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000
FXUS63 KILX 112015
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
315 PM CDT Tue Mar 11 2014

.DISCUSSION...
ISSUED 305 PM CDT Tue Mar 11 2014

SHORT TERM...Tonight through Friday

Back to winter late tonight through Wednesday with the potential
for heavy wet snow over parts of our northern counties along with
gusty winds into the daylight hours of Wednesday. Will upgrade
to a warning for our extreme north/northeast counties which
includes Marshall, Woodford and McLean and extend the Winter
Weather Advisory southward a row of counties for late tonight
through Wednesday morning.

Models in general agreement in taking the surface low across
southern Illinois late tonight and Wednesday morning putting our
far northern counties in line for some significant snow totals
by Wednesday morning. However, NAM and GFS forecast soundings
showing mostly rain for this evening, which will translate over
to wet snow a little before midnight northwest, and after midnight
across the east. Very impressive and deep omega coninciding with
deep moisture in the favored dendritic zone along and north of
the I74 corridor in the 06z to 10z time frame and that will be the
time frame where heavy wet snow will occur with a few areas seeing
snowfall rates of 2 inches per hour. With the explosive forcing
seen in the dendritic layer late tonight, along with some negative
EPV present, expect the atmospheric column to cool significantly
enough for snow to start accumulating quickly, usually quicker
than expected. Wouldn`t be surprised to see some lightning strikes
in the snow band late this evening into the overnight hours as
well to complicate matters. One negative factor for some greater
than 8 inch snow amounts will be the speed of the system as all
models suggest a fairly rapid decrease in omega/moisture from
northwest to southeast starting around 12z Wednesday.

Wind will be another factor and a strong pressure fall/rise
couplet seen on model data late tonight as the surface low tracks
east across southern Illinois. At this time, it appears our surface
wind gusts will be borderline wind advisory criteria, so for now,
will hold off any additional advisories. The stronger pressure
rises late tonight will be over south central through southeast
Illinois so that would be the area to watch.

The system should begin to push off to our east late Wednesday
morning with gusty north to northwest winds and a dramatic change
to colder weather with afternoon temperatures some 20 to 35
degrees colder than the past couple of days. As the system
continues to push away from our area Wednesday night, we may even
be faced with near record low temperatures early morning lows will
dip into the single digits to middle teens. Thursday and Friday
should bring the warmer temperatures back into the region with
our southwest counties approaching 60 degrees once again by
Friday afternoon with little in the way of precipitation expected
through the remainder of the week.

LONG TERM...Saturday through Tuesday

Unfortunately, a cooling trend sets in over the weekend and we
see temperatures back below normal by Sunday and Monday with
highs in the upper 30s to mid 40s, with the coolest readings
from I74 northeast. Temperatures then bounce back into the low
to mid 50s for highs early next week.

Quasi-zonal upper flow early in the forecast period will translate
to a trof digging south from Hudson Bay Canada into the Great Lakes
in response an amplifying upper level ridge over the western states.
Models agree on an amplified upper flow pattern early next week which
will translate into a more zonal flow pattern by the middle of next
week which should allow a warming trend over the region. Dry conditions
are expected Saturday and then we will have a small chance of light
rain and snow from overnight Saturday through Sunday night with
better chances south of IL where additional southern stream energy
passes south of our area. Otherwise, a rather quite extended is
expected.

Short Term...Smith
Long Term...07

&&

.AVIATION...
ISSUED 1255 PM CDT Tue Mar 11 2014

VFR conditions this afternoon will quickly deteriorate during this
evening as rain develop, and get even worse overnight with rain
changing to snow. MVFR ceilings and visibilities to develop with
the rain during this evening with IFR to LIFR to develop with the
snow during overnight especially along I-74 airports with vsbys
down to 1/2 mile and ceilings below 500 feet. Snow should diminish
between 12-15Z from west to east with vsbys and ceilings elevating
to MVFR with blowing snow possible Wed morning even after snow ends.
A frontal boundary over central IL just north of I-72 to settle
southward late today and evening with south winds early this
afternoon along I-72 near 10 kts to become ne this evening and
then north during overnight and Wed morning and increase to 15-25
kts and gusts of 25-35 kts overnight into Wed morning. Strong 996
mb low pressure over east central KS to move into southern IL by
06Z/1 am tonight and deepen to 986 mb over eastern WV by 18Z/1 pm
Wed. This winter storm will keep strong north winds Wed even after
the snow diminishes early Wed moring while low clouds linger Wed.

07
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from 10 PM this evening to 1 PM CDT
Wednesday FOR ILZ027>029-036-037-040>057-061.

WINTER STORM WARNING from 10 PM this evening to 1 PM CDT
Wednesday FOR ILZ030-031-038.

&&

$$