Flash Flood Warning 49, NWS Huntsville, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
631 AM CDT SUN JUN 14 2009...UPDATED

.UPDATE...FOR 12Z AVIATION
&&

.AVIATION...
PATCHY DENSE FOG AND LIFR CIGS CONTINUE TO PLAGUE BOTH TERMINALS.
CIGS/VIS WILL IMPROVE OVER THE NEXT THREE HOURS...EVENTUALLY GIVING
WAY TO A BKN CB DECK BY MIDDAY. UPSTREAM MCS ACTIVITY WILL SPUR SCT
TSRA TODAY...BUT GIVEN INHERENT UNCERTAINTY IN TIMING...WILL GO WITH
A VCTS FOR A NOW. CONDITIONS WILL REMAIN MOIST...AND BR SEEMS LIKELY
TONIGHT...WITH ADDITIONAL MCS TS IMPACTING BOTH TERMINALS TOWARD THE
END OF THE TAF PERIOD OR JUST PAST.
&&

.DISCUSSION.../ISSUED AT 233 AM CDT SUN JUN 14 2009/
SHORT TERM CONCERN IS EXPANDING AREA OF DENSE FOG AND LOW CLOUDS
PER IMAGERY AND OBS. WILL BE ISSUING A DENSE FOG ADVISORY THRU
14Z SHORTLY. AN EXPANSIVE CS SHIELD BEING VENTED FROM THE MCS IN
THE SRN PLAINS HAS ALREADY ARRIVED IN WRN AL. HOWEVER...GIVEN HOW
MOIST THE BOUNDARY LAYER IS AND CURRENT TRENDS...FG/LOW CLOUDS MAY
BECOME WIDESPREAD BEFORE 12Z.

BESIDES THE FOG...CONVECTIVE CHANCES ARE THE NEXT PROBLEM OF THE
DAY. STRENGTH OF THE STORMS MAY BE SOMEWHAT HAMPERED BY MORE
LIMITED HEATING DUE TO THE HIGH CLOUDS AND MORNING FG/LOW CLOUDS.
THAT BEING SAID...THE MODELS ARE OVERWHELMING IN THEIR QPF
SIGNALS LATER THIS MORNING ALONG A WEAK SFC BOUNDARY/8H
CONVERGENCE ZONE THAT RUNS FROM NRN AR INTO CENTRAL AL. TEMPS WILL
STRUGGLE TO GET OUT OF THE 80S ONCE AGAIN...ALTHOUGH IF MORNING
CONVECTION ESCAPES SOON ENOUGH...A PERIOD OF RENEWED HEATING THIS
AFTN COULD BUMP TEMPS HIGHER. THE GFS SOUNDING SUGGESTS A DECENT
CAPE OF OVER 3500 J/KG AND MDPI VALUES AOA 1.0. THUS...SOME OF THE
STORMS COULD PRODUCE DOWNBURSTS. THE MAIN MCS OVER ERN OK/WRN AR
COULD REJUVENATE AND ARRIVE BY LATE IN THE AFTN...BUT THE MODELS
SEEM TO BE WEAKENING THIS SYSTEM LATER THIS MORNING AS IT MOVES
AWAY FROM THE LLJ.

IT IS A TOUGHER CALL TONIGHT ON CONVECTION CHCS AS THE MODELS DIFFER
IN INITIATION AND PLACEMENT. THE NAM TAKES THE MCS/MCV NOW ALONG
THE KS/OK BORDER SE INTO THE TN VALLEY THIS EVENING WHILE THE GFS
FAVORS A MORE NORTHERLY TREND. IN BOTH CASES...DEVELOPMENT TONIGHT
SHOULD OCCUR IN SOME FASHION ALONG THE 8H THERMAL RIBBON FROM THE
OZARKS INTO THE TN VALLEY AS THE LLJ ENHANCES CONVERGENCE AND
MOISTURE TRANSPORT ALONG THIS BOUNDARY. THE GFS SHIFTS THIS AXIS
A BIT FURTHER NE WITH TIME OVERNIGHT...WHILE THE NAM TENDS TO
ANCHOR CONVECTION IN A NW-SE FASHION ACROSS OUR AREA THROUGH
MONDAY. CONCEPTUALLY...I TEND TO BUY INTO THIS TYPE OF SCENARIO
WITH THE UPPER RIDGE/CAP IN PLACE FAR TO OUR SW. IN FACT...WE
COULD SEE LCL TRAINING/HEAVY RAIN PROBLEMS DEVELOP ON MONDAY INTO
TUESDAY AS THIS EVOLVES. TO SAY EXACTLY WHERE THOUGH IS NOT SO
EASY. ALSO...THE DOWNBURST THREAT LOOKS RATHER HIGH ON MONDAY
GIVEN CAPE VALUES ABOVE 4K J/KG...MDPI OVER 1.0...AND WINDEX
VALUES APPROACHING 70KT.

WILL CONTINUE TO FORECAST CHC LEVEL POPS...MAINLY IN OUR NERN
AL/TN COUNTIES THRU TUE. WE MAY NEED TO INCREASE THESE POPS IN
LATER FCSTS AS THIS SCENARIO BECOMES BETTER DEFINED. CONFIDENCE ON
TEMPS IS BLO AVG THRU MONDAY AS WELL...BEING HEAVILY DEPENDENT ON
MESOSCALE CONVECTIVE/CLOUD TRENDS.

BY WEDNESDAY...CONFIDENCE IS INCREASING THAT THE RIDGE AND CAP SHOULD
BEGIN TO TAKE HOLD OVER THE AREA. THE 00Z GFS IS BEING IGNORED FOR
LATE THIS WEEK...A BIG FLIP-FLOP OVER OTHER ENS MEMBERS AND THE
EARLIER ECMWF WHICH STRENGTHENS THE UPPER RIDGE OVER THE SRN/SERN
CONUS.
&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR THE FOLLOWING
     ZONES: COLBERT...CULLMAN...DEKALB...FRANKLIN AL...JACKSON...
     LAUDERDALE...LAWRENCE...LIMESTONE...MADISON...MARSHALL...
     MORGAN.

TN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR THE FOLLOWING
     ZONES: FRANKLIN TN...LINCOLN...MOORE.

&&

DISCUSSION...KULA
AVIATION...JLL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HUNTSVILLE AL
412 AM CDT SUN JUN 14 2009

ALZ001>010-016-TNZ076-096-097-141800-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DEKALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
412 AM CDT SUN JUN 14 2009

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

.DAY ONE...TODAY AND TONIGHT...

A DENSE FOG ADVISORY IS IN EFFECT THROUGH EARLY MORNING FOR THE
ENTIRE CENTRAL TENNESSEE VALLEY. THIS FOG WILL BE MOST PREVALENT IN
LOW LYING SPOTS AND SHELTERED VALLEY LOCATIONS...OR IN AREAS THAT
RECEIVED RAINFALL ON FRIDAY AND SATURDAY.

TWO PERIODS OF THUNDERSTORMS ARE POSSIBLE ACROSS THE TENNESSEE VALLEY
THROUGH TONIGHT. A DECAYING THUNDERSTORM COMPLEX OVER THE PLAINS
WILL PROVIDE THE ENERGY FOR THUNDERSTORM DEVELOPMENT ACROSS THE
AREA BY MID MORNING. THESE STORMS WILL SPREAD WEST TO EAST THROUGH
THE DAY...AND SOME OF THE STORMS COULD BE STRONG TO SEVERE...WITH
GUSTY WINDS AND LOCALLY HEAVY RAINFALL.

ADDITIONAL THUNDERSTORM ACTIVITY IS POSSIBLE TONIGHT AS A SECOND
THUNDERSTORM COMPLEX OVER THE PLAINS DIVES TOWARD THE AREA. SOME OF
THESE STORMS COULD BE STRONG TO SEVERE...CAPABLE OF GUSTY WINDS AND
HAIL...IN ADDITION TO LOCALLY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

THE CENTRAL TENNESSEE VALLEY WILL REMAIN UNDER THE INFLUENCE OF A
SERIES OF UPPER LEVEL DISTURBANCES THROUGH THE MIDDLE OF THE WORK
WEEK...WITH THUNDERSTORMS POSSIBLE THROUGH THE PERIOD. SOME OF THE
STORMS ON MONDAY AND TUESDAY COULD BE STRONG TO SEVERE...CAPABLE
OF GUSTY WINDS AND HAIL...IN ADDITION TO LOCALLY HEAVY RAINFALL.
BY WEDNESDAY...THE THUNDERSTORMS WILL BECOME MORE ISOLATED IN
NATURE...AND CONCENTRATED GENERALLY EAST OF THE I-65 CORRIDOR.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL
IS POSSIBLE TODAY.

JLL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
855 AM CDT SUN JUN 14 2009

ALZ003-141445-
FRANKLIN-
855 AM CDT SUN JUN 14 2009

...SIGNIFICANT WEATHER ALERT FOR FRANKLIN COUNTY UNTIL 945 AM CDT...

AT 854 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR HODGES...OR 13 MILES SOUTHEAST OF RED BAY...
MOVING EAST AT 20 MPH.

DIME SIZE HAIL AND WINDS UP TO 40 MPH ARE EXPECTED WITH THIS STORM.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  HODGES...BELGREEN.
  BELGREEN.
  DUKETON.
  ROCKWOOD.
  ISBELL.
  SPRUCE PINE.

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

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 300 PM CDT SUNDAY
AFTERNOON FOR NORTHERN ALABAMA.

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