Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 220254
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
854 PM CST Tue Nov 21 2017

.UPDATE...
Issued at 844 PM CST Tue Nov 21 2017

High pressure centered over northern Nebraska this evening is
forecast to push into Iowa by Wednesday morning with the ridge
axis just to our west. This should bring the coldest overnight
lows to our west and northwest counties where a few locations
may see early morning lows in the upper teens, while further
east and south, winds are expected to hold up enough to keep
early morning lows in the mid or upper 20s. The large fair
weather system will drift to our southwest during the day
Wednesday bringing quiet weather to our area with afternoon
temperatures across most of the area struggling through the 30s.
Made some downward adjustments to the overnight lows, especially
across the west and northwest counties with only a few minor
tweaks for the east and southeast areas. We should have the
update out by 9 pm.

&&

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 300 PM CST Tue Nov 21 2017

The cold front will sweep out of our southeast counties by early
this evening, but not before dropping some flurries or sprinkles
across our northern and eastern counties this afternoon. The
night will be highlighted by gusty northwest winds this evening,
and clearing skies. Winds will diminish overnight, to less than
10mph, as the pressure rises weaken and the center of high
pressure gets closer to Illinois from the Plains. Plenty of cold
air will settle into the area behind the front, with lows dropping
into the low to mid 20s.

Light winds and mostly sunny skies will prevail on Wednesday as
the surface ridge axis drifts eastward directly across Illinois.
Full sunshine will not be of much help, as the cold Canadian air
limits the highs to the mid to upper 30s.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 300 PM CST Tue Nov 21 2017

The surface high pressure axis will drift southeast of Illinois
on Wednesday night, setting up a return flow for Thursday into
Friday. A warming trend will result, as the next cold front
approaches from the northwest. High temps will return to around
normal on Thanksgiving. On Friday, gusty south-southwest winds at
15 to 25 mph will help to push highs above normal.

A cold frontal passage on Friday night looks similar to today`s
FROPA, in terms of moisture content and strength of the system.
The models are likely under-doing precipitation coverage, just
like they did for this afternoon`s cold front. While the blended
extended removed the slight chance PoPs Friday evening with the
12z model run update, thinking that we will see at least some
sprinkles across our forecast area Friday evening/overnight as
the front moves across IL. Minimal impact, so a major concern
overall.

Clearing skies on Saturday will set the stage for a mostly sunny
Thanksgiving weekend. However, another round of cold Canadian high
pressure will cause Saturday`s highs to dip to around normal, with
below normal temps for Sunday afternoon (40-45F).

Yet another warm-up is projected for Monday and Tuesday, ahead of
the next low pressure system. Highs should return to the 50s on
Tuesday, as clouds increase along with a slight chance of rain in
the afternoon.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 514 PM CST Tue Nov 21 2017

VFR conditions are expected across the area through this forecast
period. A band mid and high level clouds and some sprinkles
continues to shift east and southeast, mainly south of the TAF
sites early this evening and we expect that activity to be well
off to our east later tonight. High pressure will build southeast
into the area later tonight and Wednesday which should continue
to bring dry and rather chilly weather to the region. The gusty
northwest winds early this evening should begin to diminish over
the area after 02z. Northwest winds of 10 kts or less on Wednesday
should begin to back more into a westerly direction by afternoon.


&&

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

$$

UPDATE...Smith
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...Smith



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