[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 202002
SWODY1
SPC AC 202001

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT SAT MAY 20 2006

VALID 202000Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF MT AND WY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS
VALLEY...TN VALLEY AND CAROLINAS...

...CAROLINAS/TN VALLEY/OZARK PLATAEA...
WATER VAPOR IMAGERY CURRENTLY SHOWS A BROAD BAND OF NORTHWEST FLOW
ACROSS THE MID-MS AND TN VALLEYS. AT THE SFC...A NEARLY STATIONARY
FRONT EXTENDS EWD ACROSS NRN TN INTO NC. SOUTH OF THE BOUNDARY...SFC
DEWPOINTS ARE IN THE 60S F AND MODERATE INSTABILITY EXISTS. AN MCS
IS CURRENTLY DEVELOPING ALONG THE NRN EDGE OF THE INSTABILITY AXIS
AHEAD OF A SUBTLE SHORTWAVE TROUGH IN THE SRN APPALACHIAN MTNS. THIS
STORM COMPLEX WILL CONTINUE TO EXPAND AND SPREAD ESEWD ACROSS NRN GA
AND WRN SC LATE THIS AFTERNOON INTO THE EARLY EVENING.

FORECAST SOUNDINGS LATE THIS AFTERNOON SHOW MODERATE TO STRONG
VERTICAL SHEAR PROFILES ALONG THE FRONTAL BOUNDARY IN THE TN VALLEY
AND CAROLINAS SUGGESTING SUPERCELLS WILL BE LIKELY ESPECIALLY EARLY
IN THE DEVELOPMENT OF THE MCS. THE TORNADO THREAT SHOULD BE ENHANCED
OVER NRN GA AND WRN SC WHERE THE LOW-LEVEL SHEAR ENVIRONMENT APPEARS
MORE FAVORABLE DUE TO A 30-40 KT LOW-LEVEL JET. IN
ADDITION...OBJECTIVE ANALYSIS SHOWS A PLUME OF STEEP MID-LEVEL LAPSE
RATES EXTENDING EWD ACROSS MS...AL AND NRN GA SUGGESTING SUPERCELLS
WITH VERY LARGE HAIL WILL ALSO BE POSSIBLE. AS THE MCS MATURES THIS
EVENING...THE UNIDIRECTIONAL WIND ENVIRONMENT SUGGESTS THE WIND
DAMAGE THREAT MAY ALSO BECOME ENHANCED.

FURTHER WEST ACROSS THE OZARK PLATEAU...CONVECTIVE INITIATION WILL
LIKELY HOLD OFF DUE TO A CAPPING INVERSION UNTIL THE LATE AFTERNOON
AND/OR EARLY EVENING. FORECAST SOUNDINGS IN THIS AREA FOR EARLY THIS
EVENING SHOW STEEP LAPSE RATES AND MODERATE VERTICAL SHEAR PROFILES
SUGGESTING LARGE HAIL AND ISOLATED WIND DAMAGE WILL BE POSSIBLE. THE
SEVERE THREAT MAY PERSIST THROUGH THE EVENING WITH ANY MCS CLUSTER
THAN DEVELOPS AND MOVES ESEWD ACROSS THE REGION.

...MT/WY...
WATER VAPOR IMAGERY CURRENTLY SHOWS AN UPPER-LEVEL RIDGE IN PLACE
ACROSS THE ROCKIES WITH A SHORTWAVE TROUGH TOPPING THE RIDGE. AT THE
SFC...A TROUGH CURRENTLY EXTENDS NNWD INTO NRN WY AND WCNTRL MT. SFC
DEWPOINTS EAST OF THE SFC TROUGH RANGE FROM THE MID 40S TO MID 50S F
WHERE POCKETS OF MODERATE INSTABILITY ARE PRESENT ACCORDING TO
OBJECTIVE ANALYSIS. A LINE OF STRONG THUNDERSTORMS IS ORGANIZING IN
THE FOOTHILLS AND WILL INCREASE IN COVERAGE...MOVING INTO THE PLAINS
THIS AFTERNOON. FORECAST SOUNDINGS THIS AFTERNOON SHOW MODERATE
VERTICAL SHEAR PROFILES SUGGESTING ISOLATED SUPERCELLS WITH LARGE
HAIL WILL BE POSSIBLE WHERE THE INSTABILITY IS LOCALLY MAXIMIZED. IF
LINEAR MCS DEVELOPMENT CONTINUES...BOW ECHOES EMBEDDED WITH THE LINE
WOULD ALSO BE LIKELY WITH A THREAT FOR WIND DAMAGE THROUGH EARLY
EVENING.

...UPPER GREAT LAKES...
WATER VAPOR IMAGERY CURRENTLY SHOWS A BROAD BAND OF NWLY FLOW ACROSS
THE UPPER MIDWEST. AN 80 KT MID-LEVEL JET EMBEDDED IN THE FLOW IS
PUNCHING SEWD ACROSS THE REGION WHICH IS ENHANCING VERTICAL SHEAR
PROFILES. MODEL FORECASTS SHOW LINEAR CONVECTIVE DEVELOPMENT MOVING
SEWD ACROSS THE REGION LATE THIS AFTERNOON. ALTHOUGH INSTABILITY IS
WEAK...THE STRONG SHEAR ENVIRONMENT SUGGESTS A MARGINAL WIND DAMAGE
AND/OR HAIL THREAT MAY EXIST WITH THIS CONVECTION FOR A FEW HOURS
THIS AFTERNOON.

..BROYLES.. 05/20/2006