Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 271956

Area Forecast Discussion
National Weather Service Marquette MI
356 PM EDT Sat May 27 2017

.SHORT TERM...(This evening through Sunday)
Issued at 355 PM EDT SAT MAY 27 2017

Tonight: As a broad surface low and upper level 500mb closed low
remains nearly stationary over northwestern Ontario, a cold front
will slide from the central U.P. into the eastern U.P. this evening
and stall during the overnight hours. At the same time, a quick
moving shortwave is progged to slide through the east half of the
U.P. This will help to focus scattered rain showers across mainly
the central to eastern portions of the area through the overnight
hours. There may be enough instability in the evening for a couple
rumbles of thunder; however, with the loss of daytime heating, the
thunder potential should quickly diminish. Otherwise, expect partly
to mostly cloudy skies across the CWA with the best chance of seeing
partly cloudy conditions over the west half.

Sunday: The cold front/trough is expected to be nearly stalled out
over the eastern U.P. At the same time, a surface low over the mid-
Mississippi Valley is expected to lift northeastward and ride along
the surface trough/front into Lower Michigan. The added
moisture/forcing from the approaching low along with the continued
weak forcing along the front/trough will allow for widespread
showers and thunderstorms, with the main focus being over the east
half of the U.P. The west half of the area will see heights fall
throughout the day as the broad trough begins to slide over the
area. This will allow for enough instability to cause the coverage
of showers and thunderstorm to increase for the west half as well,
during the afteroon hours. While there will be some instability
around, weak wind shear will greatly reduce any severe potential
from any thunderstorms that form with only isolated small hail
possible with lowering freezing levels. Any lightning that occurs
would be the biggest threat due to the holiday weekend.

.LONG TERM...(Sunday through Friday)
Issued at 245 AM EDT SAT MAY 27 2017

Nam shows a trough over the central U.S. with a closed low east of
Lake Winnipeg and ridges on both coasts and also the Gulf Coast. The
closed low drops southeast and keeps upper troughing in the area
through 12z Tue. 850-500 mb q-vector convergence and deeper moisture
remains over the area from Sun into Mon night. Overall, did not make
too many changes to the going forecast.

In the extended, GFS and ECMWF show a 500 mb trough across the
central and eastern U.S. with a ridge on the western U.S. 12z Tue.
This upper pattern remains the same 12z Wed. The ridge moves into
the Rockies with troughing remaining in the ern U.S. and troughing
on the west coast 12z Thu which remains into Fri. Temperatures will
remain below normal through the forecast period and the weather
will generally stay showery under the upper trough.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 138 PM EDT SAT MAY 27 2017

A weak front passing through the central U.P. will allow showers and
possibly an isolated thunderstorm to develop near the KSAW TAF site,
while the western TAF sites KIWD/KCMX will only see increased cloud
cover. Overnight, shower activity will diminish at KSAW with some
clearing possible over the western U.P. The next round of showers
and thunderstorms move in through the day Sunday as a low pressure
system moves just to the southeast of the area and an upper level
low slide in from the northwest.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 355 PM EDT SAT MAY 27 2017

Through the weekend, winds of 10 to 20 knots are expected across
Lake Superior. Early next week, winds will increase to around 20 to
25 knots as an area of low pressure is progged to dig across
portions of the Upper Great Lakes. Towards the end of the week as
the surface pressure gradient relaxes behind the exiting low
pressure system, winds will decrease to around 10 to 15 knots.

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


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