Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 251942
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
242 PM CDT Sat Mar 25 2017

.SHORT TERM...(This evening through Sunday)
ISSUED AT 241 PM CDT Sat Mar 25 2017

Nearly vertically stacked low was edging into central Missouri this
afternoon. The front has finally lifted north of the entire forecast
area, and most areas are now in the 60s, locally cooler where rain
is falling, and a few 70 degree readings were even seen along the
Indiana border. Showers have begun to increase from the south once
again and are becoming more numerous across the forecast area.
Lightning is been fairly sparse in the vicinity of the low so far,
although surface based CAPE`s in that area are currently around 500
J/kg and a few hundred J/kg will be present into the first part of
the evening this far northeast, so will continue some mention of
thunder through the evening. Severe weather threat not especially
robust, but appear more likely in the areas closer to the track of
the low where lapse rates are steepest. In our area, this would be
more in areas west of Springfield.

As the low lifts northward, the initial bands of showers and
isolated storms will track north through the area. Most of the high-
resolution guidance continues to indicate some drying wrapping
around the low with time, suggesting the western parts of the CWA
seeing only isolated showers after midnight. However, moisture being
drawn northward on the fringes of the system will result in more
numerous showers continuing closer to the Indiana border much of the
night. By late Sunday morning, the low is progged to be centered
along the Illinois/Iowa border, and the showers will continue to
diminish through the afternoon as the low lifts toward southern
Wisconsin. Will continue to mention 30-40% rain chances into the
afternoon across the areas north of I-74 and east of I-57, due to
the slow movement of the system.

&&

.LONG TERM...(Sunday night through Saturday)
ISSUED AT 241 PM CDT Sat Mar 25 2017

Weak high pressure...specifically a col or saddle point between the
outgoing low pressure system from Sunday and an approaching system
for Monday...will cross central IL Sunday night. As a result central
IL can expect a break in precipitation chances...light and variable
winds...but not much break in low cloud cover. Moist warm advection
will then promote showers developing Monday morning as the next
weakening low pressure system approaches from the southern Plains.
Model consensus tracks this low through southern IL Monday evening
although some differences exist between various 12Z forecast models
indicating some continuing track/timing uncertainty. A few hundred
to 1000 J/KG MUCAPE look to target areas from around I-72 southward
for the afternoon and evening Monday suggesting thunderstorms for
this area. Current models suggest stronger shear will be primarily
south of the central IL forecast area...although a marginal risk for
severe thunderstorms is forecast as far north as the I-70 corridor
at this time. Showers tapering off overnight Monday night as a high
pressure ridge approaches from the west. The next storm system looks
to develop in the southern Plains midweek...then large track
uncertainties are apparent in the 12Z model runs...with the low
tracking anywhere from northwest IL to northern AL by Friday. As a
result...large uncertainties in the specific timing and impacts of
the late week system continue.

Temperatures Monday through Saturday look to be a few to several
degrees above normal with forecast highs ranging from upper 50s in
Galesburg to mid and upper 60s in Lawrenceville...and featuring
little day-to-day change. Lows upper 30s to lower 40s in Galesburg
ranging up to mid 40s to lower 50s in Lawrenceville.
Nevertheless...weather pattern uncertainty toward the end of the
work week could result in subsequent changes to the forecast
temperatures as current forecast reflects a consensus of solutions.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1240 PM CDT Sat Mar 25 2017

Scattered showers are moving back north into central Illinois at
midday, and will increase as reinforcements arrive from Missouri.
Thunder chances will likely hold off for a couple hours until this
latter area arrives. The rain will linger longest at KCMI as a
weakening storm system slowly lifts northward through Missouri,
but much of the remainder of central Illinois will see the rain
diminish to scattered showers once again after 06Z. Ceilings had
earlier risen to VFR levels but were coming down again, as
stratocumulus around 1500-2000 feet lifts northeast from Missouri.
Expect a gradual lowering of cloud heights through the next
several hours, with MVFR conditions widespread by early evening
and IFR ceilings below 1,000 feet after 06Z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...Geelhart
LONG TERM...37
AVIATION...Geelhart



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