620 
FXUS63 KILX 131805
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1205 PM CST Sun Jan 13 2019

.UPDATE...
Issued at 1115 AM CST Sun Jan 13 2019

Light snow mixed with patchy freezing drizzle has been slower to
shift southward across central IL during this morning, so updated
forecast for this slower trend. Otherwise rest of forecast appears
on track today. The light snow has shifted southwest of a Peoria 
to Lincoln and Terre Haute line at 11 am. The latest hi-resolution
models continue to diminish to light snow and patchy freezing
drizzle southward thru mid afternoon though some flurries could
linger thru the afternoon and low clouds to linger into this
evening. A dusting to less than a half inch of additional snow 
accumulations possible from Canton to Springfield to Robinson sw. 
Weakening 1018 mb surface low pressure near the KY/VA border 
while new 1015 mb low pressure deepening off the NC coast. The 
coast low pressure will take over and pull away from IL while 555 
dm 500 mb low over central IL and northern IN very slowly weakens 
into tonight. Meanwhile 1036 mb Canadian high pressure over 
western Quebec and southeast Ontario ridges sw into nw IA and down
into north Texas, will ridge into central IL by dawn Monday and 
will bring dry conditions tonight. Brisk NE winds 10-20 mph and 
gusts of 20-25 mph late this morning will gradually diminish to 
NNE at 6-12 mph by dark. Temps at 11 am were in the upper 20s and
lower 30s, and temps will not rise much rest of today due to low
clouds and cold air advection with NNE winds. Highs 30-35F today. 

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 335 AM CST Sun Jan 13 2019

1016mb low analyzed over western Kentucky continues to bring light
precipitation to much of central and southeast Illinois early this
morning. Snow is falling everywhere north of I-70 while locations
further south are warm enough to support rain. A few ob sites 
have begun reporting UP over the past couple of hours...an 
indication that freezing drizzle may be mixing with the light snow
as ice crystals become less likely within the atmospheric profile.
Any icing that occurs will be minimal and of little concern. 
Frontogenetic forcing will continue to gradually weaken, resulting
in diminishing precip as the morning progresses. Based on radar 
trends and HRRR guidance, it appears very light precip will linger
into the afternoon across the W/SW KILX CWA...while the remainder
of the area becomes dry by midday. Temperatures will remain nearly
steady today, only rising a couple of degrees into the lower 30s.

As a short-wave trough noted on latest water vapor imagery over
southern Illinois tracks further eastward away from the region, 
drier air poised over the northern Great Lakes will get drawn 
southwestward later today into tonight, bringing clearing skies to
northern Illinois. Will need to keep a close eye on this trend to
see exactly how far south the clearing will spread. Forecast
soundings generally indicate continued overcast conditions across
the CWA through tonight, with areas along/northeast of a Lacon to
Paris line most likely experiencing partial clearing overnight.
Low temperatures will drop into the teens where a deep snow cover
exists, but will remain in the lower 20s south of I-70 where less
snow is present.

.LONG TERM...(Monday through Saturday)
ISSUED AT 335 AM CST Sun Jan 13 2019

Cold/dry weather will be on tap for Monday as high pressure builds
into the Midwest. Once the high slides to the east, southerly
winds on its back side will bring moderating temperatures by
Tuesday as readings climb above freezing into the middle to upper
30s. As WAA increases over the snow cover, will need to watch the
potential for fog/drizzle Monday night into Tuesday. The strongest
signal for this appears to be focused along/north of I-80, so have
not included it in the forecast at this time.

After another dry day on Wednesday, the next chance for
precipitation will develop on Thursday as a short-wave trough
tracks through the region. Models are not in particularly good
agreement with this feature, as the GFS is almost completely dry
with the wave, while the ECMWF/GEM both generate light precip
across mainly the E/SE CWA Thursday afternoon and night. Have
included chance PoPs east of the Illinois River accordingly,
although QPF will remain minimal.

The main concern in the extended is the potential for yet another
winter storm by the end of the week. 00z Jan 13 models all show a
significant upper trough digging over the western CONUS...with
corresponding surface low pressure ejecting from the southern
Rockies into the Tennessee/Ohio River Valleys over the weekend.
Obviously the exact track of this system is still in question that
far out: however, a few trends appear to be emerging on the latest
models. The 00z GFS is the fast/northern outlier...with the low 
tracking across south-central Illinois Friday night. Meanwhile, 
the ECMWF/GEM/FV3-GFS all take a slower/more southern track with 
the low into Kentucky/Tennessee by Saturday night. It is still too
early to draw any concrete conclusions: however, it is safe to 
say that another round of snow may be on tap for parts of central 
Illinois during the Friday/Saturday timeframe. Stay tuned to later
forecasts for more details. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1159 AM CST Sun Jan 13 2019

An area of light snow will affect mainly SPI next 1-2 hours with
MVFR vsbys early this afternoon. Otherwise scattered flurries 
this afternoon with VFR vsbys, and MVFR ceilings which linger 
into tonight. Ceilings could lift to low end VFR Mon morning with 
areas ne of I-74 possibly having clouds scatter out later Mon 
morning as Canadian high pressure ridge settles se into IL. Brisk 
NNE winds of 10-16 kts with gusts of 17-23 kts early this 
afternoon to veer north and diminish to 5-9 kts later this 
afternoon, and turn west to NW by Monday morning. 

&&

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

$$

UPDATE...07
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...07