Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 310151

Area Forecast Discussion
National Weather Service Lincoln IL
851 PM CDT MON MAY 30 2016

Issued at 850 PM CDT Mon May 30 2016

Isolated showers and thunderstorms over central IL this evening will
continue to dissipate through the late evening with the loss of
surface-based instability. However, a weakening upper level wave
over Missouri continues to move northeastward and could bring a
few more showers overnight to areas generally I-55
have left slight chances in that area overnight.
Otherwise...expecting temperatures to drop from the current mid to
upper 70s to the mid 60s overnight. Winds are highly variable this
evening after numerous convective outflow boundaries have
traversed the area...but should generally become light and
variable or potentially light southeasterly. Only minimal updates
to going forecast needed.


.SHORT TERM...(Tonight)
ISSUED AT 226 PM CDT Mon May 30 2016

Isolated showers and thunderstorms have developed along a weak
frontal boundary near I-72 at mid afternoon and tracking slowly
southeast. The strongest thunderstorm was along the Macon and Shelby
county line where radar estimates 0.25-0.50 inch hail. Scattered to
broken cumulus clouds giving partly to mostly cloudy skies this
afternoon. Another warm afternoon in the mid to upper 80s over CWA
with dewpoints in the mid 50s to lower 60s. A weak short wave
lifting northeast across central IL this afternoon will also help
support isolated convection into early evening. Models overall
developing more qpf over western IL near MS river valley by
overnight while eastern IL stays drier. This qpf ahead of upper
level trof along the KS/MO and OK/AR border that weakens as it
ejects northeast. Weak surface high pressure of 1018 mb over the mid
MS river valley stays near central/southeast IL overnight bringing
light winds tonight. Similar MET/MAV lows in the low to mid 60s
looks good again tonight.

.LONG TERM...(Tuesday through Monday)
ISSUED AT 226 PM CDT Mon May 30 2016

Another warm day is on tap Tuesday across central and southeast
Illinois, with most locations expected to top out in the mid 80s.
Mainly diurnally driven showers/storms are expected during the
afternoon/evening hours, but a stray shower or storm can`t be ruled
out in the morning either. Instability during peak heating will be
modest (around 1000 j/kg of CAPE), and shear will be weak, so don`t
expect any of these storms to be severe.

By later Tuesday night, an upper-level wave (currently centered over
Montana and Alberta) will track east along the U.S./Canada border.
This system will push an associated cold front through the forecast
area on Wednesday. Shower/storm chances will increase across the
forecast area from west to east late Tuesday night, with the highest
rainfall chances seen on Wednesday. Instability will be comparable
or a little stronger than Tuesday, and shear will still be rather
weak despite the passage of the system. The severe storm risk should
remain rather low as a result. If the front were to be slower in
arriving, the instability could be even greater, but do not expect
this to occur given the model consensus and current distance of the
system from the area.

Thursday and Friday are expected to be mostly dry, and somewhat
cooler, in the wake of the midweek system/front. The upper-level
flow will be out of the northwest for the duration of the forecast
period, as troffing develops across eastern North America, supporting
slightly cooler than normal temperatures. A short wave within this
flow is expected to pass through during the weekend, providing our
next chance of showers/storms.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 650 PM CDT Mon May 30 2016

Isolated showers and thunderstorms will continue for the first few
hours of the forecast period before instability diminishes later
in the evening. Have included VCTS at terminals KBMI-KSPI-KCMI
which appear to have a likelihood of thunderstorm activity in the
vicinity based on locations of various outflow boundaries across
the area. Otherwise...VFR conditions expected through the night
with only a slight chance of showers redeveloping late in the
night as a shortwave moves slowly up from Missouri. The potential
for isolated to scattered instability showers and thunderstorms
will return for Tuesday afternoon and have included VCTS in TAFs
starting 17-18Z. Winds generally S-SE less than 10 kts through the
period...although some variable directions in the vicinity of
thunderstorms and outflow boundaries. Some light fog/haze possible
from 09Z-13Z where vsbys could lower to 4-6 miles...although
current guidance doesn`t suggest high enough probabilities for
inclusion in 00Z TAFs.


.ILX Watches/Warnings/Advisories...


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