bttt
From the SPC in Norman, OK:
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT FRI MAY 31 2013
VALID 311630Z - 011200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING
ACROSS PARTS OF CNTRL OK...SERN KS...AND SWRN MO...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE GREAT PLAINS
INTO UPPER MIDWEST...
...REGIONAL SEVERE WEATHER OUTBREAK POSSIBLE TODAY OVER PARTS OF
CENTRAL/EASTERN OK...SOUTHEAST KS...AND SOUTHWEST MO. VERY LARGE
HAIL...WIDESPREAD DAMAGING WINDS...AND A FEW STRONG
TORNADOES/VIOLENT ARE POSSIBLE...
...OK/KS/MO...
ANOTHER VERY VOLATILE ENVIRONMENT IS IN PLACE ACROSS PARTS OF THE
SOUTHERN PLAINS AND MID MS VALLEY TODAY. WIDESPREAD VERY STEEP MID
LEVEL LAPSE RATES AND DEWPOINTS IN THE UPPER 60S/LOWER 70S ARE
RESULTING IN THE POTENTIAL FOR AFTERNOON MLCAPE VALUES OVER 4000
J/KG. THIS AIR MASS IS CURRENTLY CAPPED...AND THE CAP SHOULD
RESTRAIN DEEP CONVECTION THROUGH MUCH OF THE DAY ALLOWING STRONG
HEATING.
BY MID/LATE AFTERNOON...A SHORTWAVE TROUGH INDICATED IN WATER VAPOR
IMAGERY OVER THE TX PANHANDLE...ALONG WITH A SECOND AND STRONGER
TROUGH OVER CO...WILL APPROACH THE REGION. THIS WILL RAPIDLY WEAKEN
THE CAP AND ALLOW EXPLOSIVE THUNDERSTORM DEVELOPMENT ALONG THE
DRYLINE OVER WEST-CENTRAL OK...AND ALONG THE COLD FRONT EXTENDING
FROM CENTRAL OK INTO SOUTHWEST MO. DEEP LAYER EFFECTIVE SHEAR
VALUES ARE FAVORABLE FOR SUPERCELL STORMS CAPABLE OF VERY LARGE
HAIL...DAMAGING WINDS...AND TORNADOES. SHEAR VECTORS PERPENDICULAR
TO THE N-S DRYLINE OVER CENTRAL OK WILL FAVOR DISCRETE STORM
STRUCTURES. ALL 12Z MODEL GUIDANCE INDICATES RAPID INTENSIFICATION
OF THE LOW LEVEL JET OVER CENTRAL OK BY EVENING AS THE UPPER TROUGH
APPROACHES. GIVEN THESE PARAMETERS...IT APPEARS THE THREAT OF A FEW
STRONG/VIOLENT TORNADOES ARE IN PLACE. HAVE INCREASED SEVERE
PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK
WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF
SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.
DURING THE EVENING...NUMEROUS THUNDERSTORMS ARE EXPECTED TO CONGEAL
INTO A FAST-MOVING MCS THAT TRACKS NORTHEASTWARD ACROSS NORTHEAST OK
INTO SOUTHWEST KS. HIGH CAPE VALUES AND AN INCREASING LOW LEVEL JET
WILL PROMOTE THE POTENTIAL FOR WIDESPREAD WIND DAMAGE...ALONG WITH
LARGE HAIL AND ISOLATED TORNADOES.
...IA/MN/WI...
AN UPPER LOW IS PRESENT THIS MORNING OVER WESTERN SD...WITH MULTIPLE
SHORTWAVE TROUGHS ROTATING NORTHWARD ACROSS IA/MN. STRONG DAYTIME
HEATING IS OCCURRING AHEAD OF THE SHORTWAVE TROUGHS OVER PARTS OF
MN/WI/IA WHERE MODERATE AFTERNOON CAPE IS EXPECTED. SCATTERED
THUNDERSTORMS ARE EXPECTED TO FORM BY MID AFTERNOON OVER MN/IA AND
TRACK NORTHEASTWARD. A FEW OF THESE STORMS COULD BE SUPERCELLULAR
WITH A RISK OF HAIL/DAMAGING WINDS OR AN ISOLATED TORNADO.
...IL/IND...
AN ONGOING CLUSTER OF THUNDERSTORMS IN THE STL AREA MAY RE-INTENSIFY
THIS AFTERNOON AS IT TRACKS INTO AN INCREASINGLY MOIST/UNSTABLE AIR
MASS OVER IL/IND. IF THIS OCCURS...LOCALLY DAMAGING WINDS AND HAIL
WILL BE POSSIBLE.