Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 282342

Area Forecast Discussion
National Weather Service Marquette MI
642 PM EST Tue Feb 28 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 355 PM EST TUE FEB 28 2017

WV imagery and RAP analysis indicated a mid/upper level trough over
the wrn CONUS with several weak shortwaves embedded in the wsw flow
toward the nrn Great Lakes. A shortwave and area of 850-700 mb fgen
is supporting a band of light snow from cntrl mn into western Lake
Superior. Another shortwave to the se and assoc isentropic ascent
was producing shra and a few tsra over central Lower Mi. Over Upper
Mi, a trough/cold front has moved through wrn Upper Mi into ncntrl
Upper Mi, and this trough/front will continue to progress e through
the rest of Upper Mi this evening.

Tonight, the fgen band should support some light snow over the west
and into the east overnight as the colder air moves in. Dry air in
mid-levels in ice nucleation region could also support some frdz
this evening in the west and especially ncntrl Upper Mi where
upslope nne flow will enhance lift. A strengthening gradient between
low pres into lower Michigan and high pres over nrn Ontario will
result in a stiff nne wind into the region. 850 temps in the -4C to
-8C will be marginal for lake enhanced snow but with strong upslope
flow some light accumulations of 1 to possibly 2 inches can be
expected in the higher terrain of north central and far west Upper

On Wed, shortwave now in the base of wrn conus trough will be
lifting ne into Lower Mi late tonight and then another shortwave
from the Central Rockies associated with the mid-level trough axis
will follow later in the day on Wed strenghtening the associated sfc
low moving through Lower Mi. Mid-level q-vector convergence and fgen
associated with the shortwave and the deepening sfc low track could
support an inch or two of light snow to southeast portion of the
cwa. Some light lake effect could linger over north central cwa with
NNE winds and shallow moisture to near 2kft with temps of -11c to -
12c. Otherwise expect only a dusting of system elsewhere.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 402 PM EST TUE FEB 28 2017

The main weather concerns in the extend forecast will be the
potential for light lake effect snow for north to mainly northwest
wind snow belts Wednesday night through early Friday morning. Then
attention turns to well above normal temperatures for the upcoming

A surface low pressure sytem will continue to slide off to the east
of the U.P. Wednesday night through Friday morning. At the same
time, high pressure will beging to slide toward the Upper Great
Lakes region from the Northern Plains. Aloft, broad troughing will
remain in place across the area. The cooler air aloft, associated
with the trough, and the north to northwesterly flow off Lake
Superior will allow for light to occasionally moderate lake effect
snow for the aforementioned snow belts. The best potential for
seeing an increas in coverage/intensity of lake effect snow would be
Wednesday night into Thursday morning and again Thursday night into
Friday morning. This will be due, in large part, to shortwave energy
rotating through the area. Generally expecting about 1 to 3 inches
in the aforementioned snow belts with locally higher totals
approaching 5 inches under any focused banding.

The aforementioned high pressure ridge will slide across the area
Friday afternoon into Saturday morning, allowing conditions to
become fairly calm, with little to no chance of precipitation.

Saturday and Sunday the high pressure ridge will shift east of the
area as a low pressure system organizes across central Canada,
allowing for stronger southerly flow between the two. A warm from is
progged to approach/slide thorugh the CWA Saturday night into Sunday
morning, which will allow for light precipitatioin to develop across
the area. This will be around the same time that a shortwave slides
in aloft. At this point, the soundings would indicate mainly rain,
with possibly a mix of freezing rain and snow late Satuday night
into early Sunday morning. With enough variance in the models have
decided to stick with a rain and snow mixture. The upper level
ridging increase for Sunday with continued southerly flow. This
combination along with clearing skies could allow temperatures to
warm as high as the upper 40s to possibly even 50 degrees by Sunday

Early next week, Monday and Tuesday, models continue to advertise a
strong low pressure system sliding through the Upper Great Lakes
region; however, there is little agreement on exact placement of the
surface low and upper-level features. The GFS takes the low
northwest of the area keeping temps warmer with more rain, while the
EC take sthe low across the central U.P., allowing for mixed
precipitation and colder air. The 12Z Canadian takes the low even
farther south and east the EC, across southern lower Michigan,
making the system even colder with less precipitation. All of the
model disagreement has led to a consensus of the model blends with
rain trending toward a rain/snow mixture by Tuesday. Again, little
confidence in this portion of the forecast.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 641 PM EST TUE FEB 28 2017

Expect LIFR to IFR conditions to predominate most of the night with
some light mixed pcpn changing to sn with the arrival of colder near
sfc air on the heels of incrsg nne winds. CMX has the best chc to
see some MVFR conditions at times as the llvl nne flow wl present
less of an upslope component at that site. The sharper upslope wind
at SAW wl hold in the lower cigs/vsbys there longer. Conditions on
Wed should improve slowly into the MVFR range at all locations as
drier air air moves into the area as well. Expect CMX and IWD to see
VFR wx during the aftn. The lower conditions wl linger longer at SAW
with a sharper upslope wind component farther fm the dry air source.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 355 PM EST TUE FEB 28 2017

Light winds less than 20 kts to start the day but winds ramp up
quickly this aftn to 30-35 kts as low pressure system moves toward
western Great Lakes. As the low crosses the central and lower Great
Lakes into Wed and a high pressure ridge moves across northern
Ontario, expect NE gales 35-40 kts over much of the lake Tonight
with gales continuing over eastern sections on Wed morning. Winds
will then remain below 30 knots through the rest of the forecast
period. Heavy freezing spray is expected tonight into Wed,
especially for north central portions of the lake.

Upper Michigan...
Lake Superior...
  Gale Warning until 1 PM EST Wednesday for LSZ265>267.

  Heavy Freezing Spray Warning from 1 AM to 1 PM EST Wednesday for

  Gale Warning until 7 AM EST Wednesday for LSZ263-264.

Lake Michigan...
  Dense Fog Advisory until 1 AM EST Wednesday for LMZ248-250.



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