Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Lincoln Illinois
525 am CST Sat Nov 28 2015

Short term...(today)
issued at 320 am CST Sat Nov 28 2015

08z/2am surface analysis shows slow-moving cold front draped along
the Ohio River, with 1037mb high pressure centered over southwest
Minnesota. Clouds associated with the frontal boundary and a broad
southwesterly flow aloft continue to blanket much of the region.
Latest infrared satellite imagery shows the back edge of the clouds
extending from southern Wisconsin to Nebraska, while lower clouds
and even a few light rain showers persist further south across the
kilx County Warning Area. The front is expected to settle slowly southward today,
reaching the central sections of Kentucky and Tennessee by 00z.
Slightly drier air will filter southward around the Minnesota high,
essentially shutting off any light precip across the northern County Warning Area.
NAM forecast soundings suggest enough drying will be present within
the profile to warrant a dry forecast through the entire day from
the Peoria area northward. Further southward, scattered light
showers will be the rule...especially along/south of I-70 where
categorical pops are warranted. Due to overcast conditions and a
brisk northerly breeze, have undercut mav guidance numbers by a few
degrees, resulting in high temperatures mainly in the lower to
middle 40s.

Long term...(tonight through friday)
issued at 320 am CST Sat Nov 28 2015

High pressure will build into the Great Lakes tonight into Sunday,
keeping the primary baroclinic zone suppressed well to the south.
Models are in good agreement, with most solutions suggesting a dry
forecast across the area. Have reduced pops accordingly, with low
chances confined to locations along/south of a Jacksonville to Paris

As Rex block over the western Continental U.S. Breaks down and a closed upper
low currently over the Great Basin begins to track eastward, the
frontal boundary will lift back northward Sunday night into Monday.
00z Nov 28 models are in good agreement with the timing and track of
the upper system and its associated surface low. As a result, have
spread pops back to just south of the I-74 corridor late Sunday
night, then across the entire area Monday/Monday night. Temperatures
will be warm enough to support liquid precipitation through the
period, with rainfall amounts of 0.25 to 0.50 likely. After that,
model solutions begin to diverge slightly, with the GFS tracking
the 500mb low to Southern Lake Michigan by 00z Wed, while the
European model (ecmwf) keeps it a bit further west over southwest Wisconsin. This
slight difference in tracks has a significant impact on precip
chances across central Illinois behind the departing system. If
the further south track of the GFS verifies, wrap-around precip
will likely impact at least the northern half of the County Warning Area Tuesday
and Tuesday night, with a possible transition to light snow as the
precip ends Tuesday night. If the European model (ecmwf) is right, the precip on
the back side of the storm will be further north/northwest and very little
will impact central Illinois. At this point, will favor the more
consistent European model (ecmwf) and feature just a slight chance for rain showers
across the northern half of the area on Tuesday, with a slight
chance for light snow along/north of the Peoria and Bloomington
areas Tuesday night.

Beyond the early week storm system, the rest of the extended
forecast looks quiet. Temperatures will remain near normal for this
time of year in the 40s initially, but will trend warmer by the end
of the week as upper ridging builds across the plains.


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 525 am CST Sat Nov 28 2015

IFR ceilings from kspi-kcmi southward across central Illinois...with
MVFR ceilings to the north early this morning. This boundary
should settle slowly southward in response to drier north-
northeasterly low level flow. Associated light rain showers and
drizzle will also continue to push southward. As a result...12z
tafs feature slowly improving conditions...reaching VFR by 00-06z
Sunday. Winds north-NE 6-14 kts through the period.


Ilx watches/warnings/advisories...



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

National Weather Service Glossary of Abbreviations