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Area forecast discussion 
National Weather Service Lincoln Illinois
847 PM CDT Mon Sep 22 2014

issued at 847 PM CDT Monday Sep 22 2014

A large surface high pressure system is drifting eastward across
the region this evening, centered over Illinois. This result for
tonight will be calm winds, cool temperatures in the mid 40s, and
clear skies except for some high thin clouds moving into western
Illinois, associated with a low pressure system moving into the
northern plains. Light southeast winds and continued mostly clear
skies with temperatures in the low 70s are expected for Tuesday as
the high moves east of Illinois. No updates are needed this
evening other than adjustments to hourly temperature/humidity
based on recent trends.


Short term...(tonight)
issued at 226 PM CDT Monday Sep 22 2014

Large area of high pressure settling across the mid-Mississippi
Valley early this afternoon, centered from northern Missouri into
northwest Illinois. This will slowly drift southeast overnight. Dew
points most areas currently in the lower to mid 40s and that gives a
good indication of the overnight temperatures. Lows in the mid 40s
will be common overnight, with some locally cooler readings. Little
in the way of cloud cover will occur through the night.


Long term...(tuesday through monday)
issued at 226 PM CDT Monday Sep 22 2014

High pressure centered near Illinois on Monday will gradually shift
east by Wednesday as a shortwave moves across the plains toward
Minnesota. Any surface reflection of low pressure with that wave
looks to dissipate across Iowa and north Missouri Wed and Wed night.
Then high pressure re-establishes itself across Illinois as the East
Coast high retrogrades westward. A Rex block-type pattern seems to
develop for late this week into next weekend, keeping the dry
conditions into Sunday. There are some indications in the GFS and
European model (ecmwf) that a Gulf of Mexico low will lift into the ridge toward
southern Illinois on Sunday. By Monday, the low may drift into
Tennessee, with increasing lift and moisture into our far
southeastern counties. Areas southeast of I-70 could see a few light
showers develop Monday afternoon as the weakening low passes nearby
to the southeast. The all-blend slight chance pops were left in the
forecast for the southeast counties.

The thermal ridge will begin to advance eastward from the SW states
into the plains this week, but Illinois will only see a minor
increase compared to points farther west. Still, a warming trend
looks on track for central Illinois through Thursday, as highs
progress from the lower 70s on Tuesday to the upper 70s-near 80 on
Thursday. Temps will then steady out through the weekend as they
linger near or slightly above normal through next week Monday.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 602 PM CDT Monday Sep 22 2014

VFR conditions and light winds expected for the next 24 hours.
High pressure crossing the region tonight will bring light and
variable winds until morning...becoming S-southeast 4-7 kts after 14z.
Skies generally clear except for thin high clouds spreading over
central Illinois from the west starting around 12z.


Ilx watches/warnings/advisories...


short term...geelhart
long term...shimon

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