Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 271939
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
239 PM CDT Mon Mar 27 2017

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 239 PM CDT Mon Mar 27 2017

Well-defined swirl in water vapor imagery continues to push eastward
across the southern third of Missouri this afternoon, with a
convective cluster pushed into western parts of Kentucky and
Tennessee. Warm front was located just south of I-70, and the
showers north of it have been devoid of lightning activity as a
result. The surface low riding along the boundary should be crossing
southeast Illinois late this afternoon, and lingering precipitation
will quickly taper off as the low pulls away. Have pulled back
thunder mention to areas south of I-70 for the remainder of the
afternoon, and removed the mention for the evening. Dry conditions
will prevail after midnight.

Northeast flow will persist across the forecast area into Tuesday.
Forecast soundings and low-level model humidity plots show that the
clouds will be in no hurry to leave, with no low level scouring
taking place. Temperatures most areas should still reach the lower
60s, with some upper 50s north of I-74 where there will be some
residual cooler air from the flow off of Lake Michigan.

&&

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 239 PM CDT Mon Mar 27 2017

High pressure over the Midwest Tuesday night will provide for dry
conditions, followed by the onset of rain chances in west central IL
Wednesday morning as warm advection aloft develops ahead of a low
approaching via the southern Plains. Models have converged
relatively well at this point with the low tracking NW through
southern IL late Thursday evening. Ahead of the low several hundred
to over 1000 J/KG MUCAPE is likely to surge northeastward combined
with potential for significant bulk shear. As a result...SPC has
targeted a marginal risk of severe thunderstorms by early Thursday
morning as far northeast as Springfield to Effingham...and this
severe thunderstorm risk could spread eastward through the day
Thursday impacting more of central IL. Have added thunderstorm
mention for the early morning period Thursday, and continued
thunderstorm mention for Thursday afternoon and evening through
around the I-72 corridor and areas southward.

Dry conditions look to spread eastward across the state Friday as
showers from the departing storm system taper off. The next
potential storm system is on Sunday or Monday, however model
differences in handling this system remain significant. Despite
model differences...current model/ensemble forecasts indicating a
more southern track than the past few systems. Chance PoPs are
therefore included in afternoon forecast package for portions of the
forecast area Sun/Mon, however precipitation coverage predictability
remains low.

Temperatures still look to be running a few degrees above
normal...mainly mid 50s to mid 60s through the weekend. Main
temperature feature is periods of cooler temperatures Thursday
through Saturday as cooler easterly to northerly winds surge into
the area due to the circulation around the low. Expect highs ranging
from the low 50s in Galesburg to around 60 in Lawrenceville during
this time period. Lows for the period generally 40s...although a few
30s for northern portions of the forecast area Thursday night
through Saturday night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1232 PM CDT Mon Mar 27 2017

Rather challenging forecast for this TAF set. The arrival of
showers has resulted in a rising of the ceilings at many sites,
and areas from KSPI eastward are currently above 4000 feet. IFR
conditions persist near KPIA though, and that area is least likely
to see any significant improvements beyond low MVFR range. Have
removed the thunder mention as it appears the greatest threat will
be in southeast Illinois closer to the low track. As the low
starts to move away early this evening, wraparound low clouds
will bring ceilings back below 1000 feet, with only some modest
improvement expected later Tuesday morning.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...Geelhart
LONG TERM...37
AVIATION...Geelhart



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