DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 141617
SWODY1
SPC AC 141615

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1115 AM CDT THU JUN 14 2012

VALID 141630Z - 151200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
FROM THE UPPER GREAT LAKES AND UPPER MIDWEST INTO SOUTHERN PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EVENING
OVER ERN TX INTO WRN LA...

...SYNOPSIS...

COMPACT SHORTWAVE TROUGH AND ASSOCIATED 50-60 KT MIDLEVEL JET STREAK
OVER SRN SASKATCHEWAN/MANITOBA INTO THE DAKOTAS WILL TRANSLATE NEWD
INTO ONTARIO IN ADVANCE OF AN UPSTREAM SYSTEM PROGRESSING THROUGH
THE CANADIAN ROCKIES AND NRN INTERMOUNTAIN REGION. FARTHER
SOUTH...WATER VAPOR IMAGERY AND LATEST MODEL GUIDANCE INDICATE THAT
A NUMBER OF WEAK IMPULSES WILL MOVE FROM THE CNTRL/SRN ROCKIES INTO
THE ADJACENT PLAINS DURING THE D1 PERIOD.

AT THE SURFACE...NRN EXTENSION OF COLD FRONT FROM THE ERN DAKOTAS
INTO CNTRL HIGH PLAINS WILL MOVE THROUGH THE UPPER MS VALLEY INTO
UPPER MIDWEST WHILE SRN END STALLS DUE TO LEE CYCLONE DEVELOPMENT
OVER ERN CO. A WARM FRONT --ENHANCED BY CONVECTIVE OUTFLOW-- OVER
CNTRL MN WILL LIFT NWD WITHIN A PERSISTENT LOW-LEVEL WAA
REGIME...WHILE ELSEWHERE A DRYLINE/LEE TROUGH SHARPENS OVER THE SRN
HIGH PLAINS.

...UPPER MS VALLEY/UPPER MIDWEST...

SWRN FLANK OF NOCTURNAL...MN/WI MCS MAY PERSIST TODAY OWING TO
SUSTAINED WAA/ISENTROPIC ASCENT INVOF WARM FRONT/OUTFLOW BOUNDARY.
ADDITIONAL STORM DEVELOPMENT IS ANTICIPATED BY AFTERNOON ALONG COLD
FRONT AS DEEP-LAYER ASCENT IS ENHANCED BY DAKOTAS SHORTWAVE TROUGH.
12Z MPX SOUNDING SAMPLED THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES
AND THE POTENTIAL FOR DOWNWARD MIXING OF HIGHER MOISTURE
CONTENT...ALLOWING MLCAPE VALUES TO INCREASE TO 1000-2000 J/KG IN
AREAS THAT EXPERIENCE STRONGER DAYTIME HEATING. THIS INSTABILITY
WILL COINCIDE WITH GRADUALLY STRENGTHENING DEEP-LAYER SHEAR --OWING
TO THE EWD PROGRESSION OF MIDLEVEL JET STREAK MENTIONED ABOVE-- WITH
ENVIRONMENT BECOMING FAVORABLE FOR SUPERCELLS CAPABLE OF LARGE HAIL
AND DAMAGING WIND GUSTS. THE GREATEST THREAT FOR A FEW TORNADOES
WILL EXIST ALONG WARM FRONT/OUTFLOW BOUNDARY WHERE LOW-LEVEL SHEAR
WILL BE ENHANCED AND LCL HEIGHTS WILL REMAIN LOWER.

...MID MO VALLEY INTO SRN PLAINS...

12Z REGIONAL SOUNDINGS SHOW THE COLOCATION OF AN EML WITH LOWEST
100-MB MEAN-MIXING RATIOS OF 12-15 G/KG ACROSS WARM SECTOR WHICH
WILL YIELD A MODERATE-STRONGLY UNSTABLE ENVIRONMENT BY AFTERNOON
WITH MLCAPE OF 2000-4000+ J/KG. CONVERGENCE ALONG THE COLD FRONT
AND DRYLINE WILL BE AUGMENTED BY FORCING ASSOCIATED WITH WEAK
PERTURBATIONS MOVING OUT OF THE ROCKIES TO FOSTER WIDELY SCATTERED
TSTMS WITH THE POTENTIAL FOR UPSCALE GROWTH INTO MULTIPLE
CLUSTERS/MCSS TONIGHT.

MID AND HIGH-LEVEL WIND FIELD WILL REMAIN RATHER WEAK...THOUGH
FORECAST KINEMATIC PROFILES DO INDICATE VEERING WINDS WITH
HEIGHT...RESULTING IN DEEP-LAYER SHEAR APPROACHING 30 KT. THE
MARGINAL KINEMATIC ENVIRONMENT WILL BE COMPENSATED FOR BY THE DEGREE
OF INSTABILITY WITH SUPERCELLS POSSIBLE AS THE INITIAL CONVECTIVE
MODE WITH AN ATTENDANT RISK FOR LARGE HAIL AND DAMAGING WIND GUSTS.
EXPECT AN ISOLATED WIND/HAIL THREAT TO CONTINUE INTO TONIGHT IN
CONJUNCTION WITH EVOLVING TSTM CLUSTERS/MCSS.

...ERN TX/WRN LA...

TSTMS WILL LIKELY PERSIST TODAY...FORCED BY WEAK WAA/ISENTROPIC
ASCENT ALONG/E OF NNW-SSE ORIENTED OUTFLOW BOUNDARY OVER ERN TX.
12Z FWD/LCH SOUNDINGS SAMPLED THE PRESENCE OF A VERY MOIST
ENVIRONMENT ALONG ERN EDGE OF EML WHICH WILL RESULT IN A
MODERATE-STRONGLY UNSTABLE AIR MASS BY AFTERNOON. THOUGH VERTICAL
SHEAR WILL REMAIN RELATIVELY WEAK...THE PRESENCE OF STEEP LAPSE
RATES AND HIGH PW CONTENT INDICATE A RISK FOR LARGE HAIL AND
DAMAGING WINDS WITH THE MOST INTENSE STORMS.

..MEAD/MOSIER.. 06/14/2012

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