Area Forecast Discussion
Issued by NWS Central Illinois

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023
FXUS63 KILX 210924
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
324 AM CST Tue Feb 21 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 324 AM CST Tue Feb 21 2017

Slow-moving cold front continues to edge eastward early this
morning...with latest surface analysis placing it along the
Mississippi River.  Light to moderate showers are occurring
along/ahead of the boundary, primarily impacting locations along
and west of the I-55 corridor.  Showers will gradually spread
eastward across the remainder of the area, but may not reach the
Indiana border until mid-morning.  The front will tend to
dissipate as it tracks further east, so am expecting areal
coverage of showers to decrease as the day progresses.  Temperature
forecast will be a bit tricky today, as cloud cover and showers
will keep readings down across the E/SE KILX CWA.  With clearing
expected to take place across the west this afternoon, think
warmest highs in the upper 60s to around 70 will occur along/west
of I-55.  Further east where overcast conditions will persist
through the entire day, highs will only reach the lower to middle
60s.  Front will sag into the Ohio River Valley and wash out
tonight, allowing skies to become mostly clear across all but the
far SE where partial cloud cover will linger.  With clearing
skies, light winds, and a very moist boundary layer in
place...think fog will develop overnight.  Fog should become
thickest/most widespread where afternoon mixing will be the
least...generally across the eastern two-thirds of the CWA.

&&

.LONG TERM...(Wednesday through Monday)
ISSUED AT 324 AM CST Tue Feb 21 2017

Fog will gradually dissipate Wednesday morning, with mostly sunny
skies expected by afternoon.  Given abundant sunshine and increasing
southwesterly winds ahead of an approaching boundary, record high
temperatures appear to be a good bet.  Thermal ridge will be in
place across the region...with 850mb temps increasing to 12-14C. As
a result, am expecting afternoon highs to top out in the lower to
middle 70s.  Front will drop southward into central Illinois
Wednesday night, eventually stalling near the I-72 corridor.  A
distinct north-south temperature gradient will develop on
Thursday...with highs ranging from the upper 50s far north around
Galesburg and Lacon...to the lower 70s south of I-70.  Much of the
day should be dry: however, as synoptic lift increases along the
boundary in advance of a potent short-wave ejecting out of the
Rockies, scattered showers will develop during the afternoon.

Low pressure is still expected to develop in the lee of the Rockies
Thursday evening, then track into the southern Great Lakes by Friday
evening.  Minor model discrepancies are still present: however,
consensus shows a strong cold front bisecting central Illinois by
18z Fri.  Given unseasonably warm/moist southerly flow ahead of the
front, the atmosphere will become moderately unstable across east-
central and southeast Illinois...with GFS indicating MUCAPE values
of around 1000J/kg.  In addition...0-6km bulk shear values will
increase to 55-65kt as a powerful mid-level jet approaches from the
west.  Think strong to potentially severe thunderstorms will develop
along/ahead of the front Friday afternoon, mainly along and east of
I-57 where likely PoPs are warranted.  Any storms that fire will
quickly shift into Indiana by early evening, followed by breezy and
sharply colder conditions.  Models continue to suggest wrap-around
moisture will brush the N/NW CWA late Friday night into Saturday
morning.  With temperatures falling into the upper 20s and lower
30s, a period of light snow will be likely...with some minor
accumulations possible along and north of a Canton to Danville line
by Saturday morning.

Cool/more typical mid-February weather will prevail over the
weekend...with highs in the upper 30s and lower 40s on Saturday
rising into the 40s everywhere by Sunday.  The return to normal
will be short-lived however, as zonal flow will allow temps to
warm significantly by early next week.  Unfortunately the warming
trend will also be accompanied by precipitation.  At this time it
appears a brief period of light snow will be possible Monday
morning before temps warm sufficiently for all rain Monday
afternoon into Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1100 PM CST Mon Feb 20 2017

Clouds will continue to lower after midnight as an area of
showers just out to our west moves slowly east across the TAF
sites. VFR cigs will lower to MVFR as a frontal system moves
across central Illinois Tuesday morning with a low probability for
a brief period of IFR cigs in the 09z-14z time frame. Models
continue to indicate the rain will shift east of the TAF sites by
early afternoon with a return to VFR conditions by late morning
across PIA and SPI and by 20z at CMI. Winds will be south to
southwest ahead of the weak cold front tonight at 5 to 10 kts, and
then become light and variable on Tuesday as the weakening front
edges slowly away from the forecast area. The light winds and
added low level moisture from the rain tonight may lead to some
patchy fog later Tuesday night...primarily after 06z.


&&

.CLIMATE...
Issued at 312 PM CST Sun Feb 19 2017

Record Highs / Record Warm Lows - Tuesday Feb 21st...
Peoria........ 69 / 46
Lincoln....... 69 / 45
Springfield... 69 / 48
Champaign..... 67 / 47
Bloomington... 69 / 46
Decatur....... 68 / 48
Danville...... 67 / 50
Galesburg..... 68 / 40
Charleston.... 71 / 52
Effingham..... 73 / 52

Record Highs / Record Warm Lows - Wednesday Feb 22nd...
Peoria........ 71 / 51
Lincoln....... 71 / 52
Springfield... 71 / 53
Champaign..... 69 / 49
Bloomington... 70 / 53
Decatur....... 72 / 51
Danville...... 71 / 54
Galesburg..... 61 / 45
Charleston.... 71 / 52
Effingham..... 74 / 55

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith
CLIMATE...07



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