Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KILX 081146

Area Forecast Discussion
National Weather Service Lincoln IL
546 AM CST Thu Dec 8 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 349 AM CST Thu Dec 8 2016

High pressure ridge is still well west and southwest of the area
which allows the colder air and brief mid level troughs to move
through the CWA. Another weak trough in the northwest flow will be
bringing mostly cloudy skies to a portion of the CWA today.
Observations upstream of central IL have reported some flurries with
these clouds, so will be adding flurries in the forecast for this
morning and early afternoon. The area will be roughly along and
north/northwest of I-74. As the trough moves through, dry conditions
will return for late this afternoon and continue through tonight.
West to northwest winds will continue through today and breezy
conditions will continue as well. Gusts of around 25 mph will be
common across most of the CWA. Temps will be below freezing today
with the coldest temps being in the north where most of the cloud
cover will be. Overnight lows will fall into a range of 14-20
degrees by morning. Wind chill readings will be in the single digits
again overnight.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 349 AM CST Thu Dec 8 2016

Once again the precipitation forecast for the weekend is troubled,
but the cold air snaps are more concrete.  The cold Arctic air
moving into the Midwest for the end of the week will be countered by
some relatively warmer air for the end of the weekend...only to lose
ground to bitterly cold temperatures for next Tuesday and beyond.

Cold Arctic air in place over the area will keep the max temps in
the 20s for Friday. Winds Friday morning will be up a bit, dropping
wind chills to single digits. The bitter cold will be a bit of a
shock from the mild weather in place for much of the season up to
this point.  Temps begin to moderate slightly on Saturday later as
the winds take on a more southerly component and weak WAA starts up.

Models have been consistently inconsistent for the weekend. Both the
ECMWF and the GFS...and to some extent the Canadian shift from
northwesterly flow to more northerly, sheering out a wave across the
Great Lakes for Sat afternoon and overnight.  The second wave is now
starting to differentiate from the prev wave with the last few runs
for Sun afternoon and overnight as a surface system develops to the
WSW and moves into the Mid Mississippi River Valley.  The questions
remain as to how much of the models are lingering precip too long
and muddying the division of the systems or if the dynamics will be
able to interact and enhance one another.  For now...chance pops
dominate...but with some higher pops in for Sunday night and the
better sfc development/deeper wave aloft.  Mostly snow anticipated
early... but as the warm air advects into the region...the southern
half of the state could see more rain/wintry mix for Sunday,
particularly in the afternoon.

Beyond the precip issues with the weekend...cold air is coming for
next week.  Highs by midweek already showing as teens and low 20s
for Wednesday as a frigid Arctic airmass moves into the CONUS.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 546 AM CST Thu Dec 8 2016

MVFR cigs around 2kft have already arrived at PIA and BMI early
this morning and based on satellite imagery/trends, am expecting a
break in the cloud cover later this morning at both sites, but becoming
cloudy again around noon and continuing for the remainder of the
forecast period. These MVFR cigs will arrive at DEC and CMI in a
couple of hours with DEC expecting some scattered conditions for a
while later this morning. At CMI, not expecting a break in the
clouds, and looking for MVFR clouds to continue through the entire
forecast period once it arrives. At SPI, am not expecting MVFR
cigs at the site, but still some uncertainty with this, so will
have a TEMPO group for broken cigs for 4hrs from 16z-20z. Cigs
will not be that far away to the north and northeast, but do not
think it will become broken at SPI today. All sites will see windy
conditions out of the west and expecting gusts of 22 to 24kts
during the day today. This evening, gusts will diminish, but wind
speeds will still be 10-12kts at all sites.




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