Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 240848

Area Forecast Discussion
National Weather Service Lincoln IL
348 AM CDT WED AUG 24 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 347 AM CDT Wed Aug 24 2016

Showers and storms have already developed ahead of the frontal
boundary that is still out west over the plains. Based on HiRes
model data, current precip is associated with an initial wave ahead
of the front and models/HRRR/NAM-WRF show this first wave of precip
moving through this morning and then there should be a lull in the
precip late morning and into the afternoon. So will be starting out
with likely pops in the morning and then lowering to chance in the
late morning through early afternoon. An outflow boundary and
possible MCV could be left over sitting over parts of central IL for
this afternoon and this will then become the focus for additional
showers and storms to develop over the are for tonight. Highest pops
will be expected across areas along and north of I-72 during the
evening and then lifting a little northward for overnight. Locally
heavy rainfall is possible as training of storms could be possible.
However, 3hr flash flooding guidance values seem high enough that it
may not occur; but this will need to be monitored depending on what
happens this morning with ongoing pcpn. So, no flash flood watch at
this time.

Temps should be warmer today with above normal expected over the
southern half of the area. Overnight lows around 70 looks like a
good forecast again tonight.


.LONG TERM...(Thursday through Tuesday)
ISSUED AT 347 AM CDT Wed Aug 24 2016

Latest model suite continues to largely bring the front through on
Friday on a rather slow pace, courtesy of a blocking upper high over
the southeast U.S.  As such, will keep the southeast CWA dry until
Thursday afternoon, with the main focus for showers and
thunderstorms closer to the frontal boundary in central and northern
Illinois. With this ridge to the south, moisture flow from the Gulf
will be impeded, so the precipitation should generally fade off with
loss of daytime heating. Have maintained some slight chance PoP`s
Thursday evening across areas south of I-72, though.

Short period of quiet weather expected on Friday as high pressure
drifts over northern Illinois. Shortwave progged to dig southward
across the Rockies late in the week will track into the Plains on
Saturday, with the strongest energy riding over top of the upper
ridge into the northern Great Lakes. Despite this, rain chances will
ramp up late Friday night into Saturday morning as a warm front
pushes through the area. The GFS and ECMWF models favor some sort of
drier weather across at least the eastern CWA by afternoon, with a
general trend toward higher PoP`s further north as the wave passes.
Next week, trends become murkier due to potential tropical activity
across the northern Gulf Coast region around mid week. For Sunday-
Tuesday, more of a diurnal nature of showers/storms is progged,
although the ECMWF is dry for us a good part of the time with high
pressure centered over Lake Michigan. Generally will limit PoP`s to
around 30% during the period.

Temperature-wise, a mainly warm and humid period is on tap, with the
exception of some slightly cooler air Friday behind the front.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1115 PM CDT Tue Aug 23 2016

Moisture continues to increase in the low levels of the atmosphere
ahead of a warm front, which was located over north central Iowa
southeast into far western Illinois as of 04z. It still appears
the coverage of showers and thunderstorms will increase overnight
as strong low level moisture advection aided by a 40 kt low level
jet shifts into central Illinois after 08z. If storms to increase
in coverage as expected, we should see some tempo MVFR and local
IFR cigs in some of the more intense storms during the early
morning hours. After 15z, we will see a lull in the shower and
thunderstorm activity thru most of the afternoon before another
round of convection forms to our southwest late tomorrow afternoon
and shifts into the forecast area overnight. Any MVFR or brief IFR
cigs will improve to sct-bkn cumulus with bases in the 3500-4500
foot range during the afternoon. South winds tonight will range
from 8 to 13 kts, and a south to southwest wind is expected on
Wednesday at 10 to 15 kts.


.ILX Watches/Warnings/Advisories...


LONG TERM...Geelhart
AVIATION...Smith is the U.S. government's official web portal to all federal, state and local government web resources and services.