Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 010237

Area Forecast Discussion
National Weather Service Lincoln IL
837 PM CST Wed Nov 30 2016

Issued at 837 PM CST Wed Nov 30 2016

Updates this evening mainly to better account for distribution of
sprinkles and some snow flurries as low clouds continue to wrap
around a deep slow moving low over the upper Midwest. Main radar
echoes/surface observations of light snow and rain showers have
been over Iowa and appear on course to affect areas from around
Macomb to Bloomington northward through the early morning hours
before the main low and the responsible disturbance lift ENE.
Otherwise...lows near the freezing mark, cloudy conditions, and
WSW winds around 10 mph overnight look good.


.SHORT TERM...(This evening through Thursday)
ISSUED AT 225 PM CST Wed Nov 30 2016

After a brief bout of sunshine earlier this morning, clouds moved
in as moisture wrapped around the large low pressure system to the
north/northwest.  The same system has been driving the weather for
the last few days will only progress slowly eastward through
tomorrow. Deep cyclonic flow combined with low level moisture should
keep the clouds in place tonight and into tomorrow morning. Although
the temperatures are cooler, they are relatively close to the
climatological normal. The low clouds and low level moisture may
result in some flurries/sprinkles, mainly north of a line from
Peoria to Bloomington, before midnight.  For tomorrow, westerly
winds will continue, with clouds remaining in place as the
temperatures climb only to the low 40s.

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 225 PM CST Wed Nov 30 2016

Models in good agreement in moving the closed upper low at 500 mb
north of the Great Lakes Thursday night with weak upper level
ridging building over the Midwest in its wake for Friday into
Saturday. Dry weather expected to continue through Saturday across
our area as weak high pressure edges into the region. Forecast
soundings continue to show a gradual erosion of the low level
moisture as we head into Friday morning, however, we start to see
some mid and high level clouds tracking across the area at the
same time frame so no prolonged period of sunshine expected either
Friday or Saturday with seasonably cold temperatures, generally
from 40 to 45 degrees for both days.

By late Saturday, a northern stream wave is forecast to track across
the Plains and into the Midwest increasing the cloud cover with some
light precipitation developing from west to east overnight Saturday
into Sunday. With the precipitation coming in late at night and
boundary layer temperatures cooling to just above freezing, we may
see some very light snow, or a mix of light snow and rain develop
initially, with any mix quickly changing over to light rain during
the morning hours of Sunday as temperatures warm into the upper 30s
to lower 40s. Light rain should continue off and on during the day
Sunday and then POPs will lower quickly towards evening as the upper
trof shifts across the Great Lakes.

As the upper trof shifts to the east, the closed low at 500 mb over
the southwest U.S., which has not been handled well by the medium
range models, starts to eject northeast into the southern Plains on
Monday with another round of precip expected again Monday night into
Tuesday as the trof shifts across the Midwest. Once again, due to
the timing of the precip arrival on Monday night, we may see a
mix of rain and snow based on model consensus, however, just based
off the soundings, which appear warmer than what we saw 24 hours
ago, the trend may be for more rain than snow, especially if the
12z ECMWF verifies. Any mix we see overnight will become all rain
by Tuesday morning with the bulk of the precip shifting off to our
northeast with the upper trof by evening as another shortwave
drops into the southern Rockies late Tuesday threatening our area
with more rain later on Wednesday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 541 PM CST Wed Nov 30 2016

A large area of MVFR ceilings in low stratus cloud cover will
continue to affect central IL terminals through the 24 hour TAF
forecast period. Just prior to 00Z issuance time a mix of ceilings
below and above MVFR thresholds is in place across the
area...however generally lower ceilings upstream in Iowa as well
as a tendency for ceilings to decrease overnight indicate a
likelihood that ceilings will lower and be predominantly MVFR
overnight. Isolated sprinkles and flurries are possible as well
through 06Z...mainly KPIA-KBMI-KCMI northward. Winds W-WSW 8-12
kts through the period.




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