Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 211600
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1100 AM CDT Mon Sep 21 2020

.SYNOPSIS...
Issued at 301 AM CDT Mon Sep 21 2020

Dry conditions continue today, and through the first half of the
week. A chance for precipitation slides across southern Illinois
Wednesday night into Thursday, as the northern remnants from
Tropical Storm Beta move into the Ohio River Valley. Otherwise,
most will wait until next weekend before a better chance for
rainfall with a frontal system. Temperatures this week will
gradually top out in the 70s, then reach the 80s Friday.

&&

.UPDATE...
Issued at 1055 AM CDT Mon Sep 21 2020

High pressure will provide another mostly sunny day across central
and southeast IL. There remains a layer of smoke aloft from
western U.S. wildfires that will create a hazy look to the sky.
HRRR smoke modeling updates show that stream of smoke will remain
in our area for a couple more days at least. However, the smoke is
not expected to mix down to the ground levels and affect our air
quality. The 12z KILX sounding showed plenty of dry air through a
deep layer. Mixing heights are projected to reach up to 875 mb or
so, which when mixed to the surface support highs in the mid to
upper 70s. Those temps are around normal for this time of year.
South-southeast breezes will prevail in the 6-12 mph range. The
forecast appears on track, and no formal morning update will be
needed.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 301 AM CDT Mon Sep 21 2020

Not much change over the past 24 hours, as the continued dry
conditions remain overhead. High pressure dominates the weather
pattern across much of the eastern CONUS, allowing for sunshine
again today. Once again, the region will see lingering smoke/haze
due to jet stream transport of the western US wildfires. This
should start the day across western Illinois, before spreading
later today and overnight into eastern Illinois...as high pressure
slowly begins to drop sw into the mid-Atlantic states.

After another cool start to the day, highs will continue climbing
back into the 70s this afternoon. High pressure will hold mostly
sunny skies throughout the region today. However, heading through
the overnight period, clouds should slowly build from south to
north as the outer bands of elevated moisture from Tropical Storm
Beta begins to arrive. The High pressure system along the Atlantic
states will aid in the rapid northerly push of cloud coverage.
Overnight temps will not cool as the past few nights, however the
cooler conditions still remain.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 301 AM CDT Mon Sep 21 2020

The dry conditions persist throughout the week for much of the
region, however southern Illinois has the best chance for any
precip during this week as remnants from Tropical Storm Beta make
their way northward. This chance comes mid-week into the start of
the second half of the week, as the High pressure system remains
over eastern CONUS. With this projection, the remnants will lift
north into and through the Mississippi River Valley, with northern
fetch reaching the Ohio River Valley. Some light precip could
extend as far north as the I-70 corridor, but model best
predictions currently are Ohio River and locations
south...Tennessee Valley. With southerly winds lifting into the
region through much of the week, temps will remain in the mid to
upper 70s, before climbing back to the 80s late week into next
weekend.

Looking into the weekend, another Low pressure system will move
through the region. This will be the better chance for rainfall
across the region, as a deepening trof will drop through the
central Plains. Models indicate the High pressure will have moved
off the Atlantic coast, and with the deepening trof, this will
allow a stronger Low pressure system to develop across the Plains
and shift into the Midwest. The High will aid in moisture
transport through the Mississippi River Valley towards the Ohio
River Valley, along with Low pressure moisture being fed by this
transport. This should develop the precip shield over the Midwest,
and then track east through the Ohio Valley to end next weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 527 AM CDT Mon Sep 21 2020

Another mostly quiet aviation period, winds expected to be calmer
today due to High pressure drifting ssw along the Atlantic coast
to mid-Atlantic states today. This will bring se winds to the
region today, less than 8kts. Some wind shift is possible late in
the period to the south, however speeds will remain less than
10kts so did not add that minor change as of this TAF issuance.
Holding some cloud coverage at terminals today, from the mid/high
level transport of western US wildfire smoke.


&&

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

$$

UPDATE...Shimon
SYNOPSIS...Baker
SHORT TERM...Baker
LONG TERM...Baker
AVIATION...Baker


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