5304
ACUS02 KWNS 051723
SWODY2
SPC AC 051721
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1221 PM CDT SAT JUL 05 2008
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER
MIDWEST AND CNTRL PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN HIGH
PLAINS...
...UPPER MIDWEST AND CNTRL PLAINS...
AN UPPER-LEVEL RIDGE OVER THE PLAINS TONIGHT WILL DAMPEN AS A ZONAL
FLOW PATTERN BECOMES MORE ESTABLISHED ACROSS THE NRN STATES SUNDAY.
AT THE SFC...A COLD FRONT WILL MOVE SEWD REACHING MN...IA AND ERN
NEB SUNDAY AFTERNOON. AN MCS MAY BE ONGOING SUNDAY MORNING ACROSS
PARTS OF MN AND IA. BEHIND THE OUTFLOW BOUNDARY...THE AIRMASS SHOULD
RECOVER BY EARLY AFTERNOON WITH THUNDERSTORMS FIRST INITIATING
ACROSS WI AND MN. STORMS SHOULD THEN GRADUALLY EXPAND IN COVERAGE
SWWD INTO IA AND NEB. SEVERAL MODELS FORECAST MCS DEVELOPMENT ACROSS
PARTS OF THE REGION BY SUNDAY EVENING.
CONCERNING THE SHEAR ENVIRONMENT...FORECAST SOUNDINGS FOR SUNDAY
AFTERNOON ACROSS THE SLIGHT RISK AREA SHOW SUBSTANTIAL DIRECTIONAL
SHEAR BELOW 850 MB WITH SOME SPEED SHEAR IN THE MID-LEVELS. THIS
SHOULD CREATE 30 TO 40 KT OF VERTICAL SHEAR SUFFICIENT FOR ISOLATED
SEVERE STORMS. ALTHOUGH A FEW SUPERCELLS WILL BE POSSIBLE...THE
WEAKER MID-LEVEL FLOW MAY FAVOR MULTICELL LINE SEGMENTS ESPECIALLY
ALONG THE FRONTAL BOUNDARY WHERE LINEAR FORCING WILL BE ENHANCED. A
PLUME OF STEEP MID-LEVEL LAPSE RATES IS FORECAST ACROSS SRN NEB INTO
WRN IA AND THIS WILL AID LARGE HAIL PRODUCTION ESPECIALLY WITH
ISOLATED SUPERCELLS. IN ADDITION...SFC DEWPOINTS NEAR 70 F...850 MB
FLOW AROUND 20 KT AND STEEP LOW-LEVEL LAPSE RATES IN THE LATE
AFTERNOON MAY ALSO SUPPORT AN ISOLATED WIND DAMAGE THREAT. THE WIND
DAMAGE THREAT SHOULD BE GREATEST WITH ANY LINEAR MCS THAT CAN
ORGANIZE AND PERSIST INTO THE EVENING.
...NRN AND CNTRL HIGH PLAINS...
A ZONAL FLOW PATTERN IS FORECAST ACROSS THE NRN U.S. WITH A SUBTLE
SHORTWAVE TROUGH MOVING EWD ACROSS THE NRN HIGH PLAINS SUNDAY. AT
THE SFC...AN AXIS OF LOW-LEVEL MOISTURE SHOULD EXIST FROM WRN NEB
NWWD ACROSS ERN WY INTO SE WY WHERE THE MODELS DEVELOP POCKETS OF
MODERATE INSTABILITY BY SUNDAY AFTERNOON. IN ADDITION...FORECAST
SOUNDINGS SHOW 35 TO 40 KT OF VERTICAL SHEAR MAINLY DUE TO
DIRECTIONAL SHEAR BELOW 500 MB. THIS ALONG WITH VERY STEEP MID-LEVEL
LAPSE RATES SHOULD BE FAVORABLE FOR ISOLATED SUPERCELLS WITH A LARGE
HAIL THREAT. WITH LARGE TEMP-DEWPOINT SPREADS...HIGH-BASED STORMS
WITH WIND DAMAGE POTENTIAL WILL ALSO BE POSSIBLE ESPECIALLY AS
LOW-LEVEL LAPSE RATES STEEPEN IN THE LATE AFTERNOON. A FEW
MARGINALLY SEVERE HIGH-BASED STORMS MAY ALSO OCCUR IN ERN CO AS
CONVECTION MATURES IN THE ERN CO PLAINS WHERE LAPSE RATES WILL BE
VERY STEEP.
...GULF COAST STATES/ERN SEABOARD...
A VERY MOIST AND UNSTABLE AIRMASS SHOULD REMAIN IN PLACE ACROSS THE
GULF COAST STATES AND ERN SEABOARD SUNDAY. SCATTERED TO NUMEROUS
THUNDERSTORMS SHOULD DEVELOP BY MIDDAY ALONG OUTFLOW BOUNDARIES AND
OTHER CONVERGENCE ZONES. ABUNDANT BOUNDARY LAYER MOISTURE AND STEEP
LOW-LEVEL LAPSE RATES NEAR PEAK HEATING SHOULD BE FAVORABLE FOR
ISOLATED WET DOWNBURSTS. THE MORE INTENSE PULSE STORMS MAY ALSO
CONTAIN HAIL.
..BROYLES.. 07/05/2008
