Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 190347

Area Forecast Discussion
National Weather Service Lincoln IL
1047 PM CDT Mon Sep 18 2017

Issued at 828 PM CDT Mon Sep 18 2017

A band of showers and thunderstorms associated with a weakening
mid level shortwave continues to march east and northeast across
the area this evening. A few of the stronger cells will continue
to produce rainfall rates of 1 inch per hour along with gusty
winds. The shortwave is expected to push to our northeast by 09z
taking the bulk of the rain with it, although low clouds and some
fog will linger into the morning hours in the wake of the disturbance.
Once the low clouds and fog lift, another very warm and humid day
is in store for the area with afternoon temperatures well into
the 80s. Have made some adjustments to the timing of precip across
the north and east with some additional minor tweaks to the
evening grids. The updated ZFP should be out by 845 pm.


.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 06Z TAFS through 06Z Tuesday night)
Issued at 1042 PM CDT Mon Sep 18 2017

The back-edge of the showers was already pushing across west
central Illinois and this trend will continue into the early
morning hours. Once the rain shifts off to our east, the main
weather concern will be with IFR to LIFR cigs/vsbys in low
clouds and fog through about 14z Tuesday. Already seeing the
clouds starting to break up over northeast Missouri and southeast
Iowa in the wake of the system that brought us our rain this
evening. Once the skies clear, it appears the fog and low clouds
will set in rather quickly after 08z at all sites and hold
through sunrise Tuesday. The clouds and fog will gradually give
way to VFR conditions by late morning or early afternoon with
some scattered cumulus clouds developing in the afternoon. Light
and variable winds tonight will be light southerly on Tuesday with
speeds of less than 10 kts.




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