Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 261952

Area Forecast Discussion
National Weather Service Lincoln IL
252 PM CDT TUE JUL 26 2016

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 252 PM CDT Tue Jul 26 2016

18z/1pm surface analysis shows stationary frontal boundary along the
Ohio River, with 1018mb high centered further north across southwest
Wisconsin.  A cluster of thunderstorms with heavy rain that rolled
along the I-70 corridor earlier this morning is now well to the east
across southern Ohio, while additional scattered convection is
developing further west along the front from southern Illinois into
the Ozarks.  Based on radar trends and latest HRRR guidance, it
appears any convection that occurs for the remainder of the
afternoon into the evening will stay south of I-70.  Have therefore
gone with a dry forecast through tonight across much of the KILX
CWA, with low chance PoPs confined to the far SE.  With mostly clear
skies and light winds expected, there is some concern for fog
overnight.  A few high-res models are suggesting widespread
visibility reductions, while others are showing little or no fog.
Given what happened last night and the fact that ample boundary
layer mixing is taking place today, have opted to keep fog out of
the forecast except along/south of a Paris to Shelbyville line where
recent rain this morning has provided additional low-level moisture.
Once any early morning fog dissipates, partly to mostly sunny
conditions can be expected on Wednesday.  With frontal boundary
still in place just to the south, cannot rule out a few showers and
thunderstorms along/south of I-70 where low chance PoPs remain in
the forecast.


.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 252 PM CDT Tue Jul 26 2016

Surface boundary south of the area will begin to move northward late
Wed night and bring the chance of thunderstorms back into
southeastern IL Wed night. In addition, as a ridge builds in the
central plains, the boundary will get pushed east into the MO valley
and across Iowa. Thunderstorm chances will increase in western IL
and northwestern IL associated with the advancing boundary. By Thur,
a surface low pressure area will begin to move along the boundary
and into IL. This will continue the threat of showers and
thunderstorms through Friday. As the low pressure area moves east, a
cold front will get dragged through the area. By Friday night, the
front will be south of most of the CWA, but the chance for
thunderstorms will likely linger in the eastern part of the state
through Saturday.

Remainder of the extended period should be mainly dry, except for
Monday in southeast IL. However, the blending of all the models
keeps a slight chance of precip in the area Sat night through Sun
night...and then again Monday night and Tuesday.

Temps through the period will be in the lower to middle 80s.
However, by the end of the current forecast period, above normal
temps will begin to advect toward the area starting Tuesday as
ridging in the plains edges toward the mid west.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1249 PM CDT Tue Jul 26 2016

Diurnal CU-field will dissipate later this afternoon, followed by
mostly clear conditions tonight into Wednesday morning.  Any
clouds and showers associated with a stalled frontal boundary
along the Ohio River will remain south of the terminals through
the entire period.  With clear skies, light winds, and plenty of
low-level moisture still in place, there is some concern for fog
late tonight.  A few of the high-res models suggest widespread
visby reductions, while others show little or no fog.  Based on
what happened last night and the fact that quite a bit of boundary
layer mixing is taking place today, will leave fog mention out of
the TAFs at this time.


.ILX Watches/Warnings/Advisories...


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