Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 270538
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1238 AM CDT Wed Mar 27 2024

.KEY MESSAGES...

- Widespread snowfall tapers in coverage from west to east this
  evening and tonight, with snowfall persisting in far north-
  central Minnesota into the Arrowhead and along the South
  Shore.

- Scattered snow showers may (40-50% chance) bring a quick inch
  of snowfall and rapid chances in visibility to locations
  along the South Shore and along and north of US Hwy 2 in
  northeast Minnesota Wednesday mid-afternoon to early evening.

- Well-below normal temperatures in the 20s Wednesday warm to
  the low to mid-30s Thursday.

- The next round of snowfall may (30% chance) bring a few inches
  of snowfall along and north of US Hwy 2 Friday evening into
  Saturday morning.

&&

.DISCUSSION...
Issued at 335 PM CDT Tue Mar 26 2024

Satellite imagery shows warming cloud tops over the areas that
are receiving snowfall late this afternoon which lines up well
with weakening synoptic forcing as low pressure lifts well out
of the Northland into this evening. This draw down in the
heaviest snowfall potential lines up well with the current end
time of the Winter Storm Warnings and Advisories dropping off
around 7 PM today for all counties. While the primary low
pressure lifts northeastward into Ontario, a closed cut off low
within a deep central US trough ejects eastward through southern
Manitoba and into northwest Ontario tonight. Wrap-around
moisture, a much colder air mass from the north and vorticity
maxes in the cut- off low keep persistent light snowfall chances
in far north- central Minnesota through tonight and into
tomorrow morning. At this time, there is a 40% chance for an
additional couple of inches of snowfall for those north-central
MN counties by Wednesday morning. There are early signals of a
weak gravity wave that sets up along the South Shore tonight to
create a period of locally moderate snowfall for the typical
terrain ridge from east-central Douglas County to the tip of the
Bayfield Peninsula this evening and the overnight hours. Due to
the current Winter Storm Warnings in place ending this evening,
no headlines were issued for this additional snowfall, but a
low-end Advisory may be needed in time for a limited set of
zones for the overnight snow chances.

As the cut-off low pressure center drops southward to central
Lake Superior tomorrow, the northwesterly flow aloft under
significant cold air advection within a time of year of
increased solar radiation is likely to form scattered diurnal
snow showers tomorrow afternoon and early evening. Right now the
expectation is for increasing snow shower potential from 11 AM
2 PM and greatest potential for a quick burst of very localized
inch of snowfall from 3 PM - 7 PM Wednesday afternoon. While
criteria is not expected to be met for widespread snow squalls
tomorrow due to a minimal wind threat and temperatures already
being well-below freezing to limit the flash freeze likelihood,
very localized three-quarter to one inch per hour snowfall
rates could (60% chance) occur in isolated snow showers on the
Bayfield Peninsula to the Twin Ports and northward into the
Arrowhead. There are lesser chances further westward for the
higher-intensity snowfall showers, but scattered light snow
showers remain possible back to International Falls and near
Bigfork. Model analysis shows a dry air intrusion in the low-
levels into the Brainerd Lakes and east-central Minnesota which
highly limits the snow shower potential in those locations of
the Northland tomorrow, but a stray shower into Pine County
cannot be entirely ruled out. Showers will move in a east-
southeastward motion under mean west-northwesterly surface to
mid-level steering flow. The impact from these localized heavy
snow showers will be the forecast showing a fairly widespread
swath of light accumulations of 0.5 to 1" of snowfall for
Wednesday daytime, but not every location will see these
measurable amounts.

The other implication of that cooler air mass sitting over the
Northland tomorrow under still fairly cloudy skies is well-below
normal daytime temperatures in the 20s.

The formerly-cut cut off and closed low pressure quickly exits
the region by Thursday morning as a low to upper-level ridge
axis slides into the Northern Plains and ushers in a much drier
and warmer air mass. Expect a quick uptick in those daytime high
temperatures to the 30s by Thursday.

The period of dry weather on Thursday will be short-lived for
some locations in the far northern parts of the Northland by
Friday evening. A Pacific shortwave quickly crosses the Rockies
Thursday night into Friday daytime and deepens over the southern
Canadian Rockies Friday afternoon. This shortwave will bring a
quick warm front to the region and first round of possibly
wintry mixed precipitation late Friday afternoon and into the
evening before the cold front sets up over the area Friday
night. The result could be a wintry mix Friday afternoon into
the evening becoming mostly snowfall Friday night and bring (30%
chance) a few inches of snowfall to locations along and north of
US Hwy 2 by Saturday morning.

A mild and seasonable air mass Saturday lasts into Sunday to
create near-normal temperatures ahead of the next possible (a
more southerly storm track) storm system for Sunday night into
Monday night.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1237 AM CDT Wed Mar 27 2024

Mix of IFR to VFR conditions early this morning will continue
with scattered snow showers across the area. As snow moves over
terminals, visibilities as low as 1 to 2 miles are possible,
along with gusty northwest winds. At INL, more prevailing snow
is expected with additional accumulations of several inches and
a prolonged period of IFR visibilities. Upstream observations
indicate some IFR ceilings are also possible at INL. Towards the
very end of the TAF period some improvements to widespread MVFR
and VFR conditions should build across the region as snow
showers come to an end.

&&

.MARINE...
Issued at 245 PM CDT Tue Mar 26 2024

Northerly winds creating gales along the North Shore and strong,
gusty winds across the rest of the western waters this afternoon
back northwesterly this evening and then westerly late tonight.
Conditions hazardous to small craft persist for the next two
days with a long-duration Small Craft Advisory in place for the
Twin Ports and the entire South Shore through Thursday morning
at this time. After the Gale Warning ends along the North Shore
this evening, Advisories are very likely going to be needed as
well for those marine nearshore zones over a similar extended
time period. A few gale force gusts to 35 knots may affect the
Outer Apostle Islands Wednesday morning and afternoon.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory until 10 AM CDT this morning for
     MNZ010-011-018.
WI...None.
MARINE...Small Craft Advisory until 10 AM CDT Thursday for LSZ121-
     144>148-150.
     Gale Warning until 1 AM CDT early this morning for LSZ140>143.

&&

$$

DISCUSSION...NLy
AVIATION...Levens
MARINE...NLy


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