Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 301948
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
248 PM CDT THU JUN 30 2016

.SHORT TERM...(Tonight)
ISSUED AT 248 PM CDT Thu Jun 30 2016

19z/2pm surface analysis shows a cold front extending from central
Wisconsin southwestward to Nebraska.  The airmass ahead of the front
has become moderately unstable, with SBCAPE values of 1500-2500J/kg
across much of Iowa. In addition, a vigorous short-wave trough
digging into the Upper Midwest/Great Lakes is enhancing wind shear,
with 0-6km bulk shear values of 35-40kt.  Thunderstorms are already
developing along the front across northern Iowa, and these will
gradually track/develop southeastward into central Illinois this
evening.  Models have varying depictions of the exact scenario, but
consensus brings a broken line of storms across the northern half of
the KILX CWA between 00z/7pm and 06z/1am.  Based on NAM/HRRR
forecast, will carry likely PoPs during this time frame along/north
of a Jacksonville...to Taylorville...to Paris line.  Further south
where forcing will be weaker and front will be delayed until daytime
instability has waned, will only carry chance PoPs from late evening
through the overnight hours.  Some of the storms could be strong
across west-central Illinois early this evening, with gusty winds
and hail possible, mainly along/west of the Illinois River.  Rain
chances will come to an end from northwest to southeast after
midnight as the cold front settles south of the area by early Friday
morning.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 248 PM CDT Thu Jun 30 2016

Main concern over the next several days revolves around rain chances
through the holiday weekend. A couple model trends have been noted
in the latest runs. First, the chances for steadier rainfall have
been delayed. Guidance is stalling the frontal boundary that comes
through tonight a little further south, and this front also seems to
be having trouble pushing back northward, So, the WAA/isentropic
ascent forced rainfall in the vicinity of the front, ahead of the
main upper-level wave, should mostly stay south of the forecast area
into Saturday night. The main wave is still progged to move through
through the area Sunday into Sunday night, and this period should
see the most widespread rainfall. Rain chances will taper off
considerably Monday, and current model trends still support a mostly
dry forecast for any July 4th fireworks displays. Temperatures will
remain below normal through the holiday weekend with the
clouds/precipitation in the area.

Most of the remainder of the forecast period should be dry, with
temperatures trending back toward normal as upper-level heights
rise. However, a dry forecast is certainly tenuous at best, as the
mean flow is still likely to be zonal with the potential for
disturbances to pass near our vicinity.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1250 PM CDT Thu Jun 30 2016

A few lingering showers will impact KPIA/KBMI for the next couple
of hours, before completely dissipating by mid-afternoon. After
that, attention will turn further W/NW ahead of an approaching
cold front. Latest runs of the HRRR have been suggesting a line
of convection developing ahead of the front across central
Illinois this evening. Based on timing of front and latest HRRR,
have included a 2-hour TEMPO group for thunder at all
terminals....beginning at 02z at KPIA and ending by 06z at KCMI.
Once the front passes, precip chances will come to an end and
winds will veer to the northwest overnight.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Barnes


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