MESO: Mesoscale Discussion 1222

ACUS11 KWNS 252016
SWOMCD
SPC MCD 252015
ILZ000-WIZ000-IAZ000-MNZ000-252245-

MESOSCALE DISCUSSION 1222
NWS STORM PREDICTION CENTER NORMAN OK
0315 PM CDT TUE JUN 25 2013

AREAS AFFECTED...PORTIONS OF SRN MN...NRN IA...NRN IL...SRN WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 252015Z - 252245Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE AREA IS BEING MONITORED FOR INCREASING SVR POTENTIAL
THIS AFTERNOON. THE ISSUANCE OF A WW IS POSSIBLE.

DISCUSSION...THE LATEST 7-KM CAPPI DATA INDICATE AN UPTICK IN
CONVECTION ALONG AN AGGREGATE SYNOPTIC FRONT/OUTFLOW BOUNDARY LYING
FROM S-CNTRL MN ESEWD TO NEAR CHICAGO. LOW-LEVEL ASCENT ALONG THIS
BOUNDARY IS AUGMENTING BACKGROUND ISENTROPIC ASCENT ACCOMPANYING A
MODEST...20-25-KT LOW-LEVEL JET MAX. IN THE NEAR TERM...THE
MODEST...SHALLOW NATURE OF THE ASCENT BREEDS UNCERTAINTY REGARDING
THE SUSTENANCE OF STRONG/DEEP CONVECTION INTO THE LATE AFTERNOON
HOURS. HOWEVER...GIVEN STEEP MID-LEVEL LAPSE RATES ATOP HIGH THETA-E
IN THE BOUNDARY LAYER...MLCAPE VALUES OF 2000-3000 J/KG ARE COMMON
ACROSS THE AREA AMIDST SUFFICIENT DEEP SHEAR FOR ORGANIZED STORM
STRUCTURES. A CONDITIONAL THREAT FOR SVR HAIL WILL EXIST ACROSS THE
REGION WITH THIS ACTIVITY...AND SVR WINDS MAY ALSO BE OF CONCERN
NEAR/S OF THE BOUNDARY WHERE EFFECTIVE INFLOW LAYERS ARE BASED
CLOSER TO THE SFC. THIS COULD REQUIRE WW ISSUANCE DURING THE NEXT
COUPLE OF HOURS OR SO IF CONVECTIVE TRENDS SUGGEST A GREATER
LIKELIHOOD OF SUSTAINED...SVR CONVECTION.

..COHEN/KERR.. 06/25/2013

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

ATTN...WFO...LOT...MKX...DVN...ARX...MPX...DMX...

LAT...LON 43579484 44039481 44249396 44039179 42988847 42138773
41748859 41869058 42249233 42989412 43579484

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