Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241544

Area Forecast Discussion
National Weather Service Lincoln IL
1044 AM CDT SUN APR 24 2016

Issued at 1045 AM CDT Sun Apr 24 2016

Updated the forecast during mid morning to remove the dense fog
advisory over southeast IL at 9 am. Otherwise no other updates
planned today with ample sunshine, breezy south winds 10-15 mph
and gusts 20-25 mph and warmer highs in upper 70s eastern IL east
of I-55 and lower 80s west of I-55.

Late morning surface map shows 996 mb low pressure over central
SD with a warm front extending eastward across far southern MN and
southern parts of WI and lower MI. Strong low pressure to track
eastward into east central SD by midnight tonight while its cold
front moves into eastern Nebraska and central KS. Scattered
showers and thunderstorms should stay nw of IL through this
evening. Ample sunshine expected rest of today over central/se IL
as cirrus clouds increase. Warmer highs in upper 70s eastern IL
and lower 80s west of I-55 with breezy south winds 10-15 mph and
gusts of 20-25 mph with strongest winds in western IL.


.SHORT TERM...(Today)
ISSUED AT 339 AM CDT Sun Apr 24 2016

Surface ridge axis has shifted east of the forecast area early this
morning but low level flow was almost non-existent over southeast
and east central Illinois, resulting in some patchy dense fog.
Visibility at Champaign has just dropped to a quarter mile, although
web cams in that area not supporting anything close to that at the
present time. Winds are expected to slowly increase over the east
and southeast portions of the forecast area in the next several
hours, but will continue to keep the dense fog wording for an hour
or two after sunrise along the I-70 corridor with patchy dense
wording further north. Will issue a Dense Fog advisory for the far
southeast counties for the early morning hours, but if the HRRR
trends are correct, we may need to expand that a bit further north
this morning.

Further to the west, southerly flow already increasing so fog
shouldn`t be a problem early this morning, then we look for winds to
become gusty by late morning into the afternoon hours as our next
weather system pushes into the Plains. The increasing south wind
today coupled with sunshine should help push afternoon temperatures
to around 80.

.LONG TERM...(Tonight through Saturday)
ISSUED AT 339 AM CDT Sun Apr 24 2016

After the warm weather today, a series of weather systems will bring
precip off an on for the most part of this week.  The first wave
will approach on Sunday night after midnight, and continue the
chance for some showers through Monday night and into early Tuesday.
The last few runs of the models have sheared out the energy just to
the north of ILX and keeping much of the precip displaced from
Central Illinois.  As a result, the pops are considerably lower than
later in the week with the more assertive system.

The deep low over the western half of the CONUS finally ejects out
with the surface system strengthening Tues night and into Wed night.
Previously, models kept much of Central Illinois in a warm sector
feature, but is starting to slow in the northern progression of the
developing warm front.  So temperatures are now not quite as warm
for Tue/Wed ahead of the advancing storm center.  This, among other
features like the variation in the storm track will change up the
threat for severe weather on Wednesday.  Low level lapse rates
looking slightly less impressive with the current track... but that
will likely get countered by the general lift of the low center.
More detail to come. By late Thursday, the winds become more
northerly and drier air slowly tries to build back in for a brief
break Thu night through later Friday. The break looks to be short
lived again as another wave moves out of the long wave trof over the
SW and into the region, bringing precip back for next weekend.
Overall, an active pattern, with more wet than dry.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 616 AM CDT Sun Apr 24 2016

Areas of IFR and local VLIFR vsbys in fog will improve to VFR
conditions by 15z as surface winds increase from a southerly
direction. Worst vsbys this morning have been along the I-70
corridor and up near CMI, although local web cams indicating
the vsbys, at least around the city, were not nearly as bad
as what the CMI airport was reporting early this morning. We
will continue with the VLIFR conditions at the CMI airport for
another hour or two before we see rapidly improving conditions
with VFR at all sites after 15z and continuing through this
forecast period. Surface winds will increase from a southerly
direction to between 12 and 17 kts with a few gusts up to 23 kts
at times, especially west of I-55 this afternoon. Surface winds
will be southerly tonight at 10 to 15 kts with scattered to broken
cirrus expected across the forecast area. It still appears the
better LLWS setup will be west of our forecast area this evening
so will leave out of this forecast issuance.


.ILX Watches/Warnings/Advisories...


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