Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KILX 222051

National Weather Service Lincoln IL
251 PM CST SUN NOV 22 2015

.SHORT TERM...(Tonight)

Early afternoon satellite imagery showing some scattered mid level
clouds drifting east across the forecast area. Temperatures being
held down across the northern CWA due to the snow pack, mid 20s
to around 30 at 2 pm, while 30s are more widespread further south.
The challenge for tonight`s forecast will be with the
temperatures. Warm front current across the eastern Dakotas is
pushing eastward, tightening the pressure gradient over us and
causing a decent southerly wind. Winds expected to increase a bit
as the front approaches, which should be in central Illinois
toward sunrise. This should prevent a wholesale free-fall, but
temperatures over the snow pack will be starting off colder. Have
leaned more toward the NAM MOS guidance up there with lows in the
lower 20s, but temperatures over the whole CWA should not move a
whole lot overnight. Main energy with the system will be to our
north, so have kept the forecast dry.


.LONG TERM...(Monday through Sunday)

High pressure ridge will be drifting east across the area late
Monday and early Tuesday. Temperatures expected to be well above
freezing across even the northern CWA, starting to melt the snow
cover. With surface winds becoming light and warm air advection
taking place aloft (850 mb temperatures rising to near 5C by
Tuesday morning), fog will probably become an issue, and have left
the mention of it in the forecast. Tuesday night is a little
trickier in that regard, as the gradient will keep winds up around
10 mb or so. We`re in the time of year where stratus decks can be
tough to erode, and the NAM forecast sounding for Peoria for
late Tuesday evening shows a pretty good warm layer persisting
below 925 mb and a moist column for about 800 feet off the ground.
Right now, will hold off on the fog mention until this becomes a
little more clear.

After that, focus continues on the storm system that will be
affecting the central U.S. in time for the Thanksgiving travel
period. Moisture return ahead of this system is a bit lacking on
Wednesday, but comes in full force Wednesday night and especially
Thursday/Thursday night. Rainfall arrival in the southeast CWA
appears a bit slower in the most recent model runs and a good part
of Thanksgiving may end up being dry there, but periods of showers
further west will likely begin as early as midday Wednesday. The
front causing this is in no big hurry to cross the area, not fully
through until Friday afternoon, with a couple days of wet weather
on tap. Precipitable water values get pretty high for late
November, generally around 1.3 inches Thursday night, so another
period of heavier rain can be expected. Currently thinking around
1.5 inches for the extended period from Wednesday through Friday.
Will need to watch how much snow remains when this starts which
would release additional water and cause runoff. This would be
more of a threat in northern Illinois where the snow cover is much
deeper, but even that could eventually cause some river issues as
the excess water flows downstream.

Temperatures will steadily warm the next few days, but will
continue to be influenced by the diminishing snow pack. However,
even across the far northern CWA highs, should reach well into
the 50s by Thanksgiving. 50s will linger across the east into
Friday until the front passes, but temperatures over the entire
area will return to the upper 30s/lower 40s by next weekend.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)

VFR conditions will prevail through the entire 18z TAF period. A
weak disturbance will spread mid-level clouds across the area this
afternoon. 1730z satellite imagery shows the clouds with bases of
7000-9000ft along/west of the Illinois River. Satellite timing
tools and Rapid Refresh RH progs suggest they will arrive at KPIA
by 18z, then further east to KCMI by around 21z. The clouds will
clear from west to east late this afternoon into the evening, but
additional mid-level clouds further upstream across western Iowa
will arrive by mid to late evening. Winds will initially be from
the south at around 10kt this afternoon, then will veer to the
W/SW by Monday morning.


.ILX Watches/Warnings/Advisories...


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