Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 181050

Area Forecast Discussion
National Weather Service Lincoln IL
550 AM CDT TUE OCT 18 2016

.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 12Z TAFS through 12Z Wednesday morning)
Issued at 550 AM CDT Tue Oct 18 2016

A cold front is expected to push across the area this morning
along and west of I-55, and should track into east central
Illinois this afternoon. There will be a brief period of MVFR
cigs along and just behind the frontal boundary before a return
to VFR conditions in all areas for the remainder of the forecast
period. Satellite data and surface observations in eastern Iowa
indicate cigs in the 1500-2500 foot range in the cloud band
associated with the front and it appears it lasts no more than
a couple of hours as it tracks southeast. The gusty south to
southwest winds should begin to diminish this morning across the
west as the front approaches, with occasional gusty winds, up to
25 kts, continuing over our eastern TAF sites into late this
morning or early this afternoon. The south to southwest winds will
become west and then northwest with FROPA, with speeds ranging
from 10 to 15 kts. Look for the winds to veer more into a northerly
direction at less than 10 kts tonight.


.ILX Watches/Warnings/Advisories...


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