Area Forecast Discussion
Issued by NWS Central Illinois
FXUS63 KILX 142051
AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
251 PM CST SUN FEB 14 2016
ISSUED AT 251 PM CST SUN FEB 14 2016
Will continue the Winter Weather Advisory until 6 pm across CWA.
Between 2-4 inches of snow has fallen across much of central and
southeast IL so far today, with the highest amounts from Galesburg
to Lincoln and Decatur southwest to Springfield and Taylorville.
Less than 1 inch of additional snow expected east of I-57 and from I-
74 north where light snow lingers longest into late afternoon and
early evening. Some patchy freezing drizzle to develop from west to
east during late afternoon and into tonight as we lose mid level
cloud layer. Vigorous 539 dm 500 mb low over far nw IL will track
into ne IL by early evening and into Lake Erie overnight with a
lingering short wave trof hanging back over the Midwest into Monday.
This should keep low clouds around along with trace amounts of
precipitation (very light snow/flurries and patchy freezing drizzle
especially this evening). Temperatures will be nearly steady
tonight mostly in the low to mid 20s. Brisk southeast winds 10-20
mph and gusts to 25 mph this afternoon to diminish to 5-10 mph
overnight and veer more southerly.
.LONG TERM...(Monday through Sunday)
ISSUED AT 251 PM CST SUN FEB 14 2016
Monday is apt to be a mostly quiet day, with temperatures climbing
back toward normal for mid-February. Some model guidance continues
to suggest very light rain/snow falling across the western or
southern portion of the forecast area by afternoon as a weak short
wave crosses the region. However, the already weak wave is
diminishing further as it shears into the mean upper trof, and
really do not expect measurable precipitation with this feature.
Maintained a Slight Chance afternoon PoP for continuity and to blend
with our neighbors, but feel these PoPs can probably be dropped if
models continue to look as they do now.
The forecast for late Monday night into Tuesday remains problematic
as model guidance continues to show notable differences in the
timing/track of a clipper system. Run to run consistency with this
system has been a problem too. Blended guidance still suggests
temperatures warming enough by afternoon for most of the
precipitation to change to rain. However, faster solutions suggest
most, if not all, of the precipitation will have fallen by then.
Thermal profiles support all snow during the Monday night and most
of Tuesday morning hours, so it is looking increasingly likely that
at least minor snow accumulation can be expected with this system.
For now, have most locations seeing around 1" total, but this will
obviously need to be tweaked as the models come to a stronger
consensus in the next few runs.
Whatever snow we do get Tuesday will not be around long as upper
heights rise and southerly low level flow develops heading into the
end of the week. These factors support temperatures rising to well
above normal levels, with highs by Friday topping out around 60
across most of the forecast area. A cold front coming through
Friday/Friday night may have rainfall associated with it, but it
does not appear likely to be significant. Behind the cold front,
temperatures remain above normal, with the mean flow coming in off
the Pacific coast. Another disturbance within this zonal flow may
bring additional rainfall by the end of the weekend, but expected
differences (at this time range) in timing/track of this system
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 1159 AM CST SUN FEB 14 2016
Light to moderate snow that has been bringing vsbys down to
1/4-3/4 mile along with ceilings between 500-1500 ft across
central IL past few hours. The back edge of this snow was along a
Burlington, IA to Jacksonville line and HRRR has the snow
diminishing eastward toward the IN border by 21Z. But there is
some wrap around light snow over central/se IA that will affect
northern TAF sites along I-74 through dusk. Could see some patchy
freezing drizzle develop from west to east during late afternoon
and into the evening but coverage too limited to mention at this
time. SE winds 10-17 kts and gusts of 18-25 kts this afternoon to
diminish to around 10 kts this evening and then 5-8 kts overnight
and veer SSE. SSW winds 5-9 kts expected Monday morning. Kept low
clouds of MVFR to IFR around tonight into Monday morning with
vsbys becoming MVFR later this afternoon as snow diminishing and
continues MVFR vsbys with some fog/low level moisture tonight and
linger into Monday morning as winds become lighter.
Winter Weather Advisory until 6 PM CST this evening for