Severe Thunderstorm Warning 124, NWS Huntsville, AL

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
226 PM CDT SAT MAY 13 2006

.DISCUSSION...
FORECAST CHALLENGE SURROUNDS CONVECTION THREAT THROUGH THIS
EVENING...FOLLOWED BY COOL AND UNSETTLED WEATHER PATTERN ASSOCIATED
WITH SLUGGISH UPPER LOW DROPPING SOUTH INTO THE OHIO VALLEY.

SHORT TERM...
THE 12Z MODELS ARE OUT TO LUNCH WITH 18Z WEATHER.
NAM...GFS...WRF...AND NGM ALL PREDICTED CONVECTION OVERHEAD AT 18Z.
SO...WELL TAKE THE ANALYSIS APPROACH IN THE SHORT TERM.

ELEVATED CONVECTIVE CLUSTERS CONTINUE TO FESTER AND SPREAD
SE THROUGH CENTRAL AND SE AL. THIS WAS INITIALLY GENERATED EARLY
THIS MORNING (AND PRODUCING LARGE HAIL) WITHIN STEEP MID LEVEL
LAPSE RATES AND 8H- 7H THETA-E ADVECTION THIS MORNING...AND MAY
CONTINUE TO BE ON ITS WESTERN FLANK. OBVIOUSLY...WE HAVE ELEVATED
INSTABILITY IN PLACE. HOWEVER...SURFACE BASED INSTABILITY HAS BEEN
SLOWED DOWN AS THE DEBRIS CLOUDS AND OUTFLOW HAVE SERVED TO KEEP
THE LOW LEVEL AIRMASS COOL. THIS MAY INCREASE DEW POINTS THAT
OTHERWISE WERE NOT AVAILABLE WHEN THE COLD FRONT ARRIVES. LOW
LEVEL LAPSE RATES ARE STEEPENING AS TEMPS WARM INTO THE MID 70S.
VIS IMAGERY INDICATES THAT THE SLOPED TERRAIN ALONG THE CUMBERLAND
PLATEAU IS AIDING CU DEVELOPMENT...WHILE CU REMAINS RATHER FLAT
LOCALLY. LOW LEVEL MOISTURE ADVECTION WILL INCREASE THROUGH EARLY
EVENING FEEDING OFF THE HIGHER DEW POINTS IN THE 50S ACROSS MS. WE
COULD SEE CONVECTION BEGIN TO DEVELOP ALONG THE DIFFERENTIAL
HEATING ZONE TAKING SHAPE RESULTING FROM THE EARLIER MCS ACTIVITY
IN NW AL INTO MS. HOWEVER...CORFIDI/MEAN WIND VECTORS WOULD
CONTINUE TO TAKE THIS ACTIVITY MAINLY S OF THE HUN AREA...POSSIBLY
CLIPPING OUR SW COUNTIES. IM NOT TOTALLY RULING OUT DEVELOPMENT
ACROSS THE TERRAIN OF NE AL...BUT THIS SEEMS MORE UNLIKELY. THE
MORE LIKELY SOURCE OF ANY THUNDERSTORMS IN THE LOCAL AREA WILL
OCCUR ALONG THE COLD FRONT NOW APPROACHING LEXINGTON KY...BOWLING
GREEN KY...TO JONESBORO AR AS OF 18Z. THIS AS ANOTHER
SPOKE/SHORTWAVE IN THE WATER VAPOR IMAGERY IS DROPPING INTO
WESTERN KY. MID LEVEL WINDS AND DEEP LAYER SHEAR ARE SUFFICIENT
FOR SUPERCELLS WITH A HAIL AND POSSIBLY DOWNBURST THREAT DUE TO
THE STEEP LAPSE RATES AND RELATIVELY DRY LOW LEVELS.  HIGH BASED
CU IS ALREADY BEGINNING TO DEVELOP ALONG THIS FRONT WHERE DEW
POINTS ARE ONLY IN THE LOWER 40S. THE MODELS ARE IN MORE
AGREEMENT...AND PROBABLY CORRECT WITH FRONTAL CONVERGENCE AIDING
DEVELOPMENT ALONG THE FRONT THROUGH THIS EVENING. WILL MAINTAIN
CHANCE POPS...MAINLY THROUGH 06Z. HAIL/WIND THREAT HAS BEEN
ADDRESSED IN THE HWO.

LONGER TERM...
MOTHERS DAY WILL BE A COOL...BRISK AND POSSIBLY SHOWERY
DAY...ESPECIALLY ACROSS OUR TN COUNTIES. I HAVE LOWERED TEMPS INTO
THE 60S IN THESE AREAS...ESPECIALLY ON THE PLATEAU. SEWANEE COULD
BE DOWNRIGHT CHILLY WITH COOL RAIN SHOWERS THROUGH THE DAY IF THE
CLOUD BASES LOWER ENOUGH. CURRENT VIS IMAGERY SHOWS THE EXPANSIVE
LOW CLOUD SHIELD WITH THE COLD POOL ALOFT. MONDAY MORNING LOWS
WERE DROPPED A BIT AS WELL IF WINDS DIE OFF...AND IF ANY CLEARING
CAN TAKE PLACE DURING THE EVENING. THIS IS TOUGH TO CALL...BUT
SOME WESTERLY COMPONENT ON THE S FLANK OF THE LOW COULD DRY THE
AIR A BIT. SEVERAL VORTICITY SPOKES WILL FILE INTO THE AREA THIS
WEEK...WITH THE MOST ROBUST OCCURRING ON MONDAY...AGAIN
TUESDAY...AND THEN LATE THIS WEEK. WE HAVE MAINTAINED CONTINUITY
FOR NOW...BUT RAISED POPS ON MONDAY AND TUESDAY TO 30 PERCENT. FOR
NOW...WILL LEAVE THUNDER OUT...BUT THIS MAY NEED FURTHER
ASSESSMENT.
&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    52  69  44  67 /  40  30  20  30
SHOALS        51  69  44  67 /  40  30  20  30
CULLMAN       53  70  43  67 /  40  30  20  30
FAYETTEVILLE  51  66  43  64 /  40  30  20  30
FORT PAYNE    50  67  41  66 /  40  30  20  30

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

KULA

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HUNTSVILLE AL
100 PM CDT SAT MAY 13 2006

ALZ001>010-016-TNZ076-096-097-140300-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DE KALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
100 PM CDT SAT MAY 13 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH ALABAMA AND PORTIONS
OF SOUTHERN MIDDLE TENNESSEE.

.DAY ONE...THIS AFTERNOON AND TONIGHT...

AFTERNOON HEATING MAY LEAD TO THE DEVELOPMENT OF ISOLATED THUNDERSTORMS
AFTER 4 PM THIS AFTERNOON. THUNDERSTORMS MAY BECOME MORE NUMEROUS THIS
EVENING AS A COLD FRONT APPROACHES THE AREA. A FEW STORMS MAY BECOME
STRONG TO SEVERE...WITH THE MAIN THREAT BEING LARGE HAIL. AN ISOLATED
STRONG WIND GUST WILL ALSO BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW.

AN UNSETTLED AND COOL WEATHER PATTERN WILL REMAIN IN PLACE ACROSS
THE TENNESSEE VALLEY WITH SMALL RAIN CHANCES CONTINUING FOR THE
NEXT SEVERAL DAYS.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL IS
NOT ANTICIPATED TODAY. HOWEVER...SOME COUNTIES MAY BE CALLED UPON
FOR STORM REPORTS AS NEEDED.

24

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
631 PM CDT SAT MAY 13 2006

TNZ096-097-140015-
FRANKLIN-LINCOLN-
631 PM CDT SAT MAY 13 2006

...SIGNIFICANT WEATHER ALERT FOR FRANKLIN AND LINCOLN COUNTIES UNTIL
715 PM CDT...

AT 628 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 9 MILES SOUTHEAST OF FAYETTEVILLE...MOVING EAST
AT 40 MPH. OTHER STRONG THUNDERSTORMS WERE NOTED NEAR ABOUT 8 MILES
WEST OF FAYETTEVILLE...AND NEAR SHERWOOD IN FRANKLIN COUNTY.

PEA SIZE HAIL AND WINDS UP TO 50 MPH ARE EXPECTED WITH THIS STORM.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  FLINTVILLE.
  SMITHLAND.
  HUNTLAND.
  WINCHESTER.

THIS THUNDERSTORM COULD INTENSIFY QUICKLY...SO BE READY TO ACT IF A
WARNING IS ISSUED.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR THE AREA.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR YOUR LOCAL
TELEVISION STATIONS FOR LATER STATEMENTS AND POSSIBLE WARNINGS
CONCERNING THIS WEATHER SITUATION.

RSB

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