Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 211912

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

.SHORT TERM...(This evening through Sunday)
Issued at 211 PM EST SAT JAN 21 2017

Upper trough from northern Plains to Upper Great Lakes will lift
north to Manitoba and Northern Ontario through Sun while stronger
shortwave trough develops from the southern Plains to the southeast
Conus. Sfc low with northern shortwave trough is currently over
southern MN and that will weaken as it moves toward western Upper
Michigan tonight into Sun morning. The stronger low pressure system
will be tied into the southern stream shortwave trough and will stay
well to the south of Great Lakes into Sun. Expect waves of scattered
to at times widespread showers over WI to lift across cwa this aftn
into early this evening. Kept mention of sleet over western Upper
Michigan for rest of day as heavier showers could result in enough
cooling aloft to produce sleet. Just a slight chance. After the
showers move out this evening, there is only very weak large scale
forcing to support additional precipitation so will have pops
diminishing steadily by the overnight hours and on into Sun. Could
not completely rule out some drizzle at times though.

The weakening sfc low/light winds along with dwpnts rising into the
middle 30s advecting across the melting snowpack will result in more
fog tonight into Sunday morning. Already extended the dense fog advy
til midday Sun and will go ahead and expand it into the western U.P.
as well since the downslope flow that saved that area from the dense
fog last night is not as strong and dwpnts will be higher. N to NW
winds increase on Sun aftn over west cwa as sfc low lifts across Lk
Superior so should see vsby begin to improve some by that time.

.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 PM Lake Superior forecast issuance)
Issued at 211 PM 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.
Expect NW winds to increase to 25 kts by middle of next week as
low pressure over the central Plains moves toward eastern Canada.

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

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



LONG TERM...Ritzman
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