Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 290835

Area Forecast Discussion
335 AM CDT Sun Mar 29 2015

.SHORT TERM...(Today)

A shortwave moving into northwest Iowa early this morning will
continue moving rapidly ESE-ward through the morning arriving in
central IL later this morning. Precipitation with this feature
should intensify as it approaches as southerly return flow ahead of
it feeds more moisture into the region. Warm frontal boundary will
be followed closely by a cold frontal boundary, causing temperatures
to increase about 10 degrees from yesterday`s readings by late
afternoon, however cold air behind the system will not be very
pronounced. Precipitation amounts still look to be relatively light,
generally under one tenth of an inch. Southerly winds will be fairly
strong and gusty today, as model soundings showing winds into the
30-40 kt range in the near-surface mixed layer. Expect S-SW winds
15-25 mph with gusts 30-40 mph. Strongest gusts looking to be I-74
northward around noon. An outside chance for brief freezing rain
early in the morning in Knox and Stark counties, but looks like rain
will hold off until a few hours after sunrise, and temperatures
likely to rise above freezing just in time for start of
precipitation. Precipitation will be tapering off from west to east
late in the afternoon as the wave continues moving eastward.


.LONG TERM...(Tonight through Saturday)

Wave moving through the forecast area rather quickly today and the
precipitation should be coming to an end this evening.  Keeping the
slight chances in the east.  Brief dry pd expected for the first
couple days of the work week with daytime highs more seasonable into
the 60s with 850mb temps warming from 4-5C 10-11C by
Wednesday.  Westerly/southwesterly winds helping to bring some of
the heat in from the western ridging.  However, the next system
will be moving on the Pac coast Mon night/Tuesday and making its way
towards the Midwest.  Agreement on this system is not happening yet
between the GFS and the ECMWF.  The GFS is quicker and cleaner with
the development of the sfc low and progression across the region.
00Z ECMWF is starting to look more like the GFS...bringing precip
Wed night through Thursday. GFS stalling the boundary just to the SE
along the Ohio River Valley and putting the southeastern CWA on the
edge of some weak waves moving along the boundary for Thurs night
and Fri. The ECMWF is still a messier solution with the QPF,
stalling the boundary further to the north and keeping the CWA wet
from Wed night through Friday. Trending the forecast to the GFS is
preferred at this point, particularly with the trend of the ECMWF to
the GFS...but the SuperBlend is a little slower to respond.
Onset of precipitation being delayed to later on Wednesday night is
cutting down the potential thunder activity, but still keeping the
mention in for the initial fropa. Still concerned that the temps for
Thursday may be too warm considering the proximity of the cloud
cover/rain potential.  Unless the clearing behind the boundary is
clean and quick early Thursday, the sun will have little chance to
rebound the sfc temps in the wake of the precip.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)

VFR conditions will prevail through the entire 06z TAF period
despite passage of a frontal boundary Sunday evening. Clear skies
initially will give way to increasing high clouds toward dawn. As
the front approaches, a band of mid-level clouds and scattered
light showers will develop across the area Sunday morning.
NAM/Rapid Refresh timing still indicates showers arriving at KPIA
by 14z, then further east to KCMI by around 16z. Front will have
very little moisture to work with and strongest upper dynamics are
expected to stay well to the north across the Upper Midwest, so am
not expecting widespread rainfall. Will therefore maintain just
VCSH at the terminals into the afternoon. Light S/SE winds tonight
will increase markedly, with forecast soundings suggesting gusts
reaching the 25 to 30kt range by Sunday morning. Winds will
gradually veer to S/SW, then will decrease and become NW between
02z and 05z as the front passes.




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