Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 241759
Area Forecast Discussion
National Weather Service Lincoln IL
1259 PM CDT Thu Apr 24 2014
ISSUED 1046 AM CDT Thu Apr 24 2014
Area of low pressure currently located near Kansas City will track
slowly E/NE into west-central Illinois by this evening. While
showers and thunderstorms are prevalent ahead of this feature
across central and western Missouri, the airmass further east over
Illinois remains rather dry. 15z/10am surface dewpoints are only
in the middle to upper 30s, while the 12z KILX upper air sounding
showed a large amount of dry air below 700mb. With a southeasterly
low-level flow ahead of the system, am not expecting much moisture
advection before the low and its associated front arrive. High-res
models such as the HRRR and the NAM12 are suggesting that the
eastward progression of the precip will be slower than previously
expected and this seems reasonable given the current conditions.
Have therefore trimmed POPs back today. Will keep the entire KILX
CWA dry through midday, then will slowly advance precip eastward
this afternoon. Will continue with a dry forecast east of the
I-57 corridor through the entire afternoon, with POPs gradually
ramping up to categorical further west across the Illinois River
Valley. Also made adjustments to sky cover to feature more
sunshine across the E/SE. Zone update will be issued shortly.
ISSUED 1259 PM CDT Thu Apr 24 2014
Showers are beginning to spread into the Illinois River Valley and
may impact KPIA over the next couple of hours. However, overall
trend has been for precip to diminish as it moves eastward into the
dry airmass over Illinois. As atmosphere slowly moistens and upper
wave and its associated cold front approach from the west, showers
will gradually become more prevalent across west-central Illinois
late this afternoon, then will spread eastward across the
remainder of the area during the evening. Most model guidance
suggests KCMI will remain dry until mid-evening at the earliest.
Time-height cross-sections generally reveal MVFR ceilings with
skies clearing from west to east after midnight. Will end the
showers and clear skies at KPIA at 08z, then further east to KCMI
by around 12z. Winds will initially be gusty from the southeast
this afternoon, then will become northwesterly after FROPA later
ISSUED 330 AM CDT Thu Apr 24 2014
SHORT TERM...Today through Sunday
00Z models continue to be slower with cold frontal passage and
associated convection and that is the biggest change in the
forecast package. Most areas will be dry this morning with showers
and thunderstorms affecting areas from I-55 west this afternoon
and possibly getting as far east as I-57 late this afternoon. SPC
keeps slight risk of severe storms in southern IL south of our
CWA. Though there is a 5% risk of damaging wind gusts in far sw CWA
from Springfield to Lawrenceville south late this afternoon and
evening. Upper level trof over CO/NM with embedded short wave to
move into IL overnight while a cold front moves east across IL
during tonight. Have increased pops this evening due to slower
movement of front and then decreasing pops from west to east
behind cold front during overnight. Highs today in the upper 60s
nw over IL river valley to mid 70s se of I-70. Lows tonight 45-50F
over central IL and 50-55F in southeast IL. Rainfall amounts this
afternoon and tonight of a half to three quarter inch with locally
three quarter to 1 inch west of I-55.
Storm system to pass east of IL across IN/OH Friday morning with
more sunshine returning and mild highs in the low to mid 70s and
warmest over sw counties. Even a few degrees warmer on Saturday as
models have 850 mb temps of 12-14C. Still appears dry Friday
through the day on Saturday with partly to mostly sunny skies Sat.
Rather mild again on Sunday with highs in the upper 60s to mid 70s.
Models have trended warmer this weekend ahead of next storm system
over the Rockies. Continue chances of showers and isolated
thunderstorms Saturday night and Sunday as warm air advection
regime sets up again.
LONG TERM...Sunday night through Thursday
Extended models like GFS, ECMWF and GEM develop a strong/large cutoff
upper level low near CO Sunday morning and then move it into the MO
valley Tue and mid MS river valley during middle of next week.
This to bring an unsettled weather pattern with daily chance of
showers and isolated thunderstorms from Sunday through Thursday
with highest chances Sunday night through Tuesday. Mild temps
early in the week to cool by middle of next week as upper level
low moves near IL. Widespread rainfall amounts of 1-2 inches
expected during this time with heaviest amounts southern areas.
Seasonable highs in the upper 60s and lower 70s Monday cool into
the low to mid 50s Wed/Thu.