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Area forecast discussion 
National Weather Service Lincoln Illinois
828 PM CDT Tuesday Oct 13 2015

issued at 822 PM CDT Tuesday Oct 13 2015

High pressure will continue to build into the region from the
northwest overnight resulting in some rather chilly temperatures
by dawn Wednesday. Infrared satellite loop indicating a band of mid and
high level moisture pushing quickly southeast out of northern
Minnesota this evening. Forecast soundings suggest these clouds
will track southeast into our area after midnight, which should
keep the overnight lows from dropping off further than what we
currently expect. Early evening temperatures have fallen off
rather quickly, thanks to the clear sky and diminishing northwest
wind. Have made some minor adjustments to the evening temp trends
in the grids, but overall, the current forecast is in good shape
with most areas seeing overnight lows in the 40 to 44 degree
range. Some of our more favored cold spots may see the Mercury
dip briefly into the upper 30s just before dawn. No zone forecast product update
will be needed this evening.


Short term...(tonight)
issued at 310 PM CDT Tuesday Oct 13 2015

Upper level trof/low along the Quebec/Ontario province line will
pull away from Illinois through tonight taking its low clouds in NE Illinois
with it. Weak high pressure ridge of 1018 mb over the plains will
settle into the MO valley on Wed morning. Breezy NW winds of 10 to
20 mph and gusts of 20-27 mph this afternoon will diminish to less
than 10 mph early this evening. Few cumulus clouds with bases around
4k ft over northeast County Warning Area this afternoon will dissipate by sunset
leaving fair skies tonight with just few-sct mid/high clouds passing
by. Temperatures should cool close to the dewpoints in the lower 40s
for lows overnight. Stayed close to met/mav guidance lows in the
lower 40s overnight across central Illinois with Galesburg the coolest at
39f and Lawrenceville the mildest at 44f.

Long term...(wednesday through tuesday)
issued at 310 PM CDT Tuesday Oct 13 2015

The two main weather concerns are the rain chances late Thursday and
Thursday evening, then the frost potential coming this weekend.

The upper low over the Great Lakes will finally making progress to
the east on Wednesday, setting up the northwest flow for the
remainder of the week. One very weak wave is still expected to pass
across SW Illinois Wednesday night, with little affect on our
weather. The next more significant system is projected to pass
across Illinois Thursday and thur evening. The 12z models have sped up the
cold frontal passage, now pushing the front to near Lawrenceville by
00z, with all but the Canadian holding off on rainfall until after
00z/7 PM. The ECMWF, Canadian and GFS ensemble mean all show spotty
showers in our central and eastern counties, with a noticeable
downward trend in precip coverage in the European model (ecmwf). We removed the
slight chance pops in our far north counties thur afternoon, and
kept slight chance for Thursday evening south and east of a line
from El Paso to Peoria to Canton. The amount of dry air to overcome
should keep precip amounts very low, with a few areas seeing a
couple of hundredths. Most areas may escape with just sprinkles.

Our coldest air of the fall season will come this weekend, as a
1032mb Canadian surface high settles into the Midwest. 850mb
temperatures are projected to drop below zero by Saturday. The
combination of clear skies and lighter winds with those temperatures
should allow lows to dip into the mid 30s, with some low 30s
possible in traditional cold spots from Galesburg to Lacon. Patchy
frost will be possible both Friday and Saturday nights in much of
our forecast area, except for the far southeast along Highway 50.

A warming trend is expected to start on Sunday, as southerly winds
develop behind the departing surface high. High temps will climb
back near or above normal for Monday and Tuesday. There appears to
be some potential for showers on Tuesday per the GFS as a warm
frontal circulation develops across northwest Illinois. The European model (ecmwf) delays
that potential until it brings a cold front across Illinois on
Wednesday night and Thursday.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 600 PM CDT Tuesday Oct 13 2015

VFR conditions will prevail through this forecast period. High
pressure will slowly push into the region over the next 24 hours
continuing our quiet weather pattern. A band of mostly high level
clouds is expected to push off to our east this evening with a
mostly clear sky expected through 08z. Forecast soundings and
time height cross sections indicate some scattered altocumulus
clouds around 8000 feet may drift into our area after 08z but
that is about it as far as clouds are concerned this forecast
period. The gusty west to northwest winds are expected to
diminish quickly this evening and be out of the northwest on
Wednesday with speeds of 10 kts or less.


Ilx watches/warnings/advisories...


short term...07
long term...shimon

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