Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 270156

Area Forecast Discussion
National Weather Service Lincoln IL
856 PM CDT THU MAY 26 2016

Issued at 855 PM CDT Thu May 26 2016

Made a few changes to the forecast for tonight, mainly with
regards to the timing of the showers/t-storms. Many of the short
range and convective allowing models have been pushing back the
advancement of the MCS from MO/eastern KS, although it appears
that some convective elements in central MO on radar and water
vapor satellite loops are finally making slow eastward progress.

In addition, t-storms that have developed in response to a
shortwave moving out of the Ozarks, with an old outflow boundary
as its low level focus, extrapolates into central IL between
1 and 4 am. Thus, will go with chance PoPs for tonight, increasing
to likely around 4 am and later in central IL. Will continue to
hold off on likely PoPs in parts of eastern/southeast IL until


.SHORT TERM...(Tonight)
ISSUED AT 259 PM CDT Thu May 26 2016

One MCS with its showers and thunderstorms has passed southeast of
our CWA by mid afternoon, mainly along and south of I-64. A new MCS
with showers/thunderstorms was over east KS, northwest MO, southeast
NE and far sw Iowa. This convection (some thunderstorms severe) is
developing ahead of 1002 mb low pressure in far southeast CO with
its frontal boundary extending northeast across central KS and nw
Iowa. HRRR takes this convection ENE across MO toward the MS river
by 06Z/1 am and across the IL river valley and approaching highway
51 by 09Z/4 am as another shortwave ejects northeast across central
IL overnight. Isolated showers and thunderstorms possible into this
evening over CWA then increasing chances of showers/thunderstorms
from west to east during overnight. SPC day1 outlook continues a
marginal risk of severe storms over much of IL tonight while slight
chance is west of Quincy. Moist dewpoints in the mid to upper 60s
this afternoon over central and southeast IL and most areas will see
lows in the upper 60s overnight.

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CDT Thu May 26 2016

The weather across central and southeast Illinois will remain
summer-like, with warm/humid conditions and periodic chances of
showers/thunderstorms. Daytime highs through the period are expected
to be in the 80s, with nighttime lows in the 60s.

The main forecast problem is trying to pin-point favored wet or dry
periods in this unsettled weather pattern. The best chances for
showers/storms over the next week appears to be Friday into early
Sunday as remnants of the upper-level low, currently centered over
the Four Corners region, eject toward the region. The severe weather
threat with this system does not appear very high. While diurnal
instability will be fairly high at times, shear profiles are not
expected to be impressive.

Behind this wave, a relative lull in the storm threat is expected
later Sunday into at least Monday. Then, another wave will boost
chances again Wednesday into Thursday.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 700 PM CDT Thu May 26 2016

Overall, VFR conditions are expected at central and eastern IL TAF
sites, except in the vicinity of showers/t-storms. The challenge
is timing the convection into the area late tonight and into
Friday morning, and then where any convection may redevelop Friday

Mesoscale complexes from KS through southern IA into MO are
making very little eastward progress just before 00z. The forcing
associated with these complexes would tend to keep them to our
west early tonight. Each run of the HRRR and RUC are slowing down
the eastward progressing of the remnants of these storms. This
trend was followed for the latest TAFs with the highest
probability of TSRA and MVFR vsby toward daybreak.

Similar to this past morning, will keep the potential for showers
in the TAFs through the morning with sky/vsby generally in the VFR
category. With lingering clouds/boundaries from the morning
convection, timing the redevelopment in the afternoon is tricky at
best. The best upper support will be well to our west, but plenty
of moisture and gradually increasing instability will lead to
scattered convection Friday afternoon.


.ILX Watches/Warnings/Advisories...


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