Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241944

Area Forecast Discussion
National Weather Service Lincoln IL
244 PM CDT Tue Apr 24 2018

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 235 PM CDT Tue Apr 24 2018

The upper low that brought the light rain and low clouds to the
area today will get a nudge to the southeast tonight as another
upper level wave to our northwest crosses the Great Lakes late
tonight. In addition, a secondary upper level disturbance will
track across the Central and southern Plains tonight bringing
rain chances to areas to our west and south into Wednesday

One concern for tonight will be with the potential for some
patchy fog thanks to the light rain that occurred over parts
of the area. However, forecast models suggest we may have
just enough wind later tonight to prevent any widespread fog
development. Lows tonight will drop into the mid to upper
40s. With most of the weather to our north and southwest on
Wednesday, we should see some decent weather across our area
with afternoon temperatures rising into the low to mid 60s.


.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 235 PM CDT Tue Apr 24 2018

Guidance for Wednesday night into Thursday morning continues
to keep early morning lows in the 35 to 40 degree range. Will
have to keep an eye on future runs to see if the 2 meter temps
edge down a few degrees bringing a frost threat to parts of our
area. The next significant wave and frontal boundary will approach
our area Thursday night into Friday morning with little in the way
for support for any significant rainfall. POPs will only by in the
slight chance category for Thursday night into mainly Friday morning.
The upper trof over the Great Lakes will slowly shift off to the
east late Friday and for the start of the weekend gradually bringing
in warmer air to the Midwest. A fairly significant pattern change
taking shape for late in the weekend and into most of next week
with a trof setting up over the western U.S. while ridging builds
across the southeast part of the country. This should result in
warm temperatures across the forecast area for most of next week
with the latest guidance suggesting highs around 80 by Monday and
into the lower 80s for Tuesday and beyond.

Models continue to show some differences with respect to how quickly
the trof or a portion of the trof shifts east into the Midwest
bringing a front and shower and thunderstorm activity east into
our area. The ECMWF has made a significant change from the 00z run
in being much less progressive as a rather strong southeastern
ridge holds any frontal activity/showers well to our west through
Thursday. The 12z GFS has been much more consistent from its previous
run with a more amplified and slower solution with respect to the
western U.S. trof. Unfortunately, the model initialization today
included the data from the 00z ECMWF, thus POPs are in the grids
already by Tuesday afternoon across the west and over most of the
area Tuesday night. Feel that is too quick based the developing
upper pattern over the lower 48, but we have plenty of time to
work out the differences over the next several days.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1230 PM CDT Tue Apr 24 2018

Satellite data and the latest surface observations indicate the
backedge of the lower cloud deck is roughly along and east of
I-55. The MVFR cigs will prevail over DEC and CMI the longest
this afternoon with areas along and west of I-55 seeing mainly
VFR conditions. Tonight, the main forecast concern will be with
the potential for some patchy fog, although models continue to
suggest we may see the wind hold up enough to prevent much in
the way of any significant vsby issues. For now, will limit any
vsbys to 5 mi in fog late tonight. Surface winds will be northerly
this afternoon at 10 to 15 kts with a few gusts near 20 kts at
times, especially across the west with more sunshine.  Will keep
winds mainly from a northerly direction tonight into Wed. with
speeds around 10 kts.




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