Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 181752

Area Forecast Discussion
National Weather Service Lincoln IL
1252 PM CDT TUE OCT 18 2016

Issued at 1040 AM CDT Tue Oct 18 2016
A cold front in the vicinity of the Illinois River Valley is
slowly making its way through the region this morning.
Temperatures out ahead of it have climbed into the low to mid 70s
already and may have a chance to get to near 80/low 80s southeast
of the I-55 corridor. However, cooler air to the NW will temper
the maxes. Southwesterly winds will veer around to more
northwesterly behind the boundary with at least a brief increase
in cloud cover before clearing back up later this evening.
Forecast is on track and no updates are anticipated at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 247 AM CDT Tue Oct 18 2016

Gusty southerly winds helping to keep temperatures on the warm side
early this morning with readings holding in the 70s across the
forecast area, some 25 to 30 degrees above where they should be for
this time of year. Although it won`t be as warm today as what we saw
yesterday, temperatures this afternoon are still going to average
about 15 to 20 degrees above normal with highs expected to range
from the middle 70s northwest to the mid 80s southeast.

The latest surface analysis has a cold front located just west of
Dubuque and Ottumwa, Iowa and will continue to make steady progress
east across our area today accompanied by a period of cloudiness
this morning across the northwest, with the frontal system and
associated clouds settling southeast this afternoon. As the front
shifts into east central and then southeast Illinois this afternoon,
some of the high resolution convective allowing models indicate some
isolated showers and storms may develop along the front. However,
coverage will be rather limited, despite the favorable timing of the
frontal passage this afternoon, as temperatures aloft were still
quite warm and the better forcing for ascent will be well north of
the region. However, the NAM-WRF indicates that the cap may weaken
enough south of I-72 that the frontal convergence combined with
surface base capes of up to 1000 J/KG near the I-70 corridor may be
enough to produce at least an isolated shower/thunderstorm. Will
include slight chances this afternoon for areas roughly along and
south of I-72, with 20-30 POPs continuing tonight along I-70, closer
to the boundary which is forecast to stall out just south of our

Cooler temperatures will be filtering southeast into the area
tonight as high pressure builds slowly southeast into the Midwest.
Overnight lows are expected to drop to around 50 northwest to the
low 60s southeast.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 247 AM CDT Tue Oct 18 2016

Not a lot of change from the earlier thinking on the evolution of
the midweek storm system. The cold front which will cross the area
today is expected to become stationary just north of the Ohio River
by early Wednesday morning. Overrunning rain will become more
widespread through the day as a wave of low pressure rides northeast
out of Oklahoma along the front, with the evening model suite in
general consensus of the low tracking just to our south. However,
the 850 mb front will be near the I-70 corridor, with forecast
soundings showing around 300 J/kg of elevated CAPE, so will include a
chance of thunder Wednesday afternoon and night across the southeast
CWA. Rainfall amounts of about a half to 3/4 inch are likely over
areas from about I-72 southward before the system exits the area on

Deepening long wave trough will push east of the Mississippi Valley
by early Friday, with the coolest temperatures around that time as a
slug of colder air is drawn down from Ontario. However, the upper
pattern shifts to more of a zonal flow during the weekend, allowing
temperatures to moderate quickly. Longer range models showing
amplification of an upper ridge over the Rockies early next week,
keeping a milder pattern in place over central Illinois.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1249 PM CDT Tue Oct 18 2016
Pre cold front accompanied by a swath of MVFR cigs for the next
2-3 hours in ILX terminals, with the exception of PIA that is now
behind the boundary with westerly winds veering to more
northwesterly. Same trend continuing to make its way through 20z
from NW to SE. VFR behind the boundary for the overnight hours.


.ILX Watches/Warnings/Advisories...


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