#340 Postby CrazyC83 » Tue Feb 10, 2009 8:07 pm
SPC AC 110100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 PM CST TUE FEB 10 2009
VALID 110100Z - 111200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS EASTERN OK...NORTH
CENTRAL AND NORTHEAST TX...NORTHWEST LA...WESTERN AND CENTRAL
AR...AND FAR SOUTHWEST MO...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
FROM CENTRAL/ERN TX TO KS/MO/SRN IL...
...A SIGNIFICANT SEVERE WEATHER OUTBREAK -- INCLUDING SUPERCELLS
WITH STRONG TORNADOES AND SQUALL LINE PRODUCING DAMAGING WINDS --
WILL SPREAD EWD TONIGHT INTO EARLY WEDNESDAY MORNING FOR ERN OK/NE
TX...INTO NW LA...WRN/CENTRAL AR AND FAR SW MO...
...SRN/CNTRL PLAINS TO MS VALLEY...
EARLY EVENING SURFACE ANALYSIS INDICATED A COLD FRONT PROGRESSING
EWD INTO WRN OK AND TOWARD CENTRAL TX. THIS FRONT WILL ACCELERATE
EWD THIS FORECAST PERIOD AS STRONGER ASCENT SPREADS ACROSS THE SRN
PLAINS...WITH THE FRONT REACHING CENTRAL MO/AR/LA TO THE NWRN GULF
BY 12Z WEDNESDAY. MEANWHILE...A DRY LINE EXTENDED SWD FROM A
SURFACE LOW IN SRN OK TO THE TX HILL COUNTRY...AND A BOUNDARY
EXTENDED EWD THROUGH NRN AR...MARKING THE NRN EXTENT OF DEEPER LOW
LEVEL MOISTURE RETURN /SURFACE DEWPOINTS IN THE LOWER 60S/. 00Z
JAN/SHV SOUNDINGS INDICATED DEEP MOISTURE IN THE LOW LEVELS WAS
ADVECTING NWD THROUGH E TX AND THE LOWER MS VALLEY.
THE STRONG UPPER TROUGH...CURRENTLY LOCATED OVER THE SRN HIGH
PLAINS...WILL PROGRESS EWD WITH SOME DEEPENING EXPECTED AS IT BEGINS
TO TAKE ON A NEGATIVE TILT LATE TONIGHT...REACHING WRN MO TO WRN AR
BY 12Z WEDNESDAY. A SURFACE LOW OVER SERN CO AND THE OK LOW WILL
CONSOLIDATE INTO A SINGLE LOW OVER CENTRAL/NERN OK BY LATE
EVENING...AND DEEPEN AS STRONG FORCING FOR ASCENT /150-200 METER
HEIGHT FALLS/ SPREADS ACROSS THE SRN PLAINS. THE SURFACE LOW SHOULD
REACH CENTRAL MO BY EARLY WEDNESDAY MORNING.
A FAIRLY BROAD SLY LLJ LOCATED ACROSS THE ERN HALF OF OK/TX INTO THE
LOWER MS VALLEY WILL STRENGTHEN TO 60-70+ KT THIS PERIOD IN RESPONSE
TO THE HEIGHT FALLS...AS A 110-120 KT WSWLY MID LEVEL JET TRANSLATES
ACROSS NRN TX INTO AR BY 12Z. THIS WILL FURTHER ENHANCE LOW LEVEL
SHEAR/HELICITY WITH EFFECTIVE HELICITY VALUES RANGING FROM 300-600
M2/S2/. THE STRONG LOW LEVEL SHEAR COMBINED WITH 60-70 KT DEEP
LAYER SHEAR VECTORS ORIENTED ACROSS THE WARM SECTOR WILL MAINTAIN
LIKELIHOOD FOR DISCRETE TORNADIC SUPERCELLS...SOME STRONG TO
SIGNIFICANT. STRONG DEEP LAYER FORCING FOR ASCENT SPREADING EWD
ACROSS NRN/CENTRAL TX WILL SUPPORT ADDITIONAL TSTM DEVELOPMENT SWD
ALONG THE DRY LINE. DISCRETE STORMS WILL REMAIN POSSIBLE...
HOWEVER...EVENTUAL EVOLUTION INTO A FAST MOVING SQUALL LINE IS
EXPECTED AS THE COLD FRONT SURGES EWD OVERTAKING THE DRY LINE...WITH
THE POTENTIAL FOR SIGNIFICANT WIND DAMAGE ACROSS MUCH OF NRN TX/FAR
SRN OK INTO WRN AR/NWRN LA.
FARTHER N...TSTMS EXTENDING FROM SERN KS TO ALONG THE MO/AR BORDER
WILL SPREAD NNEWD OVERNIGHT AS LOW LEVEL MOISTURE/DESTABILIZATION
SPREADS NWD AHEAD OF THE DEEPENING SURFACE LOW. ALTHOUGH
INSTABILITY WILL TEND TO BE WEAKER WITH NWD EXTENT...STRONG UPPER
FORCING/INCREASING DEEP LAYER SHEAR WILL COMPENSATE AND LIKELY
SUPPORT ORGANIZED SEVERE STORMS PRODUCING HAIL AND DAMAGING WINDS.
STRENGTHENING SLY WINDS WILL ALSO RESULT IN A TORNADO THREAT INTO
THIS REGION.
..PETERS.. 02/11/2009
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