Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 230440

Area Forecast Discussion
National Weather Service Lincoln IL
1140 PM CDT Sun Apr 22 2018

Issued at 930 PM CDT Sun Apr 22 2018

Rainfall is still having trouble making its way into the forecast
area this evening. Some very light rain/sprinkles have pushed as
far north as the I-70 corridor, but no measurable rainfall has yet
occurred in the forecast area. The upper low centered near the
Missouri/Arkansas border is retrograding a bit per satellite loops,
and the high-resolution models are now just beginning to pick up
on this trend. Much of the rainfall to the east of the upper
circulation has weakened as it has moved back west, and what
remains is not making significant northward progress. These facts,
combined with the continued dry easterly low-level flow across
the area necessitate some PoP updates into Monday. The main
changes were to slow the arrival of the measurable rainfall into
parts of the area, and to trim its northwest extent across central
Illinois. Otherwise, forecast was in good shape and only minor
tweaks to hourly trends were needed at this time.


.SHORT TERM...(This evening through Monday)
ISSUED AT 203 PM CDT Sun Apr 22 2018

Dry air has been winning the battle so far in terms of the rain
potential, with radar echoes generally reflective of mid level
clouds in our area. Primary band of rain is over central/southern
Missouri extending into the southeast U.S.

Latest water vapor imagery and surface map shows the occluded
storm system to our south, centered over northern Arkansas. This
will wobble east-northeast through Monday, eventually centering
over the Tennessee Valley by late afternoon. With the dry air, the
rain threat will gradually expand northward with time, with some
showers as far north as I-70 by sunrise. A few may develop in the
afternoon as far west as the Illinois River, but mainly looking at
I-55 east and most numerous over the southeast CWA. With the more
widespread rain there, the coolest highs in the upper 50s can be
expected along and south of I-70. Further northwest, some
sunshine should help boost temperatures into the mid-upper 60s
northwest of I-55.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 203 PM CDT Sun Apr 22 2018

This system will not be in a big hurry to leave, but the digging
upper wave over Canada will finally help push it along. This
stronger wave will largely stay over the Great Lakes, with a
separate wave currently over the Pacific Northwest moving into
the central Plains by mid week. While that part of the week
remains dry, a second Canadian shortwave will dig south on
Thursday. Much of the rain with this system will be behind the
surface cold front. The GFS remains the quickest with this
feature, with a Thursday afternoon/evening passage across
Illinois, while the latest European is about 12-18 hours slower.
Not a lot of consistency at this point from run to run, so blended
model solutions are struggling. Consequently, confidence in the
Thursday night and Friday period is low at this time.

Western parts of the CWA may get to 70 on Tuesday, while the
cooler east remains plagued with more clouds and residual showers
from the departing storm system. The rest of the week still trends
below normal though not overly cold, with highs generally at least
reaching 60 each day.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1138 PM CDT Sun Apr 22 2018

VFR aviation weather conditions expected to persist across the
central Illinois terminals at least through Monday morning.
However, by the afternoon hours, rainfall and low clouds may begin
so spread into the area from the south. The rain and low cloud
cover is associated with a slow moving area of low pressure
passing south of the area, and confidence in the details with the
rainfall threat and any lower CIGs is low. At this point, feel
best chance for MVFR CIGS will be at KDEC and KCMI. These are also
the most favored terminals for rainfall, but confidence is too
low to go above a VCSH mention at this time. East to northeast
winds will persist through the period, with gusts returning by the
Monday afternoon hours.




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