Area Forecast Discussion
Issued by NWS Central Illinois

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569
FXUS63 KILX 041752
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1252 PM CDT WED MAY 4 2016

.UPDATE...
Issued at 1035 AM CDT Wed May 4 2016

CU development today in mvfr category as 850mb shows strong cold
air advection over the region through today. Should then riase
cigs to low vfr in the afternoon. Will see sct shower development
in the east with the unstable airmass, with even a storm possible
as steep lapse rates. Showers and clouds should disspiate
overnight with drop off of afternoon heating. Gusy winds today in
srong gradient and the cold air advection behind the front that
moved through last night. Some drop off in winds overnight.

&&

.SHORT TERM...(Today)
ISSUED AT 320 AM CDT Wed May 4 2016

A band of showers and a few thunderstorms is diving across central
and southeast Illinois early this morning. This convection lies just
ahead of a strong cold front, that is driven by a vigorous upper
wave diving into the Midwest. The rapid movement of this
front/precipitation will have the rainfall completely out of the
forecast area by mid-morning. It will be noticeable cooler across
the region today behind the front, with many areas only seeing high
temperatures in the 50s. Northerly post-frontal winds gusting to 30
mph at times will also make it feel cooler. Peak afternoon heating
and very chilly air aloft will combine to produce steep lapse rates
later today. This should allow a few showers or a thunderstorm to
pop this afternoon. However, coverage should not be significant and
have limited Slight Chance afternoon PoPs to roughly the eastern
half of the forecast area.

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 320 AM CDT Wed May 4 2016

Upper ridging currently along the Rockies will be edging eastward
the next couple days, but pattern overall will be rather blocky,
with closed lows on either side of it. No real breakdown expected
until this weekend, when an upper wave will drop southeast from
Hudson Bay and finally boot the eastern low out of the way. However,
the western one will remain in the picture until Monday, with a
surface boundary extending eastward into the Midwest.

Longer range models are in decent agreement with pushing the front
through the area by Saturday evening, with scattered showers and
thunderstorms during the day and evening hours, before diminishing.
After that, the boundary becomes parallel to the upper flow between
what`s left of the ridge and shortwaves rotating through the Great
Lakes region. The GFS hangs onto this until late Monday night before
the front and associated rain chances lift back north. Meanwhile,
the ECMWF is much more aggressive in pushing it back beginning
Sunday evening as the lingering ridge axis slides overhead. Leaned
more toward the latter solution, although not quite as wet, and have
chance PoP`s over most of the forecast area Sunday night and Monday.
With the remnants of the western low only into the central Plains by
Tuesday, rain chances will be steadily increasing with time early
next week.

A warming trend will commence on Thursday, with highs mostly in the
mid 60s. As the thermal ridge builds east late in the week, a couple
days are expected with temperatures reaching near 80 degrees, before
the front pushes through. However, with the main troughing remaining
near the Great Lakes, temperatures behind the front should not be
especially cooler.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1246 PM CDT Wed May 4 2016

Cu in the vfr category will be the case through the afternoon with
gusty north winds due to cold air advection. Instability showers
already deeloping on 88D and this will continue over mainly the
eastern half of central IL through afternoon. Clouds and showers
to dissipate in the evening with end of diurnal heating. Isolated
storms possible. Visibilities to remain vfr. Around 10z, upper low
center had moved well into IN and has rotated upper wave around
it. This will be enough to rotate some mvfr cigs into the eastern
areas, into the CMI TAF in the 09-14z timeframe. CU development
again possible late morning Thursday.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...Goetsch
SHORT TERM...BAK
LONG TERM...Geelhart
AVIATION...Goetsch



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