DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 AM CDT THU JUN 05 2008
VALID 051300Z - 061200Z
...THERE IS A HIGH RISK OF SVR TSTMS FROM SE SD AND SRN MN SW
THROUGH CNTRL/ERN NEB AND WRN IA INTO CNTRL/ERN KS AND NW MO...
...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK
AREA...FROM ERN SD/CNTRL MN AND WRN WI SSW INTO CNTRL OK...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ABOVE AREAS
FROM THE GRT LKS REGION SW INTO NWRN TX...
...SIGNIFICANT SEVERE WEATHER EVENT POSSIBLE ACROSS PARTS OF THE
PLAINS AND THE MID/UPR MS VLY...
...SYNOPSIS...
UNSEASONABLY STRONG UPR LOW NOW OVER THE FOUR CORNERS EXPECTED TO
EJECT RAPIDLY NE INTO ND BY 12Z FRIDAY...PROPELLED BY FAST WLY JET
OVER THE NE PACIFIC. 80-90 KT MID-LVL FLOW NOW ROUNDING BASE OF LOW
WILL REDEVELOP NE ACROSS THE PLNS TODAY AND THE MID/UPR MS VLY
TONIGHT. AT THE SFC...ELONGATED LOW NOW IN WRN KS SHOULD DEEPEN
SLIGHTLY AS IT LIFTS N TO THE NEB/SD BORDER THIS EVENING AND INTO SE
ND EARLY FRIDAY.
...PLNS INTO MID/UPR MS VLY...
SETUP DESCRIBED ABOVE YIELDS A WIDE CORRIDOR OF STRONG TO INTENSE
VERTICAL SHEAR THAT WILL IN PART OVERLAY BROAD/MOIST WARM SECTOR
FROM THE PLNS INTO THE MID/UPR MS VLY. IN SHORT...SYNOPTIC PATTERN
IS ONE OF EARLY SPRING KINEMATICS WITH LATE SPRING THERMODYNAMICS.
A SIGNIFICANT SVR WEATHER OUTBREAK IN TERMS OF BOTH COVERAGE AND
INTENSITY APPEARS LIKELY...ESPECIALLY OVER THE MDT RISK
REGION...WHERE BOTH TORNADOES AND WIDESPREAD DMGG WINDS APPEAR
LIKELY.
TSTMS HAVE ALREADY FORMED OVER ERN CO...NW KS...AND SW NEB...AS
ASCENT IMMEDIATELY DOWNSTREAM FROM UPR LOW ACTS ON MOIST PLUME
WRAPPING WWD N OF KS SFC LOW. THESE STORMS SHOULD PERSIST INTO THE
AFTN...WITH ADDITIONAL DEVELOPMENT EXPECTED NEWD INTO CNTRL/NRN NEB.
ALTHOUGH PRIMARY SVR THREAT EARLY ON SHOULD BE HAIL...A BIT LATER
THIS MORNING A THREAT FOR TORNADOES WILL ALSO DEVELOP...MAINLY IN NW
KS AND SW/S CNTRL NEB AS HEATING AND INCREASING UVV/MOISTURE
AVAILABILITY ALLOW STORMS TO FORM IN AREA OF DEEPLY VEERING WIND
PROFILES NE OF SFC LOW.
FARTHER S AND E...MAJOR QUESTIONS REMAIN REGARDING THE PREDOMINANT
STORM MODE AND CORRESPONDING SVR WEATHER THREATS FROM OK/KS NEWD
INTO SD/MN. WITH THE SERN U.S. RIDGE HOLDING FIRM...AND WITH
UPSTREAM SPEED MAX ON ITS IMMEDIATE HEELS...EXPECT THAT HEIGHT FALLS
ASSOCIATED WITH EJECTING FOUR CORNERS LOW WILL AT BEST ONLY GLANCE
ERN PORTIONS OF THE SRN PLNS /I.E. S AND E OF I-44 IN OK/. COUPLED
WITH EXISTING VERY WARM 700 MB LAYER WITH THE RIDGE...EXPECT THAT
THERE WILL BE A SHARP SERN EDGE TO THE SVR THREAT.
CONSIDERING EXPECTED CONFIGURATION/MOVEMENT OF CAP AND HEIGHT FALL
PATTERNS...EXPECT THAT MAIN SVR THREAT WILL BEGIN IN EARNEST LATER
THIS MORNING IN NEB/NW KS. A BIT LATER IN THE AFTN EXPECT THAT
STORMS WILL DEVELOP SWD ALONG DRYLINE THROUGH KS INTO OK. AT THE
SAME TIME...INCREASING UVV/SUSTAINED MOISTURE INFLOW AND MODEST SFC
HEATING MAY INITIATE SCTD STORMS ALONG OR N WARM FRONT FROM NRN NEB
ACROSS ERN SD INTO MN/WI. A FEW STORMS MAY ALSO FORM ALONG THE WARM
FRONT IN MI.
INTENSITY OF WIND FIELD THROUGHOUT THE PLNS ENSURES THAT ANY
SUSTAINED UPDRAFTS WILL ROTATE. BUT DECIDEDLY MERIDIONAL/LARGELY
UNIDIRECTIONAL NATURE OF THE PROFILES ABOVE THE NEAR-SFC LAYER
/REFLECTING EARLY-SPRING TYPE KINEMATIC SETUP/ LIKELY WILL YIELD
VERY STRONGLY ELONGATED AND SHEARED STORMS. NEVERTHELESS...GIVEN
QUALITY OF MOISTURE INFLOW AND MERIDIONAL EXTENT OF WARM
SECTOR...THESE COULD YIELD STRONG...LONG TRACK TORNADOES.
ON THE OTHER HAND...POTENTIAL FOR STRONG DOWNDRAFT DEVELOPMENT WILL
BE GREAT...ESPECIALLY OVER THE SRN HALF OF THE PLNS /AVERAGE LATE
AFTN DCAPE EXPECTED TO BE AOA 1000 J PER KG IN KS AND OK/. COUPLED
WITH DEEP UNIDIRECTIONAL WIND FIELD...AND LINEAR DEEP FORCING FOR
ASCENT /HEIGHT FALLS/...EXPECT THAT BY EVENING STORMS WILL HAVE
ORGANIZED INTO AN EXTENSIVE BROKEN BAND FROM SRN/ERN NEB SWD INTO
OK. ESPECIALLY IN NEB...KS...WRN IA AND NW MO...INTENSE
FORWARD-PROPAGATING SEGMENTS/LEWPS COULD PRODUCE LONG SWATHS OF DMGG
WIND...IN ADDITION TO A FEW STRONG TORNADOES.
...UPR OH VLY/NY/NRN PA...
SUSTAINED WAA AND BOUNDARY LAYER MOISTENING SHOULD SUPPORT THE
DEVELOPMENT OF SCTD PERIODIC STORM CLUSTERS INVOF DIFFUSE WARM FRONT
FROM PARTS OF ONTARIO E AND SE INTO UPSTATE NY/PA. ALTHOUGH LARGE
SCALE HEIGHT RISES WILL OCCUR ACROSS REGION ON NRN FRINGE OF SERN
STATES RIDGE...DAYTIME HEATING ALONG WITH TERRAIN INFLUENCES MAYS
SUFFICIENTLY BOOST INSTABILITY/UPLIFT TO POSE A RISK FOR A FEW
STRONG/SVR TSTMS WITH HAIL AND/OR LOCALLY DMGG WINDS.
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