NWS Marquette, MI wrote its last area forecast discussion before the first event at Feb 6, 6:24 AM EST, 4 hours 36 minutes earlier. Its key messages:
Area forecast discussion, Feb 6, 6:24 AM EST, 4 hours 36 minutes before
Area Forecast Discussion
National Weather Service Marquette MI
624 AM EST Thu Feb 6 2025
.KEY MESSAGES...
- Strong west winds over northwest Upper MI (Keweenaw in
particular) this afternoon and evening. Probability of peak
gusts in excess of 58mph is 40-70%. The strong, gusty winds
and developing lake effect snow showers will lead to frequent
whiteout conditions in blowing snow and falling snow. Blizzard
conditions are expected for several hours. The lake effect
snow showers, gusty winds and blowing snow arrive in areas
from around Munising eastward early this evening.
- After widespread snowfall early today, only one more system
snowfall over the next 7 days, occurring Saturday into
Saturday night. A significant snowfall is not anticipated as
the probability of exceeding only 6 inches ranges from 0%
across northern Upper MI to only 40% far south central Upper
MI. Slippery travel conditions will occur with the snowfall.
- Temperatures around normal to a little below normal into the
weekend will settle to prevailing below normal next week.
&&
.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 248 AM EST Thu Feb 6 2025
As a shortwave low continues rolling into and through northern
Ontario today, the warm front of the shortwave appears to have
brought a band of light to moderate snowfall across the area early
this morning, with the NWS Marquette office recording 0.4 inches of
fluffy new snow between midnight and 1 AM EST. However, with the
band of snowfall going through the U.P. early this morning only
lasting for about an hour before the dry slot in the lower levels
moved over us, snowfall amounts will be limited with this band of
warm frontogenesis as it continues northwards over Lake Superior. As
phasing begins with a shortwave low moving into the Lower Great
Lakes this morning, expect another band of light to moderate system
snowfall to move from west to east across the U.P. in association
with the cold front of the Ontario-based shortwave low. CAMs show
more snow falling with this round, mainly bringing an additional
inch or two to the area before passing into northern Ontario by this
afternoon.
The real 'fun' starts behind the cold front today. Due to the tight
pressure gradient and strong cold air advection moving into the area
behind the cold front, expect strong westerly winds to rip into the
U.P. from west to east this afternoon. While this will create lake
effect bands over mainly the Keweenaw (and Ontonagon and Baraga
counties) and eventually the northeastern U.P. (from Pictured Rocks
eastwards through northern Luce County), the main threat will be the
strong winds creating blowing snow in the afternoon hours. With
westerly wind gusts as high as 55 mph possible over the Keweenaw,
whiteouts from the snowfall and blowing snow are expected, with
visibilities over and around the Keweenaw expected to be 1/4 mile or
less beginning around noon today into tonight. Given these
conditions, a Blizzard Warning has been issued for the Keweenaw, as
well as Ontonagon and Baraga counties. Meanwhile, with lower winds
expected (and thus lower blowing snow impacts), a Winter Weather
Advisory was issued for Alger, northern Schoolcraft, and Luce
counties starting at 1 PM EST. To reiterate what's already been said
in the Winter Weather products: stay off the roads and remain
indoors this afternoon over and around the Keweenaw; whiteouts could
reduce your visibilities to zero and can be life-threatening. As for
the Yoopers in Alger County mainly east of Munising, in northern
Schoolcraft, and in northern Luce County, be very careful driving
this afternoon. If you can, try to delay your travel plans for a
better time as visibilities could become significantly reduced in
the areas of blowing snow, possibly down to 1/4 mile or less. As for
the other areas of the U.P. this afternoon, watch out for reduced
visibilities in spots as winds could gust up to 35 to 40 mph at
times. For the snowfall amounts this afternoon, expect 1 to 3 inches
over Ontonagon, Houghton, Baraga, and Keweenaw counties, and around
an inch or less east of Munising.
&&
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
Issued at 456 AM EST Thu Feb 6 2025
Medium range models are in good agreement on the pattern evolution
across N America into the first half of next week. Deep mid-level
low that had been centered off of the Pacific NW coast has opened up
as expected with one strengthening shortwave from it reaching the
Great Lakes today. The remaining remnant of the mid-level low will
then follow, reaching the Great Lakes over the weekend. As this
occurs, building ridge over the ne Pacific across AK into the Arctic
will set the stage for a deepening trof across much of central and
eastern Canada into the U.S. during the first half of next week.
Guidance is in excellent agreement in showing the axis of that trof
extending sw into the western U.S. For Upper MI, this evolution of
the pattern will lead to only 1 more system snow over the next 7
days after the snow early today. That snow will occur Sat/Sat night
in association with the last remnant wave from the mid-level low. It
still appears that this system snow will not be significant. Per
NBM, probability of exceeding only 6 inches of snow only ranges from
0% across northern Upper MI to 40% far s central. These
probabilities have shown no notable trends over the last 48hrs other
than a sharpening the n-s gradient across Upper MI. So, model
guidance has been fairly stable. LES will occur in the wake of the
waves passing today and Sat. Strong w to wnw winds following the
first wave will support considerable blsn snow into the evening
hours tonight in areas where LES is occurring. The amplifying
pattern over N America early next week will provide a supply of cold
air to sustain LES in the wake of the weekend system. As for temps,
around normal to blo normal temps into the weekend will be followed
by prevailing blo normal temps during the first half of next week.
Looking farther ahead, EPS/GEFS/GEPS remain consistent in showing
positive height anomalies expanding across the high latitudes thru
the last half of next week, resulting in positive height anomalies
bridged from the Bering Sea across the Arctic to the Norwegian Sea.
This will lock in troffing/negative height anomalies over Canada,
extending into the U.S., setting the stage for prevailing blo normal
temps across Upper MI thru the end of next week and into at least
the first half of the week of Feb 16. The negative height anomalies
are more consolidated from s central and sw Canada into the western
U.S., so the core of the coldest air will tend to reside to the w of
here on most days. With the cold, LES will obviously occur whenever
winds are onshore. If trof axis into the western U.S. attains enough
amplitude at times, it would send the more generous pcpn producing
shortwaves on a ne trajectory that would bring ocnl system snows to
Upper MI. At this point, the model guidance indicates that the
troffing into the U.S. will be broad, suggesting the main storm
track will be suppressed too far s of Upper MI for any significant
system snows, but obviously we're looking well out in the model
guidance, so that can change. Thus, for now, no significant snows
are on the horizon for Upper MI thru next week.
Beginning tonight, the evening begins with ongoing strong w to wnw
winds and LES into nw Upper MI, resulting in considerable
blsn/blizzard conditions as winds will be gusting to 35 to ~50 mph.
Off of western Lake Superior, inversion will fall from 7-8kft early
evening down to ~4kft overnight. So, LES intensity will fall off
evening thru early overnight. Expect an additional 1-3 to isold 4
inches of snow accumulation, least Keweenaw down along the shore of
Ontonagon County and greatest well inland in high terrain of
southern Houghton/Baraga counties. Considerable blsn in the evening
will subside overnight as winds diminish. To the e, LES will shift
onshore into Alger County eastward early this evening as w winds
veer wnw. Strong low-level convergence signature in models as winds
shift onshore and an inversion near 9kft will support a short period
of very hvy snow. Along the lake e of Munising, exposure to the
strong/gusty wnw winds to ~50mph off of the lake will lead to
whiteouts at locations such as Grand Marais. Winds won't be nearly
as strong inland over the e, gusting 25-35mph at times which will
lead to areas of blsn. From around Munising eastward, expect snow
accumulations of generally 3 to 6 inches tonight.
W to WNW winds will back toward the WSW on Fri, shifting LES
northward over western Upper MI and eastward over eastern Upper MI.
The LES will be diminishing as well under moderating/drying air mass
with approaching sfc high pres ridge. During Fri night, subtle sfc
trof will bring slight veering of winds over the lake, shifting
light LES southward again across the Keweenaw. Light LES will clip
areas from around Grand Marais eastward as well.
Over the weekend, attention turns to the remnant of the mid-level
low that was off of the Pacific NW coast. That wave reaches the
Great Lakes Sat night. Models have shown a slight southward shift in
the associated sfc low track that runs from OK to the Upper Ohio
River Valley. The low has also trended a little weaker. With that
track, the main, heavier waa/isentropic ascent forced pcpn is
focused well to the s, but weakly coupled upper jet forcing is
displaced rather far to the n than typical. That results in what is
initially a separate area snow moving from the Dakotas to the Great
Lakes, where it eventually merges with the pcpn associated with the
low. Snow will spread into Upper MI from w to e during the day Sat
then end Sat night, but it will be followed by light nw flow LES off
of Lake Superior. Current guidance suggests around 4 inches of
snowfall for southern Menominee County with amounts trending down to
an inch or less across northern Upper MI.
During next week, conditions will be cold enough to support LES
whenever winds are onshore. Overall, the low-level winds will be
predominantly w to nw. Any passing shortwaves will give the LES a
boost, and Mon night/Tue will be one period where that will occur.
That wave will be followed by a push of arctic air, but nothing out
of the ordinary for this time of year. So, Tue/Wed will be the
coldest days with highs in the upper single digits to teens F. Tue
night should be the coldest night with min temps down to at least
the mid -teens F in the interior w. If high pres ends over the area
Tue night, traditional cold spots will slip to the -20s F.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 624 AM EST Thu Feb 6 2025
Light snow across the U.P. gives way to lake effect snow across the
Keweenaw later today through tonight behind a cold front moving
through the U.P. this morning. Strong west to eventually northwest
winds this afternoon into tonight will bring blizzard conditions to
the Keweenaw, while patchy blowing snow at times cannot be ruled out
at IWD and SAW either. While vis is down to 1/4 mile during the
blizzard conditions over CMX, we could see vis down to 0SM via
whiteouts due to the blowing snow/snowfall. Overall, expect the IFR
to MVFR conditions this morning to generally become MVFR by early
this afternoon . The MVFR cigs look to generally continue across the
TAF sites through tonight, save for CMX this afternoon and evening
during the blizzard conditions (at or below airport mins expected)
and SAW this afternoon when cigs look to lift to VFR before cigs
drop back down to MVFR this evening.
Given the strong winds, expect turbulence across the region today
and into tonight. In addition, the Aviation Weather Center
highlights icing concerns into early this afternoon, especially over
the Keweenaw.
&&
.MARINE...
Issued at 456 AM EST Thu Feb 6 2025
Developing low pres that quickly deepens while tracking e just to
the n of Lake Superior today/tonight will lead to strong w winds
developing today, becoming nw tonight. Expect high end gales to
storms (45-55kt) to develop from w to e across much of the lake
today. Strongest winds will occur in a corridor from w of
Houghton/Ontonagon eastward to Stannard Rock and Grand Marais in the
aftn and early evening. Winds will gradually diminish from w to e
tonight with gales ending by sunrise on Fri. Hvy freezing spray will
occur during this period of high winds today and tonight. Expect nw
to w winds of 20-30kt on Fri. Wind will then fall to under 20kt for
Fri night and Sat and will be under 25kt on Sun.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Blizzard Warning from 11 AM this morning to 1 AM EST Friday
for MIZ001>003.
Blizzard Warning from 1 PM this afternoon to 1 AM EST Friday
for MIZ004-084.
Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
Friday for MIZ006-007-085.
Lake Superior...
Gale Warning until 1 AM EST /midnight CST/ Friday for LSZ162.
Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Friday
for LSZ162.
Storm Warning until 4 AM EST /3 AM CST/ Friday for LSZ240>242-
263.
Heavy Freezing Spray Warning from 10 AM EST /9 AM CST/ this
morning to 1 PM EST /noon CST/ Friday for LSZ240>242-263.
Storm Warning from 10 AM this morning to 7 AM EST Friday for
LSZ243>251-264>267.
Heavy Freezing Spray Warning from 1 PM this afternoon to 7 PM
EST Friday for LSZ243>251-264>267.
Lake Michigan...
Gale Warning from 10 AM this morning to 10 PM EST this evening
for LMZ221.
Gale Warning from 10 AM this morning to 4 AM EST Friday for
LMZ248-250.
&&
SHORT TERM...TAP
LONG TERM...Rolfson
AVIATION...TAP
MARINE...Rolfson