Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 290721

Area Forecast Discussion
National Weather Service Marquette MI
321 AM EDT Mon May 29 2017

.SHORT TERM...(Today and tonight)
Issued at 321 AM EDT MON MAY 29 2017

Upper air pattern consists of a closed 500 mb low over the upper
Great Lakes this morning that will slow move to between Lake
Superior and James Bay by 12z Tue. Numerous shortwave will continue
to move through the associated trough and rotate around this upper
low and this will continue to cause waves of convection to move
across the area and coverage will be determined by how strong the
diurnal heating is. Nam keeps some weak 850-500 mb q-vector
convergence over the area through 12z Tue along with some moisture.
Persistence is the way to go with this forecast and will again have
likely pops in for the afternoon into early evening with diurnal
heating being the strongest and causing the highest instability and
then diminish pops to chance tonight with diurnal cooling taking
place. Overall, did not make too many changes to the going forecast.

.LONG TERM...(Monday night through Sunday)
Issued at 445 PM EDT SUN MAY 28 2017

A slowly progressive pattern will prevail through next week with a
mid/upper level low gradually moving through northern Ontario and
Quebec through Friday and finally east of the Canadian Maritimes
next weekend. The ridge through the wrn North America will also be
undercut giving way to a more zonal pattern through the nrn
CONUS. Expect below normal temps through next week with the rain
chances diminishing from Monday night into Wednesday as the Mid
level low shifts to the east.

Monday night 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.
Isolated thunderstorms may still be possible Monday evening over the
ern cwa where some weak instability may linger.

Thursday, Although previous runs were drier, the models, with a
slower exit of the mid level low, suggest that a nw flow
shortwave and sfc trough reflection may bring another round of sct
-shra into the area.

Friday, Dry weather is finally expected as the mid level trough
shifts to the ne CONUS and sfc high pressure builds toward 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-Sunday, there is more uncertainty and low confidence with
the position/timing of a stronger shrtwv moving into the region as
the pattern deamplifies. Highs should still reach the lower to mid

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1240 AM EDT MON MAY 29 2017

As a mid-level low drops into the Upper Great Lakes, disturbances
wrapping around it will generate sct to nmrs shra at times, most
nmrs during the daylight hrs today. These shra occurring over Lake
Superior will lead to fog/low clouds over the waters, and with an
upslope wind off the lake at KCMX, conditions at that terminal will
likely fall to IFR overnight with improvement to MVFR late
morning/early aftn. At KIWD, expect conditions to fall to MVFR
overnight and mostly remain MVFR thru the remainder of the fcst
period. At KSAW, an upslope southerly wind has resulted in the
development of LIFR conditions initially. As winds veer slightly
over the next couple of hrs, the fog/low clouds/LIFR conditions
should clear out to VFR. VFR conditions should then generally
prevail for the remainder of the fcst period though -shra may drop
conditions to MVFR at times.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 321 AM EDT MON MAY 29 2017

Winds are expected to be between 15 to 25 knot through Wed as an
area of low pressure is progged to dig across portions of the Upper
Great Lakes. Toward the end of the work 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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