Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 181944

Area Forecast Discussion
National Weather Service Marquette MI
344 PM EDT Tue Oct 18 2016

.SHORT TERM...(Today and tonight)
Issued at 446 AM EDT TUE OCT 18 2016

00Z raobs/latest wv imagery and RAP analysis show the shrtwv
responsible for the heavy ra/svr storms yday evng exiting to the ne
along the most sgnft showers/TS. The associated cold fnt on the sw
flank of deepening lo pres moving into se Ontario has sank to the s
of all but the far scentral cwa. Despite some deep lyr qvector dvgc
in the wake of this disturbance, some showers/a few TS linger along
a line fm scentrl MN acrs nw WI into central Upr MI ahead of another
shrtwv aprchg fm the wsw and under axis of h85-7 fgen behind the
cold fnt and where mucapes up to 500j/kg and steeper mid lvl lapse
rates up to 7C/km linger per spc mesoanalysis/00Z MPX raob.
Farther to the nw, the 00Z INL raob shows a much drier sfc-h5 lyr,
but a good deal of hier clds linger in the mstr aoa h5 shown on that
raob and on the cyc side of the shrtwv supporting the lingering

Main fcst concerns in the short term wl be on pops today and then
cld/temp trends as the drier llvl air shown on the 00Z INL raob
grdly slides into the area.

Today...Incrsg deep lyr h85-3 qvector dvgc in the wake of stronger
shrtwv exiting to the ne with deeper convection is fcst to dominate
Upr MI, so expect the line of showers stretching fm scentral MN into
wcentrl Upr MI to diminish with time and probably by mid mrng as
they shift to the ese under axis of h85-7 fgen in the wake of the
departing sfc cold fnt. Plan to carry some sct showers thru mid mrng
mainly over the scentral. There wl be some gusty nw winds mainly
this mrng over the ne cwa in the wake of the departing/deepening sfc
lo pres, but these winds should diminish during the aftn as the pres
gradient weakens with the closer aprch of sfc hi pres toward the Upr
MS River Valley. The arrival of the drier llvl air depicted on the
00Z INL roab/larger scale subsidence/more acyc llvl flow should
result in clrg thru the day. Since h85 temps wl fall to only 6-8C by
00Z Wed, expect another relatively warm day with max temps in the
50s to as hi as the mid 60s over the se with the downslope NW flow.

Tngt...While there are hints some clds wl move into at least the wrn
cwa late as a weak shrtwv/lo pres trof aprch fm the w, lingering
llvl dry air/acyc flow most of the ngt wl maintain dry wx thru 12Z

.LONG TERM...(Wednesday night through Tuesday)
Issued at 343 PM EDT TUE OCT 18 2016

Upper trough is forecast to deepen late this week from the middle
conus to the Great Lakes. Conditions will turn cooler across Upper
Michigan with daytime temperatures falling a little below normal in
the 40s Thu-Sat. Normal highs are upper 40s to lower 50s. Temps at
about 5kft or h85 should be around -4c to -6c. Those h85 temps with
Lk Superior water temps 8-13c will result in delta t/s 12-19c which
is sufficient for some lake effect precipitation. Best chance for
precip will be Thu night into Fri morning as deeper moisture arrives
and inversions rise up to 7-8kft. Additional support for precip will
be from at least weaker shortwave energy moving through and uptick
in low-level convergence as sfc trough works across Lk Superior and
northern Upper Michigan. Low-level flow looks more cyclonic than it
did 24 hr ago, so overall the setup will be favorable for light to
perhaps moderate lake effect. Location of strongest, persistent
convergence is subject to change but attm looks like would affect
north central Upper Michigan on Fri morning. Ptype in this area
should remain rain with close proximity to warmer Lk Superior waters
and as 1000-850mb thickness remain above 1300m and sfc temps stay
aoa 38-39F. Farther inland west, wbzero heights blo 1000agl and sfc
temps aob 35F would support some snow mixing in with the rain, but
attm the overall coverage and intensity of precip for these areas
looks minimal.

Mean trough then deepens further over Quebec and the northeast conus
through the weekend while nw flow aloft continues across the Great
Lakes. Still uncertainty on how weekend works out. Even though axis
of mean trough will be well to the east and heights will try to rise
some, there may be additional shortwaves digging across area serving
to keep at least weak troughing in place. Any upper level system
working through will be moisture starved though as deep moisture
will be wrapped up in strong low spinning over Quebec. Just slight
chance pops for the weekend into early next week with temps around

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 144 PM EDT TUE OCT 18 2016

Drier air has been slower to reach KCMX than expected today. Back
edge of lower clouds is currently near the western shoreline of the
Keweenaw, but is being held up by the upslope westerly flow. Should
see low MVFR conditions break out to VFR there around 20z. May see a
period of MVFR cigs at KSAW over the next hr or two before shallow
moisture is pushed/mixed out. Other than these initial lower
conditions, drier air mass settling into the area will lead to VFR
conditions being the rule at KIWD/KCMX/KSAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 343 PM EDT TUE OCT 18 2016

Expect winds to remain 20-25 kts or less through the rest of the
week and into the weekend as a relatively weak pressure gradient

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


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