Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 191758

Area Forecast Discussion
National Weather Service Lincoln IL
1258 PM CDT Thu Oct 19 2017

Issued at 1045 AM CDT Thu Oct 19 2017

Another beautiful fall day unfolding across central and southeast
IL with ample sunshine (scattered thin cirrus clouds) and lighter
winds under 10 mph. Temperatures have been climbing a few degrees
each day the past few days and should reach the low to mid 70s
this afternoon. 1028 mb high pressure over the central and
southern Appalachians will stay anchored in place through tonight
while upper level ridge builds into IL providing the nice weather.


.SHORT TERM...(Today and tonight)
ISSUED AT 332 AM CDT Thu Oct 19 2017

Temperatures remain warm through the end of the week with precip
moving through the region for the weekend. Colder air brings more
fall like conditions for next week.

Plenty of sunshine today over an already warm airmass will bring
the max temps up into the 70s for today, well above seasonal
normals. Although the winds will generally be lighter, a southerly
component will continue through much of Central IL today. A
weakening cold front to the NW wavering in the region today...but
not much of an impact expected as it stalls near the IL River
Valley. Temps tonight a few degrees warmer than this morning as
south/southwesterly flow in the midlevels keeps the warm air
advection going.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 332 AM CDT Thu Oct 19 2017

Southerly winds pick up at the surface for Friday, increasing WAA
and pushing the max temps into the mid to upper 70s, about 10F-12F
degrees above climatological averages. Mid levels warming in the
ECMWF to 16-17C and have brought the blends up a couple degrees
across the board. Warm air continues into Saturday, but will be
tempered by increasing cloud cover ahead of an advancing cold
front. Rain associated with the front will impinge on areas NW of
the IL River later on Saturday with the precip spreading across
the state overnight and into Sunday. Models continue to show a
potential break between the upper wave breaking away from the
northern stream and creating a cutoff low over the Southern
Plains. Better instability/thunder chances to the south/southwest
with the better dynamics invof the upper low. ECMWF also showing a
slowing of the progress of the low...and pushing the front
through. Front will be moving through in the overnight hours,
likely low on instability given the timing. Still watching for
formation of a break making the activity potentially more shower
like Sat night/Sunday. The shift in the timing of the progress of
the southern low potentially making this a more prolonged and
showery end to the weekend/beginning of next week. Models
lingering the precip chances a little longer into Tuesday, finally
settling cooler air into the region. Temps trending down Sunday
through Tuesday...but by Wednesday the colder air aloft keeps the
highs in the 50s, below normals for the end of October.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1255 PM CDT Thu Oct 19 2017

VFR conditions are expected to continue across the central IL
terminals through 18Z/1 pm Friday. Few-scattered cirrus clouds
expected next 24 hours over central IL. Some very patchy shallow
ground fog expected in eastern IL around dawn Friday, but do not
think it will affect the TAF sites including CMI. BMI had a brief
vsby reduction to 3/4 mile for 10-15 minutes from crop dust from
harvesting and if this occurs again, it should be very brief. A
weak frontal boundary just south of PIA and BMI at midday will
lift back north during the afternoon with SSE winds 4-8 kts
expected this afternoon and around 5 kts tonight. South winds 7-11
kts expected after 15Z/10 am Friday.




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