SWODY2
SPC AC 241716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1217 PM CDT THU MAY 24 2007
VALID 251200Z - 261200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
PLAINS...
..NRN PLAINS...
AN UPPER-LEVEL LOW OVER MONTANA TONIGHT WILL ACCELERATE EWD AND OPEN
UP MOVING ACROSS THE NRN HIGH PLAINS FRIDAY. LARGE-SCALE ASCENT
AHEAD OF THIS FEATURE WILL INCREASE LIFT IN THE NRN PLAINS FRIDAY
AFTERNOON. LIFT WILL ALSO BECOME ENHANCED BY A DEVELOPING LOW-LEVEL
JET. AN AXIS OF INSTABILITY IS FORECAST TO BE IN PLACE EAST OF A
DEEPENING SFC LOW ACROSS WCNTRL SD AND THIS WILL BE THE FAVORABLE
AREA FOR SCATTERED THUNDERSTORM DEVELOPMENT FRIDAY AFTERNOON.
THUNDERSTORMS SHOULD INCREASE IN THE EVENING AND MCS DEVELOPMENT
WILL BE POSSIBLE FRIDAY EVENING ACROSS THE REGION.
CONCERNING THE SHEAR ENVIRONMENT...MODEL FORECASTS MOVE A 60-70 KT
MID-LEVEL JET ESEWD ACROSS THE NRN ROCKIES TONIGHT AND INTO THE NRN
HIGH PLAINS FRIDAY. THE EXIT REGION OF THIS FEATURE IS FORECAST TO
SPREAD EWD INTO NRN SD INCREASING VERTICAL SHEAR PROFILES LATE IN
THE AFTERNOON. FORECAST SOUNDINGS FROM THE NAM LATE FRIDAY AFTERNOON
ACROSS NRN SD SHOW 0-6 KM SHEAR VALUES IN THE 40 TO 50 KT RANGE
SUGGESTING SUPERCELL DEVELOPMENT WILL BE POSSIBLE. THUNDERSTORMS
WILL LIKELY INITIATE ON THE WRN EDGE OF THE INSTABILITY AXIS AND
MOVE EWD INTO INCREASING INSTABILITY BY EARLY EVENING. IN
ADDITION...FORECAST SOUNDINGS SHOW A PLUME OF STEEP MID-LEVEL LAPSE
RATES AROUND 8.0 C/KM SUGGESTING LARGE HAIL WILL BE LIKELY WITH ANY
SUPERCELLS THAT DEVELOP ACROSS THE REGION. THE BOUNDARY-LAYER SHEAR
ENVIRONMENT WILL ALSO BECOME STRONGER BY EARLY EVENING DUE TO A
40-50 KT LOW-LEVEL JET AND A FEW OF THE SUPERCELLS MAY HAVE A BRIEF
POTENTIAL FOR TORNADOES. MCS DEVELOPMENT ALSO MAY OCCUR BUT THE
OVERALL SEVERE THREAT SHOULD GRADUALLY DIMINISH IN THE EVENING DUE
TO THE RELATIVELY WEAK INSTABILITY.
..CNTRL HIGH PLAINS/SRN PLAINS...
A WEAK UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE HIGH
PLAINS FRIDAY WITH LOW-LEVEL MOISTURE GRADUALLY INCREASING WWD INTO
THE HIGH PLAINS DURING THE DAY. POCKETS OF MODERATE INSTABILITY WILL
LIKELY DEVELOP BY LATE AFTERNOON AND SCATTERED THUNDERSTORMS SHOULD
INITIATE ACROSS PARTS OF THE REGION. ALTHOUGH ENOUGH INSTABILITY
SHOULD BE PRESENT FOR SEVERE STORMS...FORECAST SOUNDINGS SHOW 0-6 KM
SHEAR VALUES IN THE 20-30 KT RANGE ACROSS MOST OF THE INSTABILITY
AXIS FRIDAY AFTERNOON. THIS WILL LIKELY KEEP THE SEVERE THREAT
MARGINAL WITH LARGE HAIL BEING THE PRIMARY THREAT DUE TO STEEP
MID-LEVEL LAPSE RATES.
..OH VALLEY...
A RELATIVELY WEAK SOUTHWEST FLOW PATTERN WILL BE IN PLACE FRIDAY
ACROSS THE OH VALLEY. AT THE SFC...A COLD FRONT SHOULD BE IN PLACE
FROM NRN PA EXTENDING WSWWD ACROSS THE OH VALLEY INTO SRN IL AND
CNTRL MO. FORECAST SOUNDINGS ACROSS THE REGION SHOW UNIDIRECTIONAL
LOW-LEVEL WIND PROFILES AND STEEP LOW-LEVEL LAPSE RATES WHICH SHOULD
BE ENOUGH FOR STRONG GUSTY WINDS NEAR PEAK HEATING. HAIL WILL ALSO
BE POSSIBLE NEAR LOCALLY MAXIMIZED INSTABILITY. HOWEVER...THE WEAK
SHEAR ENVIRONMENT SHOULD KEEP ANY THREAT MARGINAL FRIDAY AFTERNOON.
.BROYLES.. 05/24/2007
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