Area Forecast Discussion
Issued by NWS Central Illinois

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940
FXUS63 KILX 111756
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
1156 AM CST THU FEB 11 2016

.UPDATE...
ISSUED AT 1045 AM CST THU FEB 11 2016

Forecast generally looks on track today and only update will be to
increase the clouds a bit quicker during the mid/late afternoon
hours. Ample sunshine this morning with skies becoming mostly
cloudy by late afternoon/early evening with clouds arriving
soonest in western/sw CWA ahead of next clipper system. The
northern stream short wave/clipper is near the MT/SD border and
to race se across ne Nebraska and near sw IA/nw MO by sunset.
1030 mb Canadian high pressure over the upper MS river valley and
ridging over eastern IA/nw IL and northern MO will slide se across
central IL this afternoon, reaching central/southern IN and
eastern IL by 00Z/6 pm. This will keep winds light today generally
under 10 mph. Cold highs in the low to mid 20s with coldest
readings from I-74 ne.

&&

.SHORT TERM...(Today)
ISSUED AT 343 AM CST THU FEB 11 2016

Surface high pressure will drift over central IL today as a
fast moving  clipper system currently over the international border
in MT approaches. Deep long wave trough over the eastern U.S. will
continue today...promoting strong northwest flow which will rapidly
move the MT system toward central IL. Through late afternoon...main
impact of the system will be increasing high and mid clouds but dry
conditions after mostly sunny skies to start the day. The surface
high pressure will bring weak pressure gradients causing north winds
to become progressively lighter through the day...in fact light and
variable underneath the high center by late afternoon as it becomes
centered roughly over Springfield. Cold temperatures to remain
entrenched over the area with highs mainly low 20s but ranging up to
the mid 20s from around Jacksonville to Lawrenceville.

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 343 AM CST THU FEB 11 2016

A major change in the shorter term on track for tonight. Trouble
expected with the timing of the shortwaves moving through the nwrly
flow has materialized. Models have sped up the approach of the quick
clipper-like system out of the NW and into the long wave trof over
the eastern half of the country. Starting the snow in the west
before midnight, spreading across Central Illinois before sunrise
tomorrow morning. Snowfall totals could range from a half an inch to
an inch. Higher snowfall totals slated to be in the southern half of
the state...but this is a quick moving system and not expecting much
overall either way.  Concern will be for the morning commute,
particularly east of the I-57 corridor, where the snow may still be
falling. Other than that, forecast only some minor changes.  Deep
trof over the eastern half of the country will continue to dominate
the weather through the end of the week, keeping the colder air over
the region.

Lighter winds today will become more northwesterly towards the end
of the day, bringing colder air into the region.  Whereas Friday
highs may reach into the upper 20s, this cold air will knock
Saturdays highs back down into the teens. Winds pick up a southerly
component for Sunday as the upper trof finally starts to shift
eastward as another storm system takes shape moving into the
Midwest.  There is still some disagreement with the extent of the
snow, but with a diffuse area of lift moving into the region, the
snowfall totals are starting to take shape for potentially 2-3
inches across Central Illinois.  Majority of the snow will be in the
Sunday/Sunday night time frame, slowly wrapping up for the morning
commute on Monday. With this being a major pattern shift over the
country...expect changes to the details with this system.  So far,
the forecast is warming on the back side of the snow...so what snow
does fall, will likely be melting rather quickly into the first half
of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1155 AM CST THU FEB 11 2016

1030 MB Canadian high pressure over the upper MS river valley and
ridging into eastern IA and nw IL will slide se into eastern IL
and central/southern IN by 00Z/6 pm and into WV by 06Z/midnight
tonight. Nearby high pressure will continue light winds through
this evening across the central TAF sites. A northern stream short
wave/Alberta clipper over western SD will track se across MO
during this evening and into the TN valley by 12Z/6 am Friday.
Models have trended further sw track with this clipper so best
chances of light snow tonight have shifted sw into sw IL from SPI
sw. Have light snow/flurries with vsbys 4-6 miles and MVFR
ceilings spreading se along I-74 corridor 02-06Z. Steadier light
snow and vsbys down to 2-3 miles at DEC and especially SPI from
03Z-05Z along with MVFR ceilings. Light snow chances should end
late tonight from nw-se from 10-13Z as MVFR clouds linger. Light
winds this evening to become WNW by dawn Friday and increase to
10-15 kts with gusts 15-20 kts after 15Z/9 am Fri.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...07
SHORT TERM...Onton
LONG TERM...HJS
AVIATION...07



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