Area Forecast Discussion
Issued by NWS Marquette, MI

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373
FXUS63 KMQT 272347
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
747 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 afternoon 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 night through Saturday)
Issued at 435 PM EDT SAT MAY 27 2017

A slowly progressive pattern will prevail through next week with a
mid/upper level low/trough gradually moving through northern Ontario
and the northern Great Lakes into the northeast CONUS. Expect below
normal temps through next week with the best rain chances
Monday diminishing from Tue into Wed.

Sunday night into Monday, The stronger shrtwv is expected to move
to the ne of the area during the evening with diminishing shra
coverage overnight with the loss of daytime heating. However, as
the mid level low drops into the northern Great Lakes, periods of
sct shra will continue aided by weaker shrtwvs near the mid level
low. Forecast MLCAPE values into the 400-800 J/Kg range over the
east half, and stronger low level convergence near lake breeze
boundaries could support some isold tsra during peak heating from
mid Monday afternoon through the early evening. Mostly cloudy
conditions will keep highs mainly in the mid 50s to lower 60s with
lows in the 40s.

Tuesday through Wednesday, with the mid level low wobbling through
nrn Ontario, a few additional shrtwvs are likely to pivot through
the area in the cyclonic nw flow through Upper Michigan. This will
maintain at least lower end chance shower chances.

Thursday-Friday, mainly dry weather is expected as the mid level
trough shifts to the ne CONUS and sfc high pressure builds into the
region. Highs will climb mainly into the 60s. Winds will be weak
enough for prominent lake breezes and cooler conditions along the
Great Lakes.

Saturday, there is more uncertainty as the ECMWF transitions more
quickly to a less amplified pattern with a broad ridge the nrn
plains that would allow shortwaves and a faster moisture return into
the region compared to the GFS/GEFS.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 746 PM EDT SAT MAY 27 2017

VFR conditions should mostly prevail at KIWD/KCMX/KSAW thru this
fcst period. However, there are some concerns. First, with the
rainfall that occurred at KSAW this evening, there may be some fog
development (MVFR vis) late in the night. Then, a couple of
disturbances dropping into the Upper Lakes on Sun will likely
generate sct to nmrs shra across the area. Conditions may fall to
MVFR if any of the shra affect the terminals. Not out of the
question that there could be a rumble of thunder as well.
&&

.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.
&&

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

$$

SHORT TERM...KEC
LONG TERM...JLB
AVIATION...Rolfson
MARINE...KEC



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