Area Forecast Discussion
Issued by NWS Central Illinois

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579
FXUS63 KILX 280848
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
348 AM CDT THU JUL 28 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 344 AM CDT Thu Jul 28 2016

Our forecast area remains between a couple of frontal boundaries. A
stationary front is lingering across southern IL, with a cold front
approaching from eastern Iowa and SW Wisconsin. The convective
initiation prior to the cold front arriving will be random and more
difficult to pin-point. Steering flow and the mid-levels is weak, so
storm motions have been slow and locally heavy rain has occurred
with any storms that have developed. High resolution models are
pointing toward an increase in storm coverage this afternoon mainly
tied to the arrival of the cold front from the northwest. Prior to
that, storms chances appear higher in our SE counties, due to
proximity to shortwaves moving along the stationary front across
southern IL. Active showers/storms near our western counties appear
poised to drift into our area early this morning. Therefore, have
trended an increase in PoPs today starting in the western and
southern portions of the CWA, then advanced the increasing PoPs east-
northeast this afternoon.

The timing of the cold frontal passage is difficult to discern in
the models, but based on surface wind projections, it looks to reach
I-55 by Noon, and push southeast of our counties by 6 pm. Will start
to decrease PoPs this evening from west to east, with only slight
chance PoPs in all counties after midnight.

Satellite images show we should see a period of sunshine this
morning before convection becomes more widespread and clouds thicken
and increase. We should see enough sun to support high temps
approaching the mid 80s in all areas. Lows tonight should remain on
the mild side, dropping close to minimum dewpoints in the mid to
upper 60s. Light fog will once again be expected late tonight.

&&

.LONG TERM...(Friday through Wednesday)
ISSUED AT 344 AM CDT Thu Jul 28 2016

Weak open wave aloft will keep shower and thunderstorm threat in the
region through Friday/into early Saturday morning, providing some
minimal lift to an already unstable airmass. Once the system moves
to the east a bit, showers will become more widely spread, but
likely linger through Saturday. Less so on Sunday, and more confined
to the southern tier of Illinois. High pressure ridge builds into
the eastern half of the CONUS, although its influence looks somewhat
weak this far west of the ridge axis. Monday  maintaining some
consistency with small disturbance moving into the region with
another round of precip, particularly to the south. Though forecast
for Tuesday had a drying trend previously, still have to concede the
potential mesoscale influences over a warm and moist airmass will
keep the shower and thunderstorm threat in place over a large part
of the Midwest through the forecast period.

Temps trending slightly cooler through the first half of the weekend
with the more northwesterly flow and the precip influence.  850mb
temps not moderating quite as much, and holes/breaks in the cloud
cover for the next couple days could result in some isolated warmer
temps.  After the first half of the weekend, the building heat in the
western half of the CONUS begins to shift, putting another warming
trend in place for Central Illinois for next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1147 PM CDT Wed Jul 27 2016

A few spotty showers/storms have popped up in and around central
Illinois this evening. However, their very slow movement and
disorganized development makes it difficult to forecast potential
terminal impacts much in advance. The better chance for
showers/storms will be from late morning into the afternoon
Thursday as an upper=level wave moves through the area, coupled
with diurnal heating. Otherwise, outside of patchy MVFR fog
overnight, VFR conditions should prevail outside of any storms.
Winds should remain light through the period.


&&

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

$$

SHORT TERM...Shimon
LONG TERM...HJS
AVIATION...Bak



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