Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Lincoln Illinois
605 PM CST Fri Dec 26 2014

Short term...(tonight)
issued at 307 PM CST Friday Dec 26 2014

Deep trof over the western half of the Continental U.S. This morning while weak
upper level ridging remains over the Atlantic Seaboard. Surface
high pressure sliding off to the east keeping southerly flow over
the region ahead of a slow moving cold front approaching the area
tonight. Temperatures well above normal today will give way to a
chance for precipitation tonight with the passage of the front.
Forecast soundings remain rather shallow with the saturation and
looks to be more drizzle and low clouds...maybe some light rain.
Not a lot of quantitative precipitation forecast expected. Guidance shows some patchy light winds,
and close to the low center with a weaker wind gradient associated
with the immediate front...may see a little bit of mist/fog, but
should be more of a low cloud, drizzle situation.

&&

Long term...(saturday through friday)
issued at 307 PM CST Friday Dec 26 2014

Cold front to push from near Galesburg around 6 a.M. Southeastward
to around Lawrenceville by 6 p.M. Rain showers or drizzle with
this frontal boundary could turn over to snow just before ending,
however it looks as if the bulk of precipitation will fall as rain
so still expecting no snow accumulation. Precipitation amounts
should also be quite light as upper level dynamic lift bypasses
central Illinois to the northwest. Model precipitation fields are
consistent with this idea. The front should stall out just
southeast of Lawrenceville Saturday night as another upper level
wave approaches from the west. This will cause the front to move
again, with precipitation intensifying just southeast of
Lawrenceville. Temperatures will fall behind the front, with
temperatures peaking before noon from around I-55 westward.

Temperatures near normal with dry conditions Sunday and Monday, as
Arctic high pressure settles into the plains. By midweek, a series
of upper level troughs digging into the Midwest will push more cold
air into the region, with highs only reaching the low to mid 20s and
lows in the teens or potentially colder. Expecting this period to
remain dry. The next good chance for precipitation will be at the
end of next work week as a strong trough could potentially eject out
of the southwest across the Southern Plains.

&&

Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 600 PM CST Friday Dec 26 2014

An elongated cold front has progressed to northwest Illinois, with VFR
clouds across our forecast area. The front will generally remain
in place as low pressure advances NE up along the front, passing
across northwest Illinois late tonight into Saturday morning. Ahead of the
low, MVFR clouds are poised to progress over the terminal sites
this evening, with IFR clouds accompanying the low as it moves
over the area between 10z and 16z. Forecast soundings are more
indicative of drizzle than larger raindrops, so we kept with
prevailing drizzle and a tempo for rain and IFR clouds heights.

Winds will remain steady from the south at 10-14kt. An
intensifying low level jet after midnight will create low level wind shear
conditions, as winds crank up to 40kt at 2k feet from 220 deg true.
Winds may back to the southeast in the vicinity of the low, but
then shift around to the SW then west during the day on Saturday.
Colder air will arrive on the increasing northwest winds, with speeds of
13-17kt and gusts into the 20-24kt range.

&&

Ilx watches/warnings/advisories...
none.
&&

$$

Short term...hjs
long term...Onton
aviation...shimon

National Weather Service Glossary of Abbreviations