Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 300832

Area Forecast Discussion
332 AM CDT Thu Oct 30 2014

.SHORT TERM...(Today)

High pressure centered over the area will slowly drift east today
and give way to a weather system approaching from the west. This low
pressure area will move east and then southeast while another low
pressure area moves across the Great Lakes region. Both of these are
associated with an upper level trough that will be moving through
the area today. These features will not have a lot of moisture to
work with, but will bring a chance of showers to the CWA today. Pops
will be only in the chance category and not expecting any
thunderstorms at this time. Light winds this morning will become
southeast, and then easterly during the afternoon. Wind speeds
should be around 5 to 10 mph.

MOS guidance looks ok, but MAV looks a little warm in the southeast
given the expected cloud cover and chance of pcpn. So, mid to upper
50s looks reasonable for today.


.LONG TERM...(Tonight through Thursday)

An extended period of below normal temperatures is still expected
across central and southeast Illinois into next week. The coldest
period will extend from Friday to Sunday, with a hard freeze likely
early Saturday and Sunday mornings. A bit too early for a Freeze
Watch being 4th and 6th periods, but will issue a special weather
statement to address the the freezing conditions that will likely
end the growning season. This will be the first hard freeze across
the forecast area and running about two weeks later than normal.
Halloween Trick or Treat conditions will be less than ideal with
actual temperatures in the upper 30s or lower 40s and wind chill
values in the upper 20s and lower 30s late friday afternoon into
early Friday evening with blustery north winds gusting to around
35 mph at times Friday afternoon.

The short wave that tracks across MO and sw IL by sunset, and into
the mid MS river valley by midnight tonight, and into western KY/TN
by dawn Fri, will linger chances of rain showers especially over
southeast IL. A much stronger northern stream short wave, currently
diving into Saskatchewan and Manitoba, will track across the Great
Lakes/Midwest on Friday. Most of the moisture will be east of IL
Friday and Friday night and just have small chances of light rain
showers in far eastern IL Friday and then mixes with or changes to
light snow by Friday evening over IN. However, this system will be
accompanied by gusty north winds of 20-25 mph and gusts of 25 to 40
mph and will help usher in the airmass that will provide our hard
freeze for Friday and Saturday nights with lows 25-30F both nights.

Upper level ridging will shift eastward into IL late in the weekend
into early next week with temperatures modifying Mon-Wed with highs
in the mid 50s to lower 60s. The ridge will shift east of IL later
Monday into Tue while strong upper level low/trof digs into the
southern Rockies. This puts IL in an unsettled upper level sw flow
and increasing chances of showers Mon-Tue night as a frontal system
sets up from the southern plains ne into the ohio river valley.
Isolated thunderstorms may also occur Monday night and Tue south of
I-72. Best rain chances will shift se into the Ohio river valley Wed
and lingered 20-30% chances of showers over southeast IL. Drier
weather expected Wed night and Thu with highs still in the 50s on


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

High pressure centered over Illinois late this evening will drift
off to our east overnight allowing a light southerly flow to develop
across the west. As the high shifts away from our area, mid and high
level clouds, now over central Iowa, will streak into central Illinois
after 08z. Forecast soundings and time height cross sections indicate
a gradual lowering and thickening of the clouds during the day Thursday
as a weather disturbance tracks across the region. A band of showers
will develop to the north of a weak storm system forecast to shift
well south of our area during the afternoon and evening hours.

Soundings continue to indicate low VFR cigs across the area Thursday
night before a secondary wave drops southeast into the lower Great
Lakes and deepens in over the region producing MVFR or lower cigs
after 06z Friday along with strong northerly winds. Surface winds
tonight will gradually become southerly but continue to be on the
light side and then become southeast to east during the day on
Thursday with speeds in the 5 to 10 kt range.





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