Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 310858
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
358 AM CDT Sun Aug 31 2014

.SHORT TERM...(Today and tonight)
ISSUED AT 358 AM CDT SUN AUG 31 2014

Shortwave trough and jet entrance region that brought banded
convection and some locally heavy precipitation to central IL last
evening has shifted northeastward with shower activity nearly ended
over the ILX CWA. With clearing skies and good radiational cooling,
patchy fog will continue to form overnight, mainly I-55
westward.

Moist conditions with enough instability will remain through the
afternoon today for a few showers and thunderstorms, mainly I-70
southeastward, but a relatively dry day expected. Highs in the mid
80s are expected.

After sunset, convection should end quickly across the CWA with the
loss of surface heating. Late in the night, chances for
thunderstorms will spread back into west central Illinois as another
cold front approaches from the west.

&&

.LONG TERM...(Monday through Saturday)
ISSUED AT 358 AM CDT SUN AUG 31 2014

SPC continues a slight risk (15+%) of severe thunderstorms across
central IL nw of a Flora to Robinson line Monday afternoon/evening
for damaging winds and large hail. This seems reasonable considering
surface to 6 km bulk shear values of 30-40 kts, CAPES of 2-3k J/kg.
Heavy rains also possible with thunderstorms in tropical airmass
ahead of frontal boundary. Short waves and 30-40 kt low level jet
moving into IL river valley later Sunday night into Monday morning
and then spreading into eastern IL Monday afternoon/evening. Upper
level trof over northern Rockies moves east into Midwest
Monday/Monday night and drives a cold front southeast across central
IL Monday night. Continued likely pops across much of area Monday
afternoon into Monday night, though diminishing pops overnight
Monday night nw of IL river. Best chances of showers and
thunderstorms lingers over areas from I-72 south on Tue especially
in the morning. The 5% risk of severe storms Tue is southeast of
Lawrenceville. Quite warm and humid Monday ahead of front with highs
82-88F and dewpoints 70-75F and warmest temps in southeast IL where
rain arrives later.

Frontal boundary to weaken as it moves se into Ohio River valley
Tue/Wed with near zonal upper level flow over the region. Carried
just slight chance of convection during midweek from Tue night
through Thu night. Highs in the low to mid 80s Tue/Wed climb into
mid 80s to around 90F Thu/Fri as dewpoints rise back into the low to
mid 70s with heat indices approaching 100F southern counties Thu/Fri
afternoon. Next frontal boundary press southeast into IL Friday
afternoon into Sat and bringing next best chances of showers and
thunderstorms and cooler temps during next weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1150 PM CDT SAT AUG 30 2014

Tricky aviation forecast for the first several hours of the 06Z
TAF valid time. Despite the loss of diurnal heating, convection
continues to fire along an outflow boundary from previous storms.
At this point, no terminal is immediately threatened by these
storms, though the band, and some associated outflow, is making a
gradual shift to the east. this would threaten at least KBMI
within the next few hours if they persist. Also, further east,
within a deeper moist layer, MVFR cigs have started to break out,
including at KDEC & KCMI. Have a hard time seeing how this will
improve before daybreak as slightly drier air filters in from the
west. Expect condtions to improve to or remain VFR areawide on
Saturday as the more active weather shifts off to the east.

&&

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

$$

SHORT TERM...ONTON
LONG TERM...07
AVIATION...BAK






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