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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
322 am CST Sat Dec 27 2014

issued at 321 am CST Sat Dec 27 2014

06z surface analysis had weak mesoscale lows to the west and southwest of
kmli. Synoptic lows were east of klse and at kmiw with a frontal
boundary connecting both of them. An initial cold front ran from the
kmiw low into eastern Oklahoma with a secondary boundary from kmiw
into southeast Nebraska. Dew points ahead of the frontal boundaries
were in the 40s with 20s and 30s behind the front. Dew points in the
single digits and teens were across the northern plains.


Short term...(today and tonight)
issued at 321 am CST Sat Dec 27 2014

The change over to a mix and eventual snow occurs behind the low and
boundary near kmiw. Extrapolation would place this boundary near the
extreme northwest areas around 12z with the low/boundary moving into
southwest Wisconsin during the morning. Thus a mix should be
starting just prior to sunrise that may briefly change over to all

A mix will continue across the extreme northwest areas Saturday
morning that may at times be all snow. The remainder of the area
will see spotty rain/drizzle that decreases in overall areal
coverage during the morning.

The warm temperatures from yesterday and overnight has warmed the
ground. Thus the snow will melt on contact. At the very worst a
light dusting of accumulation may occur across parts of Buchanan and
Delaware counties.

Dry conditions are expected Saturday afternoon as the better
moisture and forcing is well east of the area. Skies should begin a
clearing trend during the afternoon that slowly moves from west to
east across the area.

Temperatures today will be steady to slowly falling as the frontal
boundary moves through the area. High temperatures should occur
during the morning hours.

Tonight dry and much colder conditions will be seen across the area
as high pressure builds in from the plains. Low temperatures should
be near to slightly above normal.

Long term...(sunday through friday)
issued at 321 am CST Sat Dec 27 2014

The main forecast issues in the long term period are temperatures
and potential wind chill impacts.

Surface high pressure will be in place across the forecast area
Sunday with near normal highs in the 30s. On Monday...a weak wave
will drop southeast through the region. The low level baroclinic
zone with sag into the northern forecast area Monday afternoon and
continue southward Monday night. Forcing and moisture will be
limited...and operational models are generating little or no quantitative precipitation forecast.
With the strong cold won't be difficult to squeeze out
at least some flurries but prospects for measurable snow are in
doubt and have kept probability of precipitation mainly in the slight chance category.

Monday night through Wednesday night will likely be the coldest
stretch of the long term period. Expect lows in the single digits
and teens...highs in the teens to low 20s...quite a departure from
recent mild weather. Periods of sub freezing wind chills are
expected...especially west of the Mississippi River. Tuesday night
remains on target for the coldest night...with wind chill values
approaching 20 below zero near Independence.

The next potential system would be Friday/Friday night...but
remains very much in question. The 27/00z GFS phases northern and
southern stream energy nicely across the region and generates a
significant snow event. The European model (ecmwf) is farther south and only clips
the southern counties. The GFS ensemble mean Standard deviation
would suggest the 500 mb low track will be farther south.
Thus...confidence in a widespread snow event continues to be low
and have kept probability of precipitation in the 15 to 25 range through Friday afternoon.


Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1143 PM CST Friday Dec 26 2014

Conditions to deteriorate into MVFR and IFR with areas of LIFR
overnight and Saturday morning in low clouds...fog and areas as
light rain/drizzle as low pressure lifts north and a cold frontal
passage follows. Few flurries or patchy drizzle remain possible
at Cid and dbq Saturday morning. Winds to veer to westerly by
Saturday morning and become gusty at 10-20+ kts. Anticipate gradual
lifting of ceilings to MVFR by Saturday afternoon and lingered through
the rest of taf cycle although partial clearing and improvement to
VFR is possible late in the day into Saturday night.


Dvn watches/warnings/advisories...


short term...08
long term...rp Kinney

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