SWODY1
SPC AC 050045
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 PM CDT SAT AUG 04 2007
VALID 050100Z - 051200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN
NEB...EXTREME SERN SD...IA...AND EXTREME SRN MN...
..CNTRL PLAINS TO MIDWEST...
TYPICALLY HOT AND VERY UNSTABLE AIR MASS COVERS MUCH OF THE PLAINS
THIS EVENING BENEATH GENERALLY WEAK TO MODEST WLY FLOW ALOFT. A
SURFACE LOW WAS LOCATED OVER NWRN IA WITH A TROUGH/WIND SHIFT
BOUNDARY EXTENDING SWWD FROM THE SURFACE LOW ACROSS NEB...NWRN
KS...AND INTO SERN CO. A WELL-DEFINED WARM/STATIONARY BOUNDARY
EXTENDS SEWD FROM THE LOW IN IA ACROSS THE MS VALLEY TO IL...AND
THEN TO THE LOWER OH VALLEY. DESPITE WARM THERMODYNAMIC PROFILES
/MID LEVEL LAPSE RATES AOB 7 C PER KM/...PERSISTENT AND DEEPENING
BOUNDARY LAYER CONVERGENCE NEAR THE VARIOUS WIND SHIFT BOUNDARIES
AND FRONTS...AND NEAR THE SURFACE LOW...HAS ALLOWED SCATTERED
INTENSE TSTM DEVELOPMENT TO OCCUR. EFFECTIVE BULK SHEAR ACROSS MUCH
OF THE PLAINS WAS WITHIN A MARGINALLY FAVORABLE RANGE /25-35KT/ TO
SUSTAIN UPDRAFT ROTATION. PRONOUNCED 0-1KM SRH OF OVER 300
M2/S2...AND A LOWER LFC...EXIST INVOF SFC LOW AND ALONG THE WARM
FRONT OVER IA. ACTIVITY WEST OF THE MO RIVER VALLEY SHOULD CONTINUE
TO POSE A THREAT OF WIDELY SCATTERED SEVERE HAIL AND DAMAGING WINDS
BUT LACK OF STRONGER LARGE SCALE FORCING MAY LEAD TO A GRADUAL
DEMISE OF STORM INTENSITY WITHIN A FEW HOURS AFTER DARK TONIGHT.
EAST OF THE MO RIVER...ACROSS IA...A FEW SUPERCELL STORMS WITH
POTENTIAL FOR STRONG LOW LEVEL ROTATION MAY CONTINUE TO EVOLVE. ANY
CELL NEAR THE SURFACE LOW...OR TRACKING NEAR/ALONG THE WARM FRONTAL
ZONE...WILL HAVE TORNADIC POTENTIAL...IN ADDITION TO SEVERE HAIL AND
WIND...GIVEN THE COMBINATION OF SHEAR AND HIGH BOUNDARY LAYER RH.
EVENTUALLY...THIS CONVECTION MAY CONGEAL INTO AN MCS WHICH WILL
MAINTAIN THE CHANCE FOR ISOLATED STRONG...AND INCREASINGLY ELEVATED
TSTMS...FROM NERN IA ACROSS SERN MN AND INTO SRN WI THROUGH EARLY
SUNDAY MORNING. ISOLATED HAIL AND PERHAPS DAMAGING WINDS MIGHT OCCUR
IF THE MCS CAN PERSIST AND SPREAD EAST.
FARTHER SOUTHEAST...CLUSTERS OF INTENSE MULTICELL STORMS ARE
CONTINUING WITHIN STRONGLY UNSTABLE REGIME ALONG THE STATIONARY
BOUNDARY ACROSS SRN IL/IND. COLD POOL FROM ONGOING CONVECTION WILL
LIKELY MAINTAIN THERMAL CONTRAST ACROSS THE FRONTAL ZONE TONIGHT.
LIFT MAY STRENGTHEN ACROSS THIS BOUNDARY AS LOW LEVEL JET VEERS AND
INTENSIFIES OVERNIGHT WITH THE CHANCE FOR ISOLATED STRONG STORMS
CONTINUING OVER PARTS OF THE MIDWEST...ON THE EDGE OF THE STRONGER
CAP...THROUGH LATE NIGHT/EARLY SUNDAY.
..NRN ROCKIES INTO HIGH PLAINS...
LOW AMPLITUDE MID LEVEL IMPULSE EMANATING FROM LARGER SCALE BROAD
TROUGH ACROSS THE ERN PACIFIC/NORTHWEST...COUPLED WITH OROGRAPHIC
FORCING AND WEAK DESTABILIZATION...APPEARS TO HAVE SPURRED
HIGH-BASED AND FAST MOVING STORMS FROM ERN ID TO WY/MT THIS EVENING.
IN ADDITION...STRONG HEATING WITHIN LEE/THERMAL TROUGH ACROSS THE
WRN DAKOTAS HAS RESULTED IN ISOLATED STORM INITIATION IN THIS
REGION. GIVEN LARGE DIURNAL/DIABATIC COMPONENT TO THIS ONGOING
CONVECTION...EXPECT ANY SEVERE WIND POTENTIAL FROM THIS ACTIVITY TO
DECREASE OVER THE NEXT COUPLE OF HOURS.
.CARBIN.. 08/05/2007
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