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Area forecast discussion 
National Weather Service Marquette Michigan
615 PM EST Sat Jan 31 2015

Short term...(this evening through sunday)
issued at 340 PM EST Sat Jan 31 2015

This afternoon through Sunday...high pressure sliding across central
Canada this afternoon has allow northerly flow to increase across
much of the upper Great Lakes region. This northerly flow coupled
with 850mb temperatures cooling to around -18c to -20c has allowed
lake effect snow to develop ahead of the surface high pressure
system. Initially...deeper moisture will linger into the early
evening hours allowing better snow growth with a thicker snow groth
area within the dgz. RUC soundings show inversion heights between
4kft and 5kft this afeternoon which is also verified by the MQT VAD
wind profile this afeternoon. This has allowed good Snowflake size
this afternoon resulting in a quick inch or two of fluffy snow on a
north to northwesterly wind. Dry air remains just to the north of
the area this afternoon...however...this is expected to shift
farther south around 00z/01 as inversion heights begin to fall to
around 3kft. This should help to reduce snowfall rates this evening
into the overnight hours.

As the surface ridge expands to the north of Lake Superior expect
winds to shift to the north and northeast shifting the snowbands to
the north to northeast wind favored snow belts. Again...reduced
moisture...lowered inversion heights along with anticyclonic flow
will help to keep snowfall totals in check across the u.P. With up
to 2 inches expected along the north to northeast wind favored snow
belts. As the surface ridge center shifts into the northern plains
on Sunday expect winds to shift to a more northerly direction.
Temperatures aloft will remain cold enough and low level moisture
off Lake Superior will keep lake effect snow in northerly wind
favored locations...with around an inch accumulation expected in
these areas.

Long term...(sunday night through saturday)
issued at 340 PM EST Sat Jan 31 2015

..NW flow les and poor visibility due to blsn/drsn may lead to headlines
Wednesday into Thursday...

Cold week in store as a building ridge aloft over western North
America results in mean troughing centered over Hudson Bay extending
over Great Lakes and northeast Continental U.S.. pattern does not hold much
opportunity for widespread snow. Best chance of that may actually
come Friday. Otherwise...lake effect snow and blowing/drifting snow
with poor visibility will be main issue. Appeared that moderation in
the chill would start to develop by next weekend...but recent runs of
the European model (ecmwf)/GFS have trended toward more troughing and colder
temperatures. Will have to wait and see if this is a lasting trend.

High impact weather that justifies any type of headlines through the
extended likely will be tied to the lake effect snow and poor visibility.
Best chance of seeing headlines will be Wednesday into Thursday for
northwest flow areas near Lake Superior. Will also give an honorable mention
for west-southwest flow on tip of Keweenaw peninsula late Monday into Monday
night...as though this is a very low probability event it could need
a headline if it occurs. Suppose there also could be need for wind
chill advisories Monday morning and again Thursday morning...but at this time it
does not look like a sure thing thanks to light winds and/or more in
terms of lake moderation on temperatures.

No real hazardous weather expected Sunday night into Monday morning
with diminishing winds and weak les as inversions are well below 5kft.
Plenty cold with temperatures at inverion top below -20c. Slr/S on the
higher/fluffy side so a couple of inches of snow is possible for
mainly north central Upper Michigan. Given the weakening winds...mesolow
formation remains possible which would enhance convergence and add
to the snow amounts. Highest probability of this occurring would be
between Marquette and Pictured Rocks Lakeshore...so looking at Au Train
and Munising areas. Away from the les...temperatures fall well below zero late
Sunday night into Monday morning...but with light winds and some
lake moderation/lake effect clouds...wind chills will mainly stay
higher than 20 below. Surface trough crossing the area Monday morning
should result in winds becoming more westerly which will disrupt the
les over Alger County but will increase it on the Keweenaw peninsula.

Westerly convergent flow les has potential to drop several inches of
snow late Monday afternoon into Monday night over northern sections of
the Keweenaw. Soundings show inversion at least to 5kft and
disturbance rotating through ahead of another trough moving over
upper Great Lakes on Tuesday morning. NAM sharper with trough and
backs winds enough to keep heavier les offshore of Keweenaw. GFS and
European model (ecmwf) not as backed with winds. Will continue to show highest probability of precipitation
on the Keweenaw and mention in hazardous weather outlook.

Trough sinks over northern Upper Michigan through day on Tuesday...
spreading the les to northwest flow snow belts of northern upper michgan...
especially by Tuesday night. Soundings show inversions up to 6-8 kft
in wake of the trough with as 850 mb temperatures drop to -25c by daybreak on
Wednesday. Setup will then favor a push of heavier les as the main
cold front moves through Tuesday night into Wednesday morning with
conditions quickly transitioning to small Snowflake/low visibility les
regime for the northwest wind snow belts Wednesday afternoon into
Wednesday night. Blyr winds increase through Wednesday to 25-30 kts
so blsn and drsn will also become a concern in open areas near Lake
Superior and especially where ice is built up along the shoreline.

Away from the les the main theme will be cold. Temperatures on Wednesday will
only struggle into the single digits above zero with wind chill
readings 10 to 20 below zero. As temperatures fall off well below zero on
Wednesday night over western Upper Michigan...may see wind chill
readings may come close to advisory into Thursday morning. Winds will be
slackening by this time though...especially over interior sections
of County Warning Area. A bit of moderation on Thursday for highs with readings
nearing 10 degrees or reaching the lower teens. Blyr winds back SW
later Thursday into Thursday night as high pressure ridge settles from
the middle Mississippi River valley to the Ohio Valley. Expect the
les to shift offshore by Thursday night. Since upper lakes will be
ahead of another surface trough crossing south central Canada...expect
clouds to be on the increase with even a possibility of light snow or
flurries. Thus...temperatures should not crash too much on Thursday night.

Stronger cold front with another push of colder air expected to
arrive Friday night into Saturday. Shortwave/convergence along the
surface-850 mb front and upper divergence on nose of 300 mb jet streak combine
to spread swath of snow over most of Upper Michigan Friday afternoon into
Friday evening. Timing may shift around some though considering this
solution in the models is newer development. Low chance probability of precipitation will
work for now with the snow along the cold front and then more low
chance probability of precipitation for next Saturday with developing NE flow les in wake of
the front.
&&

Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 614 PM EST Sat Jan 31 2015

MVFR conditions will continue for all sites this forecast period.
There could be brief IFR conditions at saw this evening due to
northeast upslope flow in heavier snowbands that would bring down
visibilities.
&&

Marine...(for the 4 PM Lake Superior forecast issuance)
issued at 340 PM EST Sat Jan 31 2015

A cold front that shifted south and east of the area this afternoon
along with a decent pressure gradient on the back side will allow a
few gusts to reach 35kts this afternoon and evening. Much lighter
winds will prevail Sunday as high pressure drifts across the upper
Great Lakes region. Low pressure and associated cold front will
approach the area Monday night and then sweep through the area
tuesda night and Wednesday. On the back side of this system...winds
will increase from the northwest Wednesday afternoon through
Thursday...with gale force gusts to 35 knots possible.
&&

MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
heavy freezing spray warning until 5 am EST Sunday for lsz264-
266-267.

Lake Michigan...
none.
&&

$$

Short term...kec
long term...jla
aviation...07
marine...kec

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