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Area Forecast Discussion
Issued by NWS Central Illinois
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716
FXUS63 KILX 260454
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1154 PM CDT Thu Apr 25 2019

.UPDATE...
Issued at 842 PM CDT Thu Apr 25 2019

Updated the forecast for trends related to the cold front moving
into central IL and associated precipitation trends the rest of
the evening and overnight.

At 830 pm, the cold front was along I-55, moving ESE around
25 mph. Showers were along and just behind the front. Haven`t seen
much in the way of lightning strikes with the showers, but an
isolated rumble of thunder can`t be ruled out the next few hours.
The main feature with the frontal passage is the increase in wind
from the NNW at 20-25 mph with gusts of 30-40 mph. Thus, the winds
were bumped up overnight.

Many of the short range models are consistent in showing that as
the front moves toward eastern IL, the showers will become more
scattered in nature, particularly in southeast IL. In the
meantime, moderate to heavy rain with an upper level wave moving
through the lower Ohio Valley will continue southeast of a
Robinson to Olney line until Midnight, before the rain finally
tapers off.

&&

.SHORT TERM...(This evening through Friday)
ISSUED AT 330 PM CDT Thu Apr 25 2019

A large area of light to moderate rain showers was se of I-55 at
mid afternoon, with a few thunderstorms and heavier rain showers
from Robinson to Flora southeast. This was associated with
deepening 1001 mb surface low pressure over southeast MO with a
frontal boundary extending ne into far southeast IL and into
central IN. Meanwhile a cold front was over se parts of WI/IA and
nearing the nw IL border, accompanied by a band of showers along
and behind this cold front, still nw of the Quad Cities. Some
peaks of sunshine far nw CWA at mid afternoon, while low stratus
clouds with the rain showers se of I=55 along with some lingering
fog from Taylorville to Decatur to Champaign se. Temps at 3 pm
ranged from the upper 50s to mid 60s, coolest along the I-72
corridor.

The latest hi-resolution forecast models take surface low pressure
ne from se MO into ne Ohio and Lake Erie by sunrise Fri and
deepens to 990 mb. Meanwhile the cold front approaching nw IL will
sweep thru central IL late this afternoon and evening. This will
likely continue chances of showers into this evening, with
isolated thunderstorms se of I-70. Some fog with low stratus to
also linger over se half of CWA until cold front sweep thru with
gusty nnw to nw winds behind the front. The band of showers and
possibly an isolated thunderstorms will move into the IL river
valley by sunset, into heart of CWA by late evening and east of IL
late tonight. Lows overnight mostly in the upper 40s, but range
from the mid 40s over the IL river valley to lower 50s over the
Wabash river valley. Clouds to decrease behind the cold front
overnight from west to east. This to lead to ample sunshine Friday
but strong nw winds gusting 25-35 mph, keeping temps on the cooler
side with highs in the low to mid 60s.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 330 PM CDT Thu Apr 25 2019

NW winds diminish quickly Friday evening as weak high pressure
ridge moves into the MS river valley by midnight Fri night.
Mid/high clouds to increase from the west overnight Fri night as
997 mb low pressure emerges over eastern Nebraska by dawn Sat.
Lows friday night in the low to mid 40s. Surface low pressure
tracks into our nw CWA by sunset Sat, spreading showers eastward
over central IL during Sat morning, though may not reach IN border
until early Sat afternoon. A narrow band of weak instability/low
capes spread eastward with cold front during mid Sat afternoon
into early Sat evening and cold produce an isolated thunderstorm.
Colder air over northern IL to bring chance of snow by Sat
evening, but kept our area with rain showers. Rainfall amounts
range from a tenth to quarter inch north of I-72 and less than a
tenth inch south of I-72. Dry conditions expected overnight Sat
night. Highs Sat range from upper 50s from I-74 ne and 60-65F sw
CWA including southeast IL. Cold front sweep thru Sat evening and
gusty winds bring in much cooler air, with lows by dawn Sunday in
mid to upper 30s central IL and lower 40s in southeast IL. Winds
may hold up enough to limit frost formation north of I-72 where
lows get in mid 30s.

Sunday should be mostly sunny and dry with 1025 mb high pressure
moves east into WI and Lake MI by midday Sunday. Highs Sunday in
the upper 50s to around 60F which is a good 10 degrees below
normal for late April.

An active weather pattern continues during next work week with
next low pressure moving into the northern plains Sunday evening
and spreading shower chances eastward over central IL overnight
Sunday night, with isolated thunder west of IL river late Sunday
night. Lows mostly in the mid 40s Sunday night. Low pressure
weakens as it moves into WI/IL by sunset Monday, bringing a good
chance of showers and isolated thunderstorms to the area. Highs
Mon range from around 60F northern CWA to upper 60s to near 70F
over southeast IL. Models have a frontal boundary nw of Ohio river
from into mid week and disturbances lifting ne along this front
to keep periodic chances of showers and some thunderstorms Monday
night through Thu. Between 1-2 inches of rain is possible over
area from Mon thru Thu with even higher amounts closer to MS river
valley per WPC guidance. Highs Tue range from around 60F northern
CWA to around 70F in southeast IL. Temps then warm Wed/Thu as
frontal boundary lifts northward into central IL, with upper 60s
to around 70F northern CWA and mid to upper 70s southern CWA.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1155 PM CDT Thu Apr 25 2019

A cold front continued to move quickly through the region, and was
in eastern IL, just east of I-57, at 05z. North to northwest winds
continued to gust from 20-30kts behind the front for nearly 100
miles. The sky was already clearing in west central IL, just west
of the mid/upper level trough axis. The wind gusts were also
dropping off in this same area.

The TAF forecasts for central IL generally have VFR conditions for
the next 24 hours as the low level moisture moves east with the
upper trough axis, and an area of surface high pressure moves in.
The exceptions are at KBMI and KCMI were MVFR ceilings will hang
on until 07-08z. The short range model blend is still indicating
some LLWS in west central IL from KPIA-SPI westward around
daybreak, thus will continue that going in their TAFs.

The main aviation concern during the day Friday will be a return
to gusty northwest winds. Most places will see this develop by 14z
when the lower atmosphere starts mixing up, allowing a transfer of
momentum and increasing wind gusts at the surface. The wind is
expected to diminish around dusk when the surface ridge axis
approaches the MS River Valley.

&&

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

$$

UPDATE...Miller
SHORT TERM...07
LONG TERM...07
AVIATION...Miller
National Weather Service Regional Headquarters
