Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 290930

Area Forecast Discussion
330 AM CST Thu Jan 29 2015

.SHORT TERM...(Today)

Low pressure centered just north of Moline at 08z/2am will continue
to push east and drag a cold front through our area this morning.
Warmest temperatures will be just ahead of the cold front early this
morning, and then we expect temperatures to fall off quickly just
behind the cold front during the remainder of the morning, and then
hold fairly steady this afternoon. Winds will be gusty again today
but this time out of the northwest with a few gusts of 35 to 40 mph
at times about an hour or two after frontal passage right along the
stronger surface pressure rises. Look for gusts in the 30 to 35 mph
range this afternoon.

Not seeing a lot of precip, other than some occasional very light
rain/drizzle out in Iowa and northern MO so will continue with
just a slight chance of light rain/snow this morning with POPs
decreasing from west to east this afternoon, and that would be
mainly across the north half of the forecast area. Latest
satellite data and upstream surface observations not showing much
hope for any clearing across our area in the near term. Forecast
soundings off the NAM-WRF showing a fairly strong subsidence
inversion setting up again in the wake of this system resulting in
quite a bit of low level moisture trapped beneath the inversion at
around 2500-3000 feet. As a result, we have backed off with any
decrease in cloud cover until later this evening and that may be
optimistic based on the latest (06z) forecast soundings off the


.LONG TERM...(Tonight through Wednesday)

Short wave trof to exit east and se of IL early this evening as
Canadian high pressure over the Canadian Rockies settles into the
upper Midwest tonight. However an inversion will likely trap low
level clouds longer tonight and have trended the forecast slower
with decreasing low clouds from the west. Low clouds could linger
over ne counties into Friday morning especially near IN border.
Cooler lows tonight in upper teens to near 20F northern areas to mid
20s in southeast IL. Brisk nw winds 15-25 mph this evening to slowly
diminish during overnight into Friday morning as high pressure
settles into IL on Friday. Highs Friday 29-35F with coolest readings
from I-74 ne with partly to mostly sunny skies.

High pressure settles into the Ohio river valley Friday evening and
into central Appalachians by dawn Sat and continue fair/dry weather
through at least Saturday morning. Lows Friday night in upper teens
and lower 20s again. Milder highs Sat in upper 30s and lower 40s
with mildest readings sw areas with ssw breezes. Clouds to increase
later Friday night into Sat ahead of next storm system with slight
chance of light rain/snow later Saturday afternoon west of I-55. Most
over central and especially eastern IL should still be dry through the
daytime hours on Saturday.

12Z Jan 28 forecast models trended further south with low pressure
system Sat night and Sunday, while 00Z Jan 29 forecast models have
trended back north with more phasing of southern and northern stream
upper level systems, along with higher snowfall amounts over central
and southeast IL. 00Z models have also trended colder with even
southeast IL looking like all snow with this eveng and mixed
precipitation south of I-64 toward the ohio river. Confidence is not
too high yet with this potentially high impact winter weather event
with extended period of overrunning snow developing Saturday night
and continue through Sunday before diminishing Sunday night. Several
inches of snow still appears possible over central and southeast IL.
Canadian high pressure settles into IL Monday returning dry and
colder weather. A northern stream short wave races ese into Great
Lakes region late Tue and Tue night bringing small chances of light
snow with best chances ne of central IL. Another Canadian high
pressure settles into region by Thu brining in even colder air. So
after above normal temps overall since mid Jan, next week (first
week of Feb) looks like temps will likely be below normal.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)

Low pressure currently centered over eastern Iowa will track across
north-central Illinois tonight, then into Michigan by Thursday
morning. A tight pressure gradient ahead of the low will continue
to provide gusty southeasterly winds that will gradually veer to
the southwest after midnight, before veering sharply to the northwest
after FROPA between 12z and 15z Thu. Forecast soundings remain
quite dry, although models are hinting at perhaps a few light
showers near the low track, so have included VCSH at the I-74
terminals Thursday morning. VFR conditions will prevail until the
front passes and winds become northwesterly, at which time MVFR
ceilings currently over the Dakotas and western Iowa will spill
southeastward into the area. Based primarily on HRRR timing, have
introduced MVFR ceilings at KPIA by 10z, then further east to KCMI
by 13z. Once the low clouds arrive, they will stick around through
Thursday afternoon. Winds will be quite strong as well, with
northwesterly gusts in the 25 to 30kt range.





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