Area Forecast Discussion
Issued by NWS Central Illinois

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991
FXUS63 KILX 060255
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
855 PM CST FRI FEB 5 2016

.UPDATE...
ISSUED AT 850 PM CST FRI FEB 5 2016

Quiet weather is expected to persist across central and southeast
Illinois. Surface high pressure will slowly drift away from the
region tonight, with light winds gradually shifting to the south
on its back side. An upper level trof will cross the Midwest
tonight, but it is not expected to be much of a weather producer
locally. The system does not have much moisture to work with, and
the associated forcing is not well phased or substantial. Do not
expect much more than layered clouds with the passage of this
feature tonight.

Going forecast is in good shape. Only a few minor tweaks are
needed to the hourly trends.

&&

.SHORT TERM...(Tonight)
ISSUED AT 257 PM CST FRI FEB 5 2016

A northern stream short wave trof over the eastern Dakotas into
central Nebraska, will track into nw IL by dawn Saturday. This weak
clipper system will generally keep its light snow/flurries chances
north of CWA during tonight, but will bring in more cloud cover.
Clouds have already been prevalent over central and northern CWA
today with thickening cirrus clouds over some lingering MVFR clouds
over NE half of CWA. Meanwhile southeast IL has mostly sunny skies
at mid afternoon will see clouds increase there as well overnight.
1033 mb high pressure over the southern MS river valley and
ridging northward into eastern MO and sw IL will gradually shift
into the southeast states into Sat morning. WNW winds 5-10 mph
will become light and variable this evening and become SSE near 5
mph during overnight. Lows tonight mostly in the middle 20s.

.LONG TERM...(Saturday through Friday)
ISSUED AT 257 PM CST FRI FEB 5 2016

Mild weather to dominate this weekend before much colder weather
moves into the area early next week. Models very similar with
respect to the strong shortwave forecast to dig southeast into
the upper Great Lakes, and eventually carve out a longwave trof
over the eastern U.S. early next week. Mild Pacific air will
dominate Saturday and Sunday as a strong area of low pressure
tracks east across southern Canada late Saturday through early
Sunday bringing above normal temperatures to the region. Afternoon
temperatures on Saturday will top out in the lower 40s north to
around 50 south, and by Sunday, the mercury should climb in the
mid 40s north to the lower 50s south accompanied by a rather gusty
southwest breeze.

As the cold front progresses southeast into the Midwest later on
Sunday into early Monday, rain chances will start to increase across
the north and over parts of southeast Illinois, with most areas
seeing light snow chances late Sunday night into Monday night as the
much colder air builds south. All models now showing the closed
upper system at 500 mb dropping south into central Illinois on
Monday afternoon with 500 mb temperatures forecast in the -30 to -35
degree C range during that time. The combination of the deep
cyclonic flow and cold advection occurring at all levels should lead
to better coverage of snow showers Monday afternoon with rather
steep low and mid level lapse rates expected. Even so, 30-40 POPs
should cover this type of setup with scattered snow showers
continuing into a good portion of the evening as the upper low
slowly edges away from our area on Tuesday. It still appears any
accumulations will be minor, possibly totaling up to an inch over
the 36 hour period (late Sunday night-early Tuesday) in a few
locations, with the most favorable setup being from Monday
afternoon through early Tuesday when the surface temperatures will
finally be cold enough to support any accumulations.

Coldest temperatures at 850 mb forecast to arrive Monday afternoon
and hold over our area into early Wednesday with the coldest models
close to -18 degrees C as surface temperatures are expected to be
steady or slowly falling, especially during the afternoon on Monday,
accompanied by a gusty northwest wind adding a significant chill to
the air. Scattered flurries will be possible on Tuesday across the
east with the better chances for light snow or flurries shifting
away from our area as the low level flow becomes more anticyclonic
by Wednesday with the center of the cold air mass moving over our
area.

The blustery conditions will hold through Wednesday morning as the
deep upper low only slowly pushes away from the region. Wind chills
are not expected to be as cold as we initially thought, but cold
enough, with readings ranging from 5 below zero north to 5 above
zero far south Wednesday morning. The deep trof will shift away from
the lower Great Lakes late in the week allowing a moderating trend
to settle in which will bring about a gradual moderating trend on
Thursday and Friday when temperatures will inch back closer to
normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 555 PM CST FRI FEB 5 2016

VFR conditions should prevail for the bulk of the 00Z TAF valid
time across the central Illinois terminals. An upper level
disturbance will cross the area tonight/early Saturday,
accompanied lowering VFR CIGS tonight. The lower CIGS should
scatter out again Saturday morning as the disturbance pulls away.
Light/variable winds will trend southwesterly near 10 knots by
midday Saturday.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...BAK
SHORT TERM...07
LONG TERM...Smith
AVIATION...BAK



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