Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 160524

Area Forecast Discussion
National Weather Service Lincoln IL
1224 AM CDT Wed Aug 16 2017

Issued at 948 PM CDT Tue Aug 15 2017

Quiet weather is expected for the most part across central and
southeast Illinois overnight. Some patchy fog is expected, but
should not get terribly thick. Most of the model guidance has
backed off on the rain chances for the rest of the night, despite
the slow arrival of a warm front from the southwest. Only minor
tweaks are needed to current forecast, mainly to go dry for the
rest of the night.


.SHORT TERM...(This evening through Wednesday)
ISSUED AT 241 PM CDT Tue Aug 15 2017

Weak surface ridge stretched from the Hudson Bay southward
through the Mississippi River Valley to the Gulf Coast. A slow
moving frontal boundary draped across the northern tier of
Illinois helping to provide very weak focus for some afternoon
cumulus growth, resulting in a couple showers. HRRR for the last
few runs seems to have a good handle on the showers, but has
become more diffuse with time across Central IL. Forecast
adjustments to allow for scattered activity and keeping it into
the early evening hours. Overnight, skies become partly cloudy and
once again a little warmer than the night before. For tomorrow,
increasing clouds with a warm air advection pattern as moisture
surges into the region and showers/thunderstorms start spreading
in coverage, limiting the daytime heating.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 241 PM CDT Tue Aug 15 2017

Precip continues into Thursday with the best chances for precip in
the forecast Wed night as the storm system/front moves through the
region. Extensive cloud cover Wed night keeps the overnight lows
up...and limits the morning warm up for Thursday. Models at this
point are in surprisingly good agreement to wrap up the week and
into the weekend. Precip a little slow to diminish through
Thursday night/Friday morning. But Friday will be dry with a
return to the mid 80s, with light northwesterly winds and weak
high pressure. Both GFS and ECMWF have next wave moving through
the Northern Plains bringing in precip for Saturday and Sat
evening. However, rather progressive flow aloft will likely usher
the system out quickly and wrap up the weekend dry. As for Monday,
right now, both the GFS and ECMWF are producing a weak wave, but
keeping it northwest of ILX through the daylight hours.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1223 AM CDT Wed Aug 16 2017

Area of showers and thunderstorms will be lifting northeast out of
Missouri on Wednesday. Have added a period of VCTS at all TAF
sites, beginning as early as 15Z near KSPI but holding off til
near 20Z as far east as KCMI. Initial showers are associated with
warm air advection and will be past the TAF sites by late
afternoon. However, the main storm system will begin spreading
showers and storms in from the northwest late in the period. Right
now, will only include a mention at KPIA, as the timing toward the
end of the period is more uncertain from KSPI-KBMI.




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