Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 191956

Area Forecast Discussion
National Weather Service Lincoln IL
256 PM CDT Mon Jun 19 2017

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 224 PM CDT Mon Jun 19 2017

Deep cyclonic flow will linger across central and southeast
Illinois through the period. This flow regime, coupled with
unseasonably cool temperatures aloft, is supportive of deep
diurnal mixing/gusty winds and spotty diurnal convection. The
threat for isolated showers and storms will linger for a couple
hours early this evening before peak diurnal instability is lost.
The threat for isolated showers/storms will return by Tuesday
afternoon. The relatively dry air mass in place will help keep
storm coverage and CAPE values to a minimum, but the dry air
beneath cloud level could support some strong convective wind


.LONG TERM...(Tuesday night through Monday)
ISSUED AT 224 PM CDT Mon Jun 19 2017

Upper-level flow flattens out for the middle of the week, allowing
temperatures to climb back above normal. A strong wave is progged
to track across Canada within this developing flow regime.
Shower/storm chances increase across at least northern portion of
the forecast area late Wednesday night into Thursday as an
associated storm complex may impact the area. Precipitation
chances increase across the entire forecast area Thursday night
into Friday as the wave tracks further east across Canada and a
trailing frontal boundary settles across the forecast area.

Beyond Friday, much more considerable uncertainty enters the
local precipitaton forecast. There are differences in exactly
where the trailing front eventually stalls, and how often it is
activated by disturbances riding along it. Further complicating
issues is the potential tropical system over the Gulf of Mexico
for late in the week, which may have impacts on the weather
pattern locally. Model trends will need to be watched closely as a
consensus is hopefully reached sooner rather than later.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1219 PM CDT Mon Jun 19 2017

Deep mixing will result in gusty west-northwest winds into early
evening across the central Illinois terminals. Winds should
decouple early this evening, with speeds falling below 10kts for
the remainder of the 18Z TAF valid time. Peak daytime heating,
coupled with a couple upper-level disturbances, will result in
spotty showers or thunderstorms into early evening. Coverage
should remain too low to go above a VCSH/VCTS mention at this
time. VFR conditions should prevail through the entire forecast




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