Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 301955
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
255 PM CDT Thu Mar 30 2017

.SHORT TERM...(This evening through Friday)
ISSUED AT 250 PM CDT Thu Mar 30 2017

Strong to severe convection currently ongoing along a Rushville...to
Springfield...to just west of Effingham line will continue to track
northeastward across the area late this afternoon into the early
evening.  Based on radar timing tools and the latest HRRR output, it
appears the storms will exit the KILX CWA into west-central Indiana
by 01z/8pm.  Have therefore held on to categorical PoPs for thunder
across the far E/NE around Champaign and Paris into the early
evening.  Once these storms exit, additional showers will develop
within the deformation zone of a departing low.  Models have been
consistently showing this precipitation breaking out across the
Illinois River Valley this evening...then slowly shifting eastward
overnight.  With the primary instability axis shifting well to the
east into the Ohio River Valley, do not think any widespread thunder
will occur with the precip on the back side of the low.  Have
therefore gone with likely PoPs for showers across the west this
evening...then everywhere except locations near the Indiana border
overnight.  Temperatures will cool on the back side of the
low...with overnight lows ranging from the upper 30s far north
around Galesburg...to the upper 40s south of I-70.  Deformation zone
showers will persist across the area into Friday morning before
gradually dissipating and coming to an end by midday.  Despite the
end of the precip, skies will remain overcast through the entire
day.  Clouds and brisk northwesterly winds will keep high
temperatures below normal for this time of year in the upper 40s and
lower 50s.

&&

.LONG TERM...(Friday night through Thursday)
ISSUED AT 250 PM CDT Thu Mar 30 2017

An active weather pattern to hold over the Midwest for the next
week as a series of upper level waves track into the Rockies and out
into the Plains, eventually affecting our area with showers about
every 2 to 3 days. The next system to affect us will be coming along
on Sunday and Monday, followed by a rather vigorous upper wave by
late Tuesday or Wednesday of next week bringing another chance
for showers. Models seem to have latched on to Wednesday`s system as
the one that may bring down some rather chilly air for the middle
and latter portion of next week as a large trof deepens in over the
Great Lakes. Until that happens, other than a brief cool down in the
wake of these upper waves, our temperatures are expected to average
above normal as we head into the middle portion of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1259 PM CDT Thu Mar 30 2017

Main aviation forecast concern will be timing line of convection
through central Illinois this afternoon. Latest radar shows storms
just east of the Mississippi River from near Quincy to east of St.
Louis. Based on radar trends and latest HRRR forecast, have
included a TEMPO group for thunder at all terminals except KPIA
this afternoon. The storms will reach KSPI between 19z and
21z...then further northeast to KCMI between 21z and 23z. Once the
storms pass, the threat for additional convection will end by
early evening. As winds veer to the W/NW behind the departing
system, IFR clouds poised to the northwest across Iowa/northwest
Illinois will spill into the area tonight through Friday morning.
Based on Rapid Refresh forecast soundings have spread IFR clouds
into KSPI by 02z...then further east to KCMI by 07z. It appears
KPIA will remain IFR through the entire 18z TAF period.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Barnes


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