Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 211723

Area Forecast Discussion
National Weather Service Lincoln IL
1223 PM CDT SAT MAY 21 2016

Issued at 1026 AM CDT Sat May 21 2016

The weak shortwave that produced the persistent cloud cover and
light rain over east and southeast Illinois early this morning has
finally shifted off to our east. The cloud shield associated with
the wave was edging southward through southeast Illinois this
morning and that trend should continue, but will still affect
afternoon temperatures in this area. Forecast soundings suggest
we should mix down from around 6500 feet by mid afternoon which
will push afternoon temperatures into the mid and upper 70s across
our west and northwest counties, while further southeast, temps
will be held down due to the slower departure of the cloud cover
with mostly lower 70s expected by later this afternoon. Have made
some adjustments to the forecast highs as well as the timing of
the clouds out of southeast Illinois this afternoon and should
have the updated zones out by 10:45 am.


.SHORT TERM...(Today)
ISSUED AT 238 AM CDT Sat May 21 2016

A surface low will continue moving eastward today up the Ohio River
Valley while high pressure builds into the upper Midwest. Very light
showers continue this morning over portions of east central IL and
these will slowly taper off over the morning hours as the upper low
lingers over the region. Skies will clear through the day from
northwest to southeast under the subsidence associated with the
high...although forecast soundings indicate a layer of scattered
cumulus developing around the 5000 foot level with daytime heating.
Highs today should warm a few to several degrees to the low to mid
70s...especially over southeast IL where rain held temperatures down
to the low 60s Friday. North winds around 10 mph will develop today
due to pressure gradients between the departing low and the
approaching high pressure.

.LONG TERM...(Tonight through Friday)
ISSUED AT 238 AM CDT Sat May 21 2016

Upper level ridging currently over the Plains will drift eastward
over the next couple of days, as the corresponding surface high
moves across the Midwest. This will result in some dry weather for
Sunday and Monday. Temperatures will warm nicely with the passage of
the high, generally reaching the 80 degree range both days.

Once the high passes, a more active weather pattern will prevail,
with gradually warmer and more humid conditions, along with periods
of showers and thunderstorms. Have slowed down the arrival of the
rain, mainly limiting chances west of I-55 Monday night and Tuesday.
After that, upper level waves will track out of the southwest U.S.
through the week to help produce additional showers and storms over
the entire forecast area. Have increased PoP`s on Wednesday to about
60% over the southeast half of the CWA with decent model agreement
at this range, but further out in time, the picture becomes a bit
murkier. The ECMWF tries to paint at least one dry day (Thursday),
while the GFS is stronger with its Thursday wave and thus features
more showers and storms. The lower PoP`s for Thursday are a bit of a
nod toward the ECMWF solution, but chances increase again late week
with a piece of the southwest upper trough ejecting northeast and
closing off over the northern or central Plains.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1218 PM CDT Sat May 21 2016

VFR conditions are expected to prevail through this forecast
period. High pressure will build into the forecast area over
the next 24 hours bringing quiet weather conditions. North to
northeast winds of 8 to 13 kts gusting up to 19 kts at times this
afternoon will quickly diminish towards sunset this evening and
become light northerly overnight and Sunday.


.ILX Watches/Warnings/Advisories...


LONG TERM...Geelhart
AVIATION...Smith is the U.S. government's official web portal to all federal, state and local government web resources and services.