Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 181957
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
257 PM CDT Wed Oct 18 2017

.SHORT TERM...(This evening through Thursday)
ISSUED AT 237 PM CDT Wed Oct 18 2017

Quiet weather will persist across central and southeast Illinois
through the short term period. The air mass will remain very dry,
and persistent southerly flow will help cause gradual warming. A
modified persistence forecast is likely to do well, with
temperatures moderating slightly like they have the past couple of
days.

&&

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 237 PM CDT Wed Oct 18 2017

The quiet and increasingly warm pattern will continue into the
weekend. The upper-level flow is forecast to amplify significantly
over the lower 48 states from the nearly zonal flow that exists
now. The rising heights and persistent southerly low-level flow
may have daytime highs approaching 80 by Friday & Saturday.

A major trof will push a cold front through the forecast area by
late in the weekend, accompanied by showers and thunderstorms.
There are still differences in model timing with the front, but
the consensus has the boundary and best precipitation chances
coming through Saturday night into early Sunday. There does not
appear to be a significant severe storm risk with FROPA at this
time, largely due to the unfavorable time of day of its expected
passage and associated low instability.

The forecast beyond the frontal passage is more problematic. While
the current operational GFS & ECMWF models are progressive with
the upper trof driving the front, the last couple runs of the
Canadian model develop a significant upper low over the southern
Plains. This low is currently progged to slow the progress of the
front, and also lift into the Midwest for the first part of the
week. A lingering front and/or upper low would keep a rain risk
going into at least midweek. While the Canadian solution is not
favored at this time, a similar solution is evident in some GFS
ensemble members and has been seen in prior solutions of other
models. This uncertainty is resulting in an extended period of low
PoPs to start next week. In any event, it will be notably cooler
behind the front next week. Several days of below normal
temperatures appear likely.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1247 PM CDT Wed Oct 18 2017

VFR conditions will prevail across the central Illinois terminals
through the 18Z TAF valid time. There will be little/no cloud
cover, with changing winds the primary forecast concern. The
gusty southerly winds will drop off around sunset, with winds
remaining light for the balance of the TAF valid time.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Bak
LONG TERM...Bak
AVIATION...Bak



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