Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 182257

Area Forecast Discussion
National Weather Service Lincoln IL
557 PM CDT Mon Sep 18 2017

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 251 PM CDT Mon Sep 18 2017

A broad longwave trough over the western U.S. and ridge centered
over the east coast is the basic pattern at this time. A shortwave
embedded in the southwesterly flow between the two features is over
western MO/IA and heading toward central IL. This feature will help
the stalled out front across central MO/southern IL and associated
higher temp/dewpoint air to move back northward and will result in
showers and thunderstorms spreading back northeastward across
central IL late this afternoon into tonight. As the shortwave passes
east...precipitation will end from west to east Tuesday starting
early in the morning. With partially clearing skies, light winds,
and recent rainfall patchy fog should be able to form across the
area by morning. Lows tonight will be mild...several degrees above the mid 60s as a result of the warm moist air mass and
cloud cover. Highs Tuesday in the mid to upper 80s.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 251 PM CDT Mon Sep 18 2017

The basic western trough/eastern ridge pattern will become more
amplified toward the end of the week and through the weekend. This
will result in persistent warm weather with highs near 90 degrees
through the week and possibly through the weekend. With record high
temperatures generally in the low 90s by the upcoming weekend...this
would eventually be near record levels if 90 degree highs continue.
For now, have forecast highs in the upper 80s over the weekend, up a
few degrees from previous forecast. The ridge will also promote
general subsidence over the area bringing generally dry weather. The
main chance for precipitation in the extended forecast will be from
a weakening cold front dragging into the mid Mississippi River
Valley region Wednesday into Thursday morning. Only a slight
chance of precipitation with this feature for most of central IL,
although keeping a small area of chance/30 percent PoPs north/west
of Peoria.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 552 PM CDT Mon Sep 18 2017

A weather system pushing into west central Illinois early this
evening will bring showers and thunderstorms to the TAF sites
which will lower the cigs into the MVFR to IFR range after 08z
and hold through 14z Tuesday before a return to VFR conditions
is expected later Tuesday morning. TAF sites that do see a TSRA
this evening may see a brief reduction to MVFR for cigs and vsbys
before returning to VFR. However, as the system moves to our east
later tonight, abundant low level moisture coupled with a decrease
in cloud cover towards morning will be the deteriorating conditions
to the TAF sites for Tuesday morning. VSBYs may briefly lower to
LIFR towards 12z before improving rapidly to VFR conditions by
17z as drier air filters in. Once again, winds will not be much of
a factor, except in and near TSRA where a few gusts to 30 kts will
be possible. Look for a light and variable wind tonight with winds
mainly south to southwest at less than 10 kts on Tuesday.




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