Area Forecast Discussion
Issued by NWS Central Illinois

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397
FXUS63 KILX 220921
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
321 AM CST Wed Nov 22 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 315 AM CST Wed Nov 22 2017

09Z/3 am surface analysis shows 1032 mb Canadian high pressure
over eastern Nebraska and ridging from west Texas through MN. NW
winds have diminished to 6-12 mph over central and southeast IL
and have ushered in colder and drier air. Temps currently range
from 19F at Galesburg, to 29F along highway 50 in southeast IL at
Flora, Lawrenceville and the Mount Carmel airport. Dewpoints
ranged from 16-23F from nw to se and temps will approach these
levels around sunup. Skies generally clear over CWA with cirrus
clouds spreading se into west central/sw IL. Stratus clouds were
ne of Lafayette, IN and dropping SSE and should stay east of IL
this morning.

00Z forecast models take high pressure ridge eastward from central
Texas ne into central IL by 18Z/noon and then into the Ohio and
mid MS river valley by early evening as it weakens to 1026 mb. A
fair amount of sunshine and lighter winds expected today over CWA
with high clouds increasing over the IL river valley later this
afternoon. Will be cold today with highs only 36-41F, coolest
from I-74 ne.

Temperatures will slip to 24-28F during this evening and then be
nearly steady overnight as SSW winds develop from nw to se as high
pressure ridge shifts into the TN river valley and mid Atlantic
states by dawn Thu. Also will see clouds increase from nw to se
during this evening and into southeast IL by early overnight and
help keep temps from getting as cold as this mornings readings.

&&

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 315 AM CST Wed Nov 22 2017

Upper level trof over the central Great Lakes and into the Oh/Tn
river valleys will pull away from IL on Thanksgiving day as a
frontal boundary washes out as it moves south into northern IL.
WSW winds along with partly to mostly sunny skies to modify temps
into the mid to upper 40s, which is close to normal levels for
Thanksgiving Day. Lows mostly in the lower 30s on Thu night with
fair skies and light ssw winds.

992 mb low pressure off the British Columbia coast will track
eastward across southern Canada and deepen to 980 mb as it moves
near James Bay Canada overnight Friday night and pulls a cold
front se across our CWA. Like the system yesterday afternoon,
could see isolate light rain showers ne of I-74 Fri evening, while
most areas appear to be dry as best forcing is further north and
moisture limited over our area. Breezy ssw winds on Friday to warm
temps into the mid to upper 50s, with areas from Springfield sw
near 60F, so similar weather to what we saw this past Monday.
Clouds to increase by later in the day Friday and into Friday
evening.

Cooler temperatures ahead for this weekend behind the cold front
with highs Sat ranging from 45-55F from nw to se and in the low to
mid 40s on Sunday. 1025 mb Canadian high pressure settles into the
mid MS river valley by 18Z/noon on Sunday and returns more
sunshine this weekend. A broad upper level ridge shifts east over
the Great Plains Sunday night and into IL by sunset Monday while
upper level trof digs over the Rockies. Breezy SSW winds develop
during Monday and modify temps into the upper 40s and lower 50s,
with mid 50s from Jacksonville sw. Highs back into the 50s across
area on Tuesday and continued dry weather with increasing clouds.
GFS and ECMWF models eject surface low pressure into the central
plains by 12Z/6 am Tue and eject it ne into the western Great
Lakes Tue night, with GFS model stronger and faster with low
pressure system. Brunt of moisture appears to set up north of IL
Tue night and also into southeast IL overnight Tue night into Wed
morning with passage of cold front. Highs next Wed close to
seasonal levels in the mid to upper 40s and GFS and ECMWF MOS
guidance similar.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1050 PM CST Tue Nov 21 2017

VFR conditions are expected through this forecast period. High
pressure will dominate the weather across our area into Wednesday
night with no more than some scattered high level clouds from time
to time. Surface winds will be northwest at 8-13 kts tonight,
with winds slowly backing into a westerly direction by Wednesday
afternoon with speeds ranging from 5-10 kts.

&&

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

&&

$$

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



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