Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 151131

Area Forecast Discussion
National Weather Service Marquette MI
631 AM EST Mon Jan 15 2018

.SHORT TERM...(Today and tonight)
Issued at 450 AM EST MON JAN 15 2018

...Moderate to heavy lake effect/enhanced snowfall potential
downwind of Lake Michigan this morning and then downwind of Lake
Superior late this afternoon through tonight...

Today: A surface low, centered over central and southern WI, is
continuing to allow southerly flow across Lake Michigan this
morning. This, along with an upper level closed low, is continuing
to provide support for lake effect/enhanced snow downwind of Lake
Michigan. 850mb temperatures are running around -14C to
-16C, which is cold enough for lake effect/enhancement. Radar
continues to show the very strong lake effect/convergence band
running from the Door Peninsula northward into Delta and far western
Schoolcraft county this morning. Some the heavier snow is even
making it into portions of Alger County. By mid to late morning and
into the afternoon hours, the aforementioned surface low is progged
to shift over southern Lower Michigan, which will allow easterly
flow to develop across all of the CWA. This will shift the lake
effect/enhanced bands to easterly wind favored snow belts over the
north central U.P. and Keweenaw off Lake Superior and south central
U.P. off Lake Michigan. South central will continue to see the
Winter Weather Advisory through this afternoon, while the north
central U.P. will see the Winter Weather Advisory come into effect
this evening as winds shift more northeasterly. Inversion heights
will continue to be around 10kft as the upper level low slides
overhead with fairly deep moisture lingering in the DGZ. This will
help to boost SLRs for the favored snow belts. The better system
forcing will exit to the east of the area; however, overwater
instability and upslope flow will allow for some heavier snowfall to
continue south central and develop over the Keweenaw and north
central U.P.

Tonight: As the surface low continues to shift off to the east,
winds will back from the east to northeast across the area. This
will effectively end any lake effect/enhancement off Lake Michigan;
however, lake effect snow will increase downwind of Lake Superior.
The increased upslope flow over the north central U.P. along with
the increased fetch on north to northeasterly winds will allow for a
period of heavier lake effect snow this evening into Tuesday
morning. 850mb temperatures will cool further, to around -16C to -
18C, with inversion heights around 8kft - 10kft, which will continue
to be favorable for lake effect snow. Locations over the higher
terrain could end up seeing totals approaching 8 inches by the time
the snow tapers off Tuesday morning.  Again, the high terrain would
see the heaviest totals as better upslope/convergent signatures are
showing up over those areas. This has led to the issuance of a
Winter Weather Advisory for both Baraga and Marquette counties
tonight through Tuesday morning. Wouldn`t be out of the question to
see a few warning snowfall totals in the highest terrain of
Marquette and Baraga Counties as well. As winds shift to the north
and northwest, the western U.P. will also see some lake effect snow;
however, the wind shifts look to occur quick enough that the more
focused bands should be transient enough to keep snowfall totals in
check, generally in the 3 to 6 inch range in a 24 hour period.
Again, similar to the north central, the heavier snowfall totals can
be expected over the higher terrain.

.LONG TERM...(Tuesday through Sunday)
Issued at 501 AM EST MON JAN 15 2018

Attention is on Tue morning when a quick round of lake effect snow
will result from onshore/upslope NE-N flow. Wind directions back
quickly to the NW by mid afternoon and W by evening, so favored
conditions won`t persist in any one area too long. Could see 1-3
inches of additional snow Tue over the N-central, and 1-2 inches
over the far W. Combined with amounts from Mon night (see short term
discussion), totals are in the 4-8 inch range over the N-central and
3-6 inch range over the far W.

Otherwise, will see a warmup starting Wed with highs in the 30s on
Thu through Sat and possibly into Sun. No significant precip is
expected through the rest of the forecast period. Possibly looking
at something more significant early next week, but there is far too
much uncertainty at this point to get into details.

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 631 AM EST MON JAN 15 2018

Conditions at all the TAF sites will alternate between MVFR and IFR
in light snow through this morning. LIFR visibilities will be
possible at KCMX this afternoon and evening when winds become
easterly bringing lake enhanced snow into the terminal. Winds will
turn northeast late this evening allowing persistent IFR conditions
in lake enhanced snow to develop at KIWD and KSAW into early Tuesday

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 450 AM EST MON JAN 15 2018

As low pressure tracks southeast of the area across Wisconsin and
southern Lower Michigan winds are expected to be in the 20 to 30
knot range through tonight. There may be a brief period of gales
or gale force gusts to 35 knots over the west half of Lake
Superior as funneling occurs on northeasterly winds. This would
be mainly during the evening hours. Only moderate freezing spray
is expected through the first half of the week. Tuesday through
the end of the week, expect winds to remain between 20 to 30 knots
with a chance for gales Wednesday.

Upper Michigan...
  Winter Weather Advisory until 9 AM EST this morning for MIZ006-

  Winter Weather Advisory from 7 PM this evening to 1 PM EST
     Tuesday for MIZ004-005.

  Winter Weather Advisory until 6 PM CST this evening for MIZ011-

  Winter Storm Warning until 4 PM EST this afternoon for MIZ013.

Lake Superior...
Lake Michigan...


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