Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 021251
SWOMCD
SPC MCD 021251
MIZ000-WIZ000-MNZ000-021515-

MESOSCALE DISCUSSION 1583
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT SUN AUG 02 2015

AREAS AFFECTED...PORTIONS OF E-CNTRL MN...NRN/CNTRL WI...UPPER
PENINSULA OF MI...NRN LOWER MI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 021251Z - 021515Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...MULTIPLE CONVECTIVE CLUSTERS EVOLVING WITHIN A CORRIDOR
FROM CNTRL MN INTO NRN LOWER MI ARE BEING MONITORED FOR ISOLATED SVR
POTENTIAL. WHILE WW ISSUANCE IS NOT IMMINENTLY EXPECTED...THERE IS
SOME CONCERN THAT A GREATER SVR RISK COULD DEVELOP THIS MORNING --
DURING THE NEXT FEW HOURS -- AND THIS MAY WARRANT WW ISSUANCE ACROSS
A PART OF THE REGION.

DISCUSSION...SFC OBSERVATIONS INDICATE A QUASI-STATIONARY BOUNDARY
EXTENDING FROM LOW PRESSURE ANALYZED OVER W-CNTRL MN TO LOW PRESSURE
N OF EAU...WITH THE SAME BOUNDARY ARCING EWD/SEWD INTO WRN LOWER MI.
CLUSTERS OF CONVECTION BEING FED BY UNSTABLE AIR ABOVE THE
NOCTURNALLY COOLED PBL ARE ONGOING N OF THE BOUNDARY IN A WAA
REGIME. RELATED ISENTROPIC ASCENT IS BEING ENHANCED IN CONJUNCTION
WITH A MID-LEVEL SPEED MAX CROSSING THE REGION AND IN ADVANCE OF A
SHORTWAVE TROUGH PROGRESSING ESE FROM THE SRN CANADIAN PRAIRIE
PROVINCES PER MOISTURE-CHANNEL IMAGERY.

THE 12Z RAOBS AT MPX AND ABR SAMPLED AN EML PLUME WITH H7-H5 LAPSE
RATES AROUND 8 C/KM...WHICH WILL CONTINUE TO BE ADVECTED OVER THE
UPPER MIDWEST AND UPPER GREAT LAKES REGION. MEANWHILE...RELATIVELY
RICHER PBL MOISTURE S OF THE SFC BOUNDARY -- ASSOCIATED WITH
LOWER/MIDDLE 60S SFC DEWPOINTS -- WILL CONTINUE TO SPREAD NEWD TO
THE E OF THE WI SFC CYCLONE. THIS WILL ESTABLISH AN INCREASE IN
SFC-BASED BUOYANCY ACROSS PARTS OF THE REGION...ESPECIALLY AS AREAS
OF INSOLATION ENCOURAGE SFC HEATING. AS SUCH...ONGOING CONVECTION
MAY CONTINUE TO INCREASE IN COVERAGE AND INTENSITY. ADDITIONAL TSTM
DEVELOPMENT WILL BE POSSIBLE GIVEN THE ALREADY-PRESENT FORCING FOR
ASCENT MARKED BY 2-HOURLY SFC PRESSURE FALLS AROUND 1.5-2 MB ACROSS
THE REGION. GIVEN 40-50 KT OF DEEP SHEAR SAMPLED BY AREA VWPS AND
12Z RAOBS...UPSCALE CONVECTIVE GROWTH WILL BE POSSIBLE...WITH
25-40-KT WLYS AROUND H85 FACILITATING FAST-MOVING COLD POOLS WITH
SVR-WIND POTENTIAL. SVR-WIND POTENTIAL ASIDE...THE STEEP LAPSE
RATES/MODERATE SHEAR WILL SUPPORT HAIL POTENTIAL...ESPECIALLY WITH
ANY MORE DISCRETE UPDRAFTS.

ULTIMATELY...CONFIDENCE IN UPSCALE CONVECTIVE GROWTH AND A
GREATER-COVERAGE SVR RISK -- IN THE SHORT-TERM -- IS LIMITED...AS
STRONGER DCVA IS STILL DISPLACED UPSTREAM AT PRESENT.
REGARDLESS...AT LEAST ISOLATED SVR RISK WILL CONTINUE THROUGH THE
MORNING HOURS. THE ONGOING INCREASE IN CONVECTIVE COVERAGE SUGGESTS
SOME POSSIBILITY IN WW ISSUANCE THIS MORNING. THIS WOULD ESPECIALLY
BE THE CASE IF A MORE ORGANIZED CONVECTIVE CLUSTER/BOWING SEGMENT
WERE TO BECOME EVIDENT AND JUXTAPOSED WITH HIGHER THETA-E AIR IN
CLOSER PROXIMITY TO THE SFC BOUNDARY.

..COHEN/EDWARDS.. 08/02/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...APX...GRR...MQT...GRB...DLH...ARX...MPX...

LAT...LON   45018360 44238435 43978638 44048948 44679304 45289505
            45819531 46319405 46208824 45798520 45018360



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