Area Forecast Discussion
Issued by NWS Central Illinois

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865
FXUS63 KILX 132052
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
252 PM CST SAT FEB 13 2016

.SHORT TERM...(Tonight)
ISSUED AT 252 PM CST SAT FEB 13 2016

1037 MB Canadian high pressure over IL at mid afternoon will move
into the upper Ohio river valley of WV/PA by 12Z/6 am Sunday. An
upper level short wave over MT and moving into the western Dakotos
at mid afternoon will track into IA/northern MO by 12Z/6 am Sunday.
Isentropic lift starts after 03Z/9 pm tonight and increases more so
during overnight through 15Z Sunday and to develop light snow from
west to east later this evening and overnight. Snowfall amounts
overnight by dawn Sunday to range from 1-2 inches west of highway 51
to less than 1 inch from highway 51 east with less than a half inch
near the IN border. Will continue the winter weather advisory across
CWA overnight through Sunday, starting at 3 am. Was debating about
starting the winter weather advisory at midnight for western half of
CWA, but snowfall amounts prior to 3 am should be less than 1 inch
yet in western areas and se winds still under 10 mph. Southeast
winds pick up to 10-15 mph with gusts 15-20 mph late tonight and
could start blowing some snow by dawn Sunday. Temperatures currently
are in the upper teens and lower 20s at 230 pm. Lows tonight range
from 10-15F with coolest readings ne counties, so not much
temperature drop as skies cloud up late this afternoon and evening
and southeast winds increase later tonight.

&&

.LONG TERM...(Sunday through Saturday)
ISSUED AT 252 PM CST SAT FEB 13 2016

Snow should be falling across a majority of central and southeast
Illinois as day breaks Sunday. Moderate to strong isentropic ascent
will be in place for much of the day, although it will be
diminishing from the west by afternoon. The duration of the lift and
2-3 g/kg mixing ratios still supports 2"-5" snow totals (highest in
NW portion of forecast area). Remain concerned that a period of
freezing drizzle may occur in the late afternoon/night time hours
Sunday as the deeper moisture peels away and ice crystals are lost.
Have allowed for a brief period of freezing drizzle on the back edge
of the precipitation Sunday night. In any event, current Winter
Weather Advisory looks good and can easily be extended if confidence
grows in the freezing drizzle threat.

Quiet weather is anticipated Monday in between two weather systems.
Confidence is growing in a clipper impacting the area on Tuesday,
and most guidance suggests at least a quarter inch of liquid
equivalent falling across the area. However, there is still notable
disagreement with the track of the clipper, and this will have an
impact on thermal profiles while the precipitation is falling. The
most favored solution at this point starts out as snow late Monday
night, with a possible change to rain on Tuesday, especially during
the afternoon. In any event the evolution of this system will need
to be watched closely.

Behind Tuesday`s system, mostly quiet weather is expected into the
end of the week, with temperatures trending well above normal. The
next weather system progged to impact the area will arrive by Friday
into Saturday, and temperatures will be mild enough for all rain
with this system.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1155 AM CST SAT FEB 13 2016

Ample sunshine across central IL at midday and VFR conditions to
continue into this evening across the central IL airports as
broken to overcast mid/high clouds spread in from IA during mid
afternoon into the evening. A weather system over MT and the
western Dakotas will track into IA and central/northern IL Sunday
morning. This will spread light snow ese across central IL during
overnight between 07Z-10Z with MVFR vsbys 3-5 miles at first and
then lower to 3/4 to 2 miles 2-3 hours later late tonight/early
Sunday morning. Ceilings lower to MVFR during overnight and
continue with the widespread light snow Sunday morning. NNW winds
7-10 kts this afternoon to switch east around 6 kts by sunset and
then veer SE and increase to 10-16 kts during overnight into
Sunday morning with gusts of 16-20 kts possible Sunday morning.


&&

.ILX Watches/Warnings/Advisories...
Winter Weather Advisory from 3 AM to 6 PM CST Sunday for
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...07
LONG TERM...BAK
AVIATION...07



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