Monday, June 7, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071629
SWODY1
SPC AC 071628

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT MON JUN 07 2010

VALID 071630Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
CENTRAL/SRN PLAINS AND LOWER MO RIVER VALLEY...

...CENTRAL/SRN HIGH PLAINS EWD INTO THE LOWER MO VALLEY...
SHORT TERM MESOSCALE MODELS WERE POOR IN FORECASTING EVENTUAL
EVOLUTION OF ELEVATED THUNDERSTORMS THIS MORNING FROM THE NERN TX
PANHANDLE NWD INTO CENTRAL NEB. 700-800 MB WLY WARM ADVECTION
FEEDING OVER OUTFLOW BOUNDARY FROM OVERNIGHT CONVECTION APPEARED TO
BE THE SOURCE FOR CONVECTION. ISOLATED SEVERE HAIL AND EVEN SOME
WIND DAMAGE WILL BE POSSIBLE WITH STORMS THE NEXT COUPLE OF
HOURS...ESPECIALLY SMALL CLUSTER EAST OF DDC...REFERENCE WW 279.
UNLESS COMPLEX CAN BE MAINTAINED SEWD INTO OK...STORMS SHOULD
GRADUALLY DECREASE AS WARM ADVECTION SLOWLY SHIFTS EWD INTO A LESS
UNSTABLE ELEVATED ENVIRONMENT.

ALSO DUE TO MORNING CONVECTION...HAVE ADDED SLIGHT RISK FROM WRN KS
SWD INTO THE OK/TX PANHANDLES. OUTFLOW BOUNDARIES IN THESE AREAS MAY
PROVIDE SUFFICIENT CONVERGENCE FOR STORMS TO DEVELOP THIS AFTERNOON
WITH HEATING. ALTHOUGH THE DEEP LAYER SHEAR WILL NOT BE PARTICULARLY
STRONG...ESPECIALLY IN THE TX PANHANDLE... VERY STEEP MID LEVEL
LAPSE RATES/INSTABILITY WILL EXIST ACROSS THE AREA. THE AMOUNT OF
INSTABILITY FAVORS HAIL...AND THE LARGE HIGH BASED CAPE WITH
EXPECTED 25-30 DEGREE T/TD SPREADS SUPPORT DAMAGING WINDS.

FURTHER NORTH...THE BOUNDARY LAYER IS QUITE COOL AND WIDESPREAD
EXTENSIVE LOW CLOUDS STILL COVERS MUCH OF ERN CO/SERN WY/WRN NEB.
THESE CLOUDS SHOULD DECREASE BY EARLY AFTERNOON...BUT WILL SLOW
HEATING AND TAKE TIME FOR AIR MASS TO DESTABILIZE. HOWEVER...AS
UPPER TROUGH APPROACHES NRN ROCKIES THIS AFTERNOON...STORMS SHOULD
DEVELOP IN THE UPSLOPE REGION OF THE HIGHER TERRAIN OF ERN WY/NRN
CO...WHERE SKIES ARE SUNNY THIS MORNING. STRONG INSTABILITY IS
EXPECTED BY MID/LATE AFTERNOON AND COUPLED WITH EFFECTIVE SHEAR AT
50 KT...SUPERCELLS WITH VERY LARGE HAIL AND DAMAGING WINDS ARE
LIKELY ACROSS SERN WY/WRN NEB AND NERN CO BY LATE AFTERNOON.
APPRECIABLE LOW-LEVEL DIRECTIONAL SHEAR ALSO WILL BE FAVORABLE FOR
TORNADOES.

STORMS ARE EXPECTED TO CONSOLIDATE INTO AN MCS THIS EVENING AS LOW
LEVEL JET INTENSIFIES OVER A STATIONARY FRONT/BOUNDARY... EXPECTED
TO STRETCH E-W ACROSS NRN KS INTO NRN MO. GIVEN THE RICH MOISTURE
INFLOW /PW 1.75 IN/ AND INCREASING ASCENT AHEAD OF UPPER IMPULSE...A
STRONG FORWARD-PROPAGATING MCS WITH WIND DAMAGE IS LIKELY FROM NRN
KS/NEB EWD INTO THE LOWER MO RIVER VALLEY OVERNIGHT.

...NRN UT/SRN WY/NW CO THIS AFTN/EVE...
ASCENT ASSOCIATED WITH NRN ROCKIES IMPULSE WILL ENHANCE DIURNAL
DESTABILIZATION OVER SRN WY...NRN UT...AND NW CO THIS AFTERNOON.
SUFFICIENT MOISTURE SHOULD BE PRESENT TO SUPPORT STRONG STORM
DEVELOPMENT ALONG STRENGTHENING COLD FRONT AS SBCAPE INCREASES TO
AOA 500 J/KG. GIVEN 40-50 KT DEEP WSWLY SHEAR AND STEEP LOW TO MID
LVL LAPSE RATES...THE STORMS MAY YIELD A FEW HIGH WIND AND
MARGINALLY SVR HAIL REPORTS.

..IMY/JEWELL.. 06/07/2010

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