SWODY2
SPC AC 040556
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT TUE SEP 04 2007
VALID 051200Z - 061200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN GRT
BASIN AND INTERMOUNTAIN W...
..NRN GRT BASIN/INTERMOUNTAIN W...
SPLIT FLOW IN THE WLYS WILL CONTINUE INTO MID-WEEK WITH THE PAC NW
TROUGH FCST TO DIG SEWD INTO THE NRN GRT BASIN BY WEDNESDAY AFTN.
THIS FEATURE WILL LIKELY BE PRECEDED BY A LEAD IMPULSE THAT WILL BE
IMPETUS FOR TUE NIGHT/EARLY WEDNESDAY CONVECTION OVER THE REGION.
THIS ACTIVITY SHOULD MOVE NEWD WEDNESDAY MORNING AS THE PRIMARY WARM
CONVEYOR SHIFTS EWD. IN ITS WAKE...AIR MASS WILL LIKELY RECOVER
WITH MODEST HEATING ALONG/AHEAD OF THE H7 FRONT FROM ERN ID SWD INTO
NRN/CNTRL UT. COMBINATION OF MID-LEVEL COLD AIR SPREADING EWD WITH
THE TROUGH ATOP THIS MOIST/WARM BOUNDARY LAYER WILL LIKELY
CONTRIBUTE TO AFTN DESTABILIZATION AND SUBSEQUENT TSTM DEVELOPMENT
AHEAD OF THE FRONT. ROUGHLY 45-50 KTS OF SWLY H5 FLOW ATOP SLY
LOW-LEVEL FLOW WILL BOOST BULK SHEAR SUFFICIENT FOR BRIEF SUPERCELL
STRUCTURES WITH HAIL. OTHERWISE...THE MAJORITY OF THE ACTIVITY WILL
LIKELY EVOLVE INTO LINE SEGMENTS WITH EMBEDDED BOWS/LEWPS FEATURING
DMGG WIND GUST POTENTIAL. ACTIVITY WILL MOVE QUICKLY ENEWD INTO WRN
WY WEDNESDAY EVENING WITH A GRADUAL DECREASE IN THE SVR THREATS.
..NRN MN WWD INTO THE DAKS...
A MID-LEVEL WAVE EMBEDDED WITHIN THE PRIMARY WLYS WILL SKIRT ACROSS
NWRN ONTARIO ON WEDNESDAY. A COLD FRONT WILL SETTLE SEWD BEHIND
THIS SYSTEM INTO PORTIONS OF NRN MN...SERN ND AND CNTRL SD BY 00Z
THU. PRE-FRONTAL WARM SECTOR IS EXPECTED TO BE CAPPED BY A STRONG
EML...ESPECIALLY WEST OF THE MISSOURI RVR. MODELS INDICATE A WEAK
PERTURBATION WITHIN THE SRN BRANCH MAY EJECT NEWD ACROSS THE DAKS
DURING PEAK HEATING. THIS MAY AID IN WEAKENING THE CAP SUFFICIENTLY
FOR LATE AFTN TSTM INITIATION FROM SERN ND/NERN SD INTO NRN MN ALONG
THE FRONT. GIVEN A STORM...500-1000 J/KG SBCAPES AND 30-35 KTS OF
WLY VERTICAL SHEAR MAY BE SUFFICIENT FOR ISOLD SVR HAIL/WIND GUSTS.
MORE ACTIVITY WILL DEVELOP LATER AT NIGHT UPSTREAM ACROSS THE HIGH
PLAINS AHEAD OF THE NRN INTERMOUNTAIN W TROUGH...GENERALLY ALONG/N
OF THE FRONT. THESE STORMS WILL LIKELY BE SUB-SEVERE OWING TO
COMPARATIVELY WEAKER POTENTIAL BUOYANCY.
..ERN TX NEWD INTO THE OZARKS...
CONSIDERABLE MODEL DIFFERENCES CONTINUE WITH THE HANDLING/STRENGTH
OF THE SRN PLAINS IMPULSE EXPECTED TO LIFT NEWD TUE AND WEDNESDAY.
A SURGE OF HIGH PRECIPITABLE WATER VALUES WILL CONTINUE ALONG/E OF
THIS TROUGH THROUGH MID-WEEK WITH CONSIDERABLE CONVECTION. VERTICAL
SHEAR SHOULD REMAIN WEAK AND LAPSE RATES POOR...THUS SUSTAINED
STRONG TSTMS ARE NOT LIKELY. IF LOW-LEVEL FLOW BECOMES STRONGER
THAN EXPECTED...THERE WOULD BE AN ISOLD TORNADO THREAT. POOR
PREDICTABILITY OF THE PATTERN...HOWEVER... WILL PRECLUDE AN
INTRODUCTION OF SVR PROBABILITIES ATTM.
.RACY.. 09/04/2007
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