229
FXUS63 KDLH 041134
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
634 AM CDT Tue Jun 4 2024

.KEY MESSAGES...

- Dense fog expected over much of western Lake Superior into
  this evening with some inland as well this morning, especially
  over central to northern Minnesota.

- A line of showers and thunderstorms develop along a cold front
  today, mainly this afternoon into the evening. A few storms
  may become severe and also contain a heavy rain threat which
  may lead to localized flooding.

- There will be more showers Wednesday and periodic chances that
  continue into early next week. Rainfall amounts mid week into
  the weekend will be lighter than what is expected today.

&&

.DISCUSSION...
Issued at 334 AM CDT Tue Jun 4 2024

Surface low pressure stretched from Alberta southeast through the
Plains with a center along the north central South Dakota and North
Dakota border. Water vapor imagery depicted the upper low over the
Montana/Saskatchewan border. The upper trough will move east
today and the surface low will lift northeast and congeal well
north of the International Border. A cold front will push into
the Northland this afternoon and exit tonight. Areas of fog and
stratus, most widespread over northwest Wisconsin into northeast
Minnesota will lift through the day but take longest around
Lake Superior due to off lake winds that will occur through most
of the day.

A warm and moist airmass will precede the cold front today with
PWAT values rising to 1.6" and surface dewpoints will climb
into the mid- sixties with a few spots as high as the upper
sixties. Highs will climb well into the seventies to lower
eighties, away from Lake Superior. MLCAPE values are expected to
climb to 1000-2000j/kg ahead of the front. Deep southerly flow
ahead of the front will be in place and was aiding in drawing
moisture north. Deep layer shear will be from 25 to 30 knots
ahead of the front to 35 knots very close to it. There will be a
severe threat, especially for cells close to the front where
the shear is greatest. Forecast soundings show decent low level
curvature in the hodographs but with a messier appearance above.
Given the stronger forcing with the front and upper trough,
storm mode should transition to a line or line segments fairly
quickly. CAMS do show some individual storms for a time and hail
from penny to half dollar still looks reasonable. There will
also be a wind threat, especially as storm mode changes to more
linear. Given the deep layer winds, 2-7KM, and 0-6KM shear
vectors are all parallel or nearly parallel to the front today,
heavy rain will be another threat. Storm motions will have a
south to north component within the west to east line movement.
This will lead to some training and with the higher moisture,
flooding may result. The heavy rain that fell 24-36 hours ago
over portions of the Northland will have soils primed. The HREF
is showing the heavy rain threat with some pockets in the LPMM
to 3" and some larger areas of 1-2". We will maintain the Flood
Watch.

The main window for severe will roughly be from 2 pm to 9 pm,
guidance is in fairly good agreement on this. The SPC outlook for
severe storms for much of our area is a 2 out of 5.

The upper trough will be over the region Wednesday through Thursday
and cooler temperatures will move in. The cooler temperatures aloft
and upper low will keep chances for showers going through Thursday
but they will be most widespread Wednesday. Chances will be greatest
during the afternoon and evening hours during and just after peak
heating. The rainfall Wednesday/Thursday will be much lighter than
what is expected today.

A western upper ridge does build late week into the weekend but the
Northland remains close to the upper low and we carry chances for
showers and a few thunderstorms in spots into early next week.
Rainfall amounts will be relatively light. Highs late week into
early next week will be near normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 634 AM CDT Tue Jun 4 2024

Stratus and fog were occurring across much of northwest
Wisconsin into northern Minnesota with the fog dense  and
ceilings below 500 feet in spots. The fog/stratus should lift
through the day but it will take the longest to occur, and may
not, closer to Lake Superior where onshore winds will persist. A
cluster of showers and thunderstorms were moving northeast
toward Koochiching County and should arrive there over the next
hour. This activity is expected to diminish before more showers
and storms develop along a cold front. Storms this afternoon and
evening could be quite strong and produce damaging wind and
large hail. In addition, individual storm motions will be more
south to north with a line moving west to east. This will lead
to heavy rain in spots with a few strong storms affecting the
same areas.

Winds will be southerly ahead of the front and turn to the west
or southwest behind it. Chances for showers/storms will diminish
from west to east tonight.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 334 AM CDT Tue Jun 4 2024

Fog, dense in spots, will occur today into tonight over portions
of the area. Easterly winds will continue today and then turn
westerly as a cold front moves through this evening/overnight.
The wind switch should aid in ending the dense fog threat.
Showers and thunderstorms will develop along the front as well
and some of the storms could be strong to severe with large hail
and winds to 45 knots possible. Westerly winds on Wednesday will
be strongest from Silver Bay to the Twin Ports to Port Wing and
some gusts of 20 to 25 knots will be possible.

Westerly winds will increase further on Thursday with
widespread speeds of 15 to 25 knots with gusts around 30 knots.
Hazardous conditions will occur, especially for smaller vessels
and a Small Craft Advisory will likely be needed.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ019-035-
     036-038.
     Dense Fog Advisory until 11 AM CDT this morning for MNZ020-021-
     037.
     Flood Watch from 1 PM CDT this afternoon through Wednesday
     afternoon for MNZ034-036-038.
     Beach Hazards Statement through this evening for MNZ037.
WI...Dense Fog Advisory until 11 AM CDT this morning for WIZ001.
     Flood Watch from 1 PM CDT this afternoon through Wednesday
     afternoon for WIZ001>004-006>009.
     Beach Hazards Statement through this evening for WIZ001.
MARINE...Dense Fog Advisory until 10 PM CDT this evening for LSZ140>146.
     Dense Fog Advisory until 10 AM CDT this morning for LSZ150.

&&

$$

DISCUSSION...Melde
AVIATION...Melde
MARINE...Melde