Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 240801

Area Forecast Discussion
National Weather Service Marquette MI
401 AM EDT Mon Oct 24 2016

.SHORT TERM...(This evening through Monday)
Issued at 231 PM EDT SUN OCT 23 2016

Water vapor imagery is showing two waves impacting or expected to
impact the area over the next 24 hours. The first, sliding through
late this afternoon is centered directly over the U.P. as of 18Z
with the next wave upstream over central Manitoba. Visible satellite
imagery is showing most of the Upper Great Lakes region socked-in
under cloudy skies. Radar imagery is showing an east-west oriented
line of rain showers sliding to the south and east through the U.P.
along with some noted bright banding.

Tonight and Monday: The shortwave that slid through the area this
afternoon is progged to slide southeastward into the lower Great
Lakes. Colder air will filter in over the east half of the U.P.
tonight into Monday as another shortwave dives through the eastern
half of the area. This will allow 850mb temperatures to drop into
the -5C to -6C range. This cooler air aloft, along with lake surface
temperatures around 10-11C, will allow for delta-T values in the 15
to 17C range. This combination will provide continued lake effect
cloud cover and lake effect rain showers over mainly the east half
of the U.P. as winds will be out of the northwest and that area is
under the shortwave as it slides through. Even though deeper layer
moisture will slide east, the increased fetch on the northwest flow
will keep enough lake modified air in place to keep the rain showers
around for tonight into Monday. The western U.P. may continue to see
increased cloud cover, but the cooler 850mb temperatures for lake
effect rain showers will remain over the east. Another feature
inhibiting shower potential over the west will be subsidence
associated with a surface/upper level ridge sliding into the area
through the day Monday. Lows tonight will be in the low 30s with
highs Monday expected to be mainly in the 40s.

.LONG TERM...(Tuesday through Sunday)
Issued at 358 AM EDT MON OCT 24 2016

Mean upper level troughing remains in place into this weekend.
Daytime temperatures should stay at or slightly blo normal mainly in
the 40s while nighttime temperatures in the upper 20s to upper 30s
are pretty typical for this time of year. Confluent northwest flow
on Tue will result in high pressure ridge building across Great
Lakes. Could see light lake effect hang on early in the day over
north central cwa as blyr winds veer northerly as the ridge builds
in. Probably will see good deal of cloud cover persist even after
lake effect ends as higher rh remains in the 925-850mb layer beneath
a subsidence inversion. Clouds should eventually try to clear out
later in the day with mixing, though there are indications at least
scattered clouds could linger into Tue evening.

Attn later Tue night into Wed will be on shortwave trough sliding
across the Central Plains. Sfc-h85 low tied to the wave should be
crossing vcnty of IA to southern MN by 12z Wed. Deep layer q-vector
forcing and lift within right entrance region of of jet streak from
northern Ontario to mid Atlantic will support rain moving in through
the day on Wed. Despite temps in the 30s on Tue night, soundings
look too warm in the lowest levels /wbzero heights aoa 1000 ft agl/
to support any snow as precip moves in so have took out any mention
in the wx grids. As long as circulation in low-levels remains south
of Upper Michigan, suspect heavier rain will remain there as well
closer to where better moisture influx 925-700mb is located and on
northern edge of elevated instability. Even if precip stays light,
likely pops still appear on track for Wed into Wed night. Lack of
phasing btwn lead system moving through Wed and additional shortwave
dropping across in northwest flow late Wed night into Thu continues
to lead to lower potential for much in way of accumulating snow late
Wed night into Thu, but there will be enough low-level cooling in
wake of the sfc low to keep a mix of rain/snow especiallly for the
interior as has been in forecast for a while now.

Well for at least this model cycle, there is okay agreement among
the GFS, ECMWF and GEM for Fri-Sun. Model consistency during this
time frame has been low so we`ll see if the agreement continues in
the coming days. For now though, another shortwave working through
in the nw flow will keep troughing across the region into the
weekend. Best chance for precip would be on Fri-Fri night as
associated sfc low crosses the Upper Great Lakes while deepening.
Exact track of the low still a bigger question though. If the
pressure pattern holds up as forecast, then would be chilly and
windy on Sat behind this system. High pressure/dry low-levels
building in quickly would limit lake effect precip on Sat though
probably cannot rule it out. Weaker system(s) that would produce
light precip as deep moisture is lacking crosss the region on Sun
and maybe Mon as well.

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 128 AM EDT MON OCT 24 2016

Clouds will linger into Mon morning bringing MVFR to VFR ceilings
across the area. Drier air moves in Mon afternoon and should
decrease the cloud cover.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 231 PM EDT SUN OCT 23 2016

Winds will remain below gales through the period. A tightening
gradient between a deep low pressure system moving through Quebec
and a high pressure ridge building into the Plains will lead to a
period of NW winds gusting to 30 knots over eastern Lake Superior
tonight into Monday. High pressure will then build across the area
Monday afternoon through Wednesday, keeping winds generally light
across Lake Superior. There will be a trough passage on Thursday but
winds should still remain fairly light.

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


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