Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231611

Area Forecast Discussion
National Weather Service Lincoln IL
1111 AM CDT Fri Mar 23 2018

Issued at 1102 AM CDT Fri Mar 23 2018

Very little change in forecast so far. Surface low developing over
the lee of the rockies in CO, with easterly flow over central IL
from the influence of the high pressure ridge that extends from
the Great Lakes into southern IN. Overruning pcpn still forecast
to develop late afternoon and through evening, with heavy snow
forming overnight.


.SHORT TERM...(Today through Saturday)
ISSUED AT 314 AM CDT Fri Mar 23 2018

A late season winter storm is still slated to impact north-central
Illinois tonight into Saturday...bringing heavy wet snow to the
far northern KILX CWA. 00z Mar 24 models show a less pronounced
warm layer aloft than in previous runs, suggesting the rain/snow
line will be slightly further south than originally anticipated.
QPF with this system remains virtually unchanged, with widespread
liquid amounts of 1 to 1.5 inches. Based on thermal profiles, it
appears precipitation will begin as rain this afternoon into the
early evening, then will begin mixing with and changing to snow
across the far north toward midnight. Strongest isentropic upglide
as seen on the 295K surface is focused overnight into Saturday
morning when the snow will become moderate to heavy at times. As
low pressure tracks across the Ozarks into western Kentucky,
colder air will gradually get drawn southward...allowing the
rain/snow line to slip southward toward the I-72 corridor by late
Saturday afternoon. Isentropic lift quickly wanes as the day
progresses, with any lingering rain/snow showers coming to an end
by evening. Snowfall with this system will be heaviest along and
north of a Gridley line...where 6 to 8
inches with locally higher amounts are expected. Further south,
snow totals will rapidly decrease...with 1 to 2 inches along a Paris line. Little or no snow
accumulation is expected elsewhere around central and southeast
Illinois. Given the forecast snowfall amounts, will be upgrading
the current Watch to a Winter Storm Warning for Stark, Marshall,
and Woodford counties...and will be issuing a Winter Weather
Advisory for Knox, Peoria, Tazewell, McLean, Champaign, and
Vermilion counties. In addition to the rain and snow, winds will
be on the increase across the area as well, with E/NE gusts
reaching 35-40mph late tonight into Saturday.

.LONG TERM...(Sunday through Thursday)
ISSUED AT 314 AM CDT Fri Mar 23 2018

High pressure will build into the Great Lakes behind the departing
storm system, providing cool/dry weather Sunday and Sunday night.
As upper ridging develops east of the Mississippi River early
next week, temperatures will respond accordingly...with highs
climbing well into the 50s on Monday, then into the upper 50s and
lower 60s by Tuesday. Rain chances will increase as well, as the
next storm system slowly approaches from the west. Based on model
consensus, it appears the best chance for widespread showers and
even a few thunderstorms will be Monday night through Tuesday
night before the system slowly settles southward into the Ohio
River Valley.


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 538 AM CDT Fri Mar 23 2018

A storm system developing in the lee of the Rockies will spread
low clouds and precip across central Illinois later today and
tonight. Dry easterly flow preceding the system will keep the
steadiest/most widespread precip west of the terminals until this
evening. Based on forecast soundings, it appears ceilings will
lower to MVFR at KSPI by 00z...then further northeast to KBMI/KCMI
by around 05z. Conditions will further deteriorate overnight into
Saturday morning as ceilings lower to IFR. In addition to the low
ceilings and precip, strong easterly winds will develop. Model
guidance indicates gusts of 25-30kt late tonight into Saturday


Winter Weather Advisory from 7 PM this evening to 4 PM CDT
Saturday for ILZ027-029-037-038-045-046.

Winter Storm Warning from 7 PM this evening to 4 PM CDT Saturday
for ILZ028-030-031.



LONG TERM...Barnes
AVIATION...Barnes is the U.S. government's official web portal to all federal, state and local government web resources and services.