Area Forecast Discussion
Issued by NWS Marquette, MI

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935
FXUS63 KMQT 202228
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
528 PM EST Sat Jan 20 2018

.SHORT TERM...(This evening through Sunday)
Issued at 244 PM EST SAT JAN 20 2018

Quiet weather for most though there are some minor forecast issues.
Plenty of mid-high clouds around in Pacific airmass. Arctic sfc
front with temps in the single digits above zero is over northern
Lk Superior while temps over Upper Michigan have risen to 30s and
low 40s. Generally quiet tonight. Front over Lk Superior will not
move much. Light winds over Upper Michigan and dwpnts are into the
30s, so could be some stratus/fog develop tonight if mid-high
clouds thin out. Will just have patchy fog in forecast, but any
fog that forms could be dense. Also, kept a slight chance for
light snow far scntrl as streak of mid-level moisture/fgen
interacts with lift from upper level jet. Models have trended
drier with potential mainly due to dry layer blo 10kft AGL.

On Sunday, main focus will be on cold front settling toward northern
Upper Michigan in the aftn and evening. Expect developing east to
northeast winds in wake of the front which will result in upslope
lifting from Keweenaw to north central higher terrain. A lot of low
clouds already behind the front today over northern Ontario so
expect situation here on Sunday with additional moisture off Lk
Superior. Could even be enough low-level moisture and lift for
drizzle or freezing drizzle. Only have slight chances for now as it
could end up just being a stratus deck with no precip. Both the low
clouds and increasing high clouds ahead of developing winter storm
will result in cooler temps than last couple days. Readings will be
freezing or maybe below over north U.P. higher terrain while
elsewhere expect temps mainly mid 30s.

As for the incoming winter storm, slower trend continues. Should
just start to see snow develop through the day over Nebraska and
South Dakota as the main sfc low moves from the Texas/Oklahoma
panhandle toward south central Kansas.

.LONG TERM...(Sunday night through Saturday)
Issued at 422 PM EST SAT JAN 20 2018

...Winter Storm to Impact Upper Michigan Monday into Tuesday...

The main forecast concern remains the approaching winter storm
Monday into Tuesday, where a swath of heavy, wet system snow is
expected to lift across portions of Upper Michigan. A Winter Storm
Watch has been issued for portions of western and much of central
Upper Michigan in advance of this approaching system.

Sunday night through Tuesday: The overall trend among the medium-
range models is to continue to slow the arrival of the system
expected to lift across the Upper Great Lakes during this time
period. In fact, the tail-end of high-res guidance suggests that the
timing may need to be pushed back even further then what is
currently reflected within the forecast. Prior to the onset of
system snow, easterly flow will back northeasterly and begin to
enhance localized upslope flow across the north central Sunday night
into early/mid Monday morning. Forecast soundings pick up on this
upslope flow nicely, including deepening of this shallow moisture
through early/mid Monday. Given the delay in the deeper moisture,
have included mentions of freezing drizzle across these upslope
areas in the north central Sunday night into mid/late Monday
morning. This may result in a glaze of ice, but we could also see
snow mix in with this freezing drizzle as we could see impacts on
precipitation type due to the seeder-feeder process.

The main axis of wet, heavy system snow is expected to track across
portions of Upper Michigan mid-Monday morning through early/mid
Tuesday morning, which will bring travel impacts as SLRs will lower
to around 10-15:1. Given the track of the surface and 850mb low
confidence is highest based on current guidance that the heaviest
snow will track across central portions of Upper Michigan,
especially the higher terrain in the north central where upslope
northeasterly flow will provide localized lift to enhance snowfall
amounts. However, any slight shift in the storm track may result in
this axis of heavy snow shifting a bit west or east, as well as
having impacts on precipitation type.

As the main system continues to exit the region on Tuesday,
depending on how cold 850mb temperatures get lingering lake effect
snow will be possible across the north wind snow belts. Also,
lingering gusty northerly winds may lead to blowing snow concerns,
especially near Lake Superior.

Wednesday through Friday: We could see lingering lake effect snow
near Lake Superior Wednesday into Thursday, but as surface ridging
slides across the Upper Great Lakes the 850mb winds become rather
disorganized. Therefore, not expecting much in the way of
accumulating lake effect snow during this time period. Through
Friday, we will see ridging build across the central CONUS and moves
across the Great Lakes region. The resulting warm air advection will
push temperatures into the upper 30s and lower 40s by Friday.

Next Weekend: The above mentioned warm air advection will continue
to lift northeast across the Upper Great Lakes and allow the return
of widespread precipitation out ahead of the next system progged to
track across the Upper Mississippi Valley. Based on the current
model guidance, we will initially be on the warm side of this next
surface low, so we may see rain and snow spread across Upper
Michigan.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 528 PM EST SAT JAN 20 2018

Tricky forecast coming up for the terminals as snow melt today along
with winds switching to the northeast would allow low level moisture
and upslope flow to occur and could bring conditions down this
forecast period. Will go more pessimistic with this issuance and the
snow melt today will cause some fog to form tonight even with mid
and high level clouds bring around. As a cold front currently on the
north end of Lake Superior settles across Lk Superior and northern
Upper Michigan Sunday aftn, expect developing east to northeast
winds to result in upslope low stratus at CMX and SAW by late Sunday
aftn into Sunday evening. May be some freezing drizzle as well,
especially at CMX.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 244 PM EST SAT JAN 20 2018

Strongest winds on Lake Superior during this fcst period will occur
Monday into Tuesday as low pressure tracks from the Southern Plains
to northern Lower MI and to southern Quebec. NE to N gales are
expected over most of Lk Superior during that time and a gale
watch has been posted. Heavy freezing spray will also develop late
Monday night through Tuesday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Storm Watch from Monday morning through late Monday night
     for MIZ002-009>012.

  Winter Storm Watch from Monday afternoon through Tuesday
     afternoon for MIZ004-005-013-084.

Lake Superior...
  Gale Watch from Monday evening through Tuesday afternoon for
     LSZ264>267.

  Gale Watch from Monday morning through Tuesday morning for
     LSZ162-263.

Lake Michigan...
  Gale Watch from Monday morning through Monday evening for LMZ248-
     250.

&&

$$

SHORT TERM...JLA
LONG TERM...Ritzman
AVIATION...07
MARINE...JLA



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