Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 220210

Area Forecast Discussion
National Weather Service Lincoln IL
910 PM CDT Wed Jun 21 2017

Issued at 910 PM CDT Wed Jun 21 2017

A shortwave will continue to trigger showers and isolated storms
across our northern counties the rest of the evening, and the
HRRR is finally catching up with that scenario. Many other high
res models are missing the boat with this wave. The stabilizing
boundary layer has already limited cloud to ground lighting, as
well as in-cloud lightning. However, a few strikes could still
occur this evening, so isolated thunder was left in the forecast.

Have increased our overnight clouds, especially in the south from
Tropical Storm Cindy and in the north from ongoing convection. The
clouds will increase lows a few degrees, and have adjusted up
slightly in the south and north.

Updates this evening have been to PoP/Wx, Sky, and temps. The
latest forecast info is already available.


.SHORT TERM...(This evening through Thursday)
ISSUED AT 240 PM CDT Wed Jun 21 2017

Weak convection today and associated cooling has kept the warm
front from redeveloping north of the forecast area as originally
expected. Isolated storms may still be possible near the boundary
that extends from near Springfield east to near Paris through the
remainder of the afternoon. However, ridging will once again build
into the area overnight and the delayed translation of the warm
front into Wisconsin is likely to occur late tonight or Thursday
morning as strong insolation should assist in mixing. Temps should
be higher across central Illinois compared to today due to the sun
early on. Low-level moisture will increase as southerly flow
becomes more prominent during the day but with 700mb temps
progged to climb 4-5C in 24 hours and moving well above 10C
capping of significant convection seems likely. We will keep any
chc pops confined to near I-70 and southeastward.

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 240 PM CDT Wed Jun 21 2017

Model suite from 12z continues to push frontal system southeast
into the forecast area late Thursday Night in conjunction with a
short wave expected to move across the upper Mississippi Valley.
The approach of the front should correspond with the period of best
moisture advection from the remnants of Cindy and may lead to a
brief period of heavier rain along and behind the front across
central Illinois between midnight and Friday morning. Still some
uncertianty of the evolution of the front and its interaction with
the tropical moisture particularly across southeast Illinois
Friday. Will retain likely PoPs southeast of I-57 with an
diminishing trend from northwest to southeast as the front sags
southeast and remnant circulation center moves far enough east to
cut off overrunning potential.

Clouds and cold advection behind the front should keep temps
noticeably cooler Friday. The cool weather should persist into
early next week as the area remains in cool northwest flow and 850
mb temps drop into the single digits through Monday prior to
recovering by midweek. Several weak shortwaves will move through
the northwest flow bringing periodic clouds and maybe a slight
chance of a shower, but overall dry weather should dominate the
are from the weekend into midweek.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 646 PM CDT Wed Jun 21 2017

A weak shortwave over eastern Iowa appears poised to push an area
of showers into central Illinois this evening. HRRR is the main
high resolution model indicating precip will progress across the
I-74 corridor, with others keeping showers north the I-74 TAF
sites. Based on radar and satellite trends, have added a VCSH for
a few showers to affect PIA and BMI this evening. A steady
decline in instability later this evening should preclude CMI from
experiencing rain. Beyond that VFR conditions are expected to
persist, under a veil of high clouds from tropical storm Cindy in
the Gulf of Mexico.

There are several models indicating a northward surge of low
level moisture tomorrow afternoon, triggering MVFR cloud ceilings
to develop from south to north. Have included that scenario in the
00z TAFs.

Winds will generally remain S-SW over the next 24 hours. Wind
speeds will increase tomorrow morning, with gusty conditions
developing after 15z. Gusts should reach between 20-25kt at times
on Thursday.




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