Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 201720
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1220 PM CDT Fri Apr 20 2018

.UPDATE...
Issued at 1041 AM CDT Fri Apr 20 2018

Temperatures coming up quickly this morning with copious amounts
of sunshine and light winds. Forecast soundings continue to
indicate afternoon temperatures mostly in the lower 60s across
the forecast area, which is getting closer to where we should
be for the middle of April. Other than some tweaks to the hourly
temperature trends late this morning, the rest of the forecast is
in great shape, as a result, no ZFP update is needed.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 330 AM CDT Fri Apr 20 2018

Continued the freeze warning over 8 southeast IL counties until 8
am cdt this morning. Temperatures at 3 am were in the mid 30s to
upper 30s along and south of I-70 with Terre Haute down to 31F,
while Flora at 41F. The latest HRRR and RAP runs still show temps
slipping to near freezing around sunrise then start rising after
12Z/7 am. With clear skies and light NNE winds and dry airmass,
expected temps to continue to drop next few hours, with a brief
couple hour window of frost and/or freezing conditions in
southeast IL.

09Z/3 am surface map shows 1034 mb Canadian high pressure along
the MN/IA border and ridging into nw and north central IL. This
has diminished winds light to calm over central IL early this
morning and allowed temps to slip into the upper 20s to mid 30s
over central IL and mid 30s to upper 30s in southeast IL.

Canadian high pressure to drift into the western Great Lakes and
ridge over IL during this afternoon, and providing a nice spring
day with ample sunshine and light winds. Bumped up highs a few
more degrees into the lower 60s which MAV/MET have trended in this
direction. We reached a few degrees warmer yesterday in the mid
50s, so followed that trend today as dry airmass will be quick to
warm up during today. Mid and high clouds to increase over central
IL during tonight while southeast IL stays with fair skies longer.
Lows tonight in the mid to upper 30s, and could be some patchy
frost overnight near the IN border/Wabash river valley.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 330 AM CDT Fri Apr 20 2018

A 552 dm 500 mb low near the western UT/AZ border will track into
se CO as a 560 dm 500 mb low by 12Z/Sat and into central OK by
sunset Saturday. Its moisture stays of IL but will see partly to
mostly cloudy skies, more mid level clouds in sw CWA. Have weak
upper level ridge over area on Saturday and high pressure over the
Great Lakes region keeping it dry over our area on Saturday.
Highs Saturday of 60-65F. Partly to mostly cloudy skies again on
Sunday with more clouds over southern/sw CWA.

00Z models bring 565 dm 500 mb low into east central AR by sunset
Sunday and into mid TN by sunset Monday. Brunt of models still
keep its light qpf sw of CWA on Sunday. ECMWF model has some very
light qpf over southern 3 counties Sunday afternoon. GFS keeps its
qpf se of CWA Sunday night and Monday, while Ecmwf model and GEM
model brings some qpf into central and se part of CWA Monday night.
Stayed close to model consensus early next week, with slight
chance of light rain showers along and south of highway 50 from
late Sunday afternoon through Monday evening. Highs Sunday in the
middle 60s across area and highs remaining in the 60s Monday and
Tuesday. Dry conditions still expected across CWA on Tuesday.

A northern stream system to move across the upper Midwest Tue
afternoon and Tue night and bring chance of showers into IL river
valley Tue evening and over rest of area overnight Tue night.
Showers look more likely on Wed with upper level low/trof moving
over IL by 18Z/Wed. Have chances of showers lingering from I-72
south Wed evening then drying out. Temperatures cool into upper
50s/lower 60s on Wed and possibly cooler. Upper level trof shifts
east of IL on Thu with IL in a nw upper level flow and temps
staying a bit below normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1207 PM CDT Fri Apr 20 2018

VFR conditions are expected through this forecast period. Light
easterly winds this afternoon at 7 to 12 kts may occasionally gust
up to 15 kts. Surface flow tonight will be mainly out of the east
at less than 10 kts.

&&

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

$$

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



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