Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 202015
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
215 PM CST Sat Jan 20 2018

.SHORT TERM...(This evening through Sunday)
ISSUED AT 215 PM CST Sat Jan 20 2018

Large expanse of stratocumulus has overspread most of the CWA
except for the extreme southeast, and that will fill in soon from
the south. Despite some thin spots this afternoon, the clouds
won`t be going anywhere for awhile. So far, upstream observations
have remained dry. However, the potential for drizzle will
increase this evening, as ceilings lower. Think this will
initially be more over the eastern half of the forecast area, then
expand after midnight. Will continue to mention areas of fog, with
the high-resolution guidance focusing more on the eastern half of
the CWA.

An upper level low will carve itself out of the trough currently
pushing across Nevada, lifting northeast Sunday and Monday. Precip
chances will ramp up as this system approaches. Forecast soundings
don`t really moisten up above 850 mb until Sunday evening, so
drizzle still will be the predominant precip type. With a warm
front sharpening just to our north, upper 40s to mid 50s are still
expected in the warm sector.

&&

.LONG TERM...(Sunday night through Saturday)
ISSUED AT 215 PM CST Sat Jan 20 2018

Temperatures expected to keep edging upward Sunday night as the
cold front approaches from the west. Most of the models are
suggesting formation a line of showers with some embedded
thunder immediately ahead of the front, sweeping from west to
east after midnight, and this is where the highest PoP`s are
focused.

On Monday, the models are in good agreement with a nearly stacked
system centered near the Iowa/Missouri border at midday, slowly
tracking across northern Illinois through the evening. Some dry
conditions expected for a time late morning and early afternoon,
before the wraparound showers arrive. The NAM and ECMWF models are
slowest in pulling the system out of the region, lingering light
rain or snow showers into Tuesday morning over a large part of the
area. Went with a bit more faster solution, and will generally
limit any PoP`s Tuesday morning to slight chances in the
northeast CWA.

Quiet weather is still on tap for the middle of the week, with a
broad upper trough passing through dry. Upper ridging across the
Rockies will shift east and be centered over the Midwest by
Friday, bringing temperatures back up to the 40s and 50s for us
late week. Early next weekend, a cold front is expected to arrive,
bringing the next precip chances. Currently, it looks to be warm
enough for rain.



&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1117 AM CST Sat Jan 20 2018

MVFR cloud deck has overspread all of the TAF sites as of late
morning. Some thinning seen in satellite imagery across far west
central Illinois, but clouds likely to remain at least broken
through the afternoon. Reports along the northern edge of the
cloud shield are showing some ceilings below 1,000 feet now, and
will mention continue to mention IFR conditions from KPIA-KCMI by
around mid afternoon or so. Latest HRRR and LAMP guidance suggests
KSPI may hold off on the IFR ceilings until about mid evening.
Once these low ceilings arrive, they likely will remain in place
through the end of the forecast period. Visibility-wise, several
guidance sources support fog developing over east central Illinois
this evening, though the extent of dense fog outside of KCMI is
more questionable. For now, will only mention the lowest
visibilities there, with mainly 1SM elsewhere.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Geelhart


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