Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 140000
Area Forecast Discussion
National Weather Service Lincoln IL
700 PM CDT Sun Jul 13 2014
ISSUED 255 PM CDT Sun Jul 13 2014
A weak cold front has continued to sink southward across central
and southeast Illinois this afternoon, and currently lies in the
vicinity of the I-70 corridor. However, only a very modest drop in
surface temperatures and dew points is noted behind this front.
Another front lies in the vicinity of the WI/IL border, and
extends west across IA. This second front has notably cooler and
drier air in its wake.
Main forecast problems today revolve around precipitation chances
tonight with the fronts in the area, as well as Monday as a
vigorous and unseasonably chilly upper trof pivots into the area.
Then, the forecast problems mainly revolve around temperatures
until the next system arrives by late next weekend.
SHORT TERM...Tonight and Monday: Instability remains fairly stout
in advance of the lead front, with CAPEs on the order of 2500
J/KG. However, shear profiles are not impressive, with bulk shear
values not much better than 25 kts. This fact, combined with weak
mid level lapse rates, should see the convection weakening fairly
quickly tonight as diurnal stabilization occurs. Also keeping an
eye on some spotty showers/storms along the second front. However,
this precipitation should have an even stronger diurnal component
to that of the first front and is likely to fizzle before reaching
the area (per HRRR).
The northern front will get its final push through the area Monday
as a vigorous upper trof, currently digging across Saskatchewan
and Manitoba, swings through the area. Moisture will be lacking,
but an isolated shower or thunderstorm can`t be ruled out Monday
given the passage of this wave and associated thermal trof.
LONG TERM...Tuesday through Sunday: The impacts of the
unseasonably strong upper trof will be with us for the remainder
of the week, accompanied by cooler than normal temperatures and
predominantly dry conditions. The mean trof will start ejecting
away from the area by late in the week, courtesy of a couple
strong kicker waves, and this will allow a precipitation risk with
the second wave to arrive by the beginning of next week. The mean
flow will also trend more zonal with the arrival of the arrival of
the second wave, with temperatures trending closer to normal for
the middle of July.
ISSUED 700 PM CDT Sun Jul 13 2014
Central IL TAF sites should see VFR conditions through tonight
although isold-sct TSRA will affect areas south of KMTO and
northwest of KPIA this evening. Winds light WSW in the evening and
decreasing. After 15Z Monday...isold -SHRA/TSRA developing across
the region with daytime heating...producing isold IFR/MVFR
conditions. Winds WNW around 10 kts.