Severe Thunderstorm Warning 142, 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

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