SPC AC 040059
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT TUE JUN 03 2008
VALID 040100Z - 041200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS NRN MO...CENTRAL AND
PARTS OF SRN IL...SRN HALF OF IND...SWRN OH AND NRN/NERN KY...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH PLAINS TO
THE MID ATLANTIC REGION...
...SYNOPSIS...
18Z GFS/NAM MAINTAIN LIKELIHOOD FOR FURTHER AMPLIFICATION OF LARGE
SCALE TROUGH ACROSS THE WRN U.S. AS A SHORT WAVE TROUGH...NOW
LOCATED JUST OFF THE WA/ORE COAST...MOVES SEWD WITH ACCOMPANYING
STRONG WNWLY FLOW ALOFT INTO CA/WRN NV. DOWNSTREAM A BAND OF 50-60
KT WSWLY MID LEVEL WINDS WILL EXTEND FROM THE CENTRAL/SRN ROCKIES
THROUGH THE MID MS TO OH VALLEYS.
...OH VALLEY WSWWD TO LOWER MO VALLEY/OZARKS TO SRN PLAINS...
WATER VAPOR IMAGERY INDICATED A SHORT WAVE TROUGH OVER ERN KS EARLY
THIS EVENING WITH THIS FEATURE EXPECTED TO REACH THE LOWER OH VALLEY
BY 12Z WEDNESDAY. A SECOND IMPULSE CURRENTLY LOCATED ACROSS WRN KS/
OK PANHANDLE WILL TRANSLATE EWD TO THE MID MS VALLEY BY LATE IN THE
FORECAST PERIOD. FORCING FOR ASCENT WITH THESE IMPULSES WILL
SUPPORT A STRENGTHENING SWLY LLJ EXTENDING FROM THE SRN PLAINS
THROUGH THE OZARKS TO OH VALLEY AND MID ATLANTIC REGION. SURFACE
ANALYSIS INDICATED A LOW OVER NERN KS WITH A BOUNDARY EXTENDING EWD
THROUGH NRN MO TO CENTRAL IL AND SRN IND TO NERN KY. ADDITIONAL
BOUNDARIES WERE ANALYZED FROM CENTRAL IL INTO SWRN OH...AND FROM
WEST CENTRAL IL TO NRN IND AND THROUGH LAKE ERIE. ACTIVE CORRIDOR
FOR SEVERE STORMS IS EXPECTED TO BE ALONG THE FORMER BOUNDARY THAT
EXTENDED FROM NRN MO THROUGH LOWER OH VALLEY WHERE LOW LEVEL
MOISTURE IS GREATER WITH SURFACE DEWPOINTS IN THE LOWER 70S. THE
IMPULSES TRACKING EWD WILL SUPPORT ONGOING AND NEW TSTM DEVELOPMENT
ALONG THIS CORRIDOR THROUGH TONIGHT...WITH A TENDENCY FOR CONVECTION
TO BACKBUILD INTO THE LLJ AXIS ACROSS ERN KS TO MID MS VALLEY.
STRENGTHENING LLJ THROUGHOUT THIS REGION BENEATH STRONG WLY MID
LEVEL FLOW WILL MAINTAIN STRONG EFFECTIVE BULK SHEAR AND LOW LEVEL
SHEAR FOR SUPERCELLS...SOME TORNADIC...WITH THE LIKELIHOOD FOR ONE
OR MORE MCSS TO DEVELOP OVERNIGHT INTO THE OH VALLEY. ALTHOUGH
DAMAGING WINDS...SOME SIGNIFICANT...AND HAIL WOULD THE PRIMARY
THREATS WITH THE MCSS...STRONG LOW LEVEL SHEAR SHOULD ALSO RESULT IN
A CONTINUED THREAT FOR TORNADOES WITH ANY EMBEDDED SUPERCELLS WITHIN
ANY LINE SEGMENTS/BOW STRUCTURES.
FARTHER SW...WRN KS IMPULSE IS EXPECTED TO SUPPORT ONGOING CLUSTER
OF TSTMS...NOW MOVING INTO SOUTH CENTRAL KS/NWRN OK...WITH
ADDITIONAL ACTIVITY LIKELY ALONG A PAIR OF SURFACE BOUNDARIES
EXTENDING SWWD FROM NERN KS THROUGH CENTRAL/ERN KS INTO FAR NRN OK.
A VERY UNSTABLE AIR MASS OVER CENTRAL/ERN KS /MLCAPE EXCEEDING 2500
J/KG/...WITH VERY LITTLE CAP SUGGESTS NEW DEVELOPMENT WILL OCCUR
SWWD FROM ERN KS AND ONGOING STORMS IN SWRN KS/NWRN OK WILL BE
MAINTAINED AS THEY TRACK ENEWD THIS EVENING. VERY LARGE
HAIL/DAMAGING WINDS AND ISOLATED TORNADOES WILL BE POSSIBLE WITH
THIS ACTIVITY.
...MID ATLANTIC REGION...
A CORRIDOR OF MOISTURE RETURN NWD THROUGH ERN VA TO SERN PA COMBINED
WITH SURFACE HEATING AHEAD OF THE EWD MOVING MCV/SHORT WAVE
TROUGH...NOW APPROACHING THE MID ATLANTIC REGION...HAS AIDED IN
DESTABILIZATION. TSTMS DEVELOPED ALONG THE LOW LEVEL CONVERGENCE
ZONE/MOISTURE AXIS...WITH ACTIVITY LIKELY PEAKING IN INTENSITY FROM
NOW THROUGH ABOUT 02Z. THEREAFTER...BOUNDARY LAYER COOLING/
STABILIZATION SHOULD LIMIT THE POTENTIAL FOR SURFACE BASED ACTIVITY.
A THREAT FOR DAMAGING WINDS MAY REACH PARTS OF PA SWD THROUGH MD TO
NRN VA AS A POTENTIAL MCS DEVELOPING OVER THE OH VALLEY LATER THIS
EVENING/TONIGHT MOVES EWD INTO THIS REGION LATE IN THE FORECAST
PERIOD.
...CENTRAL HIGH PLAINS EWD INTO SRN NEB/NRN KS...
THE MID LEVEL IMPULSE OVER THIS REGION COMBINED WITH A COLLECTIVE
COLD POOL ATTENDANT TO ONGOING CLUSTER OF TSTMS OVER SWRN NEB INTO
WEST CENTRAL KS SHOULD SUPPORT A FORWARD PROPAGATING MCS THIS
EVENING. DOWNSTREAM MOIST/UNSTABLE AIR MASS WITH OBJECTIVE ANALYSES
INDICATING STRONG DCAPE VALUES /1200-1800 J/KG/ SUGGESTS THE
POTENTIAL FOR DAMAGING WINDS AS THIS ACTIVITY PROGRESSES EWD. LARGE
HAIL WILL ALSO BE POSSIBLE GIVEN STEEP MID LEVEL LAPSE RATES AND
EFFECTIVE BULK SHEAR AROUND 40 KT SUPPORTIVE OF ROTATING UPDRAFTS.
ADDITIONAL STORMS MAY DEVELOP OFF THE HIGHER TERRAIN OF NERN CO
LATER THIS EVENING...AS ASCENT ATTENDANT TO A GREAT BASIN SHORT WAVE
TROUGH SPREADS EWD OVERNIGHT. SOME OF THIS ACTIVITY COULD ALSO BE
SEVERE.
..PETERS.. 06/04/2008
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