Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 250539

Area Forecast Discussion
1139 PM CST Mon Nov 24 2014


We had a wave of freezing drizzle create quite a few accidents
early this evening from Galesburg to El Paso. It appears the
focused area of enhanced lift associated with that mixed precip
has pushed east into Indiana as of 9 pm. Another shortwave is
approaching from SE Iowa with light snow showers reported in the
observations. Can not rule out patchy FZDZ again before midnight,
but satellite images show there may be enough ice crystals aloft
to feed the lower cloud layer to produce light snow instead of
FZDZ. Plus, the boundary layer is continuing to cool, helping to
keep precip as snow. No snow accumulation is expected, even with
the next wave that will affect areas mainly N of Peoria through 2

Minor updates were needed to the weather grids to match expected
trends, but the remainder of the forecast looks on track. Updated
info is already available.


.SHORT TERM...(Tonight)

Wind advisory over eastern IL this afternoon will be cancelled early
as WSW winds have slowly diminished below advisory criteria by mid
afternoon, as best 3 hourly pressure rises have shifted ne of IL.
Sustained wind speeds are down to 20-29 mph with gusts of 30 to 39
mph at 2 pm. Strong and deepening 975 mb low pressure along the Quebec
and Ontario province line will lift ne across Quebec tonight with
very tight pressure gradient relaxing tonight over IL, as high
pressure over the Rockies drifts east into the Great Plains tonight.
WSW winds will continue to diminish to 10 to 20 mph this evening and
gusts of 20 to 30 mph this evening. Area of light snow and flurries
over IA and northern IL to pivot across areas north of I-72 into
this evening but little or no additional accumulations. Areas from
Peoria north had a half to 1 inch of snow this morning with just a
dusting from Lincoln south. Cyclonic flow lingers over central IL
tonight and this should keep the low clouds around with mostly
cloudy to overcast skies continuing. Temps currently are mostly in
the low to mid 30s over central IL (Galesburg down to 28F) while
40-45F southeast of I-70 in southeast IL. Lows tonight to range from
near 20F nw of the IL river to the upper 20s in southeast IL.


.LONG TERM...(Tuesday through Monday)

High pressure will build into the region and bring and dry forecast
for Tue and Tue night. Then a clipper system will quickly move
through the area and bring a shot of pcpn during the day. Pcpn will
begin in the morning in the west and then move eastward across the
CWA and cover the whole CWA by afternoon. Pcpn type will be a tricky
forecast as warmer air will be advected into the area ahead of the
low pressure area and this will create a mix of rain and snow across
the area as the day progresses. So, looks like snow begin across the
area and then gradually become mixed with snow during the late
morning. During the afternoon, the mix of rain and snow will move
northward, while the pcpn becomes all rain in the south and
southeast. Toward the end of the afternoon as the temps decrease,
the rain and snow line will shift south with all snow being in the

Beyond Wed, a dry forecast looks to be in order for the rest of the
week as high pressure builds into the region and the upper level
flow becomes more zonal. Then a front drops through the area over
the weekend and then stalls across southern Illinois. This stalled
front will bring another chance of pcpn for Sunday and Sun night.

Temps overall will be below normal tomorrow through Thursday, but
begin to warm back up during the end of the week and through the
weekend. Warmest temps look to be Sat and Sun when highs reach into
the 50s over the whole area for Sat and the 40s for most of the area
for Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

One more meso-vortex on radar is poised to rotate from far eastern
Iowa across northern Illinois over the next few hours. The primary
precip type appears to be light snow, but patchy freezing drizzle
could still develop due to localized lack of ice crystals above
the cloud layer. Snow was the only precip type included in the
TAFs for PIA and BMI, the closest to the wave. All precip should
end before sunrise on Tuesday, with dry conditions the remainder
of the TAF period.

MVFR clouds will linger until mid-morning for the southern
terminals of SPI/DEC, and possibly into the afternoon for the
northern terminals. Clearing will develop by sunset.

Winds will remain a bit gusty for the first 3 hours of this TAF
period, with gusts near 20kt at times. Gusts will subside by
sunrise, with sustained winds tomorrow generally less than 10 kt
from the west.

A band of
mixed freezing drizzle and snow moved across our northern
terminals over the last couple of hours, and additional bands of
mixed precip could affect the same areas through 03z. Numerous
accidents have been reported on many roads including I-74 near
Galesburg and I-39 from El Paso and north to Tonica.

MVFR clouds will likely hold steady over the next 24 hours, with
precipitation generally coming to an end by 06z.

Very gusty winds will continue through at least mid-evening. Gusts
should end by 06z, but sustained winds will likely remain in the
12-15kt range in most areas overnight. PIA and SPI could see the
pressure gradient weaken enough for wind speeds to drop below 10
kt before sunrise Tuesday. Cloud heights will lift to VFR Tuesday
morning after sunrise and mixing increases.




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