Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 270525
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
125 AM EDT Sun May 27 2018

.SHORT TERM...(This evening through Sunday)
Issued at 319 PM EDT SAT MAY 26 2018

Into this evening, nw flow shortwave moving across moist and very
unstable environment with MLCAPE values of 1500-2000 j/kg has led to
initiation of numerous thunderstorms into central Upper Mi this
afternoon with isolated severe storms focusing along sfc trough and
enhanced by convergent lake breeze boundaries. One inch hail fell
here at the NWS office and at several other places in the Negaunee
area with one of the severe storms. Training storms across southern
Marquette County from Big Bass Lake through Gwinn to Little Lake
have also prompted the issuance of a flash flood warning until
around 6 pm EDT. As the shortwave and associated trough pushes east
this evening and diurnal instability begins to weaken toward 8-9 pm,
expect convection to quickly begin to dissipate.

Tonight, as sfc high pressure briefly settles in behind the exiting
surface trough, light winds will favor the possibility of patchy or
areas of fog developing especially over areas that saw heavier rain
this afternoon/early evening. Will probably need to watch for the
potential of dense marine fog along the Great Lakes shores given
added moisture from storms.

Sunday, building 5h ridge heights and warmer cap of dry air at 14C
between 850-700 mb should yield dry conditions across the area.
Expect inland high temps to climb into the mid 80s to lower 90s
while light winds will allow prominent lake breezes to bring cooling
along the Great Lakes into the upper 60s and lower 70s. Dewpoints in
the upper 50s and lower 60s will continue the uncomfortably humid
conditions.

.LONG TERM...(Sunday night through Saturday)
Issued at 340 PM EDT SAT MAY 26 2018

Sun ngt-Memorial Day: Minimal changes to prior forecast of
warm/humid conditions for the second half of the holiday weekend,
through Memorial Day. Longwave pattern continues to depict a cutoff
trough across the Southwest CONUS, which is allowing mid-level
heights to increase downstream across the Upper Midwest/Great Lakes
region. There will be a frontal boundary oriented along the northern
periphery that may be trending south due to a weak elevated trough
displaced north over Northwest Ontario. Confidence is not very high
that this will occur, and that the mid-lvl heights will keep precip
chances low due to warm air aloft trying to put a lid on vertical
growth to any cumulus clouds for much of Memorial Day. While hedging
towards that direction with a drier Monday, there is still a small
probability that some showers and isolated thunderstorms could
develop. If any convection does occur, most likely it will be
isolated to scattered at best. Temps will remain mild overnight Sun
ngt in the 50s to 60s, coolest closer to the Great Lakes. Then for
Mon temps will warm back into the 80s for most locations, and
possibly 90 in a few interior locations southwest of Marquette.
Areas adjacent to the Great Lakes will be slightly cooler with a
lake breeze progged to push inland; however, the very moist airmass
will persist keeping humid conditions in place.

Tue-Thur: The upstream cutoff trough will begin to open up and pivot
northeast towards the Upper Midwest with a frontal boundary oriented
from west to east across Northern Minnesota and Central Ontario.
This boundary will begin to drift south, with continued chances for
showers and possibly thunderstorms across the Upper Peninsula. Temps
will continue to be mild with highs in the 70s and 80s, then begin
to trend to the upper 60s to upper 70s. High pressure arrives mid-
late week and should return dry conditions to the region.

Fri-Sat: Upper level flow tries to trend towards a quasi-zonal
pattern, but temps may begin to moderate just beyond the current
extended periods. But confidence in the later periods is lower at
this time.
&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 124 AM EDT SUN MAY 27 2018

Through the early morning hours, we could see the potential for fog
over areas that saw heavy rain earlier today as winds become light
and skies continue to clear out. As high pressure moves across the
region today, winds will be fairly light. Expect ceilings to remain
VFR, except at KSAW where the marine layer may move inland as flow
becomes onshore this afternoon.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 353 AM EDT SAT MAY 26 2018

This morning, surface troughing has begun to push south across the
Lake. Along the leading edge of this trough, expect a brief increase
in winds to upwards of 20 to 30 knots. Otherwise, winds are expected
to remain less than 20 knots today, and through the middle of next
week. Expect areas of fog to develop and linger at times into the
weekend as multiple rounds of rain are expected over the lake and
the humid airmass lingers. Fog may be dense at times. Thunderstorms
are possible this afternoon into sat night, and then again early
next week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
  Dense Fog Advisory until 2 PM EDT this afternoon for LMZ248-250.

&&

$$

SHORT TERM...Voss
LONG TERM...Beachler
AVIATION...lg
MARINE...Ritzman



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