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Area forecast discussion 
National Weather Service Lincoln Illinois
858 am CDT Friday Oct 21 2016

issued at 858 am CDT Fri Oct 21 2016

Made some updates to the forecast for today, namely to increase
cloud cover and lower high temps across the far east/NE kilx County Warning Area.
1330z/830am infrared satellite imagery continues to show a band of
lake-enhanced clouds streaming southward from Lake Michigan,
generally east of a Effingham line.
Area VAD wind profilers indicate a north/NE flow in the cloud-bearing
layer, and NAM 925-850mb layer wind forecast continues this
favorable fetch off Lake Michigan until early this afternoon when
winds slowly begin to back to N/NW. As a result, have gone with a
mostly cloudy forecast through midday for locations along/east of
I-57...followed by clearing skies from west to east during the
afternoon. Due to the additional cloud cover, have lowered highs
into the lower 50s near the Indiana border from Danville to
Marshall. Elsewhere around central Illinois, the going forecast of
mostly sunny skies with highs in the middle to upper 50s is right
on track.


Short term...(today and tonight)
issued at 255 am CDT Fri Oct 21 2016

Quiet weather is expected across central and southeast Illinois
through the period. An upper-level trof axis will pull further east
of the area, with the flow trending neutral by later today. At the
same time, high pressure will begin to build into the area at the
surface. While quiet conditions are anticipated, it will be several
degrees cooler than normal, with daytime highs in the 50s and
nighttime lows in the 30s. There will be a risk of frost in many
areas tonight, although current indications are that the frost will
not be of sufficient coverage to warrant an advisory. This threat
will need to be monitored today.

Long term...(saturday through thursday)
issued at 255 am CDT Fri Oct 21 2016

Main focus remains with the storm system expected to arrive mid
week. In the interim, very quiet conditions as we will be under the
influence of high pressure much of the time. A fast moving shortwave
will pass through late Sunday, but moisture will be bottled up
closer to the Great Lakes, resulting in only temperatures returning
to near normal.

Early in the week, as a powerful storm system rapidly intensifies
off the Pacific northwest coast, a short wave further south will
swing northeast out of California. As the upper ridge over the
plains begins to break down, this wave will cross the plains Tuesday
night and should reach Illinois by Wednesday afternoon. Conditions
in our area will remain dry into Tuesday evening, as a warm front
develops near the I-80 corridor and focuses rain closer to that
area. After that, the forecast becomes a bit murkier, with the GFS
and European model (ecmwf) exhibiting some timing differences with the wave, although
both are in decent agreement with the exact track of the surface low
across northern Illinois. The GFS is stronger and faster, bringing
rain toward the Illinois River as early as sunrise Wednesday and
quickly exiting the area by evening, while the European model (ecmwf) is about 6-10
hours slower. However, both focus most of the rain and thunderstorms
on Wednesday.


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 626 am CDT Fri Oct 21 2016

VFR aviation weather conditions expected across the central
Illinois terminals through the 12z taf valid time. Building high
pressure and the associated dry airmass should keep clouds to a
minimum. However, scattered clouds off Lake Michigan will impact
kcmi this morning. Northwest winds around 10 kts will trend
light/variable tonight as the high pressure ridge builds in.


Ilx watches/warnings/advisories...


short term...Bak
long term...geelhart

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