Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 181828

Area Forecast Discussion
National Weather Service Marquette MI
228 PM EDT Thu May 18 2017

.SHORT TERM...(This evening through Friday)
Issued at 225 PM EDT THU MAY 18 2017

The main forecast highlights will be the diminishing cloud cover
tonight and a cold night in store across much of the area, with
low temperatures expected to drop to around or below freezing
across much of Upper Michigan. No frost/freeze headlines are planned
as climatologically it is not uncommon for temperatures of that
degree this late in the spring across Upper Michigan. However, if
you have plants that are sensitive to the cold you may want to
consider covering them, or bringing them indoors, if possible.

A cold and windy day was observed across much of the area as low
pressure continued to lift northeast across central and eastern
portions of Upper Michigan. Lingering rain showers will continue to
diminish across the eastern half of the area; however, areas
downwind of Lake Superior across central and eastern portions of the
area will likely see drizzle linger through the rest of the
afternoon and evening hours as onshore flow continues. Northerly
winds will diminish in speed from west to east as the stronger
pressure gradient gradually relaxes through the evening hours. As
dry air upstream of the area continues to filter eastward, skies
will gradually clear tonight. The key to how cold temperatures will
get tonight is dependent on how low dew point temperatures drop. The
models are in fairly good agreement with dew points dropping down in
to the mid to upper 20s; therefore, given the ample radiational
cooling overnight, expect overnight lows to drop down to around or
below freezing. Locations across the interior central will have the
best chance at seeing temperature dropping down into the mid 20s.
Locations near the Great Lakes will likely see temperatures remain
just above freezing, especially across the shores of Lake Superior
and west of Lake Michigan across south central Upper Michigan.

Friday looks dry and sunny as high pressure moves just north of the
area. Ample mixing through the afternoon hours will allow dew points
to gradually drop into the teens through the afternoon hours, as
drier air gets mixed down to the surface. This drier air mass should
be able to modify nicely back up into the 50s given the ample
diurnal heating expected. Along the shores of Lake Superior,
especially from the northwest to the northeast, temperatures will
likely stay a bit cooler, but still climb into the mid/upper 40s.
Cloud cover will be on the increase through the end of the day on
Friday, especially across the south, but no precipitation is

.LONG TERM...(Tonight through Wednesday)
Issued at 318 AM EDT THU MAY 18 2017

A dry hi pres moving fm Manitoba e across Ontario just n of Lk Sup
will bring uneventful but cool wx tngt thru Fri before a
disturbance/lo pres aprchg fm the sw brings a return of showers
over the weekend. Much of next week looks to be on the cool side
as an upr trof deepens over the wrn Great Lks.

Tngt...Expect lingering clds and gusty winds over the ern cwa to
exit to the e ahead of dry hi pres that is fcst to build into wrn Lk
Sup. With diminishing winds and the arrival of pwat as lo as 0.15
inch, tended toward the lo end of guidance for min temps over the
interior w. A steadier ne flow under a bit tighter pres gradient
over the rest of the cwa wl limit the diurnal temp drop there
despite the arrival of drier air.

Fri/Fri ngt...As an upr rdg axis drifts ovhd, the sfc hi pres wl bld
over the Upr Lks. The very dry airmass wl bring plenty of sunshine,
but some hi clds may drift into the area during the aftn as some hi
lvl mstr in advance of a negatively tilted shrtwv lifting newd in
the Plains spills over the upr rdg axis. Since h85 temps wl rise no
hier than about 4C, expect blo normal temps, especially near Lk Sup
with an ene flow off the chilly water. One change to the
consensus fcst was to lower dewpts in the aftn with daytime mixing
of the very dry air above the sfc. Although the diurnal temp fall
on Fri ngt wl be limited by incrsg/thickening clds ahead of the
aprchg disturbance/sfc lo pres to the sw and an incrsg gradient se
flow under the tightening pres gradient btwn the departing sfc hi
pres and the lo moving toward Iowa, min temps wl still dip into
the 30s at many places with the lingering llvl dry air. Some of
the guidance indicates some pcpn could reach the WI border by
daybreak on Sat, but dryness of the antecedent airmass suggests
only lo chc pops are in order.

Weekend...Shrtwv and sfc lo pres to the sw are fcst to lift nnewd
and thru the Upr Lks on Sun. Most of the medium range guidance shows
a lo tracking n acrs wrn Lk Sup on Sat ngt into wrn Ontario on
Sun and dragging an occluded fnt acrs the cwa on Sat ngt/early
Sun. Showers ahead of the lo/occluded fnt and under the waa/
diffluent flow alf/some dpva wl arrive fm the sw on Sat before
diminishing under some dry slotting late Sat ngt into Sun. Some of
the models show a cyc w flow lingering on Sun, but large scale
subsidence in the wake of the shrtwv passing to the n wl limit
lingering shower chcs to the lo chc category, mainly over the wrn
cwa where the llvl wly flow wl present an upslope wind component.

Mon thru Wed...Depending on how quickly the cyc flow arnd the slowly
exiting lo pres in Ontario weakens/shifts to the n on Mon, some
showers may linger into Mon. Many of the longer range models show
another shrtwv digging sewd toward the Upr MS River Valley sliding
far enuf to the s on Mon ngt within a deepening upr trof so that
accompanying pcpn should pass to the s of the cwa and thru WI. As
the upr trof continues to deepen over the Upr Lks on Wed, upr
disturbances digging thru the area and a llvl cyc flow may result in
some showers on Tue/Wed. But some of the longer range models
indicate a hi pres rdg may be present then. Although there is much
uncertainty on the details of the fcst wx for this time, looks
like temps wl be blo normal under the upr trof with h85 temps no
more than a couple degrees above 0C within the upr troffing.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 113 PM EDT THU MAY 18 2017

LIFR ceilings continue to hang out this afternoon. KCMX/KIWD will be
the first to see improving conditions into MVFR, and then eventually
clearing out through the afternoon and early evening hours. KSAW
will see the low ceilings and visibilities linger through the rest
of the afternoon and evening hours, before gradually improving
tonight into MVFR, and then eventually clearing out. The strong
and gusty northerly winds will decrease across all terminals from
west to east through the evening hours, and then eventually
becoming light and variable as high pressure begins to work into
the area from the north.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 225 PM EDT THU MAY 18 2017

Gales of 35 to 40 knots are expected through the rest of the
afternoon across the east half of the lake, before gradually
diminishing to around 10 to 20 knots tonight. Across the east
half, winds have already begun to subside to around 10 to 20
knots, and will continue to further weaken through the overnight
hours. Friday winds will be around 10 to 20 knots, increasing to
20 to 30 knots through the first half of the weekend as another
storm system lifts up across the region. By Sunday afternoon winds
will subside to around 20 knots. Through the first half of next
week, winds are progged to remain around 20 knots.


Upper Michigan...
Lake Superior...
  Gale Warning until 8 PM EDT this evening for LSZ251-267.

  Gale Warning until 5 PM EDT this afternoon for LSZ244-245-

Lake Michigan...
  Gale Warning until 11 PM EDT this evening for LMZ221-248-250.



SHORT TERM...Ritzman
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