Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 060902
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
302 AM CST Tue Dec 6 2016

.SYNOPSIS...
Issued at 240 AM CST Tue Dec 6 2016

At 230 AM CST...areas of fog and low clouds cover the region with temperatures
around freezing north to the mid 30s south. A cold front with scattered
flurries just behind the front north of I-80 is approaching northwest
sections of the area. AWIPS distance-time feature supports the front
with clearing conditions will pass through the area by 11 AM with any
flurries along and north of highway 30. Colder and drier air will continue
into the region the few days.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 240 AM CST Tue Dec 6 2016

Short term forecast confidence assessment...good or above average with
main issue the dissipating fog and if temperatures start falling by
afternoon. Area highs and lows should be within 3 degrees of forecast.

Today...cold front should pass from west to east roughly between 6 AM
and 11 AM with fog rapidly dissipating and clearing skies. Highs most
locations will tend to be mid day all but far east as falling temperatures
by afternoon with 20s most locations by sunset. West to northwest winds
of 10 to 20+ MPH will be the case late morning through the afternoon.

Tonight...fair skies with increasing clouds late and continued brisk
northwest winds. Mins to fall into teens northwest to mid 20s southeast.
This will mark the coldest night of the early winter season with wind
chill values falling to 5 to 15 degrees above zero by daybreak.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 240 AM CST Tue Dec 6 2016

Zonal to NW H5 flow will dominate the long term period.  A number of
disturbances will move through this flow leading to a highly dynamic
forecast period.  Highly energetic jet across the US along with the
H5 flow will lead to an active forecast period with high run to run
variability in the models.  As a result, overall confidence in
forecast is low.

The beginning of the long term features a vort max rotating around
cyclonic flow across our area.  Previous forecast had light snow for
southern two tiers of counties.  Latest guidance suggests that the
threat for snow across this area continues to diminish.  If it
wasn`t for the GEM and ECMWF, we would have a dry forecast.  Think
that the next run of the blends will remove this schc pop for the
southernmost tier of counties.    The main story will be the winter
temperatures across the area.  Nighttime wind chills will be around
0 for most of the area Wednesday and Thursday night as Arctic air
makes its return to the Upper Mississippi River valley. Latest run
of guidance continues H85 temps in the -12 to -14C realm, so little
change to temps this shift.

Into this weekend, Friday night looks as though the chance for snow
returns to the area as a clipper type system overruns H85 WAA.  The
GFS and GEM produce QPF across the northern CWA.  The ECMWF does
not.  So model inconsistencies begin the weekend.  The GEM and GFS
have a stronger H5 wave eject out of the Rockies and produces
another round of snow for Saturday night across the area.  The ECMWF
does not have this wave.  Current forecast has chance pops across
the area.  That said, there is definitely more time for this to
change.  What does seem more certain is the well-advertised cold air
to end the workweek.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
ISSUED AT 1151 PM CST Mon Dec 5 2016

...Updated to add overnight light precipitation potential...

Brisk southeast winds from 10 to 20 knots have delayed the anticipated
onset of dense fog, but as winds diminish ahead of an approaching
cold front, the fog is expected to thicken toward morning. Will
maintain the transition to VLIFR, due to very low visibilities and
ceilings of a few hundred feet, roughly from 08z to 12z. A cold
front will likely bring a rapid improvement to at least MVFR and
then VFR conditions around mid morning, along with winds veering
westerly and becoming gusty. A band of a mix of light rain and
light snow along the front over central Iowa is expected to weaken
as it moves east-northeast, but could still impact CID and DBQ
toward morning. This has not been included in the forecasts for
now, as if it does hold together it should be very light and
short-lived. Later Tuesday morning, confidence in the the transition
to much improved conditions is low and later forecasts will likely
be able to be more precise. VFR conditions should then follow
Tuesday afternoon and evening.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...Gibbs
AVIATION...Sheets


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