Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 142029

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
329 PM CDT Wed Mar 14 2018

314 PM CDT

Through Thursday...

Quiet and mostly clear conditions will prevail. Gusty west to
southwest winds this afternoon will subside and turn westerly
behind the passage of a surface trough overnight, then become
northerly during the day tomorrow as high pressure settles into
the western lakes.



314 PM CDT

Thursday night through Wednesday...

The primary period of interest comes Friday night as a low
pressure center moves out of the Plains and into the Ohio Valley.
Models are not in great agreement concerning the track of the low,
but the NAM and ECMWF generally have a similar solution that keeps
it farther south than the GFS and also are more progressive than
the Canadian model. Have thus leaned toward an ECM/NAM blend. The
concern for this period regards precipitation type, as warm air
aloft appears to wrap up around the colder surface airmass. MaxT
values aloft are not overly large, but soundings appear to be
somewhat isothermal which would allow for sufficient melting and
support freezing rain and sleet mixing in with rain south and snow
north. Given the QPF there could be some ice accumulation but at
this point there is still low confidence for the Friday night

After a quiet weekend the next low approaches the area on Monday.
Presently the GFS/ECM tracks keep the center south of the area and
support the idea of a rain to snow transition, perhaps with some
lake effect snow on the back end. Given the uncertainties with the
first system, will not attempt to get more detailed this far out.

Temperatures through the period will remain similar to existing
trends, with widespread 50s looking most likely on Sunday.



For the 18Z TAFs...

Gusty west to southwest winds this afternoon will relax this
evening then turn northwest overnight behind a passing cold front.
This northwesterly direction prevails through tomorrow afternoon
at which time winds flip around to the north and northeast. Skies
are expected to remain mostly clear.



314 PM CDT

High pressure over the lower Mississippi Valley will move to the
northern Gulf Coast tonight, while low pressure moves from
northern New England into Quebec. High pressure also will build
from northern Manitoba tonight to the Great Lakes on Friday.
Meanwhile, low pressure over the Central Plains will move from
the Central Plains to the Tennessee Valley Saturday, while

Small craft conditions mainly for waves along the Indiana shore
may persist beyond the end of the existing advisory.



LM...Small Craft Advisory...IL nearshore waters until 7 PM Wednesday.

     Small Craft Advisory...LMZ743-LMZ744-LMZ745...10 PM Wednesday to
     10 PM Thursday.




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