Severe Thunderstorm Warning 144, NWS Huntsville, AL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
148 AM CST FRI DEC 28 2007

.DISCUSSION...
WATER VAPOR IMAGERY CONTINUES TO SHOW A PROGRESSIVE FLOW PATTERN
ACROSS THE CONUS THIS MORNING WITH L/W TROUGH AXES POSITIONED
ACROSS NEW ENGLAND...THE HIGH PLAINS...AND ANOTHER TROUGH
APPROACHING THE PACIFIC NORTHWEST. WATER VAPOR ALSO SHOWS AN
ACTIVE SUBTROPICAL JET WITH A SUBSTANTIAL MOISTURE PLUME EXTENDING
FROM THE EASTERN PACIFIC TO THE GULF OF MEXICO.

0600 UTC SURFACE ANALYSIS SHOWS A DEVELOPING LOW ACROSS THE LOWER
RIO GRANDE VALLEY OF TEXAS WITH AN ILL DEFINED WARM FRONT HUGGING
THE GULF COAST. OVERALL...LOW LEVEL MOISTURE HAS BEEN SLOW TO
SURGE NORTHWARD SO FAR BUT THE OKOLONA PROFILER SHOWS THE H8-H7
JET BEGINNING TO PICK UP STEAM OVER THE LAST COUPLE OF HOURS. THE
FORCING ASSOCIATED WITH THE LLJ...ALONG WITH INCREASING UPPER
LEVEL DIFFLUENCE...HAS HELPED TO SPARK A CLUSTER OF ELEVATED STORMS
ACROSS THE AR/MS DELTA REGION OVER THE PAST COUPLE OF HOURS. SOME
ISOLD SHRA/TSRA ALSO NOTED ACROSS CENTRAL/SRN AL OVER THE LAST HOUR
OR SO AS WELL.

AS THE UPPER TROUGH EJECTS EASTWARD THIS MORNING THE ATTENDANT SFC
WAVE WILL MOVE NORTHEAST ACROSS THE MS RIVER VLY AND EVENTUALLY
INTO THE OH VLY TONIGHT. EXPECT THE EXPANDING AREA OF ELEVATED
CONVECTION TO SHIFT EAST WITH TIME...WITH SOME SURFACE BASED
DEVELOPMENT POSSIBLE ACROSS THE DEEP SOUTH LATER TODAY. WHILE AN
ISOLATED HAIL/WIND PRODUCING STORM CANT BE RULED OUT...THE BEST
THREAT OF SEVERE WEATHER APPEARS TO BE SOUTH OF THE HUNTSVILLE
CWFA IN THE VICINITY OF THE SURFACE WARM FRONT (AND GREATER
SURFACE BASED INSTABILITY). OF COURSE...THE DAY SHIFT WILL NEED TO
MONITOR THESE TRENDS AS THE MORNING/AFTN PROGRESSES. EITHER
WAY...WE CERTAINLY COULD SEE A DECENT AMOUNT OF RAINFALL TODAY
WITH MOISTURE TRANSPORT AND UVM IS MAXIMIZED BETWEEN 15-21 UTC
ACROSS THE REGION.

HAVE TRIMMED BACK POPS FOR TONIGHT AS MOST AREAS WILL SEE A
DRYING AND CLEARING TREND BY 00 UTC. HAVE ALSO TRENDED LOWER WITH
POPS FOR THE SAT NIGHT/SUN EVENT AS THE NAM/GFS OPERATIONAL AND
THE SREFS ARE ALL TRENDING FURTHER SOUTH WITH THE SYSTEM STREAKING
ACROSS THE GULF/SOUTHEAST US. THE ECMWF IS THE FURTHEST NORTH
WITH THIS FEATURE...BUT IS THE OUTLIER AT THE MOMENT. DUE TO THE
SOUTHWARD MOVEMENT AND A STRONGER PUSH OF COOLER AIR IN THE TN
VLY...TEMPS WERE ALSO TRENDED DOWN SLIGHTLY.

IN THE LONGER TERM...THE GFS AND ECMWF BOTH CONTINUE TO SHOW A
NICE SURGE OF COLD AIR FOR THE FIRST FEW DAYS OF 2008. THE GFS MOS
MAY BE A BIT TOO WARM ON BOTH THE MAX/MIN TEMPS FOR THE TUE-THU TIME
FRAME GIVEN THE COLD AIR ACROSS THE NRN CONUS READY TO PLUNGE
SOUTHWARD. OUR TEMP PROJECTIONS/FCST GRIDS ARE CURRENTLY SLIGHTLY
BELOW THE OPERATIONAL MOS NUMBERS WHICH SEEMS FAIRLY PRUDENT...AND
NO SIGNIFICANT CHANGES WERE MADE.

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    59  37  53  38 / 100  20  10  20
SHOALS        56  34  52  35 / 100  10  10  20
CULLMAN       62  37  53  37 / 100  20  10  20
FAYETTEVILLE  57  35  51  36 / 100  20  10  20
ALBERTVILLE   63  40  55  41 / 100  30  10  20
FORT PAYNE    65  38  57  39 / 100  40  10  20

&&

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

15/CBD

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HUNTSVILLE AL
315 AM CST FRI DEC 28 2007

ALZ001>010-016-TNZ076-096-097-281800-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DE KALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
315 AM CST FRI DEC 28 2007

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

.DAY ONE...TODAY AND TONIGHT

AN APPROACHING UPPER LEVEL STORM SYSTEM WILL COMBINE WITH A
DEVELOPING LOW PRESSURE SYSTEM AND COLD FRONT TO BRING PERIODS OF
RAIN TO THE CENTRAL TENNESSEE VALLEY TODAY. THUNDERSTORMS WILL ALSO
BE POSSIBLE AHEAD OF THE FRONT DURING THE DAYTIME HOURS. A FEW OF
THESE STORMS COULD BECOME SEVERE WITH THE PRIMARY THREATS BEING
DAMAGING WIND GUSTS AND HAIL. AN ISOLATED TORNADO CANNOT BE RULED
OUT AS WELL...ALTHOUGH AS OF NOW THE BETTER CHANCES FOR TORNADO
DEVELOPMENT APPEAR TO BE SOUTH OF THE OUTLOOK AREA. THE RAIN AND
THUNDERSTORM THREAT IS EXPECTED TO DIMINISH BY THIS EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ANOTHER SYSTEM WILL DEVELOP OVER THE NORTHERN GULF OF MEXICO THIS
WEEKEND...AND BRING A CHANCE OF RAIN TO THE AREA ON SUNDAY. THERE
IS STILL QUITE A BIT OF UNCERTAINTY IN TERMS OF THE OVERALL TIMING
AND LOCATION OF THIS SYSTEM WHICH WILL HAVE AN IMPACT ON THE RAIN
POTENTIAL ACROSS THE TENNESSEE VALLEY.

A STRONG COLD FRONT IS EXPECTED TO MOVE ACROSS THE AREA EARLY NEXT
WEEK...BRINGING THE COLDEST AIR OF THE SEASON FOR THE MIDDLE PART
OF THE WEEK. WIND CHILL VALUES COULD FALL INTO THE SINGLE DIGITS
ON WEDNESDAY MORNING ACROSS THE REGION.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL IN
SUPPORT OF SEVERE WEATHER OPERATIONS MAY BE REQUESTED LATER TODAY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
350 AM CST FRI DEC 28 2007

ALZ002-003-281030-
COLBERT-FRANKLIN-
350 AM CST FRI DEC 28 2007

...SIGNIFICANT WEATHER ALERT FOR COLBERT AND FRANKLIN COUNTIES UNTIL
430 AM CST...

AT 345 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR RED BAY...MOVING NORTHEAST AT 45 MPH.

PEA SIZE HAIL IS EXPECTED WITH THIS STORM.

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  PLEASANT SITE.
  BELGREEN.
  SRYGLEY CHURCH.
  NEW BETHEL.
  COLBERT HEIGHTS.
  SPRING VALLEY.

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

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
415 AM CST FRI DEC 28 2007

ALZ003-281045-
FRANKLIN-
415 AM CST FRI DEC 28 2007

...SIGNIFICANT WEATHER ALERT FOR FRANKLIN COUNTY UNTIL 445 AM CST...

AT 412 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
CLUSTER OF STRONG THUNDERSTORMS ACROSS SOUTHWEST FRANKLIN COUNTY.
THESE STORMS ARE MOVING NORTHEAST AT 55 MPH.

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

* LOCATIONS IN OR NEAR THE PATH INCLUDE...
  DUKETON.
  BELGREEN.
  RUSSELLVILLE.
  PLEASANT RIDGE.

THIS THUNDERSTORM COULD INTENSIFY QUICKLY AND A SEVERE THUNDERSTORM
WARNING MAY BE ISSUED SHORTLY.

CBD