Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KMQT 131135

Area Forecast Discussion
National Weather Service Marquette MI
735 AM EDT Tue Mar 13 2018

.SHORT TERM...(Today and tonight)
Issued at 448 AM EDT TUE MAR 13 2018

Water vapor imagery and RAP analysis show a broad mid-level low
centered just e of Lake Superior. One shortwave that dropped across
western Upper MI earlier in the night provided a burst of lake
enhanced snow to nw and n central Upper MI. Since then, traditional
LES has been slow to organize, likely due to the marginally cold air
mass and well-mixed boundary layer that is more typical of this time
of year. Much of the shsn activity has been pinned to the high
terrain where uploping aids development. With KMQT radar showing
reflectivities of +28dbz, the shsn just w of the office into the
Michigamme Highlands/Huron Mtns has been fairly hvy, probably on the
order of 1in or so per hr. Fairly hvy shsn have also been impacting
Alger County due to more focused convergence resulting from n winds
over s central Lake Superior and ne winds over eastern Lake
Superior. These shsn are also streaming well inland, down to US-2.
Over the w, impact of drier air in the low levels has been more
difficult to overcome, resulting in shsn that are lighter/less
widespread. Very recently, satellite and radar imagery show LES
beginning to increase over Lake Superior as another shortwave and
850mb thermal trof of -16 to -18C approach. This increase of LES is
also evident over western Lake Superior where band of
clouds/moisture streaming s from northern Ontario is combining with
approaching thermal trof to generate increasing shsn in that area as

Expect LES to continuing increasing over the next several hrs as
850mb thermal trof arrives. Shortwave will also briefly aid the
shsn. Biggest concern early this morning is the convergent band
streaming onshore and impacting Alger County in the area roughly
btwn Munising and Shingleton. Given the +28dbz echoes embedded in
the band, which translates to at least 1in/hr snowfall rates,
localized warning criteria snowfall may be achieved this morning if
the band shifts very little and maintains intensity. From this band,
a few inches of snow could also accumulate well inland toward US-2
around Cooks. Otherwise, generally expecting 2-4 inches of
additional snow this morning across Marquette/Alger Counties with
locally higher amounts. Across the w, expect 1 to 3 inches of snow.
As 850mb thermal trof departs and heights begin to rise, LES should
quickly diminish this aftn. This diminishing trend will be further
aided by daytime heating disrupting lake effect processes. By late
aftn, clouds will likely be clearing out over the w.

A few light shsn/flurries may linger this evening over the eastern
fcst area under 850mb temps around -14C. Continued waa will bring an
end to any lingering flurries by late evening, if not sooner.
Otherwise, expect clearing skies with winds diminishing to
light/calm as sfc high pres ridge moves across the area. Model fcst
soundings suggest WAA pattern may lead to some high clouds spreading
across the area during the night. Still, expect good radiational
cooling conditions across the interior central where winds will
remain light thru the night. Favored bias corrected CMC guidance for
mins due to the normally superior peformance on radiational cooling
nights. Traditional cold spots should drop well down into the single
digits to near 0F.

.LONG TERM...(Wednesday through Monday)
Issued at 438 AM EDT TUE MAR 13 2018

Fairly quiet weather expected through much of the extended forecast
with only a couple chance of light lake effect snow Wednesday night
through Thursday night.

Wednesday through Thursday night: A couple quick moving shortwaves
will slide through the area Wednesday night into Thursday morning
and then again late Thursday afternoon into Thursday night. This
will give a couple periods of increased lake effect snow showers
across the north central and eastern U.P. on a quick shift back to
north to northwest winds. 850mb temperature are progged to drop into
the 14C to -18C range as the shortwaves rotate through the U.P.,
which will create favorable delta-T values to support lake effect
snow. Moisture profiles do not look overly impressive, with only a
small portion of the moisture nosing into the DGZ; therefore,
overall snowfall totals are expected to remain light to moderate as
SLRs remain in check. For locations outside of the north to
northwest wind snowbelts, little to no snow is expected, and many of
those locations will likely see sunshine. Temperatures will
generally be near to slightly above normal for this time period.

Friday and Saturday: A surface ridge and weak upper level ridge are
progged to slide across the Upper Great Lakes through this time
period. This will bring mostly clear skies to the area under light
winds. As temperatures warm aloft and ample sunshine is in place,
look for high temperatures to warm above normal Friday into Saturday
with most locations seeing highs in the upper 30s to possibly even
low to mid 40s by Saturday afternoon.

Sunday through Tuesday: There are no indications of any major
weather impacts during this time period. Its possible that a couple
weak systems could brush to the south of the area during this time;
however, there is little agreement among the models at this point.
Will stick with a consensus of the models keeps most of the area
dry, with only a small chance of precipitation Sunday into Sunday
night. Otherwise, near to slightly above normal temperatures can be

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 735 AM EDT TUE MAR 13 2018

Lake effect snow showers will continue this morning, then rapidly
diminish during the aftn. Expect mostly MVFR conditions at
KIWD/KCMX/KSAW this morning with brief periods of IFR. Will probably
see some VFR as well. As -shsn end during the aftn, KIWD/KCMX will
improve to VFR. May not be until evening that KSAW improves to VFR.
VFR conditions will then prevail at all terminals tonight.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 448 AM EDT TUE MAR 13 2018

For the remainder of this week, the strongest winds across Lake
Superior will occur this morning and also Wed night thru Thu
evening. During these times, winds will be mostly in the 20-30kt
range, strongest over the e half of the lake. No gales are expected.

Upper Michigan...
  Winter Weather Advisory until 5 PM EDT this afternoon for MIZ005-

Lake Superior...
Lake Michigan...


SHORT TERM...Rolfson
MARINE...Rolfson is the U.S. government's official web portal to all federal, state and local government web resources and services.