Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KILX 211743

Area Forecast Discussion
National Weather Service Lincoln IL
1243 PM CDT SUN AUG 21 2016

Issued at 1028 AM CDT Sun Aug 21 2016

Surface high pressure will build into southern Illinois today
while a couple of upper level shortwave troughs move by to the
north through the large scale upper level trough positioned over
the Great Lakes and lifting ENE. This will bring mostly clear
skies across central and SE IL although some shallow cumulus will
likely build up across the area in the afternoon and a patch of
cloud cover associated with the first shortwave looks to clip
northern Champaign and Vermilion counties from around 10 a.m. to
noon. Highs much cooler today in the mid to upper 70s and breezy
NW winds 10-15 mph beginning to slow late in the afternoon.
Current forecast looks on track except have made minor
adjustments to cloud cover.


.SHORT TERM...(Today and tonight)
ISSUED AT 232 AM CDT Sun Aug 21 2016

Surface high pressure area over the plains will move east across the
area today through tonight with dry weather expected next 24hrs.
With much lower dewpoints, expecting mostly sunny skies today and
then clear skies tonight. Since there was some precip yesterday,
diurnal clouds should develop this morning and continue through this
afternoon. However, should be plenty of sunshine still today. High
temperatures should be a comfortable mid to upper 70s by this
afternoon. Lows tonight will be cooler, in the mid 50s.

.LONG TERM...(Monday through Saturday)
ISSUED AT 232 AM CDT Sun Aug 21 2016

Upper trough which is supplying the pleasant early-week conditions
will lift north of the Great Lakes early Monday, allowing for a
building of warmer and more humid conditions for Tuesday and
especially Wednesday. With our region remaining on the periphery of
the departing high pressure, the evening models have slowed the
arrival of the Tuesday night MCS, and the ramp-up of PoP`s have been
focused more in the post-midnight period as a result. However,
little change was made for Wednesday and Wednesday night, as the
incoming front slows down in the near-parallel orientation to the
upper flow. The models try to indicate some sort of short break
between the initial MCS and convective redevelopment later Wednesday
into Wednesday night. Some stronger storms appear possible with
CAPE`s around 2500 J/kg Wednesday afternoon, but bulk shear values
remain low, so a widespread severe weather threat doesn`t appear
likely at the moment. However, precipitable water values of around
2.2 inches are near the 99th percentile for climatology, and some
heavier rains will be a threat in the stronger storms. The front
will finally pass on Thursday but not at an especially speedy pace.
Rain chances will linger most of the day, although the GFS is a bit
quicker and dries out most areas west of I-55 by afternoon.

Upper low currently closing off over northwest British Columbia will
make it to near Winnipeg late Wednesday before shearing out some,
but it will still help bring another cooldown late in the week.
Currently does not appear to be quite as cool as early week, as a
split upper flow merges over the mid-Mississippi Valley and keeps
the coolest air further north, but the week should close with highs
in the upper 70s to near 80.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1243 PM CDT Sun Aug 21 2016

VFR conditions will prevail at all TAF sites next 24hrs. FEW-
SCT035 cloud cover expected for afternoon...then clearing around
00Z. Winds NW around 10 kts decreasing to under 6 kts around 00Z.


.ILX Watches/Warnings/Advisories...


LONG TERM...Geelhart
AVIATION...Onton is the U.S. government's official web portal to all federal, state and local government web resources and services.