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FXUS63 KILX 231750

National Weather Service Lincoln IL
1150 AM CST MON NOV 23 2015


High pressure over the Deep South is providing a mild southwesterly
flow across central Illinois this morning. Thanks to abundant
sunshine, 15z/9am temperatures have already risen into the upper
30s and lower 40s across areas without a snow cover. Further north
over the deeper snow field, readings remain in the lower 30s
along/north of I-74. With only a few high/thin clouds expected to
stream into the area this afternoon, am expecting nearly full
sunshine and continued southwesterly winds. Based on current rate
of temp rise, have adjusted afternoon highs up a few degrees
across the southern two-thirds of the KILX CWA. Highs will range
from the upper 30s from Galesburg to around 50 degrees
along/southwest of a Jacksonville to Flora line.


.SHORT TERM...(Today)

A weak sfc trough will move through the CWA this morning, switching
southerly winds to westerly. Pressure gradient is currently tighter
ahead of this trough so winds this morning will be higher than this
afternoon, after the trough passes through and sfc ridging begins to
build into the area. Satellite trends indicate lots of clear skies
over the area for the day. Will see some warmer temps today, which
will melt some of the snow, but without any good waa on the sfc and
still fairly good snow pack in the north and northeast, the warmer
temps will be limited to mostly areas south of I-74. Temps over the
snow pack should still be above freezing, but overall below normal
temps expected today.

.LONG TERM...(Tonight through Sunday)

Surface high pressure ridge settling into the southeast states
tonight and ridging nw into central IL will bring lighter winds to
the area tonight. These lighter winds along with boundary layer
moisture from snow melt will likely develop patchy fog over snow
pack of northern CWA later tonight into mid morning Tue. Models
continue to show streaks of mid/high clouds affecting central and
especially ne CWA tonight with weak upper level disturbances in wnw
flow. Main over level trof and short wave energy will be ne of IL
over the Great Lakes region where more cloud cover expected. Lows
tonight range from lower 20s north of Peoria to upper 20s sw CWA.

00Z models continue to show upper level ridge building into IL and
the ohio river valley Tue/Wed. Meanwhile surface high pressure
strengths as it moves into the mid Atlantic states and New England
Tue night into Wed. Increasing pressure gradient over IL Tue/Wed to
bring breezier south winds along with milder temperatures by Wed.
Highs Tue range from lower 40s from I-74 ne where lingering snow
pack to lower 50s sw CWA. Southeast winds of 8-15 mph on Tuesday.
Added patchy fog to northern CWA overnight Tue night until mid
morning Wed where more moisture from snow melt. Lows Tue night in
the low to mid 30s, with upper 30s from Springfield and Jacksonville

Strong cutoff upper level low/trof digging into northern CA by
12Z/Wed and moving into the central Rockies on Thanksgiving Day.
Increasing WAA and moisture well ahead of this storm system
possibly getting rain showers into the IL river valley later Wed and
Wed evening. Shower chances increase from nw to se overnight Wed
night into Thursday. Southeast IL likely to stay dry Wed night and
into Thu. Milder highs Wed near 50F from I-74 ne to mid 50s sw CWA
and in southeast IL. Highs Thu in the upper 50s to near 60F. Highest
chances of rain appears to be over the IL river valley Thu and
across the area Thu night and east of the IL river Friday. Better
chance of isolated thunderstorms appears to be sw of central IL Thu
and Thu night. But heavier rains of 1-1.5 inches with locally higher
amounts before diminishing from nw to se during Friday night. Could
see a mix of light snow with the light rain over central IL Friday
night especially overnight before ending. Highs Fri range from low
to mid 40s over IL river valley to the mid to upper 50s in southeast

High pressure builds into the Great Lakes region on Saturday and
Saturday night bringing cooler temperatures to IL along with drier
conditions. Lingered slight chances of light rain/snow over far
southern 6 counties closer to cold front pressing southward into the
TN river valley. GFS is quicker returning moisture back into central
IL Sunday while ECMWF model waits until Sunday night to bring back
precipitation. Will stay close to superblend pops for now that far


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

Main aviation forecast concern continues to be potential for fog
development tonight as high pressure slides overhead and winds go
light/variable. Several factors point to at least patchy fog,
including nearly calm winds after sunset and increasing boundary
layer moisture due to snow melt. However, the possible fly-in-
the-ointment will be increasing high clouds currently seen on
visible satellite imagery streaming from the Dakotas into Iowa.
All models suggest these clouds will spread into Illinois late
this afternoon then persist through much of the night. Whether
they will be thick enough to limit radiational cooling and prevent
widespread fog is still in question. Several models such as the
NAM and GFS indicate little or no restriction to visby tonight,
while the HRRR is showing fog developing from mid-evening through
the overnight hours. At this point, will continue to feature
visbys down to around 3SM tonight where snow cover exists at the
I-74 terminals, but will maintain unrestricted visbys at both KSPI
and KDEC.


.ILX Watches/Warnings/Advisories...


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