Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 230155
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
855 PM CDT Sun Oct 22 2017

.UPDATE...
Issued at 842 PM CDT Sun Oct 22 2017

The cold front that pushed across central and east central Illinois
today was located over extreme southeast Illinois this evening.
Several weak waves of low pressure were seen on the analysis along
this frontal boundary as it edges slowly to the east. The water
vapor loop indicated a shortwave over far southern Missouri and
northern Arkansas which is forecast to track across extreme
southern Illinois into far south Indiana Monday morning. Fairly
impressive lift in the exit region of a jet max at 250 mph over
southern Illinois with the IR loop depicting an expanding area of
cold cloud tops in this region. Radar mosaic showing an increase
in the rain to our south as well over southern Illinois in response
to this area of enhanced lift and 850 mb moisture transport. In
addition, precipitable water values of 1.60 inches extended from
western Tenn. northward into southeast Illinois this evening.

The last several runs of the Rapid Refresh model suggests the
steadier rainfall will be over south central through east and
southeast Illinois, with a fairly rapid drop off in precip
amounts and coverage as you head north and especially northwest
across the forecast area tonight. Have adjusted the QPF amounts up
across south central through southeast Illinois and edged the
higher POPs further west for several hours this evening. The upper
wave will get absorbed by a deepening upper level system dropping
southeast over the Great Lakes tomorrow, which should put an end
to the steadier rains to our east and south, but will be bringing
in much colder air on the backside of the storm system tomorrow
night and for the remainder of the upcoming work week. Updated ZFP
should be out by 9 PM.

&&

.SHORT TERM...(This evening through Monday)
ISSUED AT 315 PM CDT Sun Oct 22 2017

A strong cold front was moving east toward I-57 at 20Z/3 pm and
will sweep east of the IL/IN border around 00Z/7 pm. Breezy south
winds ahead of the cold front will switch gusty nw behind the
front ushering in much colder air. Temperatures were near 80F
along the Wabash river at Robinson and Lawrenceville where some
peaks of sunshine. Temps fell into the low to mid 50s behind the
cold front along and west of I-55. An area of light to moderate
rain showers were along and west of the cold front and lifting
nne.

A 569 dm 500 mb low pressure had recently formed along the
OK/AR/MO border will deep to 564 dm as it moves toward the
southern MO/IL border by 12Z/7 am Monday and to sw IN by 18Z/1 pm
Monday. The upper level low will then open up as it ejects ne into
Ohio by sunset Monday and into the eastern Great Lakes during
Monday night. This feature will likely keep showers around through
Monday morning especially east of the IL river, then becoming
more widely scattered in eastern IL Monday afternoon. Lows tonight
range from mid 40s over the IL river valley, to the low to mid
50s in eastern IL. Highs Monday in the low to mid 60s with coolest
readings in eastern IL where more clouds and showers linger
longer.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 315 PM CDT Sun Oct 22 2017

12Z forecast models continue to dig strong upper level trof
southward into IL during Monday night and Tue and more chances of
showers spread sse across area during that time along with
reinforcing colder air. Chances of light rain showers lingers over
ne CWA Tue evening. Lows Monday night in the low to mid 40s.
Highs Tue in the upper 40s from Peoria and Bloomington north and
lower 50s south. Colder lows mostly in the mid 30s Tue night with
some upper 30s southeast of I-70. If wnw winds diminish enough
overnight Tue night, could see some patchy frost formation north
of I-70. Highs Wed in the low to mid 50s, with some upper 50s from
Jacksonville sw as strong upper level trof shifts east of IL into
the eastern Ohio river valley.

Weak upper level ridging into IL Wed night and Thu to briefly
moderate temperatures on Thu. Cool lows Wed night in the upper
30s to around 40F. Highs Wed in the low to mid 60s, mildest sw
CWA. Models then dig another strong upper level low/trof southward
into the Midwest Thu night and Friday driving another cold front
se through the area. Have chances of light rain showers Fri and
Fri night in mainly eastern IL and could mix with light snow
showers overnight Fri night. Highs Fri range from 50F nw of IL
river, to the lower 60s over the Wabash river valley. Lows Fri
night in the mid 30s central IL and upper 30s southeast IL. Strong
upper level trof over IL Sat and Sat night to keep chances of
light showers over central/eastern CWA and could mix with light
snow showers Sat night. Even colder lows Sat night in the low to
mid 30s and some areas could see their 1st freeze of the season.
Highs Sat and Sunday only in the upper 40s/lower 50s except mid
50s in far southeast IL on Saturday. The Climate Prediction Center
(CPC) 8-14 day outlook for Oct 30 thru Nov 5 has a 40-50% chance
of below normal temperatures and precipitation across central and
southeast IL.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 600 PM CDT Sun Oct 22 2017

MVFR to IFR cigs expected into Monday morning mainly along and
east of I-55 as the cold front that went thru the area today
becomes stationary over southeast IL. Low pressure will move
along the boundary tonight into Monday morning bringing another
period of rain and low cigs into parts of the forecast area. As
the low shifts off to our east by tomorrow afternoon, VFR conditions
will return to the entire forecast area. Surface winds tonight will
be northerly at 10 to 15 kts and then will turn more northwesterly
on Monday with speeds once again in the 10 to 15 kt range.


&&

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

$$

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


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