[LeArc] MESOSCALE DISCUSSION 1648

[Duane Whittingham]

MESOSCALE DISCUSSION 1648
NWS STORM PREDICTION CENTER NORMAN OK
0948 AM CDT SUN JUL 06 2003
   
AREAS AFFECTED...ERN IA...NE MO...NRN IL...SE WI
   
CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
VALID 061448Z - 061645Z
   
WW MAY BE NEEDED WITHIN THE NEXT 1 TO 2 HOURS.
   
MID-LEVEL SHORT WAVE TROUGH/JET STREAK AND ASSOCIATED CENTER OF
CYCLONIC VORTICITY ARE READILY EVIDENT IN LATEST SATELLITE AND RADAR
IMAGERY OVER EASTERN IOWA.  SYSTEM IS STEADILY PROGRESSING EASTWARD
...AND WILL CONTINUE ACROSS THE MISSISSIPPI RIVER INTO SOUTHERN
WISCONSIN AND NORTHERN ILLINOIS BY THE 18-20Z TIME FRAME.  FORCING
FOR UPWARD VERTICAL MOTION IN ZONE OF DIFFERENTIAL POSITIVE
VORTICITY ADVECTION APPEARS LIKELY TO BECOME PRIMARY FOCUS FOR
INCREASING/INTENSIFYING CONVECTIVE DEVELOPMENT NEXT FEW HOURS. THIS
IS EXPECTED TO MAINLY OCCUR ALONG/EAST OF THE MISSISSIPPI RIVER FROM
PARTS OF WEST CENTRAL ILLINOIS INTO SOUTHERN WISCONSIN...WHERE
BOUNDARY LAYER STABILIZED BY NOCTURNAL COOLING AND PREVIOUS
CONVECTIVE OUTFLOW IS RECEIVING STRONG DAYTIME HEATING.
   
 AS SURFACE TEMPERATURES CLIMB INTO THE LOWER/MID 80S...MEAN MIXED
LAYER CAPE APPEARS LIKELY TO INCREASE IN EXCESS OF 2000 J/KG...
SUPPORTIVE OF VIGOROUS UPDRAFTS WITH HEAVY RAINFALL.  VERTICAL SHEAR
ASSOCIATED WITH 35-40 KT MID-LEVEL JET MAY ENHANCE POTENTIAL FOR
HAIL...THOUGH THIS MAY BE MARGINALIZED BY WARM THERMODYNAMIC
PROFILES.  LOW-LEVEL FLOW IS WEAK...BUT AS CONVECTIVE CLUSTER SLOWLY
EVOLVES...RELATIVE HUMIDITIES IN LOWER/MID-LEVELS APPEAR LOW ENOUGH
TO SUPPORT SUBSTANTIAL SURFACE COLD POOL WHICH MAY BE ACCOMPANIED BY
DAMAGING WINDS ALONG ASSOCIATED GUST FRONT.  THIS SHOULD SPREAD INTO
AREAS NEAR/SOUTHWEST OF CHICAGO BY AROUND 20Z.
   
..KERR.. 07/06/2003

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Duane Whittingham (N9SSN) - Producer
Tom and Darryl Radio Shows & Saturday Morning Confusion
Heard on C-Band Analog Satellite (W0KIE) - GE7-CH5-7.5 mHz
WTND-LP Macomb 106.3, WQNA FM, WBCQ 7415 kHz & the Internet.
Heard Fridays 9pm ET, Sundays 12am ET and Tuesdays 1am ET
An Independent Freeform Eclectic Radio Show.
http://www.tomanddarryl.org
http://www.wtnd.us

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