777 
FXUS63 KILX 281545
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1045 AM CDT Sun Sep 28 2014

.UPDATE...
ISSUED AT 1045 AM CDT SUN SEP 28 2014

Forecast generally looks on track today and just slight modifications
with sky cover today. A fair amount of sunshine expected again
today with patches of mid/high clouds and few cumulus clouds this
afternoon mainly from I-55 west and over the Wabash river valley.
Warm highs in the low to mid 80s today and Monday with light winds.

Patchy fog along the Wabash and IL rivers dissipated by 830 am
leaving sunny to mostly sunny skies by mid/late morning. 1023 mb
high pressure over lower MI and ridging westward into WI and central
and eastern IA and northern IL will remain over the Great Lakes
through monday and maintain fair wx with warm days. Dewpoints
currently in the mid 50s to near 60F will slip a few degrees this
afternoon so humidity levels will be fairly low again this afternoon.
Temps currently in the low to mid 70s (except 68F at Lacon which
had valley fog earlier this morning) will climb another 10 degrees
into the low to mid 80s by mid afternoon. Weak 580 dm 500 mb low
over far western IA near Nebraska border drift se into MO by
sunset and keep its isolated convection west of IL. RAP/NAM curule
shows few cumulus clouds this afternoon from I-55 west and over
the Wabash river valley in southeast IL. Some patches of mid/high
clouds drift over IL today but still a mostly sunny day expected.

&&

.SHORT TERM...(Today)
ISSUED AT 250 AM CDT SUN SEP 28 2014

A shallow layer of moisture below a subsidence inversion will allow 
some patchy ground fog to linger near river valleys early this 
morning (IL and Wabash rivers). Any fog should dissipate by 830 
am.   

The 580dm 500mb low centered over NW Iowa will become an open wave 
and drift southeast across IL later today. That will bring scattered 
cirrus clouds with it, but sunshine should generally prevail across 
IL today. That will help high temps climb above all guidance numbers 
again today, as the dry low levels warm quickly. Temps should top 
out in the low to mid 80s this afternoon. Winds will remain light 
under a weak surface pressure gradient, with east to southeast winds 
of 5 to 8 mph again today.

&&

.LONG TERM...(Tonight through Saturday)
ISSUED AT 250 AM CDT SUN SEP 28 2014

Quiet weather expected for the start of the work week. Shortwave 
currently entering western Saskatchewan will be digging as it 
approaches Lake Superior, forming a closed low over Lake Huron by 
early Tuesday. This will drive a cold front southward, but general 
model consensus only brings it into northern Illinois before 
beginning to lift back north. 850 mb temperatures in the 11-13C 
range will keep our highs above normal, with some modest cooling on 
Tuesday as the front approaches. Have favored the warmer MAV MOS 
guidance during this period.

Large upper low currently spinning over western Nevada still 
expected to swing northeast and weaken early this week, with a small 
closed low lifting through the Dakotas on Tuesday. This will help 
draw the previously mentioned front back north, before a stronger 
cold front moves in from the northwest. Still looks like Wednesday 
will largely be dry, before showers increase Wednesday night ahead 
of the front. Shear profiles increase nicely as the front gets 
closer on Thursday, with 0-6km bulk shear progged to reach 40-50 
knots across much of the CWA Thursday afternoon per the ECMWF model, 
while the GFS is on the lower end of that range. Will need to 
continue watching the threat for some stronger storms Thursday 
afternoon and evening. Highest PoP's will be during the evening 
hours, with a quick decrease in rain from west to east after 
midnight following the passage of the front itself.

Strong surge of cooler air to plunge into the Midwest on Friday in 
the wake of the front. Some model discrepancies exist at this range, 
as the GFS was more prominent on driving a surface low northeast 
along the front and amplifying as a significant upper low drops into 
Wisconsin. The ECMWF is continues with a smaller but strong open 
wave that races through the region on Friday. Both keep the coolest 
air to our north, but the GFS would be more of a threat with 
lingering wraparound showers. For PoP's, have continued to mention 
them in the 30-40% range, but currently think this would mainly be 
early in the morning. Temperature-wise, the GFS brings the 850 mb 
zero isotherm into central Illinois by late Friday and dipping below 
zero by early Saturday, while the ECMWF is already spreading warmer 
air back in by that point. With this discrepancy, the GFS would 
indicate highs only in the 50s on Saturday, while the ECMWF favors 
mid to upper 60s. Have favored more of a blend with Saturday as the 
coolest day, with highs mostly 60-65.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 637 AM CDT SUN SEP 28 2014

Fog has not developed near the terminal sites so far this
morning, and any light fog over the first hour of the TAF period
would be very brief if it develops. Overall, VFR conditions will
prevail for the balance of the forecast period. A weak upper low
passing over IL today will mainly bring an increase in high
clouds. A few cumulus may form in the 4-5k ft layer as the 12z ILX
sounding shows moisture in that layer. So any BKN ceilings would
remain VFR. Surface winds will remain light east or northeast
today and tonight with speeds of 3 to 7 kts.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

UPDATE...07
SHORT TERM...Shimon
LONG TERM...Geelhart
AVIATION...Shimon