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Area forecast discussion 
National Weather Service Lincoln Illinois
542 am CST Sat Feb 6 2016

Short term...(today)
issued at 321 am CST Sat Feb 6 2016

A weak shortwave low-pressure trough aloft will cross central Illinois
from early morning to early afternoon today spreading additional
low and mid cloud cover over the area. By afternoon the trough
axis should be east of Illinois causing subsidence to help this cloud
cover erode somewhat. Thin high clouds associated with a low over
southern Canada will already be approaching by late afternoon.
Winds will be light and variable to start the day as weak pressure
gradients associated with the departing high continue. By late
morning and afternoon...the approaching southern Canada low will
start SW winds in the 5-10 mph range. High temperatures will be up
to the low and mid 40s north of I-72, and mid to upper 40s to the
south as the SW winds advect milder air of Pacific origin into the

Long term...(tonight through friday)
issued at 321 am CST Sat Feb 6 2016

Weak high pressure at the surface and generally southwesterly winds
will both play a role in keeping the temperatures and weather rather
mild across the Midwest for the remainder of the weekend. One
exception persists late Sunday in the GFS with smaller
representation in both the NAM and the European model (ecmwf). The NAM solution
putting a small area of qpf ahead of the approaching upper wave, but
mainly east and southeast of ilx...the European model (ecmwf) a little weaker, with
the GFS more widespread across the in/Illinois border later on Sunday. A
little bit of a gap in btwn systems will result in a very weak sfc
trof passing through at that time, and although there will be little
in the way of surface convergence...see no reason to eliminate the
slight chance pops that are in there for now. If the trend in the
NAM/European model (ecmwf) continues, potentially pull the low pop entirely in the
next run or so.

The bigger issue for the forecast is the main system approaching and
spreading precip across the area Sunday night through Tuesday. Deep
upper low moving into the Midwest and plenty of colder Arctic air
moving in with it. What may start as rain early Sunday
evening/night, will slowly change over to all snow by Monday. Qpfs
are generally low, but with high ratios in place, could end up
seeing a widespread inch or so between Monday/Monday night. Chilly
temps are moving in behind the snow. Whereas highs on Sunday will
be in the 40s and 50s for Illinois... by Tuesday, the high
temperatures will be chopped down into the teens and 20s. 850mb
temps will be dropping to -16c to -19c. After the coldest portions
of the forecast midweek, a slow warming trend will bring the temps
back up to more seasonal values by the end of the week and into the


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 542 am CST Sat Feb 6 2016

Predominantly VFR aviation weather conditions expected across the
central Illinois terminals through the 12z taf valid time. An
upper-level disturbance will cross the area through early today,
accompanied by areas VFR cloud cover and local MVFR cigs.
However, the guidance suggests most MVFR and IFR ceilings beneath the
disturbance upstream will remain out of the area to the north and
west where snow-pack and better lift are in place. Winds
predominantly S-SW 5-10 kts through the period.


Ilx watches/warnings/advisories...



Short term...Onton
long term...hjs

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