Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 211718

Area Forecast Discussion
National Weather Service Lincoln IL
1218 PM CDT Sun May 21 2017

Issued at 950 AM CDT Sun May 21 2017

Deep cyclonic flow is pushing an extensive diurnal cumulus field
our way, now crossing the Iowa border, with some development
ahead of it across northern parts of our forecast area. This will
result in a partly sunny sky over a large part of the CWA, with
more sunshine across the southeast. West winds already gusting to
around 25 mph north of I-72 and will continue through the
afternoon. Made some adjustments to the sky trends for today, but
the going forecast is largely in good shape.


.SHORT TERM...(Today and tonight)
ISSUED AT 322 AM CDT Sun May 21 2017

Surface low center over southern Minnesota this morning making
slow progress through the Upper Midwest and dragging a frontal
system with it. Cold front is finally making its way across
Central Illinois with cooler air moving in...even with more
southwesterly winds this morning. Winds will become more westerly
throughout the day with the high pressure building into the
Plains and the upper low slowly moving NE to the Great Lakes. Day
will start clear until some clouds wrapping around the low move
through the region this afternoon. Cooler air and afternoon clouds
should keep high temperatures mainly in the 60s... with some
lower 70s south of I-70. Tonight, mild weather continues with the
high center moves across the mid Miss River Valley with more
southwesterly winds for Central IL.

.LONG TERM...(Monday through Saturday)
ISSUED AT 322 AM CDT Sun May 21 2017

Dry forecast comes to an end later on Monday as the next wave
dives into the broader trof aloft over srn Canada, resulting in a
shift to a more amplified flow. Models are dominated by rain
showers into at least mid week. Whereas the chance for precip is a
good idea for Tuesday and Tuesday night...the qpf overall may be a
bit overdone as well as the persistence of the showers as the
models look to be having a feedback issue. More sunshine in place
will help Mondays temps to move about 5 to 8 degree jump above
Sundays north of I-70. Latest runs of the models handle the second
wave (Mon night/Tuesday) wildly differently than 24 hrs ago.
Currently far more progressive, particularly the GFS with a mostly
clear forecast for the end of the week with mild temps...and both
the GFS and ECMWF are hinting to an MCS for Fri night. Considering
that the pattern is going through a shift in the long range of the
forecast, the blend is rather moderate and no plans to make big
changes to it anytime soon. Either way...confidence of forecast
beyond Wednesday is low.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1218 PM CDT Sun May 21 2017

Diurnal stratocumulus has spread over the TAF sites at midday,
although ceilings have now lifted to just above 3,000 feet and
will slowly edge upward through the afternoon. Conditions will
clear out from south to north this evening as the upper low moves
away. Gusty west winds will diminish toward sunset and gradually
turn more southwest through the night.


Flash Flood Watch through Monday morning for ILZ051.



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