Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 131438

Area Forecast Discussion
National Weather Service Lincoln IL
938 AM CDT Tue Mar 13 2018

Issued at 937 AM CDT Tue Mar 13 2018

Strong shortwave currently pivoting across northern/central
Illinois. Scattered flurries/snow showers are dropping southward
toward the northern CWA this hour, with the high-res models
focusing on some more development in northeast Illinois early
afternoon. Have updated the forecast to expand the coverage of
sprinkles/flurries this afternoon and early evening, and increased
the PoP`s in the far northeast CWA to around 30% where a bit of
measurable rain/snow may occur. Also updated sky trends into the
afternoon, as the currently mostly clear sky will quickly see
diurnal development over the eastern CWA.


.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CDT Tue Mar 13 2018

A strong 524 dm 500 mb low northeast of the Great Lakes will drop
down into the southern Great Lakes by early evening, as a
nor`easter off the mid Atlantic coast brings another winter storm
to New England today thru Wed morning. This will pivot a fairly
strong short wave currently just north of Lake Superior, southward
to along the IL/IN border by sunset. Steeping lapse rates as 850
mb temps fall to minus 8-12C by sunset over CWA (coldest in
eastern IL). This will likely develop broken stratocumulus clouds
over central and eastern parts of CWA during today, along with
isolated light snow showers and scattered flurries by afternoon
from Peoria to Effingham east. Southeast IL could also see
scattered sprinkles. Highs only in the upper 30s and lower 40s,
with mildest readings south of I-70 and from Springfield sw. Brisk
nw winds again today to factor in a wind chill.

Scattered flurries to diminish near the Indiana border during
early evening, then stratocumulus clouds and nw winds to decrease
from the west during tonight as 1036 mb Canadian high pressure
over ND settles southward into the Ozarks by dawn Wed. Colder lows
in the lower 20s expected overnight.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 345 AM CDT Tue Mar 13 2018

Strong upper level low moves over the Canadian Maritimes on Wed
while Canadian high pressure moves over the southern MS river
valley. This will bring mostly sunny skies Wed and increasing wsw
winds to start to modify temps. Highs Wed range from mid 40s over
eastern IL, to the lower 50s in west central IL. Fair skies
tonight as a weak front pushes southward through central IL during
tonight, and thru southeast IL early Thu morning. Front to pass
through dry with very limited moisture and lift. Lows Wed night in
the upper 20s and lower 30s, coolest from I-74 ne. Mostly sunny
skies on Thu with north winds less than 10 mph. Highs in the
upper 40s to near 50F from I-74 ne and 50-55F sw of I-74.

A Canadian high pressure settles into the western Great Lakes on
Friday, while low pressure emerges over western KS from southeast
CO. Models have focused light precipitation chances further sw
over sw third of CWA Thu night into Friday ahead of a warm front
near the MO/AR border, with a light mix possible overnight Thu
night into Fri morning. Cooler highs Fri in the low to mid 40s,
coolest from I-74 north. Low pressure tracks over eastern KS and
western MO during Fri night and likely spreads a band of rain
showers changing to snow showers ne across CWA during Fri night.
Could be some minor snow accumulations overnight Fri night of a
half inch or less with lows in the upper 20s and lower 30s.
Lingering light showers possible Sat morning, then dry Sat
afternoon thru Sunday evening as weak high pressure noses into IL
from the upper Midwest. Highs Sat in the upper 40s and lower 50s,
then milder 50s on Sunday.

Another storm system ejects out of the central Rockies and into
the central plains on Sunday night and ne toward IL on Monday.
This will likely bring another round of showers overnight Sunday
night and Monday, along with isolated thunderstorms especially sw
CWA. Highs Monday in the low to mid 50s, with upper 50s by


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 605 AM CDT Tue Mar 13 2018

Strong 523 dm 500 mb low spinning just northeast of Lake Huron at
dawn, will drop into the southern Great Lakes by early evening,
and into southern New England by 12Z/7 am Wed. A short wave
dropping southward over the western Great Lakes this morning will
track to along the IL/IN border by sunset today. This will develop
broken stratocumulus clouds later this morning and afternoon with
ceilings of 4-5k ft. Also continued VCSH for isolated light snow
showers/flurries this afternoon. Stratocumulus clouds to scatter
out during early evening. NW winds to increase to 11-16 kts during
mid morning with gusts of 20-25 kts expected today. NW winds to
decrease to 5-9 kts after sunset tonight as 1034 mb Canadian high
pressure over ND settles into the Ozarks at 1028 mb high at 12Z/7
am Wed and ridges into MO and sw IL.




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