Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 241554
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1054 AM CDT WED AUG 24 2016

.UPDATE...
Issued at 1049 AM CDT Wed Aug 24 2016

Weak trof ahead of approaching low this morning and a weak wave
developing showers and thunderstorms for the morning in Central
Illinois. Currently a break in the precip as the wave pulls off to
the NE and the next round still well back over central MO. Risk
for showers and thunderstorms will return later this afternoon,
and increase into the evening hours and overnight. Some minor
adjustments to the forecast this morning, but overall, the
forecast trends are doing well.

&&

.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 12Z TAFS through 12Z Thursday morning)
Issued at 650 AM CDT Wed Aug 24 2016

Line of storms moving through the area now will effect BMI and DEC
at issuance time, while CMI will get effected in about an hour.
Radar and satellite loops show some light scattered pcpn behind
this line and all sites could still something couple of hours
after this line. MVFR and IFR conditions will occur when the
storms move over the sites. Then there should be a break in the
precip til late this afternoon through early this evening with VFR
conditions. Outflow boundary left over from current storms will
become the focus for the next round of storms. Will have VCTS for
all sites in there for now but could have MVFR conditions as
storms move over the sites. As timing and location becomes more
apparent later, expect forecast to be adjusted to reflect that.
Second round of precip looks to end around midnight tonight. Winds
will be southerly through the period with speeds of 10-15kts
during the day and then decreasing for this evening.


&&

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

$$

UPDATE...HJS
SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Auten


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