SPC AC 110558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 PM CST TUE FEB 10 2009
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A BROAD AREA EAST OF THE
MS RIVER VALLEY INTO THE APPALACHIANS...
...SYNOPSIS...
A STRONG UPPER TROUGH EXPECTED TO BE LOCATED OVER THE SERN PLAINS AT
12Z TODAY WILL REMAIN NEGATIVELY TILTED AND UNDERGO FURTHER
DEEPENING AS IT TRACKS NEWD THROUGH THE OH/TN VALLEYS...REACHING THE
NERN STATES BY 12Z THURSDAY. ACCOMPANYING VERY STRONG MID LEVEL JET
/100+ KT/ WILL TRANSLATE ENEWD FROM THE ARKLATEX/LOWER MS VALLEY
THROUGH THE OH/TN VALLEYS TO MID ATLANTIC STATES THIS FORECAST
PERIOD.
IN THE LOW LEVELS...A SURFACE LOW WILL DEEPEN AS IT TRACKS ENEWD
FROM CENTRAL MO REACHING SRN LOWER MI BY EARLY EVENING AND THEN INTO
THE LOWER GREAT LAKES LATE WEDNESDAY NIGHT. GIVEN THE STRONG DEEP
LAYER WIND FIELDS ACCOMPANYING THIS DYNAMIC PROGRESSIVE STORM
SYSTEM...THE TRAILING COLD FRONT IS EXPECTED TO SWEEP EWD FROM THE
MID/LOWER MS VALLEY TO THE ERN SEABOARD BY LATE WEDNESDAY NIGHT.
...MID MS VALLEY THROUGH OH/TN VALLEYS...
A NARROW CORRIDOR OF SURFACE DEWPOINTS IN THE LOWER-MID 50S WILL
TRANSLATE EWD ALONG AND JUST AHEAD OF THE PROGRESSIVE COLD FRONT
TODAY THROUGH THE OH/TN VALLEYS. COLD MID LEVEL TEMPERATURES/ STEEP
MID LEVEL LAPSE RATES SPREADING ACROSS THIS REGION ARE EXPECTED TO
OFFSET THE WEAKER LOW LEVEL MOISTURE SUPPORTING MUCAPE 500-800 J/KG.
DESPITE THE WEAKER INSTABILITY...VERY STRONG HEIGHT FALLS /200-240 M
PER 12 HR/ AND STRONG DEEP LAYER WIND FIELDS /SSWLY LLJ 60-70+ KT/
ARE EXPECTED TO SUPPORT A FAST MOVING SQUALL LINE ACCOMPANIED BY THE
RISK FOR DAMAGING WINDS ACROSS A LARGE AREA OF THE OH/TN VALLEYS TO
THE WRN FOOTHILLS OF THE CENTRAL/SRN APPALACHIANS. SUFFICIENT LOW
LEVEL DIRECTIONAL SHEAR ALONG THE LLJ AXIS SHOULD ALSO PROVE
FAVORABLE FOR A THREAT OF ISOLATED TORNADOES.
...CENTRAL/ERN GULF COAST...
FORECAST SOUNDINGS CONTINUE TO INDICATE LOWER TO MID-TROPOSPHERIC
INHIBITION ACROSS THIS REGION TODAY. HOWEVER...BOUNDARY LAYER WILL
POSSESS HIGHER MOISTURE CONTENT THAN FARTHER NORTH WITH SURFACE
DEWPOINTS INTO THE MID 60S. THIS COMBINED WITH EVEN A FEW DEGREES
OF WARMING AT THE SURFACE /AROUND 70 F/ WILL RESULT IN MLCAPE
500-1200 J/KG. ALTHOUGH HEIGHT FALLS WILL BE MINIMAL ACROSS THE
CENTRAL/ERN GULF COAST AS STRONG UPPER FORCING REMAINS N OF THIS
REGION...FRONTAL ASCENT COMBINED WITH GREATER LOW LEVEL MOISTURE
SHOULD SUPPORT TSTMS ALONG THE COLD FRONT. EFFECTIVE BULK SHEAR
EXCEEDING 50 KT COMBINED WITH STRONG LOW LEVEL SHEAR /SFC-1 KM SHEAR
30-40 KT/ WILL SUPPORT THE POTENTIAL FOR SUPERCELLS WITH A THREAT
FOR MAINLY DAMAGING WINDS AND ISOLATED TORNADOES.
...MID ATLANTIC STATES...
REMNANT...WEAKENING OHIO VALLEY SQUALL LINE MAY SPREAD EAST OF THE
CENTRAL APPALACHIANS INTO THE MID ATLANTIC STATES LATE WEDNESDAY
NIGHT. WEAK INSTABILITY AND THE STRONG FLOW FIELD SUGGEST THE
POTENTIAL FOR A RISK OF SPORADIC DAMAGING WIND GUSTS.
..PETERS/GRAMS.. 02/11/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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