DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 021945
SWODY1
SPC AC 021943

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CDT MON JUL 02 2012

VALID 022000Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND TONIGHT
ACROSS PARTS OF THE NRN PLAINS/UPPER MS VALLEY INTO THE UPPER GREAT
LAKES...

...20Z OUTLOOK UPDATE...
NO SIGNIFICANT CHANGES HAVE BEEN MADE...ONLY A MINOR TWEAK TO 5
PERCENT SEVERE PROBABILITY LINES TO ENCOMPASS A SLIGHTLY GREATER
PORTION OF THE MIDDLE MISSISSIPPI VALLEY...WHERE DAYTIME HEATING HAS
CONTRIBUTED TO STRONG INSTABILITY...AND CONVECTIVE DEVELOPMENT IS
NOW UNDERWAY. THE SEVERE THREAT ACROSS MUCH OF THE MIDDLE
MISSISSIPPI VALLEY INTO THE SOUTHEAST STILL APPEARS LIMITED TO
RELATIVELY LOCALIZED DOWNBURSTS...AND PERHAPS SOME HAIL IN SHORT-
LIVED STRONGER UPDRAFT PULSES.

SEVERE WEATHER POTENTIAL ACROSS PARTS OF THE EASTERN DAKOTAS INTO
UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES REGION REMAINS THE
PRIMARY CONCERN LATE THIS AFTERNOON INTO TONIGHT. THERMODYNAMIC
PROFILES ACROSS THIS REGION ARE CHARACTERIZED BY HIGH MOISTURE
CONTENT IN LOW-LEVELS...STEEP MID-LEVEL LAPSE RATES...AND LARGE
CAPE. DEEP LAYER MEAN FLOW IS STILL SOMEWHAT WEAK...GENERALLY LESS
THAN 30 KT...AS THE MAIN SHORT WAVE TROUGH WITHIN THE STRONGER
WESTERLIES LIFTS NORTH OF THE CANADIAN/U.S. BORDER AREA...THROUGH
MANITOBA. HOWEVER...A WEAKER IMPULSE...OF EITHER SUBTROPICAL OR
TROPICAL ORIGINS...IS IN THE PROCESS OF LIFTING THROUGH THE CENTRAL
DAKOTAS...AND COULD CONTRIBUTE TO FORCING FOR UPWARD VERTICAL MOTION
WITHIN A LINGERING LOWER/MID TROPOSPHERIC WARM ADVECTION REGIME
ACROSS THE EASTERN DAKOTAS INTO WESTERN MINNESOTA LATE THIS
AFTERNOON. GUIDANCE REMAINS SUGGESTIVE THAT INHIBITION
...ASSOCIATED WITH VERY WARM ELEVATED MIXED LAYER AIR THAT REMAINS
PRESENT ACROSS THIS REGION...WILL WEAKEN...WITH A CONSIDERABLE
INCREASE IN STORM COVERAGE AND UPSCALE CONVECTIVE GROWTH.

STRENGTHENING AND CONSOLIDATING COLD POOLS MAY BE ACCOMPANIED BY THE
EVOLUTION OF AN ORGANIZED MESOSCALE CONVECTIVE SYSTEM THAT SHOULD
TEND TO FORWARD PROPAGATE...EAST SOUTHEASTWARD INTO PARTS OF THE
UPPER PENINSULA OF MICHIGAN AND NORTHERN WISCONSIN TONIGHT.
RESIDUAL BOUNDARY LAYER INSTABILITY...COUPLED WITH SOME
STRENGTHENING OF LOWER/MID TROPOSPHERIC WIND FIELDS...PROBABLY WILL
BE SUFFICIENT TO MAINTAIN A RISK FOR DAMAGING WINDS AND SOME HAIL
OVERNIGHT.

..KERR.. 07/02/2012

.PREV DISCUSSION... /ISSUED 1113 AM CDT MON JUL 02 2012/

...ERN ND/FAR NERN SD INTO UPR GRTLKS...
LATE MORNING OBSERVATIONS SHOW A RESERVOIR OF LWR 70F SFC DEW POINTS
SITUATED BENEATH LAPSE RATES IN EXCESS OF 7-9 DEG C PER KM FROM ERN
ND SEWD INTO THE UPR MS VLY. UNINHIBITED AFTN HEATING WILL
THEREFORE SET THE STAGE FOR MLCAPE VALUES APPROACHING 3000-4000
J/KG.

ALTHOUGH THERE REMAINS UNCERTAINTY AMONG DETERMINISTIC...ENSEMBLE
AND CONVECTION ALLOWING MODELS...THE ELEVATED TSTM CLUSTER OF
CNTRL/NRN ND SHOULD CONTINUE EWD TOWARD NRN MN THROUGH MID-AFTN. AS
DOWNSTREAM INHIBITION CONTINUES TO WEAKEN...STORMS SHOULD BECOME
MORE SFC-BASED. DEEP LAYER SHEAR OF 35-40 KTS AND MAGNITUDE OF
LAPSE RATES SUGGEST INITIAL STORMS COULD EVOLVE INTO SUPERCELLS WITH
VERY LARGE HAIL AND PERHAPS A TORNADO. EVENTUALLY...AS COLD POOLS
CONGLOMERATE...A BOW ECHO MAY EVOLVE AND ACCELERATE ESE ACROSS NRN
AND CNTRL PARTS OF MN BY EVENING...ALTHOUGH CONFIDENCE IN THIS
SCENARIO IS SOMEWHAT LIMITED. IF THE MODE INDEED DEVELOPS IN THIS
MANNER...STORMS COULD REACH PARTS OF CNTRL/NRN WI AND UPR MI BY LATE
THIS EVENING WITH AN ATTENDANT RISK OF SIGNIFICANT DMGG WIND GUSTS.
IT IS POSSIBLE THAT A PORTION OF THE SLIGHT RISK AREA
COULD BE UPGRADED TO A MODERATE RISK IN LATER D1 UPDATES.

...CNTRL/ERN SD INTO THE CNTRL HIGH PLAINS...
ISOLD TO WDLY SCTD TSTMS WILL BE PSBL ALONG A PRE-FRONTAL/LEE TROUGH
ACROSS THE REGION LATE THIS AFTN/EVE. HERE...VERTICAL SHEAR WILL
REMAIN COMPARATIVELY WEAKER THAN POINTS FARTHER N.
HOWEVER...PRESENCE OF STEEP LAPSE RATES ATOP A DEEPLY-MIXED BOUNDARY
LAYER WILL SUPPORT GUSTY WINDS AND SOME HAIL IN STRONGEST STORMS.

...SERN STATES...
THIS MORNINGS UPR AIR ANALYSIS CLEARLY SHOWS THAT THE
LOW/MID-TROPOSPHERE HAS COOLED SINCE LAST EVE AS EXTENSIVE MCS
CLUSTERS MOVED THROUGH THE REGION. STRONGEST POTENTIAL FOR TSTMS
WILL LIKELY EXIST ALONG/W OF A CONVECTIVELY INDUCED BOUNDARY FROM
PARTS OF THE MID-SOUTH SEWD INTO AL/WRN FL PNHDL. IN THIS
REGION...ERN FRINGE OF A STRONG EML STILL EXISTS AMIDST PWAT VALUES
OF 1.8 INCHES. AS A RESULT...ANY STRONGER CORE THAT EVOLVES MAY
PRODUCE A MICROBURST OR SOME HAIL.

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