Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231939

Area Forecast Discussion
National Weather Service Marquette MI
339 PM EDT Mon Oct 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 323 PM EDT MON OCT 23 2017

Strong storm will continue to develop as phasing of systems
occurs over the area. Closed low over se MO and a shortwave over
the Red River valley of the North will phase together tonight with
two closed lows eventually consolidating into one over the
eastern U.P by 18z Tue to 00z Wed. NAM shows some deeper moisture
coming in from the east along with strong 850-500 mb q-vector
convergence tonight through Tue. GFS shows about the same thing as
well. One new trend from the latest model runs is that the sfc
low is slighly further north and also a bit further east and
rather than set up in northern Lake Michigan, it now comes up from
Lake Huron and makes it about as far west as Newberry. Did not
make too many changes to the going forecast. Winds still look
strong and kept up the high wind warnings and the wind advisory.
Did expand the wind advisory into Iron and southern Houghton
Counties. Kept up the lake shore flood warnings as waves will be
high as well. Could see up to 3 inches of rain out of this system
as well. Snow should not amount to too much as ground is still
warm and will see very little accumulation in the western high
terrain tonight into Tue morning and up to an inch Tue afternoon.

.LONG TERM...(Tuesday night through Monday)
Issued at 338 PM EDT MON OCT 23 2017

Largest impacts from a very strong fall storm will be starting to
diminish at the start of this forecast period Tuesday evening.

The surface low will be somewhere near the Straits of Mackinac at
00Z Wednesday while accelerating eastward. Winds and waves will
quickly diminish through the night, with significant beach erosion
and impact from strong winds ending during the overnight hours.

As the system exits eastward Tuesday night, enough cold air will
advect in behind the low to switch precip over from rain to snow for
the high terrain of the west and north-central. With deeper-layer
synoptic moisture exiting to the east, the extent of precipitation
in the form of snow remains in question. At this time, the best
chance for a few inches of accumulating snow will be across the
Huron Mountains. Given ongoing headlines and high impacts from wind,
have opted to not highlight snow potential outside of the AFD.

A few snow/rain showers will continue into Wednesday as a secondary
weak trough crosses the CWA. Brief ridging will then bring dry
conditions Wednesday afternoon into Thursday morning.

A clipper system will pivot across the Upper MS Valley into the
Upper Great Lakes Thursday afternoon through Friday. While model
guidance differs on the track across Upper Michigan, the air mass
will be cold enough to support several inches of accumulating snow
for at least the interior west Thursday night. A slight shift north
or south in the low pressure track will result in considerable
differences in potential snow, so will continue to follow a middle-
ground approach to the forecast this far out.

Saturday through Monday, a seasonably cold air mass will support a
period of lake effect precipitation, mainly in the form of snow, for
the north to northwest wind snow belts.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 119 PM EDT MON OCT 23 2017

VFR conditions should prevail into this evening at KIWD/KCMX/KSAW.
Powerful storm system lifting n thru Lower MI tonight will spread
rain across the area and lead to the development of strong winds
that should gust to 40g50kt or higher at KCMX/KSAW toward the end of
this fcst period. Conditions will fall to MVFR at KCMX and to IFR at
KIWD/KCMX where winds will be more sharply upsloping.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 323 PM EDT MON OCT 23 2017

A powerful fall storm system will lift n across Lower MI tonight
with sfc low pressure ending up over the far eastern U.P. Tue
morning into the afternoon and get as far west as Newberry. High end
storm force winds will develop over central and eastern Lake
Superior late tonight/Tue morning with high end gales over far
western Lake Superior. Hurricane force wind gusts will likely occur
as well late tonight/Tue morning. Winds will diminish w to e Tue
aftn and Tue night. A short period of light winds under 20kt will
occur on Wed as a weak high pressure ridge arrives. Another strong
low pressure system will impact the Upper Great Lakes late this
week, bringing another round of strong gales late Thu/Fri and could
be some storm force gusts with this event.

Upper Michigan...
  Wind Advisory from 7 AM EDT /6 AM CDT/ to 5 PM EDT /4 PM CDT/
     Tuesday for MIZ010>013-084.

  High Wind Warning from 5 AM to 11 PM EDT Tuesday for MIZ001-003.

  Lakeshore Flood Warning from 6 AM to 11 PM EDT Tuesday for

  Wind Advisory from 7 AM EDT /6 AM CDT/ to 11 PM EDT /10 PM CDT/
     Tuesday for MIZ002-009.

  Lakeshore Flood Advisory from 6 AM EDT /5 AM CDT/ to 11 PM EDT
     /10 PM CDT/ Tuesday for MIZ002-009.

  High Wind Warning from 4 AM to 11 PM EDT Tuesday for MIZ005-006.

  Lakeshore Flood Warning from 5 AM Tuesday to 2 AM EDT Wednesday
     for MIZ005-006.

  Lakeshore Flood Advisory from 5 AM to 2 PM EDT Tuesday for

  High Wind Warning from 7 AM to 5 PM EDT Tuesday for MIZ004.

Lake Superior...
  Storm Warning from 2 AM to 2 PM EDT Tuesday for LSZ250-251-267.

  Storm Warning from 2 AM to 11 PM EDT Tuesday for LSZ249-266.

  Storm Warning from 4 AM to 11 PM EDT Tuesday for LSZ243>248-264-

  Storm Warning from 2 AM EDT /1 AM CDT/ to 8 PM EDT /7 PM CDT/
     Tuesday for LSZ241-242-263.

  Gale Warning from midnight EDT /11 PM CDT/ tonight to 2 AM EDT
     /1 AM CDT/ Wednesday for LSZ162-240.

Lake Michigan...
  Gale Warning from 11 PM this evening to 10 AM EDT Wednesday for



LONG TERM...Kluber
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