Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KILX 270454

Area Forecast Discussion
National Weather Service Lincoln IL
1154 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 06Z TAFS through 06Z Friday night)
Issued at 1155 PM CDT Thu May 26 2016

As has been the situation lately, the short range models are
having a hard time with the developing convective situation in
central IL for tonight. The HRRR is the closest, but it has been
all over the place with various timing scenarios for the overnight
hours. The shorter ranges of the TAFs are based on persistence of
a north-northeastward moving shortwave which is combining with the
remnants of a decaying MCS from Missouri. These features will
spread t-storms into the central and eastern IL TAF sites between
06z-09z. Ceilings/visibility may briefly dip into the MVFR
category with the heavier rain, but overall VFR conditions should
prevail overnight.

Lingering showers can be expected, in the wake of the initial
t-storms, into mid-morning. After a brief break in the showers
from mid-morning into early afternoon will re-introduce VCTS in
the TAFs. There is too much uncertainty as to the exact timing and
extent of the convective potential for later Friday, so will stick
with diurnal VCTS with plenty of low level moisture/instability.


.ILX Watches/Warnings/Advisories...


AVIATION...Miller is the U.S. government's official web portal to all federal, state and local government web resources and services.