Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 291143

Area Forecast Discussion
643 AM CDT Wed Oct 29 2014

.SHORT TERM...(Today)

Surface high pressure will begin to build into the state today, but
not until this afternoon. This morning, however, a large area of
clouds continues to move southeast-east in connection with a mid
level trough that is rotating through the Great Lakes region.
Satellite trends indicate that some of these clouds will advect into
northern parts of the area this morning and then should move east
through the day, leaving the CWA later this afternoon. So, this
morning, looking at partly sunny skies in the north, roughly north
of a Canton to Bloomington line. Satellite also indicates there are
some breaks in the clouds, so believe sunshine this morning should
help some to burn some of it off. CU rule does have some CU
developing, but only in the scattered range. Remainder of the CWA
should be mostly sunny to sunny.

Despite the sunshine today, cooler temperatures, below normal, have
returned to the area. Looking for temperatures in the 50s by this
afternoon, which is really close to both the MET and MAV guidance.


.LONG TERM...(Tonight through Wednesday)

Northwest upper level flow will persist into the weekend, helping to
keep temperatures below normal, with coldest air from Friday through
this weekend. A hard freeze still looks likely Friday night with
lows in the upper 20s across much of central/se IL and a freeze
watch will likely eventually be needed overnight Friday night into
early Saturday morning.

Weak high pressure around 1022 mb over the central plains to drift
east over IL by overnight and bring fair skies and light winds with
cool lows in the mid to upper 30s, with patchy frost overnight from
Lincoln eastward into IN. Some high clouds increase over western areas
later tonight and get a return se flow to limit frost formation in
western IL tonight. A weak disturbance over the Pacific Northwest,
is expected to dive se across MO Thursday afternoon, and into the TN
river valley by overnight Thu night. This to bring a chance of rain
showers to central IL by Thu afternoon and evening and shifting east
of I-57 overnight Thu night. The 00Z models, especially NAM model,
have increased rain chances and qpf amounts over our CWA with this
weather system. Highs Thu in the middle to upper 50s with mildest
readings sw areas and se IL.

Chances of showers will shift east into IN Friday where strong upper
level trof digs over the eastern states. Models have trended
stronger with this trof and also windier and colder over IL with
more qpf just east of IL over IN/OH/KY. Wind gusts of 25 to 35 mph
on Friday and Friday evening along with highs only in the 40s Friday
will not make for very nice weather for trick or treaters Friday
evening. Stronger Canadian surface high pressure of 1034 mb settling
into the Midwest Friday night, will produce good radiational cooling
conditions overnight Friday night and a likely hard freeze later
Friday night and early Saturday morning. Chilly highs Sat in the mid
to upper 40s. Another freeze likely Sat night with lows in the upper
20s eastern IL and lower 30s central and western IL. Highs Sunday in
the upper 40s and lower 50s.

After a chilly first weekend of November (and a sharp contrast from
the warm weekend the last weekend of October), temperatures will
moderate a bit during the 1st half of next work week with highs
55-60F Monday-Wednesday. Upper level flow becomes more southwesterly
and unsettled over IL early next work week and a frontal boundary to
set up from the southern plains ne into the Ohio river valley. This
likely to bring widespread rain of a half to 1 inch to the region
from Monday into Tuesday with isolated thunderstorms possible south
of I-72. The rain showers should diminish to slight chances on Wed
as frontal boundary weakens as it sags south of IL.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)

VFR conditions will prevail at all TAF sites next 24hrs. An area
of clouds around 4kft continues to advect into the area this
morning, and will effect all sites today. Based on satellite
trends and timing tools, looks like the broken cigs will be at PIA
and BMI around start of TAF forecast. Believe these broken cigs
will last til this evening, when it will become clear for tonight.
Satellite trends and HRRR model cloud forecast looks like the
clouds will thin as they continue to move southeast. Therefore,
will be going with just scattered clouds for the other three TAF
sites, SPI/DEC/CMI; but, will also include a 4hr TEMPO group for
broken cigs during the morning hours. Skies will clear at these
three sites around 00-02z as well, staying clear the remainder of
the TAF period. Winds will be west to northwest today at around
10-15kts, but then become light and variable tonight.




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