[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 211440
SWOMCD
SPC MCD 211440 
OHZ000-MIZ000-INZ000-ILZ000-WIZ000-211645-

MESOSCALE DISCUSSION 0794
NWS STORM PREDICTION CENTER NORMAN OK
0940 AM CDT FRI MAY 21 2004

AREAS AFFECTED...NE IL/LWR MI/NRN IND/NW OH

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 211440Z - 211645Z

CURRENT INDICATIONS ARE WW MAY NOT BE NEEDED...BUT CONVECTIVE TRENDS
WILL CONTINUE TO BE CLOSELY MONITORED.

LARGE CLUSTER OF INTENSE CONVECTION NOW PROGRESSING ACROSS THE
MILWAUKEE/CHICAGO METRO AREAS HAS BEEN SUPPORTED BY AGEOSTROPHIC
FORCING IN ENTRANCE REGION OF ANTICYCLONIC UPPER JET STREAK ACROSS
ONTARIO/QUEBEC.  HOWEVER...MODELS SUGGEST THIS FORCING WILL WEAKEN/
DEVELOP NORTHEASTWARD ACROSS NORTHERN LOWER MICHIGAN THROUGH EARLY
AFTERNOON...AS UPPER JET SHIFTS NORTHEASTWARD AND UPPER RIDGE SHIFTS
INTO THE GREAT LAKES REGION AHEAD OF NORTHERN/CENTRAL PLAINS SHORT
WAVE TROUGH.  IN RESPONSE TO UPSTREAM TROUGH...STRONG SOUTHERLY
LOW-LEVEL JET AND ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION IS
PROGGED TO REMAIN FOCUSED ALONG WARM FRONT LIFTING ACROSS MINNESOTA/
WISCONSIN.  THUS...LARGE-SCALE FORCING FOR CONTINUATION OF STRONG/
SEVERE MESOSCALE CONVECTIVE SYSTEM EAST OF LOWER LAKE MICHIGAN IS
UNCERTAIN.

COLD POOL ASSOCIATED WITH ONGOING CONVECTIVE SYSTEM LIKELY WILL
CONTINUE EAST OF LOWER LAKE MICHIGAN...ALONG WEAK FRONTAL ZONE WHICH
REMAINS NEAR THE MICHIGAN/INDIANA BORDER INTO NORTHERN OHIO.  THIS
WILL ENHANCE CONVERGENCE ALONG FRONT IN ENVIRONMENT WHICH IS
DESTABILIZING WITH HEATING OF BOUNDARY LAYER WITH DEW POINTS AROUND
70F.  WITH MEAN MIXED LAYER CAPE ON THE ORDER OF 2000 J/KG
...SUPPORTIVE OF SEVERE CONVECTION DESPITE WEAK SHEAR...PRIMARY
UNCERTAINTY IS WHETHER THIS LIFT WILL BE STRONG ENOUGH TO OVERCOME
RATHER SUBSTANTIAL...AND STRENGTHENING MID-LEVEL CAPPING.

..KERR.. 05/21/2004

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

ATTN...WFO...CLE...ILN...DTX...APX...IWX...GRR...LOT...MKX...

41678131 40828237 40638422 41078560 41178661 41058772
41238826 42258851 43148704 44698602 45718471 

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