Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 300459

Area Forecast Discussion
National Weather Service Marquette MI
1159 PM EST Tue Nov 29 2016

Issued at 956 PM EST TUE NOV 29 2016

Forecast for rest of tonight and again later Wed aftn into Wed
evening still on track. Did make a few changes to Wed morning
forecast across central Upper Michigan. Any light rain/snow this
evening should continue to fade away/end as weak shortwave lifts to
north of Lk Superior. Attn for Wed morning is on shortwave currently
producing light rain over southern MN. One of many shortwaves
wrapping around large trough aloft centered over MN.

As that southern MN wave lifts to the northeast late tonight,
associated sfc trough heads across WI and becomes more closed off as
a sfc low while lifting northward across Lk Michigan on Wed morning.
Forcing features both aloft and at the sfc and perhaps also on
western fringe of forcing that is producing the light rain showers
lifting across lower MI this evening should all combine to generate
batch of light rain showers developing over central cwa on Wed
morning, possibly mixed with snow over higher terrain of west and
north central cwa based on wetbulb zero heights 500-1000 ft agl. 18z
NAM first showed this idea and was joined recently by the HRRR and
RAP and now the 00z NAM. Any snow should be minimal with warm ground
temps and light precip intensity. Since interior east will have shot
at getting cold tonight with no clouds overhead attm, if the precip
that moves in toward 12z/7 am ET starts out as rain, it is feasible
that there could be a non-zero risk of light icing first couple
hours. Current road temps there per MDOT are in the lower 30s. This
would be the one area that the light precip coming in around daybreak
could have an impact. Will pass this concern along to mid shift.

As Wed wears on, best chances of rain/snow should set up over
western cwa with cold air advection occurring on the west side of
sfc low that will be lifting to somewhere vcnty of Munising by early
Wed aftn. Blended the changes made for the morning into the forecast
for the aftn which still looked fine attm.

.SHORT TERM...(This evening through Wednesday)
Issued at 404 PM EST TUE NOV 29 2016

WV imagery and RAP analysis indicated a closed mid/upper level low
over cntrl MN. At the surface, an elongated trough or occluded front
extended from cntrl MN through nrn Lake Superior. An area of mixed
rain and snow over cntrl Upper Michigan supported by 850-700mb fgen
was gradually diminishing as the stronger forcing lifts to the

Tonight, Models suggest that 850-500 drying will spread across the
area. With levels also drying out, expect the remaining light pcpn
to end early this evening leaving mostly cloudy skies. continued
weak CAA will drop min readings into the upper 20s inland west to
the mid and upper 30s east.

Wednesday, As the mid level low wobbles into WI the low level trough
is expected to develop over srn or southeastern Lake Superior. 850
mb temps around -2C will provide enough instability (lake temps
around 7C) with the deeper moisture and 700 mb temps to around -11c
for an increase in lake enhanced pcpn into the west half during the
afternoon as winds become nrly. However, there is uncertainty with
how the mesoscale features will evolve and affect pcpn intensity.
Wet-bulb zero heights support mainly snow over the inland west but
a mix of rain and snow closer to the lakes.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 249 PM EST TUE NOV 29 2016

With little potential for significant conditions through the rest of
the week and considerable uncertainty next week, did not make
significant changes to blended initialization. Spent majority of
shift time performing AWIPS fixes.

Without being too specific (see forecast for specific expectations),
the low currently W of the area will move E of the CWA by Wed night
and will meander over Quebec through Fri. The airmass will be cool
enough for some lake enhancement in the N-NW winds behind the
system, so expect off and on precip into Sat, with the best coverage
closer to Lake Superior. Ptype will depend largely on near-SFC
temps, so the best chances for snow will be at night and also over
the higher terrain of the W. Due to only expecting light precip and
with relatively warm SFC temps (at least during the day), only light
snowfall amounts are expected through Sat.

Still looking at a significant pattern change possible 10-14 days
out, with more active weather possible starting later next week.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1158 PM EST TUE NOV 29 2016

Low level moisture wrapping into Upper Michigan from the sw ahead of
low pressure over MN will maintain mainly MVFR cigs through the
overnight hours at IWD and CMX. At SAW expect marginal MVFR cigs to
possibly scatter out late tonight leading to possible light fog
development toward sunrise on Wed. On Wed, conditions will begin
deteriorate at IWD and CMX as rain and snow increases in the aftn
and evening as the low crosses Upper Michigan and drags a sfc trough
over Lk Superior and northern Upper Michigan. Could see vsby down to
IFR at times, especially on Wed evening as ptype becomes mainly snow
and coverage and intensity ramps up. At SAW on Wed, scattered
showers are expected much of the day and into Wed evening. Vsby
should be mainly MVFR. The prevailing MVFR cigs could dip to IFR at
times in the aftn as winds begin to turn off Lk Superior.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 404 PM EST TUE NOV 29 2016

The low pressure system will linger over the western Great Lakes
into Wednesday. However the pressure gradient is not expected to be
as tight and should allow winds to diminish below 25kt by tonight.
Northerly winds to near 30 knots may develop Thursday as the slow
moving trough moves to the east of Lake Superior into Quebec. High
pressure will then build into the area into Saturday with winds
below 20 knots.

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


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