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Area forecast discussion 
National Weather Service Lincoln Illinois
1200 PM CST Thu Mar 5 2015

Update...
issued at 1059 am CST Thursday Mar 5 2015

Made some minor adjustments to the forecast in central and
southeast Illinois for sky cover today and to lower the overnight
lows in eastern Illinois.

High pressure centered near Des Moines, Iowa late this morning will
continue to slowly push eastward resulting in decreasing west
winds and unseasonably cold temperatures today and tonight. A few
records may be set today for coldest high temperatures on this
date, and we cold get close to some record lows in eastern Illinois
overnight. Lowered the temperatures to below zero readings in all
areas east of I-57 due to the extensive snow cover and the
expectation of a clear sky and very light wind overnight. In
central and west central IL, lowered the overnight temps a bit
early, but an increasing southerly wind should result in steady or
even slowly rising temperatures toward daybreak from Peoria-
Springfield and locations to the west.

The high resolution models such as the hrrr, nam12 and to a lesser
extent the rap, continue to indicate rapidly increasing low level
cloudiness this afternoon. These models have done this a lot
lately with very few clouds actually developing. Thus, am
anticipating some scattered cloud cover and generally mostly sunny
conditions in all of central and southeast Illinois this afternoon.

&&

Short term...(today)
issued at 254 am CST Thursday Mar 5 2015

The storm system that brought snow to southeast Illinois yesterday
and last evening was finally starting to shift away from our
forecast area early this morning. At the surface, high pressure
tracking southeast across northwest Iowa will drift across our
area today bringing another 24 hours of unseasonably cold weather
with afternoon highs struggling through the teens over most of the
forecast area, which is about 30 degrees below where it should be
for the first week in March. As the large fair weather system drifts
closer to central Illinois today, the wind this afternoon will not be
as gusty as what we saw yesterday. However, this morning, that will
be a different story, as the pressure gradient will be tight enough
for a few more hours to produce just enough wind to drop wind chills
down to between -10 to -15 mainly north of I-74 for a few hours early
this morning.

&&

Long term...(tonight through wednesday)
issued at 254 am CST Thursday Mar 5 2015

Pretty tranquil weather through the period, with no precipitation
chances in the forecast into the middle of next week. Periodic upper
waves will zip through the area in the northern jet stream, but
moisture levels will be meager and little more than wind shifts are
expected in our area. The longer range models are in general
agreement with this pattern into mid week.

The main highlight will be the welcome trend toward milder weather.
The long wave trough from Lake Superior to New Mexico evident on
early morning water vapor imagery will move through the Midwest
later today. Lows in the single digits are still expected tonight,
but the coldest temperatures will be this evening, with steady or
rising temperatures overnight after surface high pressure settles
into the Ohio Valley. However, wind chills well below zero are on
tap, as low as 10 below in areas from Bloomington to Danville. After
that, nice southwest flow should get much of the western half of the
forecast area above freezing on Friday. Temperatures will continue
to warm into next week, with most areas well into the 50s by
Tuesday.

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1200 PM CST Thursday Mar 5 2015

VFR conditions should prevail across all of central and eastern Illinois the
next 24 hours. One thing we will be keeping an eye on though, is
the potential for short periods of MVFR ceilings in the entire
region this afternoon. Am anticipating scattered stratocumulus
just below 3,000 feet this afternoon. However, many of the short
range models are indicating the potential for MVFR ceilings. The
past few weeks these same models have done the same thing, with
very few clouds actually forming, so confidence is low in MVFR
ceilings developing.

High pressure centered in southern Iowa/northern MO will drift to
the east tonight, resulting in a light and variable wind and clear
sky. As the high moves into eastern Illinois late tonight, an increasing
southwest-south wind will be accompanied by warm advection clouds
at or below 10 kft. As a result, included VFR ceilings around 9,000 ft for
much of central Illinois along with a trend toward an increasing wind.
From mid to late morning, BUFKIT NAM soundings indicate plenty of
mixing developing, resulting in wind gusts in the 20-25kt range
around 15z.

&&

Ilx watches/warnings/advisories...
none.
&&

$$

Update...Miller
short term...Smith
long term...geelhart
aviation...Miller

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