Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 161806

Area Forecast Discussion
National Weather Service Lincoln IL
106 PM CDT Mon Oct 16 2017

Issued at 1125 AM CDT Mon Oct 16 2017

High pressure has a firm hold on our weather today, with chilly
Canadian air accompanying the high. The 12z ILX sounding confirmed
the depth of dry air in place across central Illinois, and little
to no cloud cover is expected, even during peak heating this

Despite full sun and light southwest winds, high temperatures
will struggle to reach the low to mid 60s. Those highs look on
track, as mixing heights are expected to reach the base of the
morning inversion, and dry adiabatic descent to the surface
supports low to mid 60s.

Only minor updates were needed to hourly temps and dewpoints,
otherwise the current forecast is on track.


.SHORT TERM...(Today and tonight)
ISSUED AT 310 AM CDT Mon Oct 16 2017
High pressure is building into the midsection of the country this
morning...dominating much of the weather map. The cold front from
last night is well to the SE as the region is sitting under a
ridge axis from the Southern Plains into the Great Lakes. Weak
northwest flow aloft is expected to flatten out throughout the
period and quiet weather to continue with ridging anchoring the
weather through the work week.

In the shorter term, winds getting a southerly component to the
light westerly flow by the end of the day. Plenty of sunshine
should help to boost the temps into the low to mid 60s this
afternoon. Tonight, temps not expected to be quite as cold as this
morning. Concern for patchy frost south of Interstate 70 with the
lighter winds overnight. However, holding off on the mention for
now as the guidance is showing a general warming trend to the
lower 40s.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 310 AM CDT Mon Oct 16 2017

Extended forecast is very mild as temps climb to a few degrees
higher than climatological norms by tomorrow, and continue the
warming trend through the end of the week. By Friday, high
temperatures are expected in the low to mid 70s. Northwesterly
flow aloft today dampens into a more zonal pattern, shifting the
more active flow off to the north. Ridging remains in place over
the south/southeastern CONUS, effectively deflecting the
precip/impact of a mid week wave to the north. Forecast remains
dry and warming through the end of the work week.

Models agree with a break in the pattern moving into the weekend
with a more amplified wave digging in over the western half of the
CONUS. A cold front is slated to move through the region late
Saturday/early Sunday. Given the pops are out in Day 6/7, the
disparity in the models is expected. For now, chance pops move
through the forecast for next weekend, but details will be
shifting as to timing and strength.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 102 PM CDT Mon Oct 16 2017

Quiet aviation weather is expected for the 18Z TAF period, under
high pressure. SW winds will sustain in the 8-12kt range, with a
few gusts to 16kt at times. The stronger winds early this
afternoon appear to be closer to the tighter pressure gradient,
near PIA and BMI. The gradient will remain relatively static the
rest of the afternoon, as the surface ridge axis extends across
south-central Illinois, roughly along I-70. Little to no cloud
cover is expected through tomorrow morning, under a very dry air




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