Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 290843

Area Forecast Discussion
National Weather Service Lincoln IL
343 AM CDT FRI APR 29 2016

.SHORT TERM...(Today)
ISSUED AT 342 AM CDT Fri Apr 29 2016

Quiet conditions are expected across central and southeast Illinois
today. We will be between weather systems, although there will be a
fair amount of cloud cover across the area. Expect light winds and
slightly cooler than normal temperatures. Daytime highs will top out
in the 60s at most locations.


.LONG TERM...(Tonight through Thursday)
ISSUED AT 342 AM CDT Fri Apr 29 2016

Deep trof over the western half of the CONUS will eject out another
low for the Midwest this weekend. Same kind of set up with a slow
moving system keeping much of the Midwest wet, and putting in excess
of an inch of rain anticipated for Central Illinois. A slower trend
in the models as the precip spreads from southwest to northeast
overnight tonight...mainly after midnight.  The region sets up for
mainly a warm sector event from the developing low to the west.
Southerly flow of warm moisture feeding into the ongoing
precipitation for Saturday and Saturday night.  Precip slowly
decreasing through Sunday night as the upper low finally progresses
through the region. Sunday night will have some clearing of the
precip with drier air wrapping around the system.

Models have had several problems...the 00z runs for the last three
nights have been different. Models are still not in agreement with
handling the pattern shift with the shearing out of the energy
remaining in the trof in the southwest. It seems an attempt at more
northwesterly flow ...but so far, the lack of gradient aloft is weak
at best, with no consistency for the energy trying to dig out a trof
over the Great Lakes.  Remaining forecast is dry for now...with some
slight chances creeping in mid/end week.  Temperatures are moderate
and holding near seasonal.  Confidence in forecast for next week
remains weak and highly conditional.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1148 PM CDT Thu Apr 28 2016

Latest satellite images and observations show a lingering VFR OVC
CU cloud mass covering all but DEC late this evening, with
clearing just south of SPI and DEC. The southern edge of the
clouds has been starting a slow progression northward, in response
to a subtle northward shift in the trough axis. However, the
trough is expected to drift back southward later tonight and
Friday morning, putting the 850mb baroclinic zone directly across
our forecast area. The proximity of cooler air just to our north
and the frontal circulation in the baroclinic zone will help keep
cloud cover in the area more than sunshine. Therefore, we expect
cloud coverage to remain broken to overcast over a majority of
the area during this TAF period. SPI and DEC will have the best
chances at noticeable breaks in the cloud cover on Friday, with
shorter breaks for the northern TAF sites. Any breaks in the
clouds tonight will aid in fog formation, so will continue to
light fog of 3sm br for the northern TAFs. HRRR is not hitting fog
quite that hard at the terminal sites, but winds should become
light toward sunrise, helping tip the scales toward fog as
dewpoints linger in the upper 40s tonight.

Based on forecast soundings and HRRR output, we are still expecting
MVFR ceilings to develop from north to south tonight and linger
into Friday morning. IFR ceilings are projected to develop along
I-74 early Friday morning. Ceilings should improve with turbulent
mixing after sunrise helping lift the LCL. Winds stay fairly
light next 12-18 hours under the weak surface trough. WNW winds 4
to 7 kts will veer NW late tonight and then NE Friday morning and
eventually E during the afternoon. Wind speeds should remain in
the 5-10 kt range on Friday, with speeds increasing to 10-14kt
Friday evening ahead of approaching low pressure from the Plains.
Increasing isentropic lift will aid in mid-level saturation and
spotty showers after 03z Fri eve for SPI and DEC. Better chances
of rain will hold off until after this TAF valid period.


.ILX Watches/Warnings/Advisories...


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