Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 240830

Area Forecast Discussion
National Weather Service Lincoln IL
330 AM CDT Thu Apr 24 2014

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.



ISSUED 1155 PM CDT Wed Apr 23 2014

A break in the precipitation will occur as a tongue of dry air
follows the initial wave of warm advection precip. The warm front
will develop near the Missouri-Illinois border tomorrow morning,
then progress eastward tomorrow afternoon just ahead of the cold
front. A slower trend is being depicted in the 00z models, and
thunder chances will be focused mainly between 23z and 05z from
west to east. There should be a period of steady rains in the warm
sector ahead of the cold front, with thunder chances highest during
that time as well. A VCTS was included starting at 23z in PIA and
03z at CMI. A tempo for MVFR or possibly IFR may be needed for a
couple hours tomorrow evening.

Winds will increase quickly tomorrow morning, as the nose of an
850mb LLJ advances into western IL. Gusts early in the morning may
actually be a few knots higher than the afternoon based on the
strength of the LLJ as depicted in the HopWRF and RAP. A few gusts
may top out over 30kt for PIA/SPI between 14z-16z. Wind directions
will be SE for the first 12-15 hours of the TAFs, then it will
shift toward the south into the afternoon as wind speeds remain
strong in the 18g28kt range. By evening, wind speeds should
subside a bit as the pressure gradient weakens near the cold



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