Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 151130

Area Forecast Discussion
National Weather Service Marquette MI
630 AM EST Wed Feb 15 2017

.SHORT TERM...(Today and tonight)
Issued at 415 AM EST WED FEB 15 2017

The main weather impacts in the short-term will be the slowly
diminishing lake effect snow along with slowly decreasing winds
throughout the day. The winter weather advisory will continue
through 7 am due to the combination of gusty winds and continued,
mainly light snow. The wind gusts will steadily diminish along with
snowfall intensity; therefore, there is no reason to extend the

Today: Surface low pressure will continue to shift to the east and
southeast of the area today, which will keep northwesterly flow over
much of the area. Overall, the deeper moisture will exit with the
departing low; however, the  flow across the longer fetch of eastern
Lake Superior will allow lake effect snow to continue as 850mb
temperature only modify to around -15C over the eastern portions of
the U.P. Inversion heights are expected to slow trend downward
throughout the day, to around 3 to 4kft by late this afternoon.
850mb temperatures over the western portions of the U.P. will warm
to around -10C, which will allow any lake effect snow to diminish to
very light snow or flurries at best. Generally expecting only a
couple additional inches for areas from Munising and east near Lake
Superior. Blowing snow will also be an issue near Lake Superior
through early afternoon as the pressure gradient slowly relaxes
across the area. Otherwise, clouds will likely linger over most
areas along Lake Superior, while south central locations may see
some sunshine breaking out on downsloping winds. This will also help
temperatures to remain a bit warmer in the clearing areas as well,
probably in the mid to upper 20s, while other locations will be in
the upper teens to low 20s.

Tonight: 850mb temperatures are progged to remain around -13C to -
15C over the eastern portions of the U.P. tonight, which will help
to keep continued, very light lake effect snow going across the
eastern U.P. The chilly 850mb temperatures in place will be
partially in response to another quick moving shortwave progged to
slide through during the evening hours over the east. Western
portions of the U.P. will be influenced by approaching high
pressure, which will allow the lake effect to completely end over
the western half of the area. Not really expecting much more than an
inch or so of accumulation over the east as inversion heights
continue to decrease to around 3kft. Again, there will probably
continue to be lake effect cloud cover along Lake Superior, with
clearing possible over the south central locations. Where skies
clear, temperatures will likely fall into the single digits above
zero, while the cloudy locations will only fall into the low to mid

.LONG TERM...(Thursday through Tuesday)
Issued at 311 AM EST WED FEB 15 2017

Nam shows a 500 mb ridge over the Rockies 12z Thu that moves into
the northern Plains 00z Fri. This ridge moves into the upper Great
Lakes on Fri and Fri night. Basically, pretty quiet for this
forecast period.

In the extended, GFS and ECMWF show a closed 500 mb low over the
southern plains 12z Sat with a shortwave over the upper Great Lakes.
A 500 mb ridge moves into the plains 12z Sun and this ridge moves
into the upper Great Lakes on Mon. A shortwave moves into the upper
Great Lakes Mon night with more shortwave energy moving into the
area for Wed. Temperatures will be above normal for this forecast
period and the pcpn will be mostly rain for late Mon into Mon night.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 629 AM EST WED FEB 15 2017

A cold air mass flowing across Lake Superior will yield MVFR
ceilings at KIWD/KCMX/KSAW through early this afternoon, influx of
drier air will result in diminishing -shsn that will be affecting
mainly KCMX/KSAW. Visibility will mainly be in the MVFR range in the
snow showers that do impact the TAF sites; however, BLSN at the KSAW
TAF site may cause visibility to drop a bit lower at times this
morning with gusty winds. As drier air continues to push into the
area this afternoon, -shsn will diminish and/or end. While KIWD
should break out to VFR this afternoon through Thursday morning,
MVFR cigs will likely persist at KCMX/KSAW through much of the TAF

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 415 AM EST WED FEB 15 2017

Gales to 35 knots will continue over the eastern half of Lake
Superior through much of the morning hours before the pressure
gradient decreases through the afternoon as low pressure slides
farther away from the area. Since colder air will continue to filter
into the area, heavy freezing spray warnings will continue through
late this afternoon for central and eastern Lake Superior. Winds
will remain below. Winds through the weekend will remain at or less
than 20 knots as the pressure gradient remains week across the area
in the absence of any major pressure systems.

Upper Michigan...
  Winter Weather Advisory until 7 AM EST this morning for MIZ006-

Lake Superior...
  Heavy Freezing Spray Warning until 1 PM EST this afternoon for

  Gale Warning until 9 AM EST this morning for LSZ266-267.

  Gale Warning until 7 AM EST this morning for LSZ265.

Lake Michigan...


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