Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 240200

Area Forecast Discussion
National Weather Service Lincoln IL
900 PM CDT Mon Apr 23 2018

Issued at 855 PM CDT Mon Apr 23 2018

Light rain/sprinkles have become fairly widespread this evening
across parts of the forecast area, roughly between the Illinois
River and I-70. This flare-up of rainfall is associated with a
lobe of energy revolving around a pesky upper-level low, which is
currently centered over extreme western Kentucky. The latest
high-resolution guidance suggests this area of rainfall will
greatly diminish over the next few hours, and recent radar scans
suggest this trend may be beginning.

Have had to make some adjustments to the PoP forecast this
evening, to boost chances and coverage. Otherwise, going forecast
is in pretty good shape and only minor tweaks to the hourly trends
were needed.


.SHORT TERM...(This evening through Tuesday)
ISSUED AT 230 PM CDT Mon Apr 23 2018

Upper low across southern Missouri has spread showers into south-
central Illinois with the northern periphery of the rain shield
having a tough time edging further north. The main forecast
challenge for the overnight hours is how far north the rain will
go. Forecast soundings continue to indicate a very dry air mass
below 10,000 feet early tonight across our central and northern
counties before shortwave energy pivots north around the upper
low to our south and brings enough lift across the central and
northeast counties for scattered shower activity. West of the
Illinois River, little if any rain is expected overnight into
early Tuesday morning with before the shortwave shifts away from
the forecast area.

Models continue to show some additional lift pushing to our east
around the departing upper low so will continue to keep 20-30 POPs
going across the east on Tuesday. Temperatures will be a challenge
Tuesday afternoon due to the extensive cloud cover. However, forecast
soundings indicate areas west of I-55 may see enough breaks to push
afternoon highs well into the 60s, possibly 70 degrees across the
far western and northern parts of the forecast area, while our far
east and southeast counties will be held down to the lower 60s due
to the thicker cloud cover that is expected.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 230 PM CDT Mon Apr 23 2018

Models continue to suggest the next shortwave tracking southeast
across the upper Great Lakes will remain well north of the forecast
area while additional energy moving across the central Plains
Tuesday night into Wednesday will keep the better lift and energy
to our southwest. As a result, we should remain dry into Thursday.
Will have to keep an eye on low temperatures early Thursday morning
as guidance has lows dropping into the mid and upper 30s over parts
of the forecast area. A stronger system is slated to push across
the region Thursday night into Friday morning bringing a frontal
boundary and the threat for scattered showers. Temperatures ahead
of this disturbance on Thursday afternoon should warm into at least
into the mid and upper 60s before we briefly cool down a few
degrees on Friday.

Models in decent agreement next weekend and into early next week
as upper level heights gradually build over the central U.S. in
response to a trof developing over the western U.S. As is usually
the case, there are differences with respect to how quickly the
western U.S. trof pushes east into the Plains next week and the
eventual shower and thunderstorm chances. However, with the ridge
building over the area during the weekend and into early next week,
there will be an extended period of dry weather and warming
temperatures with guidance suggesting our afternoon highs by Sunday
and Monday of next week may approach 80 degrees.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 643 PM CDT Mon Apr 23 2018

Central Illinois will continue to be impacted by a slow moving
area of low pressure through the 00Z TAF valid time. Light showers
on the north side of the system are spreading west across the
region this evening. The showers are accompanied by a rapid
decrease to low-end MVFR or locally IFR conditions. The rainfall
should not amount to much and will be ending later tonight.
However, the low cloud CIGS should linger well into Tuesday.
Easterly winds will trend northerly tonight as the system starts
to pull away from the area.




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