[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 181722
SWODY2
SPC AC 181721

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1221 PM CDT TUE JUL 18 2006

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN PLAINS ACROSS THE
UPPER MS VALLEY INTO THE UPR GREAT LAKES...

...SYNOPSIS...
PROGRESSIVE UPPER FLOW PATTERN WITHIN THE STRONGER WESTERLIES ALOFT
IS FORECAST TO CONTINUE ACROSS THE NRN TIER OF STATES TOMORROW AS
UPPER RIDGE REMAINS ANCHORED ACROSS THE CENTRAL PARTS OF THE PLAINS
AND ROCKIES.  PRIMARY SHORT WAVE TROUGH CURRENTLY MOVING ACROSS SRN
ALBERTA AND SRN BRITISH COLUMBIA IS EXPECTED TO PROGRESS ESEWD
REACHING THE UPPER MS VALLEY/UPPER GREAT LAKES BY THE END OF THE
PERIOD.  ASSOCIATED NE/SW SURFACE COLD FRONT WILL MOVE EWD ACROSS
THE NRN PLAINS AND UPPER MS VALLEY...REACHING A WRN LAKE
SUPERIOR/SWRN MN/NRN NEB LINE BY 20/00Z...AND CONTINUING TO ERN LAKE
SUPERIOR/SWRN WI/SWRN IA BY THE END OF THE PERIOD.  A WARM FRONT
WILL LIFT RAPIDLY NWD ACROSS THE UPPER MS VALLEY DURING THE MORNING
WITH A VERY MOIST WARM SECTOR DEVELOPING BY AFTERNOON.

...NRN PLAINS/UPPER MS VALLEY INTO THE UPPER GREAT LAKES...
THERMODYNAMIC ENVIRONMENT WILL BE INCREASINGLY FAVORABLE FOR
STRONG/SEVERE CONVECTION AS LOW LEVEL MOISTURE RETURNS NWD BENEATH
PRE-EXISTING PLUME OF STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH
THE ELEVATED MIXED LAYER FROM THE NRN PLAINS ACROSS THE UPPER MS
VALLEY.  ELEVATED THUNDERSTORMS MAY BE OCCURRING IN THE MORNING
ACROSS PARTS OF THE DAKOTAS WITH STRONGER STORMS CAPABLE OF
PRODUCING ISOLATED HAIL AND STRONG WIND GUSTS. PRIMARY SEVERE
THREAT IS EXPECTED TO DEVELOP DURING THE AFTERNOON AND EVENING AS
THE ELEVATED CONVECTION SPREADS EWD TOWARD THE FRONTAL ZONE WITH
POTENTIAL TO BECOME ROOTED IN THE BOUNDARY LAYER...AND ADDITIONAL
STORMS ARE LIKELY TO DEVELOP ALONG/JUST AHEAD OF THE FRONT AS LOW
LEVEL CONVERGENCE AND STRONG HEATING LOCALLY WEAKENS THE CAP.

ENVIRONMENT IS FORECAST TO BECOME VERY UNSTABLE NEAR THE FRONT AS
SURFACE TEMPERATURES WARM INTO THE 90S AND DEW POINTS INCREASE INTO
THE 70S...CONTRIBUTING TO MLCAPE OF 2500-4000 J/KG.  VERTICAL SHEAR
IS ALSO EXPECTED TO STRENGTHEN AS FORECAST SOUNDINGS EXHIBIT WIND
PROFILES THAT VEER AND INCREASE WITH HEIGHT...IN RESPONSE TO A 50-60
KT MID LEVEL JET STREAK MOVING ACROSS ND INTO MN ON THE SOUTH SIDE
OF THE SHORT WAVE TROUGH.  COMBINATION OF STRONG INSTABILITY AND
MODERATE DEEP LAYER SHEAR INDICATES POTENTIAL FOR A FEW SUPERCELLS
TO DEVELOP...PRIMARILY FROM ERN SD INTO CENTRAL/SRN MN DURING THE
AFTERNOON SPREADING EWD INTO PARTS OF WI AT NIGHT.  STEEP LAPSE
RATES/LARGE INSTABILITY AND A FAVORABLY SHEARED ENVIRONMENT SUGGEST
STRONGER STORMS WILL BE CAPABLE OF PRODUCING VERY LARGE
HAIL...DAMAGING WIND GUSTS...AND A FEW TORNADOES.  THE TORNADO
THREAT WILL BE ENHANCED IF DISCRETE CELLS CAN BE MAINTAINED INTO THE
EVENING HOURS. CONVECTION IS EXPECTED TO GROW UPSCALE INTO ONE OR
MORE MCS/S DURING THE OVERNIGHT HOURS WITH SEVERE THREAT CONTINUING
AFTER DARK TOWARD THE UPPER GREAT LAKES.  UNCERTAINTY IN CONVECTIVE
MODE PRECLUDES INTRODUCTION OF A HIGHER RISK CATEGORY ATTM BUT
REGION WILL BE MONITORED FOR POSSIBLE UPGRADE IN LATER OUTLOOKS.

...ERN NC INTO SERN VA...
TROPICAL DEPRESSION OFF THE NC COAST IS FORECAST TO TURN NWWD TOWARD
THE NC OUTER BANKS TOMORROW /SEE LATEST FORECASTS FROM TPC/.  THIS
MOTION WILL PLACE REGION OF STRONGER CYCLONIC LOW LEVEL
FLOW/VERTICAL SHEAR INTO COASTAL SECTIONS OF NERN NC/SERN VA
BEGINNING LATER TOMORROW AFTERNOON.  THIS SUGGESTS INCREASING
POTENTIAL FOR STRONGER CONVECTION ACROSS THIS AREA...ALTHOUGH
CURRENT TRACK FORECAST WILL KEEP FAVORED CLIMATOLOGICAL SECTOR FOR
TROPICAL CYCLONE TORNADOES MAINLY OFFSHORE.

..WEISS.. 07/18/2006