DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 192000
SWODY1
SPC AC 191958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT TUE JUN 19 2012

VALID 192000Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY TO THE
CNTRL HIGH PLAINS...

...UPPER MIDWEST...
CONSIDERED AN UPGRADE TO A WIND-DRIVEN MODERATE RISK IN PARTS OF
CNTRL MN. A STRONGLY UNSTABLE WARM SECTOR IS PREVALENT S OF A WARM
FRONT ARCING ACROSS E-CNTRL SD TO NRN WI WITH PRIMARY SURFACE LOW
NEAR HON AND AHEAD OF A COLD FRONT EXTENDING SWWD INTO SWRN NEB.
VERY STRONG DEEP-LAYER SHEAR EXISTS WITHIN THE WARM FRONTAL ZONE.
PRIMARY CONCERN IS WITH REGARD TO WARM MID-LEVEL TEMPERATURES AS
LEAD SHORT WAVE IMPULSE IS WELL REMOVED TO THE NW ALONG THE
MT/SASKATCHEWAN BORDER...AND UPSTREAM IMPULSE IS STILL OVER THE NRN
INTERMOUNTAIN WEST. CONVERGENCE INVOF SURFACE LOW SHOULD BE
SUFFICIENT FOR TSTM DEVELOPMENT BY EARLY EVENING...BEYOND THE
ELEVATED ONGOING CONVECTION OVER NRN MN. UPSCALE GROWTH AND
CONSOLIDATING COLD POOLS WILL BE NECESSARY FOR AN MCS TO OVERCOME
OPEN WARM SECTOR INHIBITION. IF THIS INDEED OCCURS...POTENTIAL IS
CERTAINLY THERE FOR HIGHER-END COVERAGE/INTENSITY OF ALL SEVERE
TYPES.

...CNTRL HIGH PLAINS...
WITH APPROACH OF THE SHORT WAVE IMPULSE OVER THE NRN INTERMOUNTAIN
WEST...ASCENT WILL STRENGTHEN AND YIELD TSTM CLUSTERS AFTER DARK.
SUFFICIENT VERTICAL SHEAR AND MUCAPE WILL EXIST FOR HAIL-PRODUCING
STORMS AND THUS HAVE EXTENDED SLIGHT RISK WWD.

..GRAMS.. 06/19/2012

.PREV DISCUSSION... /ISSUED 1110 AM CDT TUE JUN 19 2012/

AN AMPLIFYING UPPER TROUGH IS PRESENT THIS MORNING OVER THE
NORTHWEST U.S...WHILE UPPER RIDGING MAINTAINS CONTROL OVER THE
REMAINDER OF THE NATION. AT THE SURFACE...A LOW IS ANALYZED OVER
CENTRAL SD WITH A PRONOUNCED WARM FRONT EXTENDING EASTWARD INTO
SOUTHERN MN. THIS LOW AND WARM FRONT ARE FORECAST TO MOVE NORTHWARD
THROUGH THE DAY...ALLOWING A VERY MOIST/UNSTABLE AIR MASS TO SPREAD
ACROSS MUCH OF SOUTHERN/CENTRAL MN. THIS WILL SET THE STAGE FOR A
ROUND OF STRONG/SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING.

PRESENT INDICATIONS ARE THAT SCATTERED ELEVATED CONVECTION WILL
PERSIST THROUGH MUCH OF THE DAY ACROSS CENTRAL/NORTHERN MN WHERE
WARM ADVECTION AND LIFT IS OCCURRING. A FEW OF THESE STORMS COULD
PRODUCE MARGINALLY SEVERE HAIL.

THE PRIMARY SEVERE CONCERN WILL EVOLVE LATE THIS AFTERNOON AND
EVENING AS STORMS DEVELOP ALONG THE SURFACE WARM FRONT OVER CENTRAL
MN AND NORTHEAST SD. A COMBINATION OF MLCAPE VALUES OVER 3000 J/KG
AND STRONG LOW LEVEL/DEEP LAYER VERTICAL SHEAR WILL PROMOTE
SUPERCELL/BOW STRUCTURES CAPABLE OF LARGE HAIL...DAMAGING
WINDS...AND A FEW TORNADOES. THIS ACTIVITY MAY CONGEAL INTO A
FAST-MOVING BOW ECHO DURING THE EVENING...TRACKING ALONG THE
CORRIDOR OF HIGHER OUTLOOK PROBABILITIES ACROSS CENTRAL MN.

...SD/NEB...
FARTHER SOUTHWEST...THE LOW LEVEL JET IS FORECAST TO BECOME VERY
STRONG OVER NEB AFTER DARK. THIS SHOULD HELP TO INITIATE SCATTERED
THUNDERSTORMS ALONG AND JUST BEHIND THE SURFACE COLD FRONT MOVING
ACROSS THE AREA. FORECAST SOUNDINGS SHOW AMPLE CAPE AND SUFFICIENT
VERTICAL SHEAR FOR A RISK OF HAIL-PRODUCING STORMS.

...UPPER MI...
A LONG-LIVED BOW ECHO CONTINUES TO TRACK EASTWARD ACROSS UPPER MI.
LOCALLY DAMAGING WINDS REMAIN POSSIBLE ALONG THE LEADING EDGE OF THE
STORMS. THE ACTIVITY SHOULD MOVE INTO LAKE HURON AFTER 18Z...ENDING
THE SEVERE THREAT ACROSS THIS REGION.

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