Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 141041

Area Forecast Discussion
National Weather Service Lincoln IL
541 AM CDT Thu Sep 14 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 328 AM CDT Thu Sep 14 2017

Light and variable to calm winds dominated Central IL this morning
under a weak high pressure ridge axis. Plenty of low level
moisture trapped under the inversion overnight resulted in pretty
widespread fog, a lot of it dense down to less than a quarter of a
mile. Sporadic obs come in with higher visibilities...but the
dense fog is predominant and a dense fog advisory will remain in
place for the entire warning area through 10am. Portions of the
advisory will likely get pared down early as the sun rises and
starts to burn off the fog. Once the fog burns off...should be a
mostly sunny day in the west, partly sunny in the east.
Temperatures will range with cloud cover...upper 70s for highs in
the east, mid 80s in the west. Will need to watch the dewpoints in
the east this afternoon...if there is not significant
mixing...could end up with another fog set up, particularly east
of Interstate 57.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 328 AM CDT Thu Sep 14 2017

A warm weekend in store for Central IL. Winds become more
southerly on Friday. The western ridge drifts east somewhat,
warming the midlevels a couple of degrees to 17-19C at 850mb.
Temperatures aloft may not be drastically different, but the
southern winds and sunshine will more than make up for it, pushing
high temps Fri and Sat well into the mid to upper 80s. Sunday
will warm as well, but may be tempered a bit by increasing cloud
cover from the next wave ejecting out of the west. Time of arrival
on the front/wave speeding up a bit in the latest runs of ECMWF
and GFS.  A deep low moving out of the Rockies and lifting to the
NE will pull the cold front across the Midwest later on Sunday
afternoon/evening. Expecting next round of precip with this front,
with the best chances with the fropa Sunday night.  Dissipation
of the slowing front/end of precip has varied solutions in the
models for Monday and beyond, but the thermal profile remains very
similar and highs stay in the mid 80s all the way into midweek.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 535 AM CDT Thu Sep 14 2017

Widespread fog this morning...and most terminals down to VLIFR,
with DEC holding at LIFR and CMI at 6sm in the observation. CMI
surrounded with lower visibilities and variable reports from 1/4
to 5sm. Not willing to leave CMI out of advisory, nor leave their
forecast higher than 1/4sm in the immediate term. Changes in
visibilities are not gradual tonight, rather quite quick. Sunshine
will eventually burn off the fog and conservatively have improving
conditions btwn 14-15Z...and light and variable winds under a
clearing sky going into the afternoon. Little in the way of clouds
anticipated tonight. Some variability to the wind, but S/SEerly as
the afternoon/evening wears on. Watching crossover temps in the
far east this afternoon as guidance slow to mix out llvl moisture
and fog potential may linger for CMI again tonight.


Dense Fog Advisory until 10 AM CDT this morning for ILZ027>031-



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