SWODY1
SPC AC 020602
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0102 AM CDT MON JUN 02 2008
VALID 021200Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE
NRN/CENTRAL PLAINS TO THE UPPER/MID MS VALLEY...
...SYNOPSIS...
MODELS MAINTAIN A PROGRESSIVE LARGE SCALE PATTERN THROUGH THE DAY 1
PERIOD. AN UPPER LOW/TROUGH...CURRENTLY MOVING INTO THE PACIFIC NW
PER WATER VAPOR IMAGERY...WILL EVOLVE INTO AN OPEN WAVE TODAY AS IT
TRANSLATES EWD THROUGH THE NRN ROCKIES TO NRN HIGH PLAINS BY 12Z
TUESDAY. HEIGHT FALLS ARE EXPECTED ACROSS MUCH OF THE CENTRAL PART
OF THE U.S. WITH THE APPROACH OF THE PACIFIC NW SYSTEM...AND
GREATEST FALLS SHOULD OCCUR OVER THE NORTH CENTRAL STATES.
IN THE LOW LEVELS...A SURFACE LOW IS EXPECTED TO DEEPEN OVER ERN CO
WITHIN A LEE SIDE TROUGH. AS THE PACIFIC NW TROUGH APPROACHES THE
NRN HIGH PLAINS TONIGHT...THE ERN CO SURFACE LOW WILL TRACK NEWD
INTO NRN/ERN KS. A WARM FRONT LOCATED OVER OK AT 12Z TODAY WILL
LIFT NWD AND SHOULD EXTEND EWD ALONG THE KS/NEB BORDER INTO ERN KS
BY LATE AFTERNOON.
...NRN/CENTRAL HIGH PLAINS EWD TO SD/NEB TO SRN MN/IA/NRN MO...
A CLUSTER OR TWO OF TSTMS ARE EXPECTED TO BE ONGOING ACROSS PARTS OF
SD/NEB AT 12Z TODAY...WITH THIS ACTIVITY LIKELY TRACKING TOWARD THE
LOWER MO VALLEY TODAY. REMNANT CLOUDINESS FROM THESE EARLY MORNING
TSTMS MAY TEND TO LIMIT SURFACE HEATING...ESPECIALLY ACROSS ERN
PARTS OF SD/NEB...AND THE RESULTANT DEVELOPMENT OF STRONGER
INSTABILITY BY AFTERNOON. FARTHER W...STRONGER SURFACE HEATING
SHOULD OCCUR ACROSS WRN NEB/SD INTO THE ADJACENT PORTIONS OF THE
CENTRAL/NRN HIGH PLAINS. THIS COMBINED WITH MOISTURE RETURN ACROSS
THE CENTRAL PLAINS BENEATH PLUME OF STEEP MID LEVEL LAPSE RATES WILL
SUPPORT A VERY UNSTABLE AIR MASS BY PEAK HEATING. MLCAPE VALUES
ACROSS NWRN KS INTO WRN NEB SHOULD RANGE FROM 2000-3500 J/KG.
SURFACE HEATING COMBINED WITH SEVERAL WEAK MID LEVEL IMPULSES
EMANATING ENEWD FROM THE BASE OF THE WRN TROUGH ARE EXPECTED TO
SUPPORT TSTM DEVELOPMENT OVER THE HIGHER TERRAIN OF CO/WY WITHIN LOW
LEVEL UPSLOPE FLOW REGIME. ADDITIONAL TSTMS SHOULD ALSO DEVELOP
ALONG ANY DIFFERENTIAL HEATING BOUNDARIES LEFT OVER FROM MORNING
CONVECTION AND OUTFLOW BOUNDARIES FROM SUNDAY EVENING/NIGHT TSTMS.
TSTMS DEVELOPING WITHIN OR MOVING EWD INTO THE VERY STRONG
INSTABILITY AXIS WILL BECOME SUPERCELLULAR...GIVEN EFFECTIVE BULK
SHEAR VALUES EXCEEDING 50 KT...OWING TO 50+ KT WSWLY MID LEVEL FLOW
ACROSS THIS REGION. GIVEN EXISTENCE OF STEEP LAPSE RATES AND DEGREE
OF AVAILABLE INSTABILITY...LARGE HAIL /SOME VERY LARGE/ WILL BE
POSSIBLE ESPECIALLY ACROSS WRN/CENTRAL NEB. LOW LEVEL HODOGRAPH
CURVATURE WILL BE SUPPORTIVE OF TORNADOES...ESPECIALLY IN THE
VICINITY OF THE WARM FRONT LATER THIS AFTERNOON INTO THE EVENING.
IF GREATER INSTABILITY DEVELOPS FARTHER EWD INTO ERN NEB WITH
GREATER TSTM COVERAGE...THEN PARTS OF THE CENTRAL PLAINS MAY REQUIRE
AN UPGRADE TO HIGHER PROBABILITIES/CATEGORICAL MODERATE RISK IN
LATER OUTLOOKS.
00Z NAM/GFS BOTH INDICATE A VERY STRONG SLY LLJ /60+ KT/ DEVELOPING
OVER OK INTO KS THIS EVENING...AND VEERING TO SWLY TONIGHT. THIS
COMBINED WITH EFFECTIVE BULK SHEAR REMAINING STRONG OVER NEB/SD TO
MN/LOWER MO VALLEY TONIGHT AND MODERATE ELEVATED INSTABILITY NORTH
OF THE WARM FRONT SUGGEST THE POTENTIAL FOR ONE OR MORE MCS/S
TRACKING EWD FROM SD/NEB. HAIL AND DAMAGING WIND GUSTS WILL BE THE
PRIMARY THREAT WITH THE OVERNIGHT MCS/S.
...ERN KS THROUGH LOWER MO/MID MS VALLEYS...
ASCENT ATTENDANT TO A LEAD MID LEVEL IMPULSE IS EXPECTED TO BE
AIDING AN ONGOING TSTM COMPLEX/MCS ACROSS PARTS OF SD/NEB AT 12Z
TODAY. THIS IMPULSE IS PROGGED TO TRACK TOWARD THE SE REACHING THE
OH VALLEY THIS EVENING. FORCING FOR ASCENT WITHIN THE RIGHT
ENTRANCE REGION OF NWLY MID/UPPER LEVEL JETS ACCOMPANYING THIS WEAK
SHORT WAVE TROUGH AND LOW LEVEL WAA REGIME ACROSS AT LEAST ERN KS/MO
EARLY IN THE PERIOD SHOULD SUPPORT NEW TSTM DEVELOPMENT WITH SOME
RE-INTENSIFICATION OF THE SD/NEB MORNING MCS POSSIBLE AS THIS SYSTEM
TRACKS TOWARD THE LOWER MO VALLEY. MODERATE INSTABILITY AND
EFFECTIVE BULK SHEAR AROUND 50 KT WILL SUPPORT ORGANIZED STORMS WITH
A THREAT FOR HAIL AND DAMAGING WINDS. SELY SURFACE WINDS ALONG AND
E OF RETREATING WARM FRONT ACROSS ERN KS/WRN MO...WITH WINDS VEERING
WITH HEIGHT...SUGGESTS THE POTENTIAL FOR ISOLATED TORNADOES IN THIS
REGION INTO THE AFTERNOON.
...ERN ID/MT/WY...
DESPITE RESIDUAL LOW LEVEL MOISTURE /SURFACE DEWPOINTS CURRENTLY IN
THE UPPER 40S TO LOWER 50S/ OVER MUCH OF MT...MODELS SUGGEST WEAK
INSTABILITY ACROSS ERN ID INTO MT/NRN WY TODAY. THERE IS MODEL
AGREEMENT THAT A FORWARD PROPAGATING TSTM COMPLEX SHOULD DEVELOP
OVER THE HIGHER TERRAIN OF ERN ID DUE TO ASCENT ATTENDANT TO THE
PACIFIC TROUGH SPREADING EWD. 50 KT OF WLY MID LEVEL FLOW
ACCOMPANYING THE MID LEVEL TROUGH WILL SUPPORT SUFFICIENT DEEP LAYER
SHEAR FOR ORGANIZED STORMS...WITH THE MAIN THREAT BEING ISOLATED
STRONG WIND GUSTS AS THE TSTM COMPLEX TRACKS EWD THROUGH MT. WEAK
INSTABILITY SHOULD LIMIT THE OVERALL SEVERE WEATHER THREAT. PARTS
OF MT MAY REQUIRE AN UPGRADE TO A SLIGHT RISK...IF INSTABILITY IS
EXPECTED TO BE GREATER THAN CURRENTLY FORECAST.
...FL INTO SRN GA/SC...
-8 TO -10 C 500 MB TEMPERATURES ACROSS THE SERN STATES INTO FL TODAY
COMBINED WITH SURFACE HEATING IN A MOIST BOUNDARY LAYER WILL SUPPORT
MODERATE INSTABILITY ACROSS THIS REGION. AN MCV CURRENTLY TRACKING
ESEWD THROUGH THE CENTRAL GULF COAST STATES SHOULD MOVE ACROSS GA/SC
AND NRN FL THIS MORNING/AFTERNOON AIDING IN TSTM DEVELOPMENT.
MODEST DEEP LAYER SHEAR MAY LIMIT STORM ORGANIZATION...BUT ISOLATED
STRONG WIND GUSTS AND HAIL WILL BE POSSIBLE WITH THE STRONGER
ACTIVITY.
..PETERS/HURLBUT.. 06/02/2008
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