Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 142336
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
736 PM EDT Sat Apr 14 2018

.SHORT TERM...(This evening through Sunday)
Issued at 429 PM EDT SAT APR 14 2018

At this point, the only remaining uncertainties to the forecast for
tonight through Monday are the finest of details, such as the timing
of the onset of snow, and just how much will end up blanketing the
area. High confidence exists on close to or more than a foot of snow
falling for much of the forecast area, primarily during the day
tomorrow. One consideration is the possibility of drier air
filtering into the region as compared to what the models are
currently showing, just given the dewpoint depressions currently in
place over much of the U.P. That said though, there is a tight
gradient just over the border in WI, yielding confidence that this
drier air will have no problems eroding and allowing for the
impressive snow amounts to fall as forecast, given the plentiful
availability of moisture transporting in aloft. Regardless of how
much ends up falling, the primary thing to focus on needs to be the
impacts of the combination of the snow and wind falling, which will
create very dangerous travel conditions. It is highly encouraged to
NOT go out and travel in the Upper Peninsula Sunday through Sunday
night.

What the area can expect overnight tonight into tomorrow/tomorrow
night is already being seen across the southern half of MN into WI.
This deformation zone will transition itself into the U.P. as the
well-advertised low pressure system inches closer to the Great Lakes
region. Latest model runs have upped QPF amounts, especially as some
of the higher-res ones key in on the more localized upsloping
effects expected to impact the higher terrain of Marquette into
Baraga counties. Given the winds already seen today, and the
pressure gradient tightening even more so tomorrow, the NE winds
coming off of the nearly ice-free lake certainly looks to enhance
the available moisture in the aforementioned counties, especially in
higher terrain.

What also needs to be mentioned with this spring winter storm is the
potential for mixed wintry precipitation to fall across the eastern
portions of the U.P. later tomorrow into tomorrow night as a warm
nose attempts to nudge its way northward. Model soundings seem to be
wavering back and forth with respect to just how stout of a warm
nose it`ll be for portions of the forecast area. Have gone with
mentioning the possibility of freezing rain mixing in for locations
east of Marquette and Dickinson counties, with little to no ice
accumulations expected, although sleet is not entirely out of the
question, depending on that warm nose. The combination of possible
ice glazing on top of fallen snow overnight Sunday into early Monday
will cause dangerous travel conditions, even given that snow amounts
should end up being much lower in comparison to locations off toward
the west. Again, the focus should not be on amounts so much as the
impacts expected as a result of this dangerous winter storm. Stay
safe.

.LONG TERM...(Monday night through Saturday)
Issued at 411 PM EDT SAT APR 14 2018

...More snow possible midweek then trending warmer by late week...

A very quiet long term, well at least compared to the strong storm
system through will affect Upper Michigan into Mon. On Mon evening,
elongated upper trough will extend from northern Ontario to the
lower Great Lakes on Mon evening while wrapped up sfc low lifts to
northern Georgian Bay. SREF ensembles indicate low could be even
closer to Sault Ste Marie and that would result in stronger north
winds and areas of blowing snow lingering longer near Lk Superior on
Mon night. N-NNW cyclonic flow and deep moisture with H85 temps
around -9c will keep light lake enhanced snow going mainly north
central and northeast forecast area. Lingering snow will diminish
Tue morning and at least all the direct affects from the storm will
finally be done. Depending on how much snow we receive from the
storm, could be still cleaning up in some areas.

Quiet weather Tue/Tue night as upper and sfc ridge cross the area.
Could see temps reach 40F over southern Upper Michigan Tue if there
are enough breaks in the cloud cover. Could see another wave of
maybe moderate to heavy snow for especially south central Upper
Michigan. Timing of main upper level wave and sfc waves driving the
snow is variable with GFS/GEM more progressive and the ECMWF up to
12 hours slower. GEFS more in between. They all agree that a swath
of moderate snow could occur, but those timing differences lead to
chance pops at this point. Beyond that system, nothing too major at
the end of the week. Could see temps begin to warm into the 40s most
areas by next Fri/Sat, which along with the higher sun angle should
help melt off some of our late season snow.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 735 PM EDT SAT APR 14 2018

An incoming complex, strong low pressure system will bring in snow
overnight into Sunday morning dropping conditions to IFR/LIFR
categories and/or minimums for an extended period. Additionally,
already gusty NE winds will see some additional increases in
speeds as the pressure gradient tightens over the region. IWD will
be the first terminal to see reductions in visbys and ceilings
overnight, with CMX and SAW following suit Sunday morning. Look
for VC snow showers later this evening out ahead of the main snow
event.

&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 411 PM EDT SAT APR 14 2018

As a strong low pressure system slides just south and east of Lk
Superior through the weekend, winds will remain strong across Lake
Superior. Gales of 40-45 knots are expected into Sunday night. A few
storm force gusts are possible over far western Lake Superior toward
Duluth. Expect the gales to slowly diminish to 30 kt winds Sunday
night into Monday. Winds for the rest of next week will diminish to
less than 25 kts, though may see a period of winds to 30 kts on Wed
as quick moving low pressure system crosses the Upper Great Lakes.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Storm Warning from 2 AM EDT /1 AM CDT/ Sunday to 8 AM EDT
     /7 AM CDT/ Monday for MIZ001>006-009-084.

  Winter Storm Warning from 2 AM EDT /1 AM CDT/ Sunday to 2 AM EDT
     /1 AM CDT/ Monday for MIZ007-010>014-085.

  Lakeshore Flood Advisory until midnight EDT /11 PM CDT/ Sunday
     night for MIZ001>006-009.

Lake Superior...
  Gale Warning until 2 AM EDT /1 AM CDT/ Monday for LSZ162-240>251-
     263>267.

Lake Michigan...
  Gale Warning until 8 PM EDT Sunday for LMZ221-248-250.

&&

$$

SHORT TERM...lg
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA



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