Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 022013

Area Forecast Discussion
National Weather Service Lincoln IL
313 PM CDT MON MAY 2 2016

.SHORT TERM...(Tonight)
ISSUED AT 313 PM CDT Mon May 2 2016

Main short-term forecast concern will be timing of potential
clearing tonight.  While the main surface boundary has dropped south
of the Ohio River, a trailing upper trough extending from Wisconsin
southwestward to Kansas has provided enough synoptic lift to produce
widespread overcast conditions today.  Visible satellite loops show
the low cloud cover pivoting southward on the back side of a subtle
upper wave currently over central Illinois.  As this feature tracks
further eastward, think clouds will gradually dissipate/clear the
Illinois River Valley this evening.  Due to trajectory of cloud
cover and relatively light flow, clouds will likely hold throughout
the entire night along/east of the I-57 corridor.  May see a few
isolated light showers this evening: however, most locations will
remain dry.  Overnight low temperatures will range from the lower
40s northwest of the Illinois River where clearing will occur around 50 degrees far southeast around Robinson and


.LONG TERM...(Tuesday through Monday)
ISSUED AT 313 PM CDT Mon May 2 2016

Cyclonic flow will continue over the area through Wed. A lull in the
pcpn chances will be seen Tuesday as CWA will be in between troughs
rotating through the area. However, will still keep a slight chance
of showers in the east and southeast Tuesday due to a 500mb trough
moving south through the area...just without any surface reflection.
A bigger and more dominate trough will drop into the area Tue night
through Wed. Pcpn will start in the north Tue evening and then move
south through the area the remainder of the night and then in the
east on Wed. Isolated thunder will also be possible given greater
lapse rates due to cold 500mb temps moving over the area in
association with the upper level low. The pcpn will move off to the
east Wed night, which will allow high pressure to build into the
region with dry weather and slowly warming temps for Thur through
Fri. This surface high pressure ridge will get flattened by the end
of the week as another frontal system drops into the area for the
weekend. With warm and moist air being advected into the area Friday
and Saturday, will be plenty of instability for thunderstorms along
and ahead of the front Sat night through Monday. The front does seem
to hang around the area through the weekend since there will be an
upper level low just east of the US and another one over the
southwest US.

Temps will remain below normal most of the week, but begin to warm
back up as the high pressure that builds in Thursday moves off to
the east, bringing back southerly winds. The warmer temps will
continue through the weekend and into the beginning of next week.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1253 PM CDT Mon May 2 2016

MVFR ceilings prevail at the central Illinois terminals early this
afternoon. Latest water vapor imagery shows a weak short-wave
trough over west-central Illinois between KSTL and KUIN. As this
feature tracks eastward, the low cloud cover will tend to pivot
southward in its wake, resulting in rising ceilings and eventually
a clearing trend from west to east later this afternoon and
evening. HRRR forecast suggests ceilings improving to VFR at KPIA
as early as 20z...but holding off until 03-04z further southeast
at KCMI/KDEC. Think skies will clear along/west of I-55 during the
evening, then further east late tonight toward dawn Tuesday. After
that, forecast soundings indicate steep lapse rates developing on
Tuesday, which should lead to at least SCT diurnal clouds at
around 5000ft. Winds will be light through the entire
period...initially from the northeast this afternoon, shifting to
the northwest by Tuesday morning.


.ILX Watches/Warnings/Advisories...


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