Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Lincoln Illinois
1128 PM CDT Wed Jul 30 2014

issued 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the Central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.



issued 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous taf set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to



Previous 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 air mass 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 dew point 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 dew points
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.



Ilx watches/warnings/advisories...


National Weather Service Glossary of Abbreviations