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Area forecast discussion 
National Weather Service Lincoln Illinois
850 PM CDT sun Aug 28 2016

Update...
issued at 845 PM CDT sun Aug 28 2016

Except for southeast Illinois where a few storms were continuing,
the bulk of the precipitation has ended. The frontal boundary that
was the primary focus for the afternoon storms was still located
over north central Illinois, while the outflow boundary from the
thunderstorm complex to our north this afternoon has shifted south
of Springfield this evening. This may be a focus for additional
widely scattered storms to develop overnight, similar to the past
several nights. A second area of concern is over southeast
Illinois where the hrrr has been consistently suggesting showers
and storms to continue at least several more hours this evening.
Precipitable water values were the highest across the north with
1.9" analyzed on the Storm Prediction Center mesoanalysis. The 00z ilx sounding
continues to show rather weak wind fields aloft so any storm will
be slow moving, with the primary threat being from torrential
rainfall.

Making some adjustments to pops in the southeast counties to take
into account the ongoing convection and the potential it may
continue in that area for a few more hours. Very few changes made
further to the north overnight. We should have the updated zones
out by 900 PM.

&&

Short term...(this evening through monday)
issued at 252 PM CDT sun Aug 28 2016

Slow-moving thunderstorms with locally heavy rainfall continue to
track across north-central Illinois this afternoon, with 1930z/230pm
radar imagery showing most of the activity along and north of a
Galesburg to Minonk line. Will continue to monitor this area for
the next few hours, as training cells could produce localized flash
flooding through sunset. Once evening arrives and daytime
instability begins to wane, the thunderstorms will diminish and come
to an end. Hrrr has been consistently showing the precip fading
away by 03z/10pm and this seems reasonable. Main question tonight
will be whether or not additional convection forms late. While the
hrrr remains dry through dawn Monday, the NAM suggests widely
scattered showers/thunder will re-develop over at least the western
kilx County Warning Area. Following a persistence forecast from the past several
nights, will trend toward the wetter NAM in this case. As a result,
after a lull in the precip late this evening into the first part of
the overnight, have brought slight chance pops back into the picture
toward dawn everywhere west of the I-57 corridor. With synoptic
frontal boundary remaining stalled just north of the area, think
scattered thunderstorms will once again develop everywhere during
the day Monday. High temperatures will reach the middle to upper
80s, with readings around 90 along/south of I-70.

Long term...(monday night through sunday)
issued at 252 PM CDT sun Aug 28 2016

A broad subtropical high pressure ridge aloft will be in place
across the southern and central U.S. By Monday evening with surface
high pressure centered over the eastern Great Lakes. A moist air
mass with 1.75-2.0 inches of precipitable water will be in place
over much of the southern and central U.S. Including central Illinois.
Expect a chance of mainly afternoon and evening thunderstorms
Tuesday with the moist and unstable conditions. Heavy localized
rainfall from slow moving thunderstorms will be the main threat.
Highs will range from 84 in Galesburg to 88 in Lawrenceville.
Lows Monday night and Tuesday night upper 60s to around 70.

The surface high over the eastern Great Lakes...trailing a cold
front moving into the northeast U.S. Tonight and Monday...will keep
a light prevailing east-NE wind across central Illinois through
Tuesday...although it looks that any drier air associated with the
high will not make it as far west as Illinois. By Wednesday...a deep
upper level trough amplifying into the northeast U.S. Will rapidly
push out the high pressure and drive a cold front into central Illinois
from the north bringing much drier air of around 0.5 to 0.75 inch
precipitable water into central Illinois. After a chance of thunderstorms
along the front...the drier air and high pressure building into the
Midwest should bring dry conditions to central Illinois from Wednesday
night through Saturday...along with cooler highs in the upper 70s to
lower 80s, gradually rising through the period. Lows in the upper
50s and lower 60s will be typical. Wednesday's highs expected to
range from near 80 along the I-74 corridor to the mid 80s south of I-
70, although the high will be sensitive to the exact timing of the
front and precipitation that day.

&&

Aviation...(for the 00z tafs through 00z Monday evening)
issued at 600 PM CDT sun Aug 28 2016

A weak frontal boundary/wind shift line to our north was the
focus for showers and thunderstorms to develop this afternoon
with a few of the storms affecting our northern taf sites over
the past hour. The outflow boundary from the complex of storms
to the north has just shifted south of Mason City, Lincoln,
Clinton to near Champaign and continues to drift south. Away
from the storms, VFR conditions prevail and are expected to
continue through the evening hours before another night where
we may see some patchy fog and MVFR cigs develop after 09z.
Late tonight, similar to the past few mornings, widely scattered
showers and storms may redevelop but coverage looks to be limited
enough to leave out of this set of tafs. What fog and or MVFR cigs
develops in the early morning hours should begin to lift by mid
to late morning with another threat for afternoon convection.
Surface winds will once again be a non-factor with light and
variable winds tonight becoming east to southeast at 5 to 10 kts.



&&

Climate...
issued at 252 PM CDT sun Aug 28 2016

As of noon today Springfield has reached the 2nd wettest Summer on
record with 21.43 inches of precipitation since June 1st. The
wettest Summer on record was in 1981 when 24.93 inches fell from
June-August.

&&

Ilx watches/warnings/advisories...
none.
&&

$$

Update...Smith
short term...Barnes
long term...Onton
aviation...Smith
climate...Onton

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