Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 061633

Area Forecast Discussion
National Weather Service Lincoln IL
1033 AM CST Tue Dec 6 2016

Issued at 1033 AM CST Tue Dec 6 2016

Rain has pushed east of the area and visibilities are improving.
Clearing line now moving across Mississippi River attm and will
push into forecast area by midday. Have made some minor tweeks to
timing in the grids, otherwise forecast package on track.


.SHORT TERM...(Today and tonight)
ISSUED AT 356 AM CST Tue Dec 6 2016

Precip is finally getting into the CWA early this morning, and
though mosaic radar returns showing precip as far northwest as I-55,
local radar returns showing that precip not getting that far. So,
radar returns combined with observations indicating that precip is
reaching mainly southeast IL at the moment. Based on blend of
models, highest pops should be in eastern and southeastern parts of
the CWA, just for this morning. Lower pops will extended northwest,
with all areas northwest of I-55 being dry this morning. With temps
being below freezing in northeast areas currently, the slight chance
of freezing rain is still warranted, so will be leaving it in the wx
grids. Fog has developed over most of the area north of I-70 with
some areas in the north seeing visibilities below 3 miles, and even
PIA at 1/4 mile. Fog will remain in the grids as well and since
cloud cover will continue through the day, fog will likely hang
around til around noon.The remainder of today through tonight will
be dry as the weather system quickly moves east and a high pressure
ridge builds into the area tonight from the west. Skies should
scatter out and then clear tonight as the ridge moves in. Cloud
cover today will allow temps to range from the mid 30s in the north
to the mid 40s in southeast IL. Clear skies and high pressure
building in will cause temps to drop well below freezing, reaching
the lower to mid 20s across the area.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 356 AM CST Tue Dec 6 2016

Cold temperatures on the way through the end of the week.  Next
precip system for the weekend still with immense variation in the
models. Chances for snow this weekend and into the first portion of
the week kept rather low considering the inconsistent forecasts.

Cold Arctic air makes its way into the region and by Wednesday, most
areas north of Interstate 70 have high temperatures at or below
freezing...everywhere on Thursday. Overnight lows dropping each day
until widespread teens Thu night/Friday morning.  Winds Friday
morning will be up a bit, dropping wind chills to single digits.

Models still having issues with the weekend.  GFS and ECMWF are
lacking consistency and continuity with themselves, much less each
other.  The 500 mb flow across the CONUS after Friday becomes almost
zonal.  The GFS, ECMWF and Canadian global have a wave moving into
the Pac NW on Friday night.  The ECMWF and the Canadian both dampen
the wave considerably, maintaining the zonal flow. The GFS amplifies
more, and as a result deepens the surface low whereas the ECMWF and
Canadian treat it essentially like an open wave.  The deeper and
more progressive GFS starts the precip quicker on Sat night...and
ends it by Sunday night. The ECMWF and the Canadian are slower to
start and slower to end.  As a result...pops remain in the forecast
for the latter half of the weekend and into the first portion of the
work week.  The upside of the pattern shift for the weekend is that
southerly flow ahead of the storm system will warm the temps enough
so that the max temps by Sun are at least a touch over freezing.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 546 AM CST Tue Dec 6 2016

MVFR conditions continue at SPI/DEC/CMI this morning, but IFR
conditions will begin to effect the these TAF sites early this
morning and continue into the afternoon. Models suggest the lower
clouds will clear out late this afternoon, but high cirrus will
continue over the sites into the evening. Does appear that
clearing will finally take place around midnight at all sites.
VLIFR and LIFR conditions will continue at PIA and BMI, but
improving conditions into IFR category will effect PIA and BMI
later this morning, and continue into the afternoon. Then, like
the other three sites lower clouds clear out late afternoon
leaving high cirrus over the area, and then clearing takes place
around midnight. Winds will become northwest through the day, then
westerly for this evening into overnight.




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