Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 172023

Area Forecast Discussion
National Weather Service Lincoln IL
223 PM CST Sat Feb 17 2018

.SHORT TERM...(This evening through Sunday)
ISSUED AT 222 PM CST Sat Feb 17 2018

Vigorous upper wave, approaching the Illinois/Iowa border early
this afternoon, has produced some decent snow across the northern
part of the CWA. Have received a report of 2.5 inches of snow
over far northern Knox County, with 1/4 mile visibilities as far
south as Peoria. Lightning data suggested a bit of thundersnow in
northeast Knox County shortly before noon, which could explain the
higher snow amounts there. Areas south have had more of a
snow/rain mix over the last couple hours. Radar mosaics showing
the back edge of the precipitation approaching Galesburg, and
extrapolation has it east of I-39/US-51 by mid afternoon and
largely out of the CWA by sunset.

High pressure will move over the area tonight, with a nice warmup
starting Sunday as southerly winds kick in behind the high. Highs
still look to be in the upper 40s to lower 50s.


.LONG TERM...(Sunday night through Saturday)
ISSUED AT 222 PM CST Sat Feb 17 2018

Not a lot of changes with the timing of rain with the early week
system. Bulk of it should start coming in Sunday night after
midnight, and will go with categorical PoP`s most of the time
through Tuesday night. Heaviest rain axis continues to shift
slightly to the northwest, with areas currently in moderate
drought conditions getting a good soaking. As for the timing of
the frontal passage, the models are coming into better alignment,
with generally late Tuesday afternoon and evening the favored

Some concerns with the tail end of the precipitation Tuesday
night. Forecast soundings off the GFS and ECMWF models show a warm
nose of air lingering around 850 mb, as the colder air comes in at
the surface. This signal has been seen for a few model runs now,
so will go ahead and add a mention of freezing rain Tuesday night,
mainly from about I-55 west.

Models diverge quite a bit in regards to the late week storm
system. The ECMWF model is about 24 hours slower than the GFS and
Canadian models in bringing the precipitation back into the area.
With that model being a bit of an outlier at the moment, will go
with high PoP`s for Friday and Friday night.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1120 AM CST Sat Feb 17 2018

Steadier snow has spread as far northeast as KCMI at 17Z, and
some reports of flurries as far north as KBMI. Will be seeing a
period of lower visibilities with this snow, as well as
precipitation that will be pushing from west to east through the
afternoon. Ceilings have fallen to IFR levels with the snow from
KSPI to near KCMI, and will generally stay down until an upper
wave passes mid to late afternoon. Further north, KPIA and KBMI
have recently gone to MVFR conditions, and will see some periods
of ceilings below 1,000 feet as well. Conditions generally should
improve late afternoon with a return to VFR.




SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Geelhart is the U.S. government's official web portal to all federal, state and local government web resources and services.