Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 132018

Area Forecast Discussion
National Weather Service Marquette MI
318 PM EST Fri Jan 13 2017

.SHORT TERM...(Today and tonight)
Issued at 431 AM EST FRI JAN 13 2017

Today: Low pressure will continue to slide off through Quebec as
high pressure builds in from the Northern Plains. This morning,
winds ahead of the approaching high and behind the departing low
will be gusty out of the northwest before slowly shifting to the
west and then southwest by mid afternoon. The northwest flow, along
with 850mb temperatures between -16C and -18C, will be sufficient to
keep lake effect snow going for those favored areas this morning;
however the wind shift this afternoon will allow the lake effect
snow to will shift most of the lake effect snow over Lake Superior
and perhaps the tip of the Keweenaw. As the winds shift, the
pressure gradient will continue to relax, allowing winds to steadily
decrease through the afternoon hours. Temperatures will be below
normal with most locations over the western U.P. remaining in the
single digits above zero, while eastern location remain in the low

Tonight: The surface ridge will be directly overhead during the
evening hours before shifting off to the east overnight. The main
impact that this will have on the area will be mainly clear skies in
the evening, which may allow temperatures to drop fairly quick,
before slowly rebounding as the high edges farther to the east and
winds/clouds increase from the south. The southerly winds will help
to keep most of the lake effect snow over Lake Superior, but it is
not out of the question that the tip of the Keweenaw could see some
light lake effect snow. Otherwise, expect it to be a very quiet and
cold night.

.LONG TERM...(Saturday night through Friday)
Issued at 318 PM EST FRI JAN 13 2017

Sat night thru Sun night...High pres is fcst to build over the Upper
Lakes, bringing a period of dry wx. With flow becoming more zonal
across Canada and the northern CONUS, the air mass will moderate as
850mb temps rise from around -7C Sat evening to around 0C by Mon
morning. Under light/calm wind and mostly clear skies, favored the
low end of guidance for min temps Sat night. Looks like this will be
the last night of subzero temps in the western and central interior
for quite a while as it appears the warm pattern will persist thru
late month as noted on the CPC and CFSv2 outlooks which maintain a
positive height anomaly centered in the vicinity of Hudson Bay thru
late month. Under sunny skies Sun, max temps should rise to the
mid/upper 20s, perhaps above 30F in a few spots.

Vigorous shortwave currently dropping s thru CA will lift ne in a
much weaker state early next week, reaching the Great Lakes region
on Tue. The Canadian models and especially ECMWF are more aggressive
with warming ahead of this system than the GFS, suggesting a
potential wintry mix at the onset (late Mon/Mon night) changing to
more rain on Tue. The ECMWF shows more pcpn as well, on the order of
1/3 to 3/4 of an inch. Majority of ensembles and operational model
trends support a warmer look, but probably not to the degree of the
00Z/12Z ECMWF which raises 850mb temps to +4-6C over much of the
area for Tue. At this point, plan to carry a wintry mix, spreading N
Mon aftn/night with a change over to mainly rain on Tue. Pcpn may
end as -sn or -sn/-ra mix Tue night.

Mostly dry weather and well above normal temps should prevail for
the last half of the work week as broad ridging remains in control.
Weak disturbances rippling through the ridge should have little
impact given expected dry airmass in place. If any pcpn does occur,
it should be on the light side.

Late in the week, models fairly consistent showing mid-upper trough
amplifying over the western CONUS, resulting in a deep southerly
flow and unseasonable warmth into the Great Lakes for the weekend.
Whatever shortwave emerges from the trough, it looks like the
associated sfc low will track west of the region resulting in a
period of rain for the area next weekend. Some thunder may even be
possible for next Saturday if some of the more amplified solutions
are on the right track as both the operational ECMWF and GFS
indicate negative Showalter indices.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1243 PM EST FRI JAN 13 2017

IFR conditions at KIWD and KSAW.

At KCMX, expect lake effect to clear out of the next few hours.
Conditions will then go IFR for a time before a trough moves through
that will bring snow and lowered CIGs back tomorrow morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 431 AM EST FRI JAN 13 2017

Expect northwest winds to steadily decrease this morning as the
tighter pressure gradient, between low pressure to the east and high
pressure to the west, begins to relax. Heavy freezing spray will be
possible this morning before the winds and waves decrease, so the
heavy freezing spray warning continues into the morning hours. The
pressure gradient will increase once again tonight, between a low
pressure crossing Ontario and the high pressure system moving to the
east of the area tonight, expect southwest winds to increase up to
30 kts and then shift to the west following a low pressure trough
passage on Saturday. There may be a few gale force gusts tonight
into Saturday morning; however, the coverage of these stronger gusts
are expected to be limited. High pressure will then build back into
the area Saturday afternoon into Sunday and possibly even linger
into Monday, allowing winds to diminish under 20-25 kts. An area of
low pressure will approach the Upper Great Lakes Tuesday and move
through Tuesday night; however, the system is not expected to be too
strong, so winds are expected to remain at or below 25 knots through
this time period.

Upper Michigan...
Lake Superior...
Lake Michigan...


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