Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 221154

Area Forecast Discussion
National Weather Service Marquette MI
654 AM EST Sun Jan 22 2017

.SHORT TERM...(Today and tonight)
Issued at 454 AM EST SUN JAN 22 2017

WV imagery and RAP analysis indicated a shortwave trough over
western Lake Superior that was slowly lifting to the north. Most of
the rain associated with this feature had lifted to the north of
Lake Superior. However, radar still indicated some isolated light
rain showers or drizzle over the west half of Upper Michigan.
At the surface, low pressure was located central Upper michigan.
With light winds and abundant low level moisture over the melting
snow, areas of dense fog (vsby aob 1/4sm) persisted over much of the

Today, large scale subsidence with 700-300 mb qvector div will
dominate today as the shrtwv lifts to the north. So, mainly patchy
drizzle is expected with isolated showers over the west. With only
weak winds or advection, areas of dense fog are expected to persist
through this morning until marginal sfc heating brings some
improvement. Some weak dry advection should move in later this
afternoon as wrly flow develops as the low moves off to the north.
Thick clouds will again limit highs to the upper 30s.

Tonight, diurnal cooling will favor redevelopment of dense fog.
However, confidence is not as high for widespread dense fog as the
slightly drier air moves into the area. Dry mid levels and lack of
ice nuclei will limit pcpn to patchy drizzle. With temps falling at
or slightly below freezing over the west, some -fzdz may also

.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 12Z TAFS through 12Z Monday morning)
Issued at 654 AM EST SUN JAN 22 2017

A good deal of low level moisture and light winds over a melting
snow pack will result in LIFR/VLIFR conditions at all the TAF
sites through at least this morning. There will be some
improvement this afternoon as a wind shift to the nw draws a bit
drier air into the area, but overall conditions are likely to rise
no hier than IFR. LIFR to VLIFR conditions wl likely return in the
evening with some nocturnal cooling.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 454 AM EST SUN JAN 22 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 Northerly winds to increase to 25 kts by middle of the 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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