Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 311938
Area Forecast Discussion
National Weather Service Lincoln IL
238 PM CDT Thu Jul 31 2014
ISSUED 238 PM CDT Thu Jul 31 2014
Low pressure will remain stalled in eastern Canada through the end
of the week...keeping scattered showers and isolated storms in the
forecast through Saturday. A dry period is indicated for Sun and
Monday before a frontal boundary moves south into IL and
stalls out across the area. Rain chances will gradually expand
southward beginning Tuesday and extending through Thursday night.
SHORT TERM...Tonight through Saturday night.
Diurnally driven showers are still possible the rest of the
afternoon. Towering cumulus at 2 pm have been developing in small
areas across central and southeast IL. Showers do not appear
imminent in most of our forecast area, but we will keep a 20 pct
chance in our NE areas through 6-7pm. Diurnal stabilization should
bring any of our showers to an end by that time, with clearing
developing by mid-evening. Weak high pressure over C IL will keep
winds light, and radiational cooling will help lows dip into the
upper 50s to around 60 again tonight.
Friday will bring an eastward shift of the upper low in eastern
Canada, but an increased chance of showers for our forecast area
due to a shortwave diving into the back side of the low across
IL. We kept the chance PoPs Friday afternoon across all but SW
of Springfield to Effingham. A few showers could develop already
in the morning, but forecast soundings show the better instability
will hold off until afternoon. SPC discussions indicate that a few
of the storms north of Peoria to Bloomington could contain some
hail, but most of the area should just see rain.
A few showers could linger into Friday evening before dissipating
with diurnal subsidence. Saturday will see additional isolated
shower chances due to another shortwave and a pocket of cold air
in the upper trough axis passing across IL. Instability will be
slightly less than Friday, but a few rumbles of thunder will still
Additional cloud cover Friday and Saturday may keep highs a
little cooler in some locations, but areas with more sun could
still climb just over the 80 degree mark for highs. Lows will
continue to drop back into the upper 50s to around 60s into early
LONG TERM...Sunday through Thursday.
Drier conditions are forecast for Sunday and Monday as upper level
ridging diminishes afternoon instability and a warming trend
develops. Highs should be firmly in the lower 80s Sunday with mid
80s more common on Monday. A frontal boundary will approach
central IL from the north on Tuesday and Tuesday night. That will
bring an increase in rain chances north of Peoria, with slight
chance PoPs extending as far south as Lincoln to Champaign. Precip
chances will expand southward on Wednesday as the front pushes
south into central IL. Rain chances will remain primarily north of
a the front from Rushville to Lincoln to Bloomington. A wave of
surface low pressure is forecast to move east along the front Wed
night and Thursday, passing across Illinois. That will increase
rain chances across all of our area during that time.
High temps will climb into the upper 80s south of I-72 Tues
through Thursday, south of the front. North of the front on Wed
and Thur, highs may remain a little cooler in the low 80s.
ISSUED 1244 PM CDT Thu Jul 31 2014
VFR conditions are expected to continue across the central IL
airports through 18Z/1 pm Fri. Scattered cumulus clouds 4-6k ft
could go broken at times this afternoon and then diminish after
sunset. Scattered cumulus clouds to redevelop again late Friday
morning. Isolated showers and thunderstorms from mid afternoon
into early evening to be ne of I-74. Isolated convection to
develop further south over central IL Friday afternoon after 18Z.
Some light fog/haze is possible late tonight/early Friday morning
between 09Z-14Z with lowest vsbys of 4-6 miles possible. Winds
expected to stay below 10 kts next 24 hours with very weak
pressure gradient in place over central IL. WSW winds of 4-7 kts
this afternoon become light to calm after sunset tonight and SSW
near 5 kts after 15Z Fri.