Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 210213

Area Forecast Discussion
National Weather Service Lincoln IL
913 PM CDT Tue Jun 20 2017

Issued at 910 PM CDT Tue Jun 20 2017

Sufficient elevated instability and wind shear is present to
allow scattered showers and a few storms to linger this evening,
well ahead of an approaching weak cold front. The areas with the
better chances to see rain the rest of the evening look to be east
of Bloomington to Champaign, and south of Shelbyville to Paris.
All precip activity should dissipate by 06z/1am, with skies
becoming mostly clear by morning. Light and variable winds and
decreasing cloud cover the rest of the night will allow for
radiation cooling to put low temps down near or below seasonal
normals (59-66F).

Looking ahead to Wednesday, a weak wave will pass by across N
Illinois, but dry conditions should prevail in central and
southeast IL.

Updates this evening were done mainly to PoPs/Weather, with minor
adjustments down to low temps. Other forecast grids look on track.
Updated info is already available.


.SHORT TERM...(This evening through Wednesday)
ISSUED AT 230 PM CDT Tue Jun 20 2017

Early this evening should be much like 24 hours prior, with
isolated to scattered thunderstorms that fade in coverage and
intensity with loss of diurnal heating. A short wave will track
through the Midwest tonight, providing just enough dynamic support
to produce convection despite relatively dry air and associated
low instability. However, the dry air beneath the cloud bases
will once again support some strong wind gusts on the stronger

Otherwise, the remainder of the period should exhibit quiet
weather as the upper-level flow trends neutral and surface high
pressure builds across the area.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 230 PM CDT Tue Jun 20 2017

The remainder of the forecast period appears to be trending drier
overall. It is looking increasingly like the MCS progged for
Wednesday night into Thursday will stay north of the forecast
area. Then, an upper-level wave tracking across Canada will
slowly drop a cold front across the region Thursday night into
Friday. This period stands the best chance over the next several
days of widespread precipitation across the forecast area. It is
looking increasingly like the front will settle south of the area
by Friday night, with the remainder of the forecast period
trending cooler and drier in its wake. While the Friday night to
Tuesday period will probably not be completely dry, the model
guidance is certainly trending that way. There are varying
solutions of weak disturbances within the developing northwest
upper-level flow that may have rainfall associated with them, but
there is no consensus that warrants going above Slight Chance PoPs
at this time.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 651 PM CDT Tue Jun 20 2017

A line of convection continues to drift southeast across central
Illinois. It has less vigorous updrafts than yesterday
early evening, so no damaging downburst winds are expected for
this TAF period. However, lightning will be possible at all but
PIA over the couple hours of the 00z TAFs. Stabilization of the
lower troposphere after sunset will cause thunder to drop off,
with a few showers lingering into the later evening hours, but
mainly south of I-72 and the TAF sites.

No significant cloud cover is expected beyond this evenings
storms, and VFR conditions should prevail.

The current southwest winds will diminish with sunset, then become
variable as the winds shift around to the northeast and east
tomorrow morning. Afternoon winds will eventually settle out from
the southeast, but remain at less than 10kt.




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