Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
000
FXUS63 KILX 282000
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT WED SEP 28 2016

.SHORT TERM...(This evening through Thursday)
ISSUED AT 259 PM CDT Wed Sep 28 2016

Latest upper air analysis shows a 553dm 500mb low centered over
southern Lake Michigan, with a well-defined short-wave trough
rotating around the low into central Illinois.  At the surface...a
cold front is dropping southward toward the I-72 corridor.  Despite
an initially dry environment ahead of the front, a few light showers
have been observed across the N/NE KILX CWA early this morning. The
upper low and its associated surface front will gradually sink
southward today, resulting in mostly cloudy and cool conditions.
Upper cold pocket directly beneath the low will remain just east of
the area across Indiana, where resulting instability parameters will
support isolated thunder.  Further west into central Illinois, lapse
rates will be weaker...so am only expecting isolated to widely
scattered showers.  High temperatures will range from the lower 60s
far north around Galesburg and Lacon...to the upper 60s south of the
I-70 corridor. The showers will be diurnally driven, so have dropped
PoPs everywhere except the far NE CWA for tonight as low
temperatures settle into the lower 50s.

&&

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 259 PM CDT Wed Sep 28 2016

What you see is largely what you get over the next several days
across central and southeast Illinois. A pesky upper-level low will
continue to wobble over the Midwest through Sunday. It will be
accompanied by unseasonably cool temperatures, considerable cloud
cover, and scattered showers. The clouds and showers should exhibit
diurnal peaks. The model agreement is quite good in this
scenario. Any warming over the next few days should be quite
gradual, primarily through airmass modification.

The upper low will finally lift away from the area early next work
week, to be replaced by strong ridging and much warmer temperatures.
The next chance of appreciable rainfall will occur around the middle
of next week as strong cold front pushes into the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1212 PM CDT Wed Sep 28 2016

Extensive MVFR cloud deck associated with upper low over northwest
corner of Indiana has started to lift some, and central Illinois
TAF sites should be in VFR territory by 20-21Z. Clouds expected to
erode some with loss of daytime heating, but another deck of
ceilings at or below 2000 feet expected to push westward later
tonight, as the low will only drift across Indiana. Some
uncertainty as to how far west this will reach. Have only
mentioned TEMPO periods of MVFR ceilings at KPIA/KSPI, but sites
further east should see the lower ceilings moving in during the
09-11Z time frame, sticking around the remainder of the morning.
Gusty winds today will settle a bit late in the afternoon and
gradually turn more northerly overnight.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Geelhart
LONG TERM...Bak
AVIATION...Geelhart



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.