Area Forecast Discussion
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FXUS63 KILX 251755

Area Forecast Discussion
1255 PM CDT Wed Mar 25 2015


In between two sfc lows this morning with plenty of llvl moisture
trapped at the sfc and the stratus not showing many signs of
diminishing just yet. With this trend in mind... have pulled down
todays highs a bit and will send out updates momentarily. Some
echos on radar mosaic out to the west working towards western
CWA...but eroding on approach and not all of the echoes are
reaching the ground. Keeping the pops at slight chance later this


.SHORT TERM...(Today)

08z/3am surface analysis shows a 1010mb low over Peoria, with a warm
front extending southeast into Kentucky. Radar loops show the bulk
of the rain has departed to the northeast, with no more thunder
expected in our counties the rest of the night. The speed of the low
to the northeast indicates that all rain should be out of our
forecast area by 5 am, and possibly a little sooner. Very low clouds
and fog under the low and behind it will overspread central IL for
several hours this morning. Have included a mention of fog for a few
hours early this morning. Forecast soundings show dry air above the
cloud layer, and mixing this morning should provide at least partial
sunshine for the S-SW portions of the area early this afternoon. A
brief clear slot is already poised to move across our counties south
of I-70, with additional clouds projected to arrive behind that
clearing. Overall, it appears that any clearing today will be short
lived as the next wave of moisture is expected to push into western
IL by 00z/7pm. The Rapid Refresh model is not too optimistic about
sunshine, so will trend toward more clouds than clearing across a
majority of the area.

A few light rain showers may develop west of the IL river before the
end of the afternoon, but most areas should remain dry until evening.

The predominance of clouds today will keep most areas a little
cooler, especially in the north. Highs may be limited to the low to
mid-50s toward Galesburg, but a few breaks of sunshine in the south
could push areas S of I-70 into the mid to upper 60s.


.LONG TERM...(Tonight through Tuesday)

A 1007 mb surface low pressure organizing in northeast NM and
southeast CO will eject northeast into the mid MS river valley by
06Z/1 am tonight, and then track up the Ohio river to near the KY/OH
border by dawn Thu and into sw PA by noon Thu. 00Z forecast models
have trended a bit further south with low pressure track and SPC has
shifted slight risk south of IL into southern MO tonight and even
marginal risk is south of highway 50. HPC still has a slight chance
of excessive rains over southeast IL counties tonight and will
continue the Special Weather Statement for areas along and southeast
of I-70 tonight to address rises on rivers/streams. Have 1-1.5
inches of rain tonight over southeast of I-70 with highest amounts
overnight and near Lawrenceville. This is below flash flood guidance
values around 2 inches per hour and 2.5-3 inches per 6 hours. Lows
tonight range from mid 30s over IL River valley where lower rain
chances will be, to 40-45F in southeast IL from I-70 southeast.

Continued chances of rain showers over eastern IL Thu morning with up
to another tenth inch near the Wabash river. Then rain shifts east
of IL by midday Thu with surface low pressure moving into New
England by sunset Thu. Clouds to break up Thu afternoon with skies
becoming partly sunny especially sw counties. NW breezes will usher
in colder air with highs Thu in the mid to upper 40s. Strong upper
level trof digging into the Midwest Thu continues over Ohio river
valley Fri with another chilly day across IL with even colder highs
in the upper 30s and lower 40s with coolest readings ne counties.
Could be a few light snow showers or flurries Thu night and Fri morning
northeast of I-74 and near the IN border.

1030 mb Canadian high pressure settles into the Great Lakes region
Saturday and continues chilly weather over central/se IL with highs
in the lower 40s after lows Fri night in the lower 20s as clouds and
winds decrease with high pressure settling near IL.

A strong surface low and upper level trof moves east into Lake
Superior by sunset Sunday and bring isolated light rain showers to
central IL on Sunday and possibly lingering in southeast IL Sunday
evening. Better chances of precipitation will be north over the
Great Lakes region closer to low pressure system. Milder highs in
the 50s Sunday, mid 50s to around 60F Monday and low to mid 60s
Tue/Wed. This warmup due to upper level flow becoming more zonal
during 1st half of next week as strong upper level trof pulls ne
across eastern Canada. Next chance of rain showers appears to arrive
Tue night and Wed of next week with surface low and upper level trof
moving into the Midwest with ECMWF model much further north passing
over the northern Great Lakes next Wed while GFS is over mid MS
river valley.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Very complicated forecast as terminals are between sfc lows and
the models are not handling the llvl moisture well. Persistent
stratus deck not mixing out as advertised, though the SWrn edge is
finally starting to erode. Forecast problem is how much will erode
before sunset...and before the developing rain/storms get into the
area. SPI and DEC are the more likely to break out of MVFR, if
only briefly, later this afternoon...but have kept the forecast
MVFR for now. W/NWrly winds through the pd...getting a little
after 06z, but not quite mentionable in most circumstances. IFR
and rain hanging on a little bit longer in DEC and CMI. Keeping
the TS mention to DEC and SPI for this afternoon with the further
south terminals and more likely to get a decent convective
component in the early evening. Clearing times on this weather for
tomorrow morning...confidence is not high. Remains of the TAFS
beyond 08-10Z highly based on models clearing out the skies in the
wake of the overnight precipitation.




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