Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 191701

Area Forecast Discussion
National Weather Service Lincoln IL
1101 AM CST Sun Nov 19 2017

Issued at 1057 AM CST Sun Nov 19 2017
High pressure building into the midsection of the country this
morning as the storm system from yesterday moves out over New
England. Some persistent stratus breaking up over far east central
Illinois, and a few cirrus are streaming into the region. Even
with plenty of sunshine...high temperatures are only going to
climb into the mid 30s to low 40s with the colder airmass in
place. Some gusty winds throughout today are expected as well,
with the pressure gradient between the systems. Forecast is going
well and no major updates are anticipated at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CST Sun Nov 19 2017

09Z/3 am surface analysis shows a strong and still deepening 983
mb low pressure just east of Lake Ontario while 1033 mb high
pressure was over the central Rockies and ridging into the central
and southern plains. Still a fairly tight pressure gradient over
central and eastern IL giving brisk WNW winds of 10-20 mph and
gusts of 20-30 mph. This was ushering in much colder air with
temps ranging from upper 20s nw of the IL river, to the mid 30s in
southeast IL. Wind chills were as cold as 15-25F. Stratocumulus
cloud deck 2-3k ft bases was over eastern and ne IL east of a
Peoria to Taylorville line.

The latest HRRR and Hi Res Rapid Refresh model runs are similar
in handling these low clouds fairly well, and gradually decrease
these clouds from west to east from mid morning into early
afternoon as deep upper level trof over eastern parts of the Great
Lakes and Ohio valley pulls further away from IL into the Atlantic
states by sunset. So have painted a cloudier picture over eastern
IL from highway 51 eastward to IN during first half of this
morning, then decreasing clouds. WNW winds to diminish to 10-15
mph and gusts 15-25 mph through early afternoon and further
diminish later today. Highs only 35-40F today (coldest from I-74
ne) and will be the 4th day this season we have been this cold,
including Oct 28th, Nov 10th & 16th. Expect similar highs of
35-40F again on Wednesday and next Sunday.

A 1025 mb chunk of high pressure settles into the TN and lower MS
river valleys by overnight. This will bring fair skies tonight and
lighten winds as they shift sw and bring a seasonably cold night
with subfreezing lows 27-32F.

.LONG TERM...(Monday through Saturday)
ISSUED AT 345 AM CST Sun Nov 19 2017

Quiet/dry weather still forecast from Monday through Friday
evening across central and southeast IL. High pressure drifts
over the Carolinas by midday Monday and to bring ample sunshine.
Increasing sw winds to breezy levels and moderating temperatures.
Highs Monday in the lower 50s, except mid 50s from Springfield
southwest. Not quite as cool Monday night with stronger sw winds
with lows in the mid to upper 30s.

996 mb low pressure over west central British Columbia to deepen
to 990 mb as it tracks ESE into eastern Ontario by dawn Tue and
swings a cold front se through CWA during Tuesday. Most forecast
models continue to show a dry frontal passage on Tuesday over CWA
with patchy qpf over northern/ne IL and better chances of
precipitation over the Great Lakes region. Highs Tue range from
mid 40s nw of the IL river to mid 50s by Lawrenceville. Brisk nw
developing behind the cold front by Tue afternoon will likely
have temps slipping especially over IL river valley. Cold Tue and
Wed nights with lows in the low to mid 20s Tue night and mid 20s
Wed night. Highs Wed in the mid to upper 30s and then low to mid
40s Thu (mildest sw CWA). 1030 mb Canadian high pressure settles
se into MO by midday Wed and into Ohio and mid MS river valleys
Thu bringing dry wx but cold temperatures.

Models track another strong area of low pressure eastward over
southern Canada Fri/Sat bringing a cold front se through IL Friday
night. Moderating temps ahead of this front on Fri with highs in
the upper 40s/lower 50s. We will be on the southern fringe of this
storm system so isolated showers possible Friday night with better
chances of rain/snow showers ne of CWA overnight Fri night into
Sat. Temps cool back down during next weekend with highs back to
35-40F next Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 555 AM CST Sun Nov 19 2017

An area of stratocumulus clouds with MVFR ceilings of 1.5-3k ft
will affect CMI through mid morning, and be scattered to broken at
BMI and DEC thru 15Z/9 am. PIA and SPI should be far enough west
of these clouds to just see few-scattered clouds this morning.
Broken MVFR ceilings should be east of CMI by late morning with
VFR conditions expected across area rest of TAF 24 hour period as
upper level trof pulls further east of IL. Some cirrus clouds over
the Northern Plains to spread se over central IL during this
afternoon and into tonight. WNW winds of 10-17 kts and gusts of
15-25 kts this morning, to diminish by late afternoon and veer sw
toward sunset at 5-10 kts. Winds then turn SSW at 7-13 kts during
overnight as high pressure over the central Rockies and into west
Texas settles over the TN valley by 12Z/6 am Monday.




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