Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 171752
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1252 PM CDT Tue Oct 17 2017

.UPDATE...
Issued at 1115 AM CDT Tue Oct 17 2017

The only clouds of note for the rest of today over central and
southern Illinois will be thin cirrus clouds triggered by a weak
wave of upper level energy. That will do little to limit the
insolation from the sun this afternoon. The dry surface air will
continue to steadily heat into the upper 60s to lower 70s.

Southwest winds will become even more gusty this afternoon as the
pressure gradient across Illinois tightens between high pressure
to our southeast and low pressure to the northwest. Wind gusts
of 20-25 mph will be common across the area this afternoon, with
diminishing gusts toward sunset.

The overall forecast looks on track, and no formal updates will be
needed this morning.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 332 AM CDT Tue Oct 17 2017

Not a lot of large scale changes in this round of the forecast.
Models still in a warming trend with nothing in the way of precip
until the weekend. A break in the continuity of the weekends
system is hinted in the 00z run.

High pressure ridge is still in place, with the axis stretching
from the Southern Plains to New England. A small disturbance
creating a few clouds over the region the only break in the mild
weather. This morning is slightly warmer than yesterday, and the
beginning of a warming trend through the week. Todays highs should
reach around or near 70 degrees across Central IL, with
southwesterly winds assisting warm air advection for the region.
Tonight will be a couple degrees warmer than this morning...again
continuing the trend.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 332 AM CDT Tue Oct 17 2017

Latter half of the work week continues the warming trend with
temperatures considerably warmer than climatology. By Friday, 850
mb temps climb to 15C-18C, and reflective high temperatures are
expected in the mid to upper 70s. Have boosted the max temps a
degree or two above guidance Wed-Fri. Aloft, the trof shifts
eastward, beginning a trend to a more zonal flow for the end of
the week. With the ridging over the south/southeastern CONUS, the
more active stream shifts north, minimizing a wave midweek for the
area. Forecast remains dry and well above normal through the end
of the work week.

Models agree with a break in the pattern moving into the weekend
with a more amplified wave digging in over the western half of the
CONUS. However, the 00z run of the ECMWF is now dropping the
energy into a cut off low to the south, chopping the QPF depiction
in half...and potentially putting Central IL in a break. For now,
forecast keeping to a fropa and associated pops this weekend...but
have limited to likelies...and pulling categorical should the GFS
shift similarly. The cold front is slated to move through the
region late Saturday/early Sunday, resulting in a rainy weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1252 PM CDT Tue Oct 17 2017

Winds are the main concern for aviation for the 18z TAF period. A
tightening pressure gradient across Illinois is producing
southwest wind gusts of 24-26kt this afternoon. The stabilizing
effects of sunset will cause gusts to diminish by early evening,
and wind speeds will drop below 10kt as the wind direction becomes
southerly.

Winds will increase from the south by mid-morning tomorrow, with
some gustiness expected again.

No significant clouds will develop over the next 24 hours.

&&

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

$$

UPDATE...Shimon
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Shimon



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