Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241136

Area Forecast Discussion
536 AM CST Sat Jan 24 2015

.SHORT TERM...(Today)

A weak surface trof is expected to push across the area this morning
switching our winds more into a west to northwest direction. In
addition, latest satellite data and surface observations indicate
another band of clouds approaching from the northwest, immediately
behind the weak frontal boundary. Based on its current movement, it
appears the eastern half of the forecast area will be affected the
most from the southeastward moving clouds later this morning. This
will have an impact on afternoon highs with our east and northeast
counties trending a bit below guidance, with low to mid 40s common,
while over west central and southwest Illinois, not as much cloud
cover is expected and as a result we should push into the mid or
upper 40s this afternoon.


.LONG TERM...(Tonight through Friday)

00Z forecast model suite has trended further south and west surface
low pressure track going se into central IA (1003 mb) by 06Z/midnight
tonight, into south central IL by 18Z/noon Sunday, and nearing the
eastern KY and WV border by 06Z/midnight Sunday night. Have trended
a bit higher with qpf over central IL Sunday along with cooler temps
Sunday/Sunday night and bringing chances of snow further south with
the cooler air/further south track of storm system. Have increasing
chances of light rain after midnight tonight over central IL with
just slight chances of light rain late tonight in southeast IL from
I-70 southeast. Light snow could mix with light rain late tonight
north of I-74, but most areas should be rain overnight with lows in
the low to mid 30s. Raised pops to 60-90% Sunday with highest pops
northern counties where rain changes to snow especially late Sunday
morning/afternoon. Have snow chances as far south as I-70 by late
Sunday afternoon with southeast IL seeing light snow too during
Sunday evening before ending overnight Sunday night. Have 1-2 inches
of snow ne of a Canton to Lincoln to Paris line Sunday and Sunday
evening with locally higher amounts 2-3 inches in far ne CWA. A
winter weather advisory may eventually be needed in ne counties but
will issue SPS for now due to models shifting track of low pressure
past few runs. Highs Sunday range from mid 30s northern counties to
40-45F from Springfield to Terre Haute south with mid 40s near
Lawrenceville. Temperatures will likely be slipping Sunday

Another clipper system diving se across the western Great Lakes
Monday and Monday night to bring a chance of light snow showers to
northern/ne counties with best chances of accumulating light snow
appears to be ne of central IL. Highs Monday range from low to mid
30s from I-74 ne to the upper 30s to around 40F in sw counties. Dry
conditions expected Tue/Wed as high pressure settles into the upper
MS river valley Tue and into the Ohio river valley Wed. Highs in the
mid 30s to near 40F on Tue and climbing into the upper 30s to mid
40s Wed, with upper 40s from Jacksonville sw.

Surface low pressure system tracks into the Midwest and southern
Great Lakes region Wed night and Thu bringing a 20-30% chance of
light rain/snow. Models have trended quicker with this feature.
Above normal highs Thursday in the low to mid 40s with upper 40s in
southeast IL. Temps then cool behind this feature with highs in the
30s Friday and even colder temperatures expected next weekend with
another chance of light snow next Saturday.


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

Band of MVFR cigs approaching PIA this hour and based on its
current movement will affect all but SPI thru the morning hours.
Cig bases range from 2500-3500 feet with the western edge of
the cloud deck possibly skirting PIA to the east, but for now,
will include an hour or two of the cigs at the PIA airport.
Short term models suggest some IFR or LIFR cigs and vsbys will
advect southeast into at least the northern half of the area
later this morning but have seen the models backing off that
solution in this hours run. Not seeing much in the upstream obs
to support this so will handle with a tempo group for a few hours
this morning, especially with the TAF sites along the western
periphery of the cloud band. The next weather system will push
southeast into our area after midnight bringing a gradual lowering
of the cigs along with the chance for rain to develop from northwest
to southeast after 06z. Surface winds today will be westerly at
10 to 15 kts and then start to back more into the southwest and
then south this afternoon and evening with speeds averaging from
7 to 12 kts.




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