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FXUS63 KILX 262058

National Weather Service Lincoln IL
258 PM CST THU NOV 26 2015

.SHORT TERM...(Tonight)

A slow frontal boundary stretched across most of the CONUS will make
its way through the Midwest today and tonight.  Plenty of llvl
southerly flow ahead of the boundary feeding moisture and
unseasonably warm temperatures into the region.  The available
moisture will lend itself to plenty of rain for tonight into
tomorrow.  Models have been differing somewhat with the timing of
the boundary. However, for the most part, the rainfall will remain
NW of the Illinois River Valley before 03z, and west of I-55 through
midnight.  Rain will concentrate south and east of the Illinois
River by morning.  Rain is expected most everywhere before
morning...with only the far southeastern portions of the state
potentially still ahead of the boundary enough to see showers. Rain,
low visibility, and gusty southerly winds will keep holiday travel
concerns active, but little in the way of freezing temperatures will
moderate them somewhat.  Although severe weather is not expected,
rainfall totals by early morning is expected from 0.25 inches to 1


.LONG TERM...(Friday through Thursday)

Split flow pattern to continue across the lower 48 into early next
week with two distinct upper waves to affect our area. The first is
a northern stream shortwave that will track east across the upper
Great Lakes and shift a cold front across the region late tonight
across the far northwest, and over the remainder of the area during
the day Friday. Strong lift associated with the upper wave and
copious moisture along the frontal boundary, precipitable water
values up near 1.50 inches on the NAM-WRF, will fuel the rainfall
over the forecast area starting later tonight and slowly track from
northwest to southeast on Friday.

As the front settles into far southeast Illinois later Friday, the
better plume of moisture and low level convergence shifts southeast
as well bringing the threat for heavier rain along the I-70 corridor,
with lighter rainfall further north as colder air works its way into
the area. Latest NAM more bullish in bringing in drier air in the lower
levels late Friday night into Saturday, as a result, have pushed the
better POPs a bit further south. Still the outside chance that we may see
a brief period of light freezing rain or rain along the far northwest
periphery of the precip shield during this time frame, but the probabilities
have decreased from the last model run so will hold off adding into the
grids with this model run with just a mention of light rain or snow for now.
Forecast rainfall amounts still focus the heaviest rains over southeast
Illinois with the potential for 1.5 to 2.5 inches, especially along and south
of the I-70 corridor.

The second and stronger upper wave over the southern Rockies will shift slowly
northeast into the Midwest by early next week bringing a renewed threat for
rain to the region. With the deeper tropical moisture tied up long the frontal
boundary to our south and Canadian high pressure settling over the region, the
better QPF with this system looks to remain south of our area early next week.
As the upper low slowly shifts northeast into the Midwest late Sunday into
Monday, POPs start to increase again further north Sunday night and especially
on Monday. Forecast soundings, except in the far northwest, suggest mostly
light rain, with a mix of light rain or snow far northwest later Monday night
into Tuesday morning. The upper low will shift into lower Michigan on Tuesday
with POPs slowly decreasing across the area from southwest to northeast. Coldest
temperatures will be close to the upper low early next week, but as the system
pushes away from our area late Wednesday into Thursday, temperatures aloft start
to warm as we head towards the end of the week with mainly seasonably cold weather


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)

Expecting deteriorating conditions later this evening and through
the overnight. In the short term, cloudy w/ VFR cigs and very
gusty southerly winds. Keeping in the trend of dropping cigs to
MVFR later this afternoon/evening and into IFR through the
overnight with the advance of the front. Very strong winds off the
sfc in this mornings sounding as well as on the profiler, so have
decided to keep the mention of LLWS. Clouds/visibility restrictions
due to rain have the potential to improve for PIA later in the
morning tomorrow...however, the front and its position are close
enough to stalling in that time frame so am keeping the ending as
is. Also will put best chances of wind shift in the tafs from 11z
to 14z as it progresses across the area. But the precip may linger
a big beyond that.


.ILX Watches/Warnings/Advisories...


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