DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 290102
SWODY1
SPC AC 290100

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT THU JUN 28 2012

VALID 290100Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS EXTREME NERN IL TO WRN
PA...

...SYNOPSIS...
UPPER-AIR PATTERN WILL REMAIN DOMINATED BY STG ANTICYCLONE ALOFT
THAT COVERS MUCH OF CONUS S OF ABOUT 40N. SLGT WEAKNESS/COL IS
EVIDENT IN THAT REGIME OF RIDGING OVER OK...MARKING NRN PORTIONS OF
TROUGHING THAT EXTENDS NWD FROM BROAD/WEAK UPPER CYCLONE CENTERED
OVER S TX. THIS WILL CONTINUE TO SPLIT ANTICYCLONE IN TWO...WITH
ERN MEMBER OVER TN VALLEY REGION AND WRN UPPER HIGH CENTER OVER NM
BY END OF PERIOD. RIDGING ALOFT WILL EXTEND FROM 4-CORNERS REGION
NNWWD ACROSS N-CENTRAL ROCKIES TO NRN HIGH PLAINS. MOISTURE CHANNEL
IMAGERY INDICATES SHORTWAVE TROUGH FROM SERN LM TO NRN LOWER
MI...NWRN LH AND ADJOINING PORTIONS ONT...MOVING GENERALLY EWD.
THIS PERTURBATION IS EXPECTED TO TRACK ESEWD...REACHING SRN NEW
ENGLAND AND JUST OFFSHORE NJ BY 12Z.

AT SFC...AT 23Z...COLD FRONT WAS NEARLY COLLOCATED WITH MID/UPPER
TROUGH OVER MI/LM...EXTENDING WSWWD ACROSS S-CENTRAL IA AND BECOMING
QUASISTATIONARY OVER S-CENTRAL NEB. IA/IL PORTION OF FRONT SHOULD
STALL THROUGH REMAINDER PERIOD WHILE ERN SEGMENT PROCEEDS EWD/SEWD
OVER LOWER GREAT LAKES AND INTERIOR MID-ATLC REGION.

...GREAT LAKES...
REF WW 433 AND ACCOMPANYING MESOSCALE DISCUSSIONS FOR LATEST
NEAR-TERM INFO.

IN ADDITION TO COLD FRONT...LAKE BREEZE BOUNDARIES ARE AFFECTING
CONVECTIVE DEVELOPMENT OVER NERN IL/NWRN INDIANA...IN ENVIRONMENT
OTHERWISE CHARACTERIZED BY INTENSE MLCINH THAT HAS BEEN PREVENTING
PERSISTENCE IN EARLIER DEVELOPMENT. AREA ALSO LIES WITHIN ERN
PORTION OF PLUME OF VERY UNSTABLE BOUNDARY-LAYER AIR...WITH SFC
TEMPS 90S TO NEAR 100 F AND DEW POINTS MID 70S CONTRIBUTING TO
4000-6000 J/KG MLCAPE. MLCAPE DECREASES AND MLCINH INCREASES WITH
EWD EXTENT ACROSS NRN INDIANA AND OH...BUT NOT TO AN EXTENT
PROHIBITIVE FOR SWATH OF SVR HAIL AND TSTM WIND POTENTIAL -- GIVEN
RISK OF UPSCALE GROWTH AND STG COLD-POOL ORGANIZATION AND RELATE
FORCED ASCENT ON MESO-BETA TO STORM SCALES. AS SUCH...PROBABILITIES
HAVE BEEN BOOSTED TO CATEGORICAL OUTLOOK LEVELS FOR PART OF THAT
REGION ENCOMPASSING AND DOWNSHEAR OF WW AREA. MEANWHILE...WILL
MAINTAIN ERN LOBE OF CATEGORICAL THRESHOLD SVR PROBABILITIES IN
DEFERENCE TO SVR POTENTIAL DOWNSHEAR FROM TSTMS DEVELOPING OVER SERN
LOWER MI...PER EARLIER OUTLOOKS. REF SPC MESOSCALE DISCUSSION 1298
FOR ADDITIONAL NOWCAST INFO.

...CENTRAL PLAINS...
LARGE AREA OF ESSENTIALLY NON-SVR MULTICELLULAR CONVECTION HAS
DEVELOPED OVER CO...MOVING EWD TO ENEWD INTO REGIME CHARACTERIZED BY
WEAK DEEP-LAYER FLOW BUT INTENSE SFC HEAT AND INCREASING BUOYANCY
WITH EWD EXTENT OVER SRN NEB. DEEP/WELL-MIXED BOUNDARY LAYERS S OF
SFC FRONT WILL SUPPORT POTENTIAL FOR STG-SVR GUSTS WITH MOST INTENSE
CELLS...ESPECIALLY THOSE ON ERN PORTIONS OF COMPLEX AND ENCOUNTERING
POCKETS OF RESIDUAL/HOT BOUNDARY LAYERS NOT YET IMPACTED BY OUTFLOW.
ISOLATED SVR HAIL ALSO CANNOT BE RULED OUT.

..EDWARDS.. 06/29/2012

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