Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 282340
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
540 PM CST Wed Jan 28 2015

.SHORT TERM...(Tonight)
ISSUED AT 329 PM CST WED JAN 28 2015

A low pressure system currently centered over western Iowa will
track eastward across northern Illinois from around midnight to 6
a.m. tonight. As it does so, a warm frontal boundary followed by a
cold front will push across central Illinois in quick succession.
The warm front will cause temperatures to remain steady or even rise
slightly through much of the night, with primarily upper 30s and
lower 40s expected, followed by little increase in temperatures
after sunrise as the cold front pushes east across the area. This
system will be relatively moisture starved, so precipitation amounts
are expected to be very light. A potent surface pressure gradient
will be present with this system, keeping breezy winds going through
the night in the neighborhood of 15 to 20 mph with some higher
gusts. Winds will gradually turn from SSE this afternoon to SSW
overnight, shifting abruptly to northwest after the cold frontal
passage.

&&

.LONG TERM...(Thursday through Wednesday)
ISSUED AT 329 PM CST WED JAN 28 2015

Main concern today is the system over the weekend.
Morning upper air shows weak wave to move through tonight. Then
continued general northwest flow aloft as a cutoff low in the
southwest begins to drift to the east. A piece of shortwave energy
comes out from the southwest on Saturday and develops overrunning
pcpn Saturday night, as another wave in the northwest flow tracks to
the southeast into the area for Sunday. The result is a prolonged
period of light lift over the area Saturday night into Sunday
evening, which will produce light pcpn. Temperatures will be cold
enough for all over cwa but the far southeast to result in all snow
most of the period. At this time, lift seems to be light and just
the prolonged period from the 2 systems causing the pcpn. Will still
have to watch it as periods near to see if lift increases and thus
the resultant amounts. Kept amounts similar in the grids as previous
run at this time.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 540 PM CST WED JAN 28 2015

Low pressure currently centered over western Iowa will track
across north-central Illinois tonight, then into Michigan by
Thursday morning. A tight pressure gradient ahead of the low will
continue to provide gusty southeasterly winds through the evening
hours. Winds will gradually veer to the S/SW after midnight,
before veering sharply to the northwest after FROPA between 12z
and 15z Thu. Forecast soundings remain quite dry, although models
are hinting at perhaps a few light showers near the low track, so
have included VCSH at the I-74 terminals Thursday morning. VFR
conditions will prevail until the front passes and winds become
northwesterly, at which time MVFR ceilings currently over the
Dakotas will spill southeastward into the area. Based primarily on
HRRR timing, have introduced MVFR ceilings at KPIA by 10z, then
further east to KCMI by 13z. Once the low clouds arrive, they will
stick around through Thursday afternoon. Winds will be quite
strong as well, with northwesterly gusts in the 25 to 30kt range.

&&

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

$$

SHORT TERM...Onton
LONG TERM...Goetsch
AVIATION...Barnes





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