Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 140455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Mon Aug 13 2018

.UPDATE...
Issued at 908 PM CDT Mon Aug 13 2018

High clouds are beginning to flow into western IL as the upper
trough in the central Plains slowly pushes into the prevailing
ridge across the Illinois/Indiana area. Those clouds should remain
thin due to antecedent dry air at the mid-upper levels, so low
temps should not be held too much warmer due to cloud cover. The
eastern areas will remain clear the remainder of the night, with
higher potential for patchy fog again. High res guidance is
keeping all vis reduction in our counties above 5SM, but they
have not done well with fog coverage and intensity the past few
nights. So we added patchy fog along the Indiana border for late
tonight. Not sure how far west to expand fog mention, but left out
CMI to Effingham at this point.

Low temps look on track for upper 60s toward Jacksonville/
Rushville, and lower 60s for areas east of I-57.

Still tracking the arrival of rain/storm chances later tomorrow
afternoon for areas west of SPI. However, dry air will delay
precip onset for most of central Illinois until Tuesday night.

Updated forecast info will be available by 910 pm.

&&

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 229 PM CDT Mon Aug 13 2018

Upper low over the western Oklahoma Panhandle hasn`t moved much
from this time yesterday, but it will begin a northeast push
tonight. A fair amount of dry air will remain in place over our
area ahead of this system, so dry conditions should continue into
early Tuesday. Have bumped up PoP`s a bit in the afternoon,
though it still looks like mainly areas from about Galesburg-
Taylorville westward stand the best chances of seeing anything.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 229 PM CDT Mon Aug 13 2018

Main surge of moisture will begin later Tuesday evening, with the
eastern CWA more likely to stay dry until after midnight. As the
upper low opens up on Wednesday, an extended period of high PoP`s
is on tap until the core of the upper wave passes Thursday night.
A secondary wave currently over the Pacific Northwest will drop in
behind it later in the week, bringing another round of showers.
Between the two, rainfall amounts should be around an inch in many
areas. The threat of severe weather is rather low, though the
southeast CWA may see a few stronger storms Wednesday with a
little more shear in that area.

The cold front with the main system will have some difficulties
fully exiting as the tail end starts to line up with the upper
flow. Thus, some residual showers may linger into the first part
of the weekend south of I-70. Beyond that, the forecast becomes
more uncertain, as a narrow ridge builds across the Mississippi
Valley. The GFS is more progressive with moving it out and another
wave approaching from the west, while the European solution digs
the wave quite a bit late in the weekend. This latter solution
would be much slower with the next round of rain.

Much of the extended period will see seasonable temperatures,
though the rain on Wednesday will likely keep highs confined to
the upper 70s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1155 PM CDT Mon Aug 13 2018

Fog remains in the picture for later tonight, as surface dewpoints
have climbed again with a slight southerly breeze already
developing. Eastern counties still look to have the better chance
of fog formation. Have tempo`s for MVFR fog at CMI, DEC and BMI.
Can`t rule out some patchy dense fog near the terminal sites
again, but chances are low enough to leave out of the TAFs.

The dry mid-level air will help keep advancing rain showers at
bay until late tomorrow afternoon near SPI. While the better
chances of storms will come during the evening, advancing from SW
to NE. Included VCTS for SPI after 22z tomorrow, and after 04z for
PIA and DEC.

VFR conditions should prevail for the majority of the 06z TAFs
outside of SPI. Any storm could produce brief periods of MVFR vis
and/or cigs.

Winds will remain light and variable tonight, with a southerly
wind increasing to 8-10kt tomorrow.

&&

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

$$

UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Shimon


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