Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 210756

Area Forecast Discussion
National Weather Service Lincoln IL
256 AM CDT FRI OCT 21 2016

.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 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 ECMWF is about 6-10
hours slower. However, both focus most of the rain and thunderstorms
on Wednesday.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1129 PM CDT Thu Oct 20 2016

High pressure advancing into Illinois will provide VFR conditions
over the next 24 hours. Showers have departed well southeast of
CMI to DEC, and clouds will continue to clear from west to east
the rest of the night. CMI should be the last to clear out by 08z.
No TAF sites have MVFR clouds in place, and satellite loops and
upstream OBS indicate that should remain the case as clouds clear

NW wind gusts of up to 23kt re-developed at DEC and CMI in the
last hour, but they should diminish by 07z. A relatively tight
surface pressure gradient appears sufficient to keep sustained NW
winds around 10-12kt for the rest of the night for all sites
except PIA. During the day tomorrow, NW winds will hover in the
08-12kt range under mostly clear skies. Some lake effect clouds
could drift over CMI from mid-morning to early afternoon at 2.5K
ft levels, but any ceilings should remain east of CMI. Clear skies
and light NW winds are expected by sunset tomorrow and through
the evening.


.ILX Watches/Warnings/Advisories...
Frost Advisory until 8 AM CDT this morning for ILZ027>031-036-



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