Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 220843

Area Forecast Discussion
National Weather Service Marquette MI
343 AM EST Sun Jan 22 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...(Monday through Saturday)
Issued at 343 AM EST SUN JAN 22 2017

A shortwave moving through from the south late Mon into Mon night
will lead to a fairly narrow band of precip over eastern Upper MI
Mon afternoon into Mon night. Precip should start as rain then
gradually transition to snow, with a wintry mix in between. Tricky
event as exact placement of the narrow band is in question, as are
QPF amounts and ptype. Depending on these factors, could see low end
advisory level impacts, but it remains too uncertain to get that
specific at this point.

Next system to move through will be on the leading edge of a big
pattern change. A shortwave will move through the area as upper
toughing shifts from the western CONUS to the eastern CONUS. The
shortwave is currently off the Pacific Coast, so there is quite a
bit of uncertainty. As the shortwave passes, if it move farther
north like the GFS and ECMWF suggest, snow will move in from the SW
late Tue and continue into Thu before transitioning to LES with the
colder air that moves in. The NAM and GEM are farther S and leave
the CWA dry for the most part. Let the blends handle most details
with this system, which is currently forecast to bring 1-2 inches of
snow to the U.P.

More normal conditions with cooler temps and NW wind LES are then
expected through the rest of the week. Even so, 850mb temps will not
be all that cold, so LES is not expected to be heavy in most areas.
Blends handled the extended quite well, so made few changes.

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1247 AM EST SUN JAN 22 2017

A good deal of llvl mstr/light winds over a melting sn pack wl
result in LIFR/VLIFR conditions at all the TAF sites thru at least
this  mrng. There wl be some improvement on Sun especially at IWD as
a wshft to the nw draws a bit drier air over that site, but overall
conditions are likely to rise no hier than IFR. LIFR to VLIFR
conditions wl likely return in the evng with some nocturnal cooling.

.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/ this afternoon for

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



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