Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211721

Area Forecast Discussion
National Weather Service Marquette MI
1221 PM EST Sat Jan 21 2017

Issued at 1147 AM EST SAT JAN 21 2017

After coordinating with WFO GRB have extended the dense fog advy
into midday Sun. Though fog is dense, it has been more patchy
today. But with higher dwpnts in the mid 30s moving in tonight and
continual light east winds off the Great Lakes, would expect the
fog to become widespread and dense tonight into Sun morning. Only
other change was to add mention of sleet over west this aftn/early
evening as showers with shortwave and steep mid level lapse rates
lifts across northern WI and over western Upper Michigan.
Forecast soundings indicate pcpn staying liquid but with the
possible convective elements think some sleet could occur in
heavier showers. Temps will only rise into the middle 30s this
aftn and with ground temps still around freezing continued to
mention potential for slippery travel on untreated roads.

.SHORT TERM...(Today and tonight)
Issued at 424 AM EST SAT JAN 21 2017

Low clouds, fog and rain chances continue through the short term.

Fog will continue to be dense at times into this morning, with
general fog then continuing through tonight. 2M temps are currently
very near or above freezing, but ground temps remain below freezing,
resulting in ice accretion on untreated and lesser traveled roads.
Will continue to advertise slick untreated roads in any text

A vigorous shortwave currently over IA will move into the western
CWA this afternoon and evening. As it does so, widespread rain
showers will result over roughly the western half of Upper MI,
including potential for heavy showers and an outside chance at some
thunder. Models are painting an area of QPF up to a half inch in 6
hours (ruling out a couple of the high-res models that seem quite
overdone) over portions of western Upper MI late this afternoon and
evening, but not expecting any hydro related issues from those
amounts. Most of the precip moves out by tonight and 2M temps are
forecast to be AOA freezing, so the ice threat would mainly be
confined to untreated roads due to the colder soil and road surface
temps like early this morning.

.LONG TERM...(Sunday through Friday)
Issued at 401 AM EST SAT JAN 21 2017

The unseasonably warm and dreary conditions are expected to
linger through the first part of next week as the cold arctic air
remains well north of the area. Afternoon high temperatures are
expected to climb into the mid to upper 30s through Wednesday.
Overnight lows will start off around freezing before gradually
cooling through the week. However, the medium range models are
consistent with the pattern finally changing in favor of cooler
temperatures, albeit still above normal, by mid to late next week
as longwave troughing is progged to dominate the central and
eastern CONUS.

On Sunday as shortwave energy lifts north across the area, expect
rain to diminish from south to north. However, cannot rule out
some lingering drizzle during the day with lingering stratus. Forecast
soundings across the area show cloud ice diminishing Sunday night
into Monday morning. This coupled with cooling temperatures at
night may lead to freezing drizzle concerns. However, right now
cloud top temperatures look to be right around the threshold of
supporting ice. Therefore, not too confident that freezing drizzle
will develop at this time, but have at least included mentions of
it. Also, Given the recent warm temperatures and rainfall, with
ample moisture at the surface would not be surprised if areas of
patchy fog continue to impact the area.

The attention that turns to cutoff energy that will lift north
across the Appalachian Mountains pushing deeper moisture towards
the area on Monday. Along with this deeper moisture, comes warmer
air aloft. The big question is where the 850mb freezing line will
set up, as that will bisect areas that see predominately rain and
snow. Right now most of the models push this line back across
central Upper Michigan. Given the uncertainty right now have opted
to run with a rain/snow mix for now. Highest chances of
precipitation remaining all snow will be across far western
portions of the area and then all rain across the east. A few
pockets of freezing rain/sleet mixture may develop Monday night
into Tuesday, but this will be highly depending upon how far west
the nose of warm air aloft can get. Lingering upper-level energy
on Tuesday will allow for light rain/snow chances to remain
primarily in the east and downwind of lake superior.

The attention then turns to a storm system progged to develop in
the lee of the rockies and lift northeast across the Great Lakes
region Tuesday night through Wednesday. There is quite a bit of
uncertainty with this system, with the GFS being the quickest and
the Canadian being the slowest of the medium range models. The
ECMWF and GFS Ensemble mean seem to be the middle of the road at
this point, and would suggest the bulk of the precipitation with
this storm would track across much of Wisconsin and southern
portions of Upper Michigan. With the storm expected to track well
south of the area at this point, with relatively mild air still in
place we could still be dealing with a rain/snow mix in many
locations. However, after this system lifts out of the region
large-scale troughing will dominate the central and eastern CONUS
allowing for multiple waves of colder air to drop south. This will
knock temperatures down to at least more seasonable and allow for
LES to return to the region, with perhaps a few chances to see
area-wide system snows as shortwaves periodically dig south across
the area.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1220 PM EST SAT JAN 21 2017

IFR to VLIFR conditions will continue in fog through Sun. The worst
conditions will be at CMX and SAW where winds will continue to
provide upslope lifting. The low visibility may improve at times
this aftn as rain showers lift across the area.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 424 AM EST SAT JAN 21 2017

A relatively weak pressure gradient over the Upper Great Lakes in
the absence of any strong weather systems will result in winds under
20 kts over Lake Superior most of the time into early next week.
Abundant low-level moisture will result in fog over northern Lk

Upper Michigan...
  Dense Fog Advisory until 1 PM EST /noon CST/ Sunday for MIZ001-

Lake Superior...
Lake Michigan...
  Dense Fog Advisory until 1 PM EST Sunday for LMZ248-250.



LONG TERM...Ritzman
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