS TODAY AND LEANED AWAY FROM IT AND WENT WITH
SCATTERED POPS. KEEP THE SCATTERED POPS IN THE FORECAST THE ENTIRE
PERIOD WITH THE BEST CHANCE DURING THE MAXIMUM HEATING EACH
AFTERNOON AND LASTING INTO THE EARLY EVENING. IT IS REALLY TOO
EARLY TO TELL IF ANY DISTURBANCE WILL ENHANCE RAIN CHANCES AND
POTENTIALLY ORGANIZE SOME STORMS...BUT CAN NOT RULE IT OUT
COMPLETELY ON ANY DAY. THE WET MICROBURST POTENTIAL IS TOUGH TO
FORECAST BEYOND A DAY OR SO BUT THE POTENTIAL APPEARS MUCH LOWER
AFTER TODAY. A FEW COLD FRONTS APPROACH THE AREA FROM THE NORTH
AND NORTHEAST...GETTING A PUSH FROM THE SYSTEMS MOVING THROUGH THE
NORTHERN STREAM. THE FIRST ARRIVES WEDNESDAY NIGHT INTO THURSDAY
WHILE ANOTHER ONE APPEARS AROUND MONDAY. REALLY DO NOT THINK THESE
FRONTS WILL PUSH THROUGH THE AREA BUT MAY DROP THE DEW POINTS A FEW
DEGREES AS THEY WASH OUT....ESPECIALLY NORTHEAST. MEAN MOISTURE AND
INSTABILITY APPEAR GOOD ENOUGH FOR THE POPS TO REMAIN JUST ABOVE
CLIMATOLOGY FOR THE ENTIRE PERIOD AS CONFIDENCE WAS NOT HIGH ENOUGH
TO LOWER MENTION.

IT LOOKS LIKE ONE MORE DAY OF HEAT INDICES BETWEEN 98 AND 105
DEGREES ACROSS CENTRAL ALABAMA. THE COMBINATION OF HIGH
TEMPERATURES AND HUMIDITY WILL NOT BE QUITE AS HIGH THE REMAINDER OF
THE FORECAST...ALTHOUGH THE HIGHS ARE STILL IN THE 90S. WILL ISSUE
THE SPS FOR ONE MORE DAY.

75

&&

.AVIATION...12Z TAF DISCUSSION.

A HOMOGENEOUS AIRMASS ACROSS ALL OF CENTRAL ALABAMA WILL RESULT IN
NEARLY IDENTICAL EXPECTED CONDITIONS AT ALL SITES TODAY.  HOWEVER AS
INDIVIDUAL THUNDERSTORMS DEVELOP LOCAL CONDITIONS WILL VARY
GREATLY.  THUNDERSTORMS SHOULD BEGIN TO DEVELOP AROUND 17Z ACROSS
THE AREA AND CONTINUE WELL AFTER SUNSET...ALTHOUGH COVERAGE AND
INTENSITY SHOULD BEGIN TO DIMINISH AFTER 01Z.  MICROBURSTS ARE A
CONCERN TODAY AND COULD RESULT IN WIND GUSTS IN EXCESS OF 50 MPH.
RADAR SIGNATURES WILL NEED TO BE MONITORED VERY CLOSELY FOR THIS
HAZARD.

BY 06Z MOST OF THE CONVECTION SHOULD HAVE DISSIPATED.   ADDITIONAL
GROUND MOISTURE FROM THUNDERSTORMS WILL LIKELY RESULT IN PATCHY
FOG.

NOTICE...KEET TAF WILL HAVE (AMD LTD TO VIS WIND AND WX) AMENDED TO
THE END OF THE FORECAST UNTIL FURTHER NOTICE WHILE CEILOMETER DATA
IS BEING MONITORED FOR ACCURACY.

12/SIRMON

&&

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

&&

75/75/27

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
600 AM CDT TUE JUN 15 2010

ALZ011>015-017>050-161100-
AUTAUGA-BARBOUR-BIBB-BLOUNT-BULLOCK-CALHOUN-CHAMBERS-CHEROKEE-
CHILTON-CLAY-CLEBURNE-COOSA-DALLAS-ELMORE-ETOWAH-FAYETTE-GREENE-HALE-
JEFFERSON-LAMAR-LEE-LOWNDES-MACON-MARENGO-MARION-MONTGOMERY-PERRY-
PICKENS-PIKE-RANDOLPH-RUSSELL-SHELBY-ST CLAIR-SUMTER-TALLADEGA-
TALLAPOOSA-TUSCALOOSA-WALKER-WINSTON-
600 AM CDT TUE JUN 15 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...TODAY AND TONIGHT.

STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON ACROSS
ALL OF CENTRAL ALABAMA.  A FEW STORMS WILL HAVE THE POTENTIAL TO
PRODUCE GUSTY WINDS TO 50 MPH OR GREATER AS WELL AS BRIEF HEAVY
RAINFALL.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT IS NOT
EXPECTED AT THIS TIME.

12/SIRMON