SWODY2
SPC AC 061730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT JUN 06 2009
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CENTRAL
PLAINS AND MIDWEST...
...CENTRAL PLAINS TO MIDWEST/WESTERN GREAT LAKES...
AS NOTED BY THE PRIOR DAY 2 OUTLOOK...UNCERTAINTY CONTINUES IN
REGARD TO SUNDAY/S ULTIMATE LOCATION OF ROUGHLY WEST-EAST EFFECTIVE
FRONTAL ZONE ACROSS NEB/NORTHERN KS AND IA/PERHAPS NORTHERN MO INTO
NORTHERN IL. THIS IS LARGELY ATTRIBUTABLE TO POTENTIAL FOR
OVERNIGHT/EARLY MORNING MCS/S AND THE POSSIBILITY OF SCATTERED TO
NUMEROUS SHOWERS/TSTMS WITHIN THIS CORRIDOR EARLY IN THE DAY. THERE
IS SOME POTENTIAL THAT REMNANTS OF THIS ACTIVITY MAY DIURNALLY
UPSWING IN TERMS OF COVERAGE/INTENSITY ACROSS NORTHERN IL VICINITY.
HOWEVER...THE PRIMARY SEVERE EPISODE SHOULD UNFOLD SATURDAY
AFTERNOON/NIGHT FARTHER WEST ACROSS PORTIONS OF NEB/IA/NORTHERN KS
AND PERHAPS FAR NORTHERN MO.
ACROSS EASTERN/SOUTHERN NEB AND NORTHERN KS INTO IA/FAR NORTHERN
MO...IT SEEMS LIKE THE EXISTENCE OF A STRONG ELEVATED MIXED LAYER
SHOULD CAP SURFACE BASED DEEP CONVECTION THROUGH EARLY/MID
AFTERNOON. BUT EVEN WITH A STRONGLY CAPPED WARM SECTOR /CAP BASED
AROUND 800-750 MB/...IT SEEMS PROBABLE THAT SURFACE BASED TSTMS
SHOULD STEADILY INCREASE THROUGH LATE AFTERNOON/EARLY EVENING. AS AN
UPPER TROUGH APPROACHES FROM THE CENTRAL ROCKIES/CENTRAL HIGH PLAINS
AND DOWNSTREAM HEIGHT FALLS OCCUR ACROSS THE CENTRAL PLAINS DURING
THE DAY...SUCH DEVELOPMENT SEEMS MOST PROBABLE ALONG/IMMEDIATELY
NORTH/NORTHWEST OF THE WSW-ENE ORIENTED FRONTAL ZONE...WITH
INCIPIENT DEVELOPMENT SEEMING MOST PROBABLE AT THIS TIME ALONG THE
NEB/KS BORDER VICINITY INTO WESTERN IA.
IT SHOULD BE NOTED THAT 12Z BASED NUMERICAL GUIDANCE AGAIN APPEARS
ABOUT 5 DEG F TOO HIGH WITH RESPECT TO BOUNDARY LAYER MOISTURE
ACROSS THE WARM SECTOR. NEVERTHELESS...RATHER STEEP MID LEVEL LAPSE
RATES AND GENERAL EXPECTATION FOR LOWER TO MIDDLE 60S F SURFACE
DEWPOINTS SHOULD CONTRIBUTE TO FAIRLY STRONG BUOYANCY OF 2000-3000
J/KG OF MLCAPE. FAVORABLE THERMODYNAMIC ENVIRONMENT AND EFFECTIVE
BULK SHEAR OF 45-55 KT WILL SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL
AND SOME TORNADOES...WITH THE LATTER LIKELY TO BE MOST PROBABLE WITH
TSTMS INTERACTING WITH/MOVING PARALLEL TO THE SURFACE FRONT AND/OR
RESIDUAL OUTFLOW. OTHERWISE...LARGE HAIL/DAMAGING WIND POTENTIAL
WILL CONTINUE WELL THROUGH THE NIGHT EASTWARD ACROSS THE MIDWEST VIA
POTENTIAL MCS DEVELOPMENT...WITH SEVERE HAIL POSSIBLE AS FAR
NORTHEAST AS THE WESTERN GREAT LAKES VICINITY.
...CENTRAL HIGH PLAINS...
ISOLATED SEVERE TSTMS INCLUDING SUPERCELLS MAY ALSO FORM ALONG/NORTH
OF THE WEST-EAST FRONT WITHIN UPSLOPE REGIME ACROSS PORTIONS OF
SOUTHEAST WY/WESTERN NEB/NORTHEAST CO INTO NORTHWEST KS. SEVERE HAIL
WILL BE THE PRIMARY THREAT.
...SOUTHERN PLAINS...
AS LARGE SCALE HEIGHT FALLS GRAZE THE REGION...ISOLATED SEVERE TSTMS
MAY DEVELOP SOUTHWARD ALONG THE LENGTH OF THE DRYLINE FROM SOUTHERN
KS TO WEST CENTRAL/SOUTHWEST TX. INCREASING MID TROPOSPHERIC FLOW
AND A HOT/DEEP MIXED BOUNDARY LAYER MAY SUPPORT A FEW HIGH BASED
SUPERCELLS WITH HAIL AS THE PRIMARY RISK SUNDAY AFTERNOON/EARLY
EVENING.
...SOUTHERN FL PENINSULA...
ALTHOUGH SLIGHT MID LEVEL WARMING MAY OCCUR INTO SUNDAY...RESIDUALLY
COOL TEMPERATURES ALOFT IN ASSOCIATION WITH REMNANT UPPER LOW MAY
SUPPORT SUFFICIENT BUOYANCY FOR A FEW TSTMS CAPABLE OF SEVERE HAIL
AND STRONG WIND GUSTS.
..GUYER.. 06/06/2009
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