DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 280600
SWODY1
SPC AC 280559

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT THU JUN 28 2012

VALID 281200Z - 291200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
UPPER-AIR PATTERN TODAY WILL BE DOMINATED AGAIN BY COMBINATION OF
1. INTENSE RIDGING ACROSS SRN 1/2 OF CONUS FROM SWRN DESERTS TO SC
COAST AND BEYOND...AND
2. BELT OF RELATIVELY FAST FLOW FROM PAC NW ACROSS NRN PLAINS AND
GREAT LAKES TO MID-ATLC/NEW ENGLAND REGIONS.
WITHIN THAT BELT...SHORTWAVE TROUGH NOW LOCATED OVER CO/WRN NEB/SD
IS FCST TO MOVE ENEWD ACROSS UPPER MS VALLEY EARLY IN PERIOD TO
WI...THEN CROSS LOWER MI BETWEEN 28/18Z-29/00Z...TURNING SEWD AND
REACHING MID-ATLC COAST BY END OF PERIOD. MEANWHILE...COMPACT
SHORTWAVE TROUGH NOW OVER NWRN CA COAST WILL MOVE NEWD ACROSS NRN
ROCKIES AND WEAKEN...AS SYNOPTIC-SCALE RIDGE ATTACHED TO SRN CONUS
ANTICYCLONE BUILDS OVER ROCKIES...BUT MAY SUPPORT SOME TSTM
POTENTIAL OVER NRN ROCKIES REGION. SWLY FLOW WILL PERSIST OVER PAC
NW REGION AHEAD OF NERN PAC TROUGHING. WEAK TROUGHING...IN ELY FLOW
ALOFT S OF MID-UPPER HIGH...WILL DRIFT ERRATICALLY OVER S TX.

AT SFC...WAVY FRONTAL ZONE WAS ANALYZED FROM LS SWWD ACROSS WI...ERN
NEB...NWRN KS AND ERN CO...BECOMING ILL-DEFINED OVER CENTRAL HIGH
PLAINS AMIDST ASSORTED TSTM OUTFLOWS. GREAT LAKES PORTION OF FRONT
WILL REMAIN PROGRESSIVE...MOVING EWD ACROSS LOWER MI DURING DAY AND
REACHING ERN NY AND CENTRAL/SRN PA BY 29/12Z. REMAINDER OF FRONT
WILL BECOME QUASISTATIONARY OVER PORTIONS NRN IL...IA AND
NEB...AGAIN BEING MODULATED ON MESOSCALE BY CONVECTIVE PROCESSES.

...GREAT LAKES STATES TO ERN IA...
SCATTERED TO WIDELY SCATTERED TSTMS IN CLUSTERS ARE
POSSIBLE...PRIMARILY INVOF SFC COLD FRONT WHERE LIFT PROVIDED BY
FRONT WILL HELP TO OVERCOME STG CAPPING AS IT IMPINGES UPON
DIABATICALLY DESTABILIZING DIURNAL BOUNDARY LAYER. ACTIVITY MAY
DEVELOP EARLY IN DAY OVER UPPER MS VALLEY REGION/WI AND MORE
PROBABLY NEAR LM AND LOWER MI BY MIDDAY TO MID-AFTERNOON. TSTMS
SHOULD INCREASE IN COVERAGE THROUGH AFTERNOON AS REGIME SHIFTS EWD
ACROSS LOWER MI...NRN OH AND WRN PA REGIONS. THOUGH WORKING WITH
MORE LIMITED SFC MOISTURE THAN SPECTRAL AND MANY SREF
MEMBERS...MOISTURE STILL WILL BE SUFFICIENT TO SUPPORT 1000-2000
J/KG MLCAPE ATOP WELL-MIXED BOUNDARY LAYER. SUBSTANTIAL WLY
COMPONENT OF FLOW AHEAD OF FRONT MAY LIMIT CONVERGENCE...BUT
POTENTIAL FOR AT LEAST ISOLATED DAMAGING GUSTS AND SVR HAIL WARRANTS
5% PROBABILITIES FOR THOSE SVR MODES.

...CENTRAL PLAINS...
LIFT ALONG FRONT AND OUTFLOW BOUNDARIES...ALONG WITH VERY INTENSE
SFC DIABATIC HEATING...WILL WEAKEN MLCINH THROUGH AFTERNOON IN
SUPPORT OF DEVELOPMENT OF HIGH-BASED/MULTICELLULAR TSTMS ACROSS
PORTIONS OF SRN/WRN NEB...NERN KS AND/OR NERN CO. THOUGH DEEP-LAYER
FLOW/SHEAR WILL BE WEAK...HIGH DCAPE AND DEEP/WELL-MIXED BOUNDARY
LAYERS WILL SUPPORT POTENTIAL FOR ISOLATED DAMAGING DOWNDRAFTS FROM
MOST INTENSE CELLS. POTENTIAL ALSO EXISTS FOR COLD-POOL
ORGANIZATION THAT COULD ENHANCE SVR POTENTIAL ON MESO-BETA
SCALE...BUT SUCH PROCESSES ARE TOO UNCERTAIN IN TIMING AND LOCATION
TO WARRANT GREATER THAN 5% UNCONDITIONAL LINE ATTM.

..EDWARDS/COHEN.. 06/28/2012

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