Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 032355
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
555 PM CST Tue Mar 3 2015

.SHORT TERM...(Tonight)
ISSUED AT 330 PM CST TUE MAR 3 2015

Freezing rain and sleet developed over western Illinois around
midnight and quickly tracked east over all but extreme southeast
Illinois by 08z/2am. Already seeing the back edge of our second
band of wintry precip entering west central Illinois, so it appears
we will have a brief lull in the freezing rain and sleet. However,
the latest HRRR suggests another band of rain, freezing rain and
sleet will move northeast across our area at or just after dawn
Rainfall rates have not been much with these quick moving bands
of freezing rain/sleet with most areas seeing less than 0.05" per
hour, but certainly enough for some light icing to occur on bridge
decks and overpasses and on lesser traveled roads.

RAP forecast soundings continue to suggest temperatures will rise
above the freezing mark over southeast Illinois by dawn...central
sections of the forecast area by 900 am...and between 10 am and Noon
roughly along and north of the Interstate 74 corridor. By late
morning into the afternoon hours the stronger lift associated with
the low level warm advection/ isentropic ascent shifts off to our
east and southeast with a gradual lowering of POPs warranted from
northwest to southeast. Best 850-700 forcing edges into southeast IL
by mid to late afternoon where our highest POPs will be located.
Guidance temperatures look reasonable for this afternoon with highs
ranging from the upper 30s far north to the upper 40s far southeast.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 330 PM CST TUE MAR 3 2015

The cold front currently passing through the forecast area will
stall out south of the Ohio River Valley early Wednesday as it
becomes parallel to the upper-level flow. A 180+ kt jet streak will
be in our vicinity on the cool side of this front/low level
baroclinic zone for much of the day Wednesday. A very small portion
of our forecast area south of I-70 will be at least nicked by the
good frontogenetical forcing/jet dynamics in this flow regime. With
this in mind it is looking like 2-4 inches of snow will fall late
tonight through Wednesday evening across at least Clay, Richland,
and Lawrence counties. There is some model disagreement on where the
axis of heavier snow will set up, and the snow totals may need to
be boosted a little and pushed further north or decreased and pulled
further south depending on future model runs.

The snow threat in southeast IL diminishes later Wednesday night, as
the current system finally pulls away, and another Arctic high
(hopefully the last of the winter) builds into the entire forecast
area. This high will be accompanied by a couple nights of mainly
single digit lows Wednesday night and Thursday night, and highs
mainly in the teens for Thursday.

Temperatures are still expected to gradually moderate beginning
Friday and continuing into next week. High temperatures may actually
be above normal for a change by early next week, with highs in the
50s possible by next Tuesday. The models do not suggest the passage
of any significant system from Thursday-Tuesday, so predominantly
dry weather looks to be the rule through the period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 555 PM CST TUE MAR 3 2015

Ceilings have been slowly improving over the past couple of hours:
however, latest obs still show IFR conditions at KSPI, KDEC, and
KCMI. Think these sites will climb to MVFR between 01z and 04z.
Satellite imagery shows plenty of cloud cover extending westward
across Iowa, with the nearest clearing across Minnesota and far
northwest Iowa. Based on Rapid Refresh 925mb RH profiles, think
MVFR ceilings will hold firm through much of the night, with
ceilings rising to VFR at KPIA by 11z, then further east to KCMI
by 14z. Even when the lower clouds dissipate, a mid-level cloud
deck at 12000-15000ft will remain as low pressure tracks along a
frontal boundary draped along the Ohio River. Any associated
precip will remain south of the central Illinois terminals,
although overcast conditions will persist through the entire 00z
TAF period. Winds will initially be from the west at around 10kt
this evening, then will become northwesterly with gusts to between
15 and 20kt overnight into Wednesday.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from 6 AM to 6 PM CST Wednesday FOR
ILZ071>073.

&&

$$

SHORT TERM...Onton
LONG TERM...Bak
AVIATION...Barnes





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