Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 060121
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
821 PM CDT MON OCT 5 2015
ISSUED AT 817 PM CDT MON OCT 5 2015
Have made some minor adjustments to cloudiness, otherwise current
package looks on-track.
Low clouds have made it as far southwest as KPNT at 01z and
should continue to overspread area under influence of northeast
flow. Fog development still looks like a good bet, particularly
along I-74 from east of Peoria through Danville.
ISSUED AT 232 PM CDT MON OCT 5 2015
Stratus deck held firm a good part of the morning, but started to
rapidly erode toward midday and most of it is now gone from the
forecast area as of 2 pm. Still getting some cirrus streaming up
from the southwest, but most areas at least are now partly sunny.
This has helped temperatures recover nicely and much of the CWA has
reached into the 70s. A few 80 degree readings have been observed in
the far southeast, where skies have been mostly sunny the entire
High pressure ridge from Wisconsin to Oklahoma will move little
overnight, keeping our northeast flow continuing. 925 mb RAP
humidity plot showing some southern building of the lower clouds
once again overnight, and have indicated mostly cloudy conditions
spreading over most of the forecast area overnight. It has also been
persistent over the last few hours on a widespread dense fog
scenario expanding southwest to cover the southeast half of the
forecast area. The 4km NAM-nest shows this a bit further northwest,
mainly from about I-55 eastward, and the tail end of the HRRR is
more patchy in nature, but in that same general region. At the
moment, will only mention patchy fog in the forecast and continue to
watch how the stratus evolves this evening.
.LONG TERM...(Tuesday through Monday)
ISSUED AT 232 PM CDT MON OCT 5 2015
High pressure ridge will dominate the weather across central IL
through mid week. Though there could be some cloud cover, partly to
mostly sunny skies should be the rule, with temps warming to above
normal, mid to upper 70s...into the lower 80s, for Wed and Thur.
Then models are in very good agreement with timing and intensity of
a cold front moving through the area Thursday night. Pcpn will begin
just ahead of the front Thursday morning northwest of the IL river
and then spread eastward through the afternoon and into the evening
for the southeast. The front should move through the area quickly
Thursday night with pcpn likely over the northeastern portion of the
CWA during the night. The pcpn should be exiting the area from late
Thursday night through early Friday morning. Lingering pcpn will in
southeastern IL Friday morning, with all pcpn gone before the
afternoon. This front will bring cooler temps in for Friday and
Saturday, but with another high pressure ridge moving into the area,
temps will again warm to above normal levels for Sun and Mon. Dry
weather is also expected Friday afternoon through Monday.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 619 PM CDT MON OCT 5 2015
Surface Ridge remains to our northwest through early Tuesday
keeping flow generally northeast over the central Illinois
terminals which will keep us under the influence of Lake
Michigan. Although clearing spread over the area today, MVFR cigs
are not too far away and should spread back into the area
overnight. KVYS has been back and forth this afternoon with KIKK
Short-Range models (RAP, NAM, HRRR) are consistent in pushing low
clouds and vsbys into most of the area starting with KCMI and
spreading southwest. HRRR is the least agressive and keeps
terminals VFR until after 09z. Given the proximity of the deck
will generally follow the more pessimistic RAP which brings MVFR
counditions into KCMI by around 04z and into all sites by 09z.
Best probabilities of IFR conditions would be at KCMI and KBMI.
Will keep conditions MVFR elsewhere with this package, but
potential for lower cigs/vsbys will certianly need to closely
With weak flow, conditions will only slowly improve on Tuesday.