Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 200120
SWOMCD
SPC MCD 200119
INZ000-ILZ000-WIZ000-IAZ000-MNZ000-200245-

Mesoscale Discussion 1357
NWS Storm Prediction Center Norman OK
0819 PM CDT Wed Jul 19 2017

Areas affected...Northern IL...Southern WI

Concerning...Severe Thunderstorm Watch 423...

Valid 200119Z - 200245Z

The severe weather threat for Severe Thunderstorm Watch 423
continues.

SUMMARY...Severe squall line will progress across central into
eastern portions of WW423 over the next two hours.

DISCUSSION...Long-lived MCS has cycled and matured into a
fast-moving complex as it progresses across southern WI and northern
IL. Latest radar data suggests the leading edge of a bow-shaped
squall line is surging southeast at roughly 50kt. Given this
speed/movement it appears the squall line will approach the
northwestern Chicago metro between 0200-0230z, and the lake shore
around 0230z. There is a possibility for widespread damaging winds
along the leading edge of this convection.

..Darrow.. 07/20/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LOT...MKX...DVN...ARX...

LAT...LON   43539162 42968743 41228743 41799162 43539162




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