Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 031644
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1044 AM CST Tue Mar 3 2015

.UPDATE...
ISSUED AT 1044 AM CST TUE MAR 3 2015

Temperatures have risen above 32 degrees at all sites with an
immediate threat for precipitation this morning, with all sites
expected above freezing in the next hour, therefore the winter
weather advisory has been allowed to expire. Temperatures expected
to continue to rise to the upper 30s to mid 40s this afternoon as
central Illinois remains in the warm sector of the current system.
Winds breezy S-SW 10-20 mph with dewpoints well into the 30s will
help melt the light ice accumulations off. Scattered light showers
continue to stream into the area from the southwest and this will
continue until after a cold front moves in from the northwest
later this afternoon and evening.

&&

.SHORT TERM...(Today)
ISSUED AT 244 AM 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...(Tonight through Monday)
ISSUED AT 244 AM CST TUE MAR 3 2015

Current system will not fully clear our area until Thursday, as the
trailing end of the cold front becomes parallel to the upper flow
over the Ohio Valley. Most of the evening models keep the threat for
precipitation from about I-70 southward, although the NAM has a
secondary surge on Wednesday afternoon all the way up to about I-72.
Leaning more toward the ECMWF/GFS blend for PoP`s tonight and
Wednesday. Lingering precip north of I-70 should end this evening,
but kept higher PoP`s all night into Wednesday. This evening, most
areas will see the precipitation switch briefly to snow before
ending, with little accumulation. While the transition to snow south
of I-70 occurs late tonight, temperatures will be supportive of all
snow through Wednesday. Greatest snow amounts expected near the Ohio
Valley, but currently think that 1 to 3 inches in southeast Illinois
is likely. Light snow will linger into Wednesday night before ending
late.

The other feature of note is what hopefully will be the last Arctic
blast of the winter. Digging upper trough currently coming into
Manitoba will spread a chunk of unseasonably cold air over much of
the Midwest Wednesday and Thursday, with 850 mb temperatures down
into the -18C range by Thursday morning. Highs both days will
struggle to get out of the teens in some areas -- normal highs are
well into the 40s by now -- and lows Thursday morning should be a
few degrees either side of zero. Current indications are that a wind
chill advisory would be needed across the northern CWA Wednesday
night and early Thursday, as the system to our south keeps the winds
up and slows the arrival of high pressure.

Heading into the weekend and early next week, 40s should become more
widespread, and the latest 8-14 day outlook introduces a foreign
concept called "above normal temperatures".

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 500 AM CST TUE MAR 3 2015

MVFR cigs expected to deteriorate to IFR/LIFR this morning as the
freezing rain/drizzle continues. We expect a change over to light
rain at SPI between 14z-16z, CMI between 15z-17z and BMI and PIA
between 17z-18z. IFR to LIFR cigs will continue this afternoon
along with some light rain at times with short term models
suggesting a slight improvement to MVFR cigs after 21z as drier
air works east into the region. However, will continue with MVFR
cigs thru at least 02z this evening. Surface winds at all sites
will become south and increase to between 12 and 17 kts by 16z
with gusts in the 20-23kt range into the afternoon hours. We will
see the direction begin to veer more into the southwest and west
as a cold front approaches the area this afternoon and then into
the northwest at 10 to 15 kts just after 00z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Onton
SHORT TERM...Smith
LONG TERM...Geelhart
AVIATION...Smith






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