Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 190953

Area Forecast Discussion
National Weather Service Lincoln IL
353 AM CST Mon Feb 19 2018

.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CST Mon Feb 19 2018

An amplified upper level flow regime across the country will
prevail during the upcoming week, and keep central and southeast
IL in a very moist sw flow with several chances of moderate to
heavy rain. Will see a growing threat for flooding as the week
progresses, therefore will reissue the ESF product to cover this
potential developing flood situation during this week.

Radar mosaic shows scattered showers and isolated thunderstorms
south of Macomb to Rantoul line at 330 am and were tracking
quickly ne. This convection caused by a warm front lifting
northward across central IL and precipitable water values rising
to 1-1.25 inches. Breezy SSE winds of 8-18 mph and some gusts to
around 25 mph have been causing temperatures to slowly rise during
the night. Current mercury levels range from 41F at Galesburg and
Lacon, to lower 50s along and south of a Pittsfield to Effingham
to Terre Haute line. Breezy south winds 15-25 mph and gusts of
25-35 mph today to bring unseasonably mild air today with highs in
the 60s, warmest from Springfield and Robinson sw where upper 60s
to near 70F.

Latest forecast models shows 999 mb surface low pressure over ne
KS ejecting ne into nw IL by early this evening, and into the
western Great Lakes by dawn Tue while pushing cold front toward
the IA/IL border. Very moist air mass spreading over CWA today as
precipitable water values peak around 1.50 inches across heart of
CWA during the day. This will continue periods of showers and
isolated thunderstorms spreading ne over much of CWA especially
from I-70 north today and tonight. Rainfall amounts range from
three quarter to 1.5 inches along and north of I-70 through
sunrise Tuesday. Unseasonably mild lows tonight in the upper 50s
and lower 60s, except near 50F far nw CWA by Galesburg.


.LONG TERM...(Tuesday through Sunday)
ISSUED AT 345 AM CST Mon Feb 19 2018

00Z forecast models have trended a bit quicker with pushing strong
cold front se through the IL river valley during Tue afternoon and
thru rest of central IL during Tue evening, and into southeast IL
overnight Tue night, approaching the Ohio river by dawn Wed.
Heaviest rainfall over the IL river valley Tue afternoon, shifts
into central IL Tue evening and into southeast IL overnight Tue
night. Another 1-2 inches of rain expected from Tue through Wed
morning across CWA, with 2-2.5 inches se of I-55. This time frame
it the most vulnerable for flooding over central and southeast IL
from Tue afternoon through Tue night, and continue over southeast
IL into Wed. A flood watch may eventually be needed during this
time frame. Highs Tue contrast from upper 50s by Galesburg, to
the lower 70s in southeast IL. Rain Tue evening, will change to
freezing rain and sleet late Tue evening at Galesburg and spread
into central IL during overnight Tue night with around a tenth
inch of ice possible by Wed morning west of a Rantoul to Decatur
to Taylorville line and this area may eventually need a winter
weather advisory. The IL river valley dries out briefly on Wed
while rain likely continues in southeast IL, with mixed pcpn over
central part of CWA Wed morning and mainly light rain Wed
afternoon. Highs Wed range from mid 30s over IL river valley, to
low to mid 40s in southeast IL.

Stayed close to consensus of models for forecast from Thu through
this weekend. Thu and Thu evening appear to be a dry period as
strong high pressure drifts east across the Great Lakes. But more
rain spreads ne across area during overnight Thu night into Fri
and continues through Sat night as a couple waves move ne along
frontal boundary se of CWA. Mixed pcpn including snow is possible
over nw CWA overnight Thu night into Fri morning and again
overnight fri night into early Sat morning. Additional rainfall
amounts of 1-2 inches possible south of I-72 late this week with
locally 2-3 inches by Lawrenceville. Highs range from 40-50F from
nw to se on Thu, and from 45-55F Fri-Sun, except upper 50s in
southeast IL this weekend.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1150 PM CST Sun Feb 18 2018

Showers are developing and moving across the area so all sites
will see vcsh/-shra overnight. Do not see a lot of rain back to
west, but models continue to forecast more showers moving across
the area during the overnight hours. Cigs will also drop into MVFR
category as lower layers moisten more. Then expecting IFR cigs
toward morning as more rain moves through, and also lower
vis...some sites seeing 2sm with the rain. Cigs and vis could come
up some during the afternoon but then drop back down again during
the evening. Also have VCTS for tomorrow afternoon and evening.
Winds will be southerly through the period with gusts some
overnight but mostly tomorrow during the day and into the evening.
Also continue to have LLWS around 50kts tonight at all TAF sites.
Could be some again tomorrow night, but gusty winds on the
surface causes criteria not to be met.


Issued at 330 AM CST Mon Feb 19 2018

With a good portion of the forecast area abnormally dry with areas
from Lincoln to Newton southwest in moderate drought, the rain
will initially be able to soak into the soil. However areas north
of Peoria still has several inches of frost depth. This should
erode quickly with the warm temperatures today and Tuesday. With
time, the extended rain periods will begin to run off more into
area rivers and streams. Latest significant river flood outlooks
from the North Central and Ohio River Forecast Centers highlight
the increasing risk of rivers reaching moderate flood stage over
our area. Flooding is forecast to develop on the Little Wabash
River as early as Tuesday morning, and other rivers are likely to
follow. Additional rains late this week in parts of the area
especially southeast of I-55 will help keep river levels high
into this weekend. People with river interests should monitor the
latest projections closely.


Issued at 330 AM CST Mon Feb 19 2018

Record highs Monday and Tuesday:

               Monday    Tuesday
Bloomington... 70/1930   68/2017
Champaign..... 68/2017   71/2017
Decatur....... 66/1930   70/2017
Lincoln....... 71/1930   74/2017
Olney......... 72/1930   70/1930
Peoria........ 71/1930   74/2017
Springfield... 71/2017   76/2017





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