Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 051811
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1211 PM CST Mon Dec 5 2016

.UPDATE...
Issued at 1210 PM CST Mon Dec 5 2016

Decided to extend the dense fog advisory until 1 pm as several
locations were still at 1/4 mile. However, there has been
generally an improving trend and this will continue through the
afternoon. There may be locations where there is deeper snow that
visibilities will remain in the 1 to 3 mile range most of the
afternoon. May need to mention areas of fog tonight ahead of a
strong cold front that will be arriving towards morning, bringing
colder and windier conditions for Tuesday which will quickly scour
out any fog and low stratus.

UPDATE Issued at 912 AM CST Mon Dec 5 2016

Dense fog has now spread into nw IL so have expanded the advisory
into that area. The advisory goes until noon but there is the
potential the headline may need to be extended in the afternoon in
some areas if the visibilities remain 1/4 mile or less.

The current forecast has high temperatures in the 40s in our far
southern cwa but with several inches of snow on the ground this
may be difficult to achieve.

UPDATE Issued at 554 AM CST Mon Dec 5 2016

Will extend the dense fog advisory east as the slow creep of dense
fog has taken over the next row of counties. This time went
another row of counties east to include all of Iowa.

UPDATE Issued at 349 AM CST Mon Dec 5 2016

Have gone with a dense fog advisory due to expanding fog across
the area. At this time will keep it close to the boundary with the
snowpack and stratus clouds. The stratus clouds could continue
this morning and that would inhibit expansion east of the dense
fog. However, not completely sold on that idea, as such will
expand the advisory east if it becomes more clear that it needs to
be.

&&

.SYNOPSIS...
Issued at 255 AM CST Mon Dec 5 2016

Cloud cover over a fresh fallen snow has lead to temperatures
staying near or just above freezing tonight across the area. This
has lead to the development of dense fog across the western CWA.
High pressure across the area will drive todays weather.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 255 AM CST Mon Dec 5 2016

Surface high pressure and a snowpack are the main drivers during
the day today, before another weak boundary moves into the area
overnight. As previous shifts mentioned, the snowpack has
definitely thrown the blended and cons guidance into too warm
temps. The GFS, HRRR and NAM have a good handle on snowpack.
Started with the superblend then tweaked highs to just above
freezing over the snowpack. This likely will lead to fog most of
the day today over that snowpack. This could one of these days
where we see dense fog develop this morning and last all day. I`m
not confident enough to go there yet, however it isn`t out of the
realm.

Later tonight, a boundary sweeps through northern zones. Have gone
with schc pops across the area. The forcing for this appears weak
so schc pops are warranted. Hires guidance also has a broken band
of precip across this area. The thermal boundary suggests mixed
precip, with a rain/fzra/ changing to all snow.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 255 AM CST Mon Dec 5 2016

Dry to generally dry with below normal temperatures.

Long Term Forecast Confidence Assessment...good or above average
with risk of some flurries or light snow Wednesday/Thursday and then
better chances for snow this weekend.  Forecast highs and lows
should tend to be mostly within 3 degrees of forecast.

Tuesday...Minor changes mostly for sky conditions.  Partly Cloudy
and colder with northwest winds of 10 to 15+ MPH.  Highs lower 30s
northwest to upper 30s far southeast. Tuesday night...clearing and
cold with northwest winds of 10 to 20 MPH. Lows upper teens
northwest to the middle 20s southeast remain reasonable.

Wednesday and Thursday...Little changes made with risk of some
passing flurries or light snow south with little or no accumulations
from passing disturbance with a brisk northwest wind.  Trimmed
temperatures a few degrees. Highs mostly in the lower to middle 20s.
Mins in the upper single digits to middle teens remain on track.
Northwest wind of 15 to 25 MPH with cold wind chills Thursday &
Friday AM still likely to fall to near zero or below zero for
several hours.

Friday...Fair and remaining quite cold with light westerly winds as
high pressure moves in.  Highs still in the 20s with mins mostly
still in the teens.

Saturday and Sunday...minor changes made.  Unsettled with a chance
or likelihood of snow as passing disturbance moves through with poor
confidence due to track and strength of disturbance from the west.
This uncertainty will likely take another couple of days to clarify.
Trends and jet axis do suggest some light to potentially moderate
snow totals may occur near to over the area. Highs mostly in the 25
to 35 degree range.  Area lows generally in the lower 20s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1210 PM CST Mon Dec 5 2016

Widespread IFR/LIFR conds in low stratus and fog through tonight
ahead of a strong cold front that will arrive by Tuesday morning.
Colder and windier conditions behind the front will scour out the
low stratus/fog. Southeast to south winds 10 to 15 knots this
afternoon and tonight then west to northwest 15 to 25 knots on
Tuesday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 1 PM CST this afternoon for Benton-
     Buchanan-Cedar-Clinton-Delaware-Des Moines-Dubuque-Henry IA-
     Iowa-Jackson-Jefferson-Johnson-Jones-Keokuk-Lee-Linn-Louisa-
     Muscatine-Scott-Van Buren-Washington.

IL...Dense Fog Advisory until 1 PM CST this afternoon for Bureau-
     Carroll-Hancock-Henderson-Henry IL-Jo Daviess-McDonough-
     Mercer-Putnam-Rock Island-Stephenson-Warren-Whiteside.

MO...Dense Fog Advisory until 1 PM CST this afternoon for Clark-
     Scotland.

&&

$$

UPDATE...Haase
SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Nichols
AVIATION...Haase



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