Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 252022

Area Forecast Discussion
National Weather Service Marquette MI
322 PM EST Sat Feb 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 322 PM EST SAT FEB 25 2017

Upper air pattern consists of a 500 mb trough over the lower Great
Lakes this morning and a shortwave in the Canadian prairies. The
trough will continue to move away from the area and this shortwave
will head southeast and affect the area late tonight into Sun. Nam
shows some 850-500 mb q-vector convergence along with deeper
moisture moving through the area on Sun before moving out by Sun
evening. GFS and ECMWF are similar with the 850-500 mb q-vector

Going forecast has things well in hand. Did not make too many
changes to the going forecast. Lake effect snow continues to wind
down with temperatures still staying cold enough for lake effect
snow for this forecast period. Only thing is winds back to the wsw
and this would put the Keweenaw peninsula into play with several
inches of snow possible late tonight into Sun with convergence and
lake enhancement helping to focus a band across that area. This
would be where the heaviest snow will fall with up to 4 inches in 18
hours. Could be a little lake enhancement from Lake Michigan with a
southwest wind and could see 2 inches of snow there. Did not make
too many changes to temperatures either.

.LONG TERM...(Sunday through Friday)
Issued at 511 AM EST SAT FEB 25 2017

Models suggest that a progressive pattern will prevail through
next week which will bring several rounds of precipitation into
the northern Great Lakes. Colder weather will move in toward the
end of the week as a mid/upper level trough shifts from the north
central CONUS into the Great Lakes and northeast.

Sunday into Sunday night, a mid level shortwave trough and weak sfc
front will move through Lake Superior and Upper Michigan bringing a
period of snow showers to the CWA. With only moderate 700-300 mb
qvector conv and limited moisture inflow, any accumulations will
only amount to around an inch in most locations. Expect likely POPs
into the nw CWA during the morning shifting to the east in the
afternoon. Westerly flow with 850 mb temps around -11C, the Keweenaw
should see potential for higher lake enhanced totals to near 3
inches. Some light lake effect snow showers may linger into the
evening over the Keweenaw and east of Munising.

Monday, WAA ahead of the next trough will boost temps into the mid
30s under partly to mostly cloudy skies.

Tuesday into Tuesday night, as southwest mid/upper level flow
develops ahead of a trough into the wrn CONUS, the models have been
consistent in bringing a shortwave, bands of fgen, and an
associated sfc low/wave toward the nrn Great Lakes. However, there
has been considerable variability with the strength/timing/location
of this feature. However, it should be strong enough to support
QPF at least into the 0.25 to 0.50 inch range. Precipitation type
also remains uncertain. Wet-bulb zero heights favor mainly snow
over the northwest and a mix or mainly rain changing to snow over
the southeast half as highs climb into the upper 30s in most area.
For now, both rains/snow will be mentioned. If the cooler
scenario occurs, several inches of snow will be possible.

Wednesday-Saturday, clipper shortwaves may affect the region in the
developing nw mid/upper level flow. Confidence is higher that enough
cold air will slide into the area for increasing nw flow LES from
late Thursday into Friday. A stronger Pacific shortwave and sfc
moving toward Manitoba will bring increasing WAA Saturday with a
chance of snow ahead of an advancing warm front.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1215 PM EST SAT FEB 25 2017

The aprch of a high pres rdg/drier llvl air wl result in improving
conditions at all sites. The gusty winds wl slowly diminish by later
today with the aprch of the rdg/weaker pres gradient. Another system
will bring in light snow late tonight into Sunday. Have began to
highlight this system by bringing in lower vsby at CMX and IWD. Best
chance of IFR vsby will be at CMX with w winds and lingering cold
air providing some lake enhancement.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 322 PM EST SAT FEB 25 2017

NW gales to 35 knots are expected over the east half of Lake
Superior into this evening. Winds will stay 25 kts or less through
Sun and then increase to 30 knots Sun night behind the next system
that moves through on Sun. Winds will become NE to 30 kts Tue night
into Wed behind another low pressure system crossing Great Lakes.
Winds diminish to 25 kts or less into Thu as the low moves toward
New England and a high pressure ridge builds from western Canada to
the central Conus.

Upper Michigan...
  Winter Weather Advisory until 7 PM EST this evening for MIZ006-

Lake Superior...
  Gale Warning until 10 PM EST this evening for LSZ265>267.

  Gale Warning from 7 PM to 10 PM EST this evening for LSZ264.

Lake Michigan...


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