853
FXUS63 KMQT 281805
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
105 PM EST Fri Feb 28 2025

.KEY MESSAGES...

- Travel conditions will deteriorate quickly this afternoon and
evening, especially over the counties bordering Lake Superior, as
snow and strong winds develop.

- The snow, combined with quickly falling temperatures, could lead
to icy roads developing this evening. Visibility will be reduced in
snow and blowing snow. Additional snowfall totals this afternoon
through tonight range from around 2 inches near the lakeshore to
near 8 inches in the higher terrain of the north-central and western
UP.

- Winds gusting to 40-55 mph, strongest over the Keweenaw, central,
and eastern UP, could lead to a few downed tree limbs and power
outages.

- Lake effect snow ends Saturday, followed by mostly dry conditions
and a warming trend into at least early next week. Widespread above
freezing temperatures expected for Monday and Tuesday.

- Strong low pressure system will bring wet and heavy snow to the
Great Lakes Tuesday night into Wednesday. Exactly how much will
depend on the track of the storm, which is uncertain at this time.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 435 AM EST Fri Feb 28 2025

Snow has already begun to fall across much of the UP ahead of
deepening 987mb low pressure over northwest Ontario per 08Z RAP
analysis. Southerly flow has already begun to ramp up, with KIWD
seeing gusts to 25mph already at the 0756Z METAR. This warm
southerly flow will create some complications with this forecast
period as there are several hours today that the HREF
probabilities of rain are 30-40%. A few soundings even show an
hour or two this morning that brief freezing rain may occur in
the west, though the period of freezing rain will not be long
enough to accumulate anything more than a minor glaze. Still,
even if probabilities are higher in snow than of rain, soundings
showing much of the bottom 10kft below the DGZ through the
morning and then the dry slot intruding into the DGZ by the time
the DGZ lowers lend credence to SLRs at or below 10:1 prior to
18Z. HREF 6-hourly QPF PMMs still highlight the areas east of
M-77 and Keweenaw County as having 0.25" of QPF prior to 18Z and
more favorable SLR setups, translating to 3-5"/6hr snowfall
rates for those areas while the rest of the Keweenaw Peninsula
and the rest of the eastern third of the UP see 1-3"/6hr.
Meanwhile, the remainder of the UP battling Ptype issues and
eventual dry slotting will struggle to see more than an inch of
snow prior to 18Z.

Moving into the afternoon, the HREF shows some minor differences but
for the most part shows a track that has the low bottoming out at
984mb off the tip of the Keweenaw at 18Z and tracking southeast to
the eastern UP into the evening closer to 988mb. With strong high
pressure over the Canadian Prairie building and encroaching behind
the low, the 07Z HRRR shows 6-hour pressure rises of a staggering
+19/mb over Keweenaw County and much of the west half of the UP at
+16mb/6hr. This will have a strong impact on the winds, with several
CAMs calling for sustained winds over 40 kt over western Lake
Superior and wind gusts along the shorelines approaching 45+ mph and
widespread gusts of 35 mph across much of the UP. This in addition
to the moderate to heavy snowfall rates expected will lead to
occasional whiteout conditions and drifting snow over roadways
especially close to Lake Superior. CAMs are a little split on
whether or not there will be a notable lull in precipitation in the
late morning to early afternoon hours, further adding uncertainty to
the snow totals. However, by 21Z, virtually all CAMs show
precipitation patterns reflective of a change to lake enhanced to
lake effect snowfall over the western UP, especially in the north-
facing sloped terrain. Soundings also show a saturated DGZ closer to
the surface, leading to bumping the SLRs back up especially as
surface temperatures quickly drop back sub-freezing. HREF 6-hourly
QPF PMM of around 0.2" in the high terrain of the Porkies and on the
Marquette/Baraga county line in conjunction with those raised SLRs
will lead to snow rates of up to 3-4"/6hr in those areas, with
surrounding areas closer to 1-2"/6hr. Have elected to maintain
winter headlines at this time as snow totals do not quite reach
Winter Storm thresholds in the west, and the impacts from Winter
Storm Warning criteria snowfall are going to be limited as it is all
well north of US-41. If the 12Z HREF guidance shows higher LES
potential (especially over a populated area), then short-fused
upgrades may become necessary. Have elected to expand the Wind
Advisory to include Marquette County as wind gusts right off of Lake
Superior impacting the City of Marquette may become impactful.

&&

.LONG TERM /TONIGHT THROUGH THURSDAY/...
Issued at 257 AM EST Fri Feb 28 2025

Upper air pattern consists of a 500 mb closed low off of SW CA and a
trough in the eastern U.S. 00z Sat. The closed low goes to the lower
Colorado River Valley 00z Sun with the trough in the eastern U.S.
This closed low gets ejected to the western high plains of KS 00z
Mon with another closed low moving onto the CA coast and then the
two lows move further east, the western one into the desert sw and
the eastern one to central Nebraska by 12z Mon. One change made to
the going forecast as I increased qpf amounts a bit tonight into Sat
morning. Reasoning was lake enhancement and upslope areas and looked
at some forecast sounding to the east where there was some omega in
the dgz zone in Munising, Grand Marais areas. Overall though, this
did not affect snow amounts that much. The heaviest snow will be in
the evening and then winds down after midnight as deeper moisture
with the clipper moves out.

In the extended, the GFS and ECMWF show a 500 mb trough over the
desert sw, a shortwave over the central plains and a trough off
the east coast 12z Mon. The upper trough moves into the southern
Rockies 12z Tue and ejects northeast into the mid Mississippi
Valley 12z Wed and into the Appalachians 12z Thu. The upper
Great Lakes is under broad upper troughing 12z Fri. Temperatures
go from above normal Monday and Tuesday to near normal
Wednesday and to below normal Thursday and Friday. Did bump up
winds on Wed due to a tight pressure gradient across the area.
Rain and snow mix on Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1225 PM EST Fri Feb 28 2025

Strong clipper system will track across Lake Superior for the rest
of today, bringing high winds and low visibilities due to snow and
blowing snow behind it. The low conditions have already started at
CMX where LIFR conditions are expected to prevail, and conditions
below airport mins cannot be ruled out (30% chance through 00Z - if
chances increase, this will be handled with amendments). LIFR
conditions will likely develop at IWD/SAW later this afternoon as
well. There is potential for a flash freeze to occur this afternoon
into the evening as temperatures plummet in concert with the
snowfall. Conditions slowly improve late tonight into Saturday
morning as lake effect snow tapers off.

&&

.MARINE...
Issued at 257 AM EST Fri Feb 28 2025

A strong Alberta clipper system will move through the area today and
bring with it a period of strong gales up to 45 knots with a few
storm force gusts to 55 knots. Southerly gales will become north
this afternoon as the low passes by. Gales of 35 to 40 kt are
expected to linger out of the north tonight before falling to 20 to
30 knots out of the NW Saturday and falling below 20 kt late
Saturday and Sunday. The next significant wind event will be on
Wednesday with a tight pressure gradient over the area and a strong
gale event looks likely. Heavy freezing spray is expected into
Saturday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Storm Warning until 1 AM EST Saturday for MIZ001-006-
     007-085.

  Wind Advisory until 1 AM EST Saturday for MIZ001-003-005>007-
     085.

  Coastal Flood Advisory until 11 PM EST this evening for MIZ001.

  Winter Weather Advisory until 1 AM EST /midnight CST/ Saturday
     for MIZ002>005-009-084.

  Coastal Flood Advisory from 6 PM this evening to 5 AM EST
     Saturday for MIZ005-006.

  Wind Advisory until 1 AM EST Saturday for MIZ013-014.

  Winter Weather Advisory until 10 PM EST this evening for
     MIZ014.

Lake Superior...
  Gale Warning until 1 AM EST /midnight CST/ Saturday for
     LSZ240>242-245>248-263-265.

  Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ162.

  Heavy Freezing Spray Warning from 7 PM EST /6 PM CST/ this
     evening to 7 AM EST /6 AM CST/ Saturday for LSZ162.

  Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/
     Saturday for LSZ240>242-263.

  Gale Warning until 4 AM EST Saturday for LSZ243-244-249>251-
     264-266-267.

  Heavy Freezing Spray Warning until 7 PM EST Saturday for
     LSZ243-244-249>251-264-266-267.

  Heavy Freezing Spray Warning until 1 PM EST Saturday for
     LSZ245>248-265.

Lake Michigan...
  Gale Warning until 1 AM EST Saturday for LMZ221.

  Gale Warning until 1 AM EST Saturday for LMZ248-250.

&&

$$

SHORT TERM...GS
LONG TERM...07
AVIATION...Thompson
MARINE...07