Area Forecast Discussion
Issued by NWS Marquette, MI

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154
FXUS63 KMQT 262024
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
324 PM EST Sun Feb 26 2017

.SHORT TERM...(This evening through Monday)
Issued at 315 PM EST SUN FEB 26 2017

Upper air pattern consists of a 500 mb trough over the upper Great
Lakes this morning that will move through today. This will bring
some light snow through the area through this afternoon and then the
snow moves out by evening. Nam shows some 850-500 mb q-vector
convergence and deeper moisture moving through the area through mid
afternoon before both exit by evening. Both return on Mon with the
deeper moisture staying to the north of the area. Overall, pretty
quiet this forecast period. The snow will be moving out rapidly
early this evening and there could be some light lake effect snow
showers overnight in the keweenaw and east of Marquette, but
inversion heights are really low and very dry air is in the low
levels overnight. Lowered low temperatures a bit tonight with light
winds and clear skies which will allow some good radiational cooling
to take place.

.LONG TERM...(Monday night through Sunday)
Issued at 324 PM EST SUN FEB 26 2017

Looking ahead to next week, still expecting a fairly active weather
pattern with a lead shortwave expected to lift across the area ahead
of a deep, longwave trough towards the middle of next week. As the
longwave trough axis traverses the region and resulting northwest
flow lingers through the end of the week, expect embedded shortwaves
to move across the area bringing additional chances for
precipitation, especially in the northwest wind snow belts where LES
is expected to linger from the middle to end of the week.
Temperatures will be on a roller coaster, starting about 10 degrees
above normal then dropping down into the lower 20s and upper teens
by Friday, with rebounding back into the 30s through the weekend.

As warm air advection lifts across the area on Tuesday, widespread
precipitation will be possible across Upper Michigan. With a nose of
warm air aloft coming overhead, initially there may be a period of
freezing rain across central portions of the area early on Tuesday
before transitioning over to rain. The better deep moisture does not
look to arrive across the east until surface temperatures will be
above freezing, but still could see some freezing drizzle/drizzle
develop across the east before transitioning over to rain. This warm
air advection aloft will meet cold air advection dropping south from
Canada, allowing for a fairly stout low to mid-level baroclinic zone
to develop in between northern Minnesota and western portions of
Upper Michigan. Models have been consistent hitting the QPF rather
hard over this area given the potential for the development of
convective banding. With an inverted surface trough spanning the
Keweenaw and further south into northern Wisconsin, expect the focus
for precipitation to remain across the far west and the Keweenaw.
Expect precipitation to start off as snow and then possibly mix in
with rain and/or transition over to all rain during the afternoon
hours. Expect SLRs to be rather low, so minimal accumulations are
expected at this time, but expect snow to be wet and slushy. During
the late afternoon/evening hours, as shortwave energy lifts across
the area, this mesoscale banding of precipitation across far western
portion of the area is progged to lift northeast. This will allow
better cold air advection to lifter south and precipitation to
transition back over to snow from west to east across the area
through the overnight hours into Wednesday. The best chance for
accumulation snow during this time period looks to remain across the
Keweenaw Peninsula and the higher terrain in the northeast wind snow
belts as upslope flow develops. With cold air advection increasing
behind the shortwave, snow should transition from wet and slushy
characteristics to more fluffy, especially across the west as SLRs
will increase towards 15-20:1.

As the lead shortwave lifts across the area, longwave troughing
across the western CONUS will begin to eject out across the central
CONUS allowing a broad area of low pressure to eject out across the
Middle Mississippi River Valley. Although this area of low pressure
looks to remain rather weak, with the Gulf of Mexico progged to be
open well in advance of the longwave trough, ample moisture will be
in place for the system to work with. The GFS continues to be all
over the place with the track of the surface feature with model
trends initially trending slower and further south; however, the
most recent model run tracks the low across the northern Great Lakes
area. Considering the ECMWF has been much more consistent with the
track of this system, keeping the track and much of the
precipitation across southern portions of the Great Lakes, tend to
favor the ECMWF solution at this time. Closer to Lake Superior, with
850mb flow out of the northeast ahead of the system beginning
northwest through the day on Wednesday and into Thursday, with the
arrival of better cold air advection, expect light LES to develop.

On Thursday, much colder air will begin to filter south with 850mb
temperatures progged to drop to around -15 to -18C. Therefore,
expect LES to intensify across the northwest wind snow belts.
Thursday into Friday as upper-level ridging begins to build across
the area, 850mb flow will back to the west allowing LES to
transition from the northwest to west wind snow belts on Friday.
Friday night into Saturday as 850mb flow back southwest and warms
fairly dramatically, this will allow LES to lift north over Lake
Superior.

This weekend a clipper system is progged to drop across the area,
but the GFS and ECMWF disagree on the strength and timing of the
system. The GFS is quite a bit slower than the ECMWF as it lifts
shortwave energy across the area; whereas, the ECMWF digs shortwave
energy much further south. The impacts from this system will depend
on the strength, timing, and track.
&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1223 PM EST SUN FEB 26 2017

Some -shsn wl continue off and on much of the day, especially at
CMX, where vsbys wl end up in the IFR range a good portion of the
time. The best chc for the lower vsbys wl be under more focused shsn
along a lo pres trof that wl move w-e acrs Upr MI in the aftn.
Expect at least a brief period of lower IFR vsby associated with the
heavier sn showers that occur along this trof in IWD and CMX that wl
clr SAW arnd 27/00Z. The arrival of much drier air behind this trof
wl then bring a return of VFR conditions this evng through the
rest of the forecast period.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 315 PM EST SUN FEB 26 2017

Winds will remain 30 kts or less through mid Tue afternoon. There
will be a brief period of gales late Tue afternoon and evening
across the west half of Lake Superior. Winds will then remain below
30 knots through the rest of the forecast period.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...07
LONG TERM...Ritzman
AVIATION...07
MARINE...07



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