Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 271102

Area Forecast Discussion
502 AM CST Tue Jan 27 2015

.SHORT TERM...(Today)

What we feared yesterday morning at this time panned out with the
freezing drizzle breaking out late yesterday afternoon and evening
along the tail end of the band of light snow that brought a few
areas a half inch to one inch of snow. The 4km WRF forecast soundings
were showing the ice crystals departing around 400 pm yesterday
afternoon with some weak omega/lift remaining in the low levels of
the atmosphere where moisture was still present, along with just
enough shear in the 950-850mb layer. Radar mosaic showing the last
batch of light snow and freezing drizzle tracking south through east
central Illinois early this morning and based on the present
movement, most of it should push out of our forecast area by 14z.
Based on that, we will continue the Freezing Rain Advisory until
the expiration time of 600 am.

Current surface analysis indicating weak low pressure shifting to
our south with an inverted trof extending north from the low through
central and northern Illinois. The main forecast concern today will
be with temperatures as the extensive cloud cover is expected to hold
over our area as forecast soundings depict most of the low level
moisture trapped beneath a strengthening subsidence inversion thru
the day. We are seeing some breaks in the cloud cover from time to
time early this morning but as our boundary layer winds become more
north to northeast, the large area of low clouds to our north will
filter south across our area today. Coolest readings, generally in
the lower 30s, will be found over our east and northeast counties,
while over far southwest Illinois, look for afternoon temperatures
around 40 degrees.


.LONG TERM...(Tonight through Tuesday)

Low clouds to decrease during the evening as 1027 mb high pressure
drifts over IL/IN by overnight. Lows tonight range from upper teens
to near 20F ne counties (where clearing may occur soonest) to mid
20s sw counties. High pressure drifts east into eastern Ohio river
valley by 18Z/noon Wed and get a breezy SSE flow developing over IL
and bringing in milder air with partly to mostly sunny skies. Highs
Wed range from lower 40s eastern IL to the upper 40s to around 50F
from Jacksonville west to the MS river.

Low pressure ejects east from northern Rockies into western Great
Lakes by dawn Thu and pulls cold front east across IL late Wed night
into Thu morning. This to bring chances of light rain overnight Wed
night into Thu morning and possibly lingering over eastern IL Thu
afternoon where light snow could mix in over northern counties
before ending. Lows Wed night of 33-38F with coolest readings in
east central IL. Highs Thu in upper 30s and lower 40s central IL and
mid 40s in southeast IL southeast of I-70.

1040 mb Canadian high pressure moves down into the Midwest Friday
and returns mostly clear to partly cloudy skies and cooler
temperatures Thu night through Fri night. Cooler highs Friday of
30-35F. Most of Saturday now appears dry over central and eastern IL
with chance of light snow/rain moving into west central IL later
Saturday ahead of next storm system. Seasonable highs Saturday in mid
to upper 30s.

00Z extended models show more phasing of southern and northern
stream system this weekend and bring better chances of light snow to
central and southeast IL Sat night into Sunday evening as surface
low deepens ne from southeast Texas into the eastern OH/TN river
valleys. This could bring a few inches of snow accumulations
especially in southeast IL where even a mix of precipitation appears
possible south of Highway 50. Another Canadian high to drift
southeast into IL early next work week bringing colder/below normal


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)

Areas that have seen their cigs improve to VFR will soon see MVFR
and local IFR cigs move back into the area this morning. Most of
the improvement has occurred from PIA to SPI and southeast, while
MVFR and IFR cigs were prevalent to the east roughly along and
east of I-55. This is the same area that received the freezing
rain/drizzle last night and early this morning. Most of that has
pushed southeast of the area so will not include in any of the
TAFs, although we can`t rule out some patchy freezing drizzle
at BMI and CMI for the next several hours. HRRR forecasts indicate
the potential that the MVFR and IFR cigs will slowly improve from
northeast to southwest late this afternoon. Will start to bring cigs
up late this afternoon and continue with the improving trend this
evening as weak high pressure settles over the area. Surface winds
will be out of the north to northeast at 10 to 15 kts with an
occasional gust around 20 kts. Look for the winds to diminish this
evening out of the northeast with speeds of less than 10 kts.


FREEZING RAIN ADVISORY until 6 AM CST early this morning FOR



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