Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Lincoln Illinois
611 PM CDT Tue Sep 2 2014

Short term...(this evening through wednesday)
issued at 254 PM CDT Tuesday Sep 2 2014

18z/1pm surface analysis shows slow-moving cold front extending from
Chicago to just east of Quincy. Ahead of the front, central
Illinois remains partly to mostly cloudy and there have even been a
few showers east/NE of Bloomington over the past hour. Will continue
to carry slight chance pops across the eastern kilx County Warning Area through the
afternoon accordingly. Frontal boundary will continue to push
slowly eastward tonight, eventually washing out across central
Illinois. Winds will go light/variable due to the weak pressure
gradient and with skies expected to clear, fog will likely develop
overnight. NAM forecast soundings suggest the most widespread fog
will form across east-central Illinois where skies will clear the
slowest this afternoon. Have therefore included areas of fog after
midnight along/east of I-57, with patchy fog further west across the
remainder of the area. After early morning fog dissipates, skies
will initially be mostly sunny before clouds begin to increase in
advance of an approaching warm front on Wednesday. Based on 12z
NAM/GFS, have slowed the introduction of pops until afternoon.


Long term...(wednesday night through tuesday)
issued at 254 PM CDT Tuesday Sep 2 2014

Low pressure moving from the plains toward the western Great Lakes
on Wed night will begin a significant push of warm air from the
Southern Plains into Illinois. A shortwave clipping north Illinois in the
could trigger a few storms from Peoria and northward overnight. By
Thursday, the warm front will re-define north of Illinois, as 850mb
temps of 20-24c surge into our counties. Gusty south winds will aid
in moisture transport pushing humidity levels up, as surface
dewpoints climb into the mid 70s. Mixing that warm air to the ground
supports high temps into the upper 80s and lower 90s, depending on
the amount of sunshine we get into the afternoon. The 12z guidance
are slowing down the advance of storms into Illinois on Thursday, except
for the GFS, so sunshine could prevail for much of the day. Peak
heat index readings could reach between 100-105f.

Storm chances increase later Thursday night as the cold front
approaches northwest Illinois. Rain chances become widespread across the kilx
forecast area for Friday and Friday night, as the cold front
progresses across Illinois. Severe potential is hard to Pin-Point this
early, but very heavy rainfall will be possible as precipitable water values climb
toward 2". Friday will be another warm and muggy day ahead of the
cold front, but not quite as hot due to increasing cloud cover and

The cold front will begin to slow down Friday night, allowing
scattered storms to linger across our southeast counties into

A significant airmass change will follow that frontal passage, as
cool and dry Canadian high pressure builds southeast into the
western Great Lakes. Highs from Saturday through Tuesday will be
mainly in the 70s, with lows mainly in the 50s, with Sunday night
the coldest night.

Storm chances increase next week Tuesday as a cold front arrives
from the west.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 611 PM CDT Tuesday Sep 2 2014

Cumulus has dissipated and only clouds left will be some cirrus this
evening. Based on satellite trends, the cirrus will advect east of
the area tonight. So clear skies expected overnight with winds
becoming light and variable as ridging moves into the area. With
lots of low level moisture still around, expecting fog to develop
overnight and last until morning. Then scattered SC around 2.5kft
will develop over the area, effecting each of the taf sites. Winds
will also increase to around 10kts out of the south.


Ilx watches/warnings/advisories...


Short term...Barnes
long term...shimon

National Weather Service Glossary of Abbreviations