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Area forecast discussion 
National Weather Service Lincoln Illinois
551 PM CDT Monday Jul 6 2015

Short term...(tonight)
issued at 307 PM CDT Monday Jul 6 2015

Isolated showers and thunderstorms were developing during past hour
along outflow boundary east of the Illinois River from mesoscale convective system over Iowa from
north of Lincoln to east of Ottawa. Have stronger convection with
heavy rains around St Louis metropolitan while more widespread
showers/thunderstorms over Iowa...WI...northern Illinois and northwest MO. This
convection in a very unstable airmass with convective available potential energy 2-4 j/kg over
central/southeast Illinois (3-4k j/kg west of I-57 at 19z). Bulk shear is weak 20
kts or less over County Warning Area so organized severe weather . Cold front was
extending from 1007 mb surface low pressure over northwest WI with cold
front extending SW through central IA/KS. Isolated to scattered showers
and thunderstorms to continue to develop during rest of this
afternoon and early evening especially from I-57 west. Cold front to
push southeast toward I-55 by 12z/Tuesday with increasing chances of showers
and thunderstorms from northwest to southeast during the evening over central Illinois
and into southeast Illinois later tonight into Tuesday. Storm Prediction Center has slight risk of
severe storms northwest of I-55 late this afternoon and evening for
damaging wind gusts along with hail. Heavy rains and frequent
lightning may also occur with some of these thunderstorms. Lows
tonight range from middle 60s northwest of the Illinois River to the lower 70s southeast of
I-55 which stays in warm sector through tonight.

Long term...(tuesday through monday)
issued at 307 PM CDT Monday Jul 6 2015

Front that is moving into the area tonight will be sitting over
southeastern part of the state Tuesday. This will be the focus for
more thunderstorms for Tuesday and Tuesday night...that should
effect mostly the southern half of the state...or the southern part
of the County Warning Area. Then models are similar in forecasting another wave
lifting out of the Southern Plains along the front and across
central Illinois Wednesday through Wednesday night...and then moving east of the
area early Thursday. Thunderstorms with moderate rain can be
expected tomorrow and tomorrow night...but then heavy rainfall will
be possible when the surface low pressure area moves across the area for
Wednesday and Wednesday night. Flash Flood Watch may be necessary for this time
period but think another look tonight and/or tomorrow is
warranted...after seeing what the convection does with the
front/ouflow boundary tomorrow and tomorrow night.

Unfortunately the boundary remains around or near the area the
rest of the week...which will keep a chance or likely precipitation in the
area through Friday night. The front should be lifting Friday night as
well...which will push the chance of precipitation north of the I-74 Friday
night through Sunday. Then models bring another weather system
across Illinois with more precipitation for Sunday night and Monday.

After this front moves through the area...temperatures will cool a little.
But then they will warm again for the weekend and into next week.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 545 PM CDT Monday Jul 6 2015

Main concern this forecast period will be coverage of thunderstorms and rain across
the forecast area and affect on cigs/vsbys. Cold front well out to
our west early this evening will take until tomorrow morning
before it makes it across the area. Most models suggest a band of
showers and storms will accompany the front slowly east and
southeast tonight into Tuesday morning. Initially...we should see
VFR conditions but as the precipitation tracks across the area...low VFR
to brief MVFR ceilings can be expected. Post frontal MVFR ceilings are
expected generally in the time range between 08z and 12z from
west to east. Then as winds shift from a south to southwest
direction into the northeast by morning...most of the forecast
models indicate at least MVFR ceilings will hang around into the
afternoon hours with a few models suggesting some periodic
IFR ceilings as well as the northeast to east flow builds in during
the day. Wind speeds tonight will be at 8 to 13 kts from the
south to southwest and then northeast at 10 to 15 kts during
the day on Tuesday.


Ilx watches/warnings/advisories...


Short term...07
long term...auten

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