Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 301133

Area Forecast Discussion
National Weather Service Marquette MI
633 AM EST Wed Nov 30 2016

.SHORT TERM...(Today and tonight)
Issued at 502 AM EST WED NOV 30 2016

Radar imagery this morning has been showing most of the radar
reflectivities over the western WI/eastern MN border as well as over
the Arrowhead of MN. Addtitonally, there have even be a couple
lightning strikes over northeatern Lower MI this morning. Surface
obs have been showing that the precip has been a mix of rain and
snow in WI with mainly snow over northern MN. WV imagery shows a
broad rotation associated with the upper level low, which is center
over the western WI/eastern MN border. There are also multiple
impulses that can be seen rotating around the upper level low. IR
satellite imagery has been showing a break in the cloud cover over
central and eastern portions of the U.P. while much of the western
U.P. remain overcast. Additionally, some fog can be seen over
portions of the eastern half of the U.P. with temperatures in the
mid to upper 20s where skies have cleared and in the low to mid 30s
where cloud cover remains or has moved back into the area.

Today: As one of the aforementioned waves wrap into the U.P. later
this morning, models have been depicting a surface low developing
over northern Lake Michigan by 12Z and then lifting to the north as
it becomes the main surface low through this afternoon. As this low
develops, initially the drier air over the eastern U.P. should limit
any sort of precipitation through the early morning hours; however,
by mid morning, increased moisture is expected to slide into the
area from the southwest, which will increase the potential for
precipitation. The best overall system forcing will likely remain
over the eastern half of the U.P. this morning; therefore, have kept
better pops in that area early in the day. At this point, it looks
like there will be a fairly significant warm layer that the
precipitation would be falling through, which would keep it in the
form of rain. The only caveat is if the rain starts before daybreak
over the far eastern areas where the skies cleared early this
morning. If the rain does start a little earlier than expected it is
not out of the question that there could be some very light freezing
rain, but indications are that it would be closer to mid morning
around 15Z before the precip starts, keeping it mainly in the form
of rain. As the low is parked over eastern Lake Superior this
afternoon, colder air will begin to filter into the western U.P.
both at the surface and aloft. This will allow the rain to mix with
and slowly change to snow over the high terrain of the west through
the late afternoon hours. 850mb temperatures are progged to fall to
around -5C this afternoon over the west half of the U.P., which
would give delta-T values in the 10C to 12C range giving increased
chances of lake effect/lake enhanced precipitation for north to
northeast wind favored locations. The eastern half will still see
mainly rain during the afternoon with no lake enhancement expected
as 850mb temps stay closer to -1C to -2C and winds stay out of the
west to southwest.

Tonight: The aforementioned surface low and upper-level 500mb low
are expected to remain over eastern Lake Superior through tonight.
At the same time, 850mb temperatures are expected to remain around -
5C over the western half of the U.P. keeping a continued lake
effect/enhanced snow in the forecast for north to northwest wind
favored locations. At this point, only expect a couple inches of
accumulation over the higher terrain with lower amounts expected
closer to the Lake Superior shoreline. The eastern U.P. will
continue to see westerly winds and 850mb temperatures only in the -
2C to -3C range, which should limit any lake effect potential over
the east. Snow will begin to mix in with the rain over the east half
as temperatures continue to slowly cool; however, only minor
accumulations are expected at this time.

.LONG TERM...(Thursday through Tuesday)
Issued at 320 AM EST WED NOV 30 2016

Thursday and Friday: Models indicate the closed low will linger
northeast of the Upper Great Lakes Thu into Thu night over Ontario
and Quebec before weakening and opening up as shortwave trough which
lifts east through Friday toward New England. Behind the closed
low/trough colder air will filter into the region, at the surface
and aloft, allowing the rain to transition to snow through the
period. Currently it looks like the north to northwest wind favored
snowbelts would be most likely to see the best chances for
precipitation. It does look like temperatures overall will trend
colder but not dramatically so for lake effect as 850 mb
temperatures are progged to cool only to the -5C to -8C range for
Thursday into Friday. Snow will be the primary precip type through
this time period during the overnight hours, but a mix of rain is
possible along the shoreline and east during the daytime hours.

Saturday: Light lake effect precipitation should be dwindling or
ending over the east half by early afternoon as the high pressure
ridge axis moves across Upper Michigan and winds back more west to
southwest. Models suggest a weak shortwave moving across the area
which along with diurnal instability could produce some isold -shsn
in the afternoon.

Sunday: Models have backed off from developing strong system over
Lower Mi. They now advertise that the next shortwave trough from the
Northern Plains will move into the area late Sun into Sun night
bringing the next chance of snow. Given limited moisture with this
system expect snow amounts generally less than an inch.

Monday into Tuesday: Models trending toward more amplified pattern
for next week as a 120+ kt 300-250 mb jet max and assoc shortwave
energy digging in from the eastern Pacific will carve out a broad
mid-upper level trough over the Western CONUS by early next week.
Downstream ridging into the Great Lakes region in response to the
developing western CONUS trough will keep Upper Mi mostly dry Mon
into Mon night with a slight warming trend. A few of the models
indicate shortwave energy lifting out the base of the western CONUS
trough and propelling a sfc trough toward the area which could
result in some pcpn moving back into the area by late Tue.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 633 AM EST WED NOV 30 2016

Conditions will begin deteriorate at IWD and CMX as rain and snow
increases in the afternoon and evening as low pressure moves through
Upper Michigan. The more concentrated area of rain and snow showers
will remain over the west and evening increase tonight as the
precipitation changes over to mainly snow. VFR to MVFR conditions
early in the day will give way to MVFR to IFR conditions in the
afternoon through the overnight hours at IWD and CMX. Visibility may
also become an issue, especially late tonight as winds begin to gust
with fresh snow. Would not expect them to drop to low as the snow
will be fairly wet. KSAW will stay VFR to MVFR through most of the
day with minimal chances of reduced visibility as the precipitation
should remain in the form of rain into the late afternoon hours.
With winds becoming westerly through this evening at SAW have kept
ceilings a bit higher than previous forecast due to the favored
downslope direction.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 502 AM EST WED NOV 30 2016

Low pressure will linger over the western Great Lakes through
Thursday. However the pressure gradient is not expected to be as
tight today and winds should remain below 25 knots. Northerly winds
to near 30 knots are expected to develop tonight into 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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