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Area forecast discussion 
National Weather Service Lincoln Illinois
300 PM CDT Wed Jul 30 2014

Discussion...
issued 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the Continental U.S. Will
continue to keep Illinois in an unseasonably cool airmass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into Illinois. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

Short term...tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 PM remained in
Indiana closer to the better mid-level instability. Rap sounding
analysis east of Champaign showed only 150-200 j/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dewpoint trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of pia to bmi to mto. Highs
will top out in the low 80s with relatively comfortable dewpoints
around 60f.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

Long term...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the plains. No strong to severe weather is anticipated at
this point. A warm front developing north of Illinois will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon
&&

Aviation...
issued 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z taf period. Scattered
to occasionally broken diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with scattered diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the northwest this afternoon, then will shift to
the west/SW on Thursday.

Barnes
&&

Ilx watches/warnings/advisories...
none.
&&

$$

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