Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Lincoln Illinois
331 am CDT Fri Oct 31 2014

Short term...(today)
issued at 330 am CDT Friday Oct 31 2014

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially northwest of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most


Long term...(tonight through thursday)
issued at 330 am CDT Friday Oct 31 2014

A potent Canadian shortwave will dive SSE from Lake Superior and WI
across in/Kentucky tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30f and
bring a killing freeze to much of Illinois overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast Illinois. Moisture flow off Lake Michigan could
bring a few snow showers near the in border especially over
Vermilion County this evening. A taste of early winter weather for
Halloween trick or treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern Illinois.

Strong Canadian high pressure of 1039 mb over ND will settle over Illinois
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50f.

More unsettled weather pattern takes shape Monday-Wednesday as Illinois
gets in a southwesterly upper level flow with upper level ridge
shifting east of Illinois and strong upper level trof digging into the
southern rockies. A frontal boundary will set up from the Southern
Plains NE into the Ohio River valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central Illinois Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast Illinois during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60f
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast Illinois Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60f in southeast Illinois.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1105 PM CDT Thursday Oct 30 2014

VFR conditions will give way to a brief period of MVFR cigs in the
08z-12z time frame as a strong cold front tracks across the area.
Once the front shifts thru the area, strong northerly winds are
expected thru much of the day Friday with sustained winds of 20 to
30 kts with a few gusts around 35 kts at times. With the fropa, we
may see some scattered rain showers with the cigs lowering to
MVFR and a low probability for a brief period of IFR cigs with
any bands of rain that persist. Satellite data indicating cigs
around 2500 to 3500 feet north of the cold front over parts of
northern Iowa into central Wisconsin. Latest hrrr forecast indicates
the stratocumulus should begin to decrease in coverage and affect
mainly areas east of i55 by afternoon as subsidence develops in the
wake of the upper level shortwave. Surface winds will gradually
diminish, especially the gusts, towards evening with sustained winds
of 10 kts or less after 02z.


Ilx watches/warnings/advisories...
freeze warning from midnight tonight to 9 am CDT Saturday for



Short term...shimon
long term...07

National Weather Service Glossary of Abbreviations