878
FXUS63 KDLH 062047
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
347 PM CDT Sat Jul 6 2024

.KEY MESSAGES...

- Isolated thunderstorms and scattered rain showers persist
  mainly over northeast Minnesota into the evening.

- A few stronger storms may form in northwest Wisconsin Sunday
  afternoon, with lingering chances into the late evening
  hours.

- Monday and Tuesday feature continued daytime storm chances
  before a downturn in activity is expected Wednesday and
  Thursday.

&&

.DISCUSSION...
Issued at 345 PM CDT Sat Jul 6 2024

A stationary boundary remains parked over the Iron Range and
into central Minnesota this afternoon, which has been aiding
formation of widely scattered thunderstorms and numerous rain
showers in mainly north-central to far northeast Minnesota so
far today. Updrafts are not staying aloft very long though due
to very little mid-level support from weak lapse rates and
highly disorganized and weak shear. Collapsing storms have
created outflow winds to 35 mph today, which is about the peak
expected into the early to mid-evening hours today. Fairly warm
low-levels and the weak support aloft have limited hail product,
with high liquid rainfall amount signatures being seen on the
dual-pol radar data with the stronger thunderstorms. Although,
mixed layer CAPE to 1000 J has promoted up to dime size hail
with most being favored for only pea size reports. These storms
are expected to last into the mid-evening hours today, but are
already showing signs of weakening where earlier activity was
prevalent (Cass/Crow Wing/Itasca Counties).

An incoming shortwave vort max, currently in the Dakotas, moves
into central Minnesota after Midnight tonight. Forecast model
soundings show lingering MUCAPE overnight potentially aiding in
isolated storm development within a broader line of weak rain
showers as a quasi-warm front crosses over the Northland from
south to north late tonight into Sunday morning. As the vort max
lifts northeastward into the Arrowhead tomorrow afternoon,
stronger and veering southwest to westerly low to mid- level
flow sets up in northwest Wisconsin. Under areas with partial
clearing, most favored along the MN/WI stateline counties Sunday
afternoon a few stronger thunderstorms are expected to form.
The primary threat would be small hail and wind gusts to 50 mph.

A backdoor cold front drops southward Sunday evening and brings
an end to storm chances by Midnight Sunday night. A period of
cooler air aloft under north-northwesterly flow and diurnal
instability will lead to additional non-severe thunderstorm
chances for Monday and Tuesday afternoon and evenings. A mid-
level drier airmass works into the Northland from Ontario
Wednesday and lasts into Thursday and Friday to create very
little or no rain shower or thunderstorm chances over the region
for mid-week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1245 PM CDT Sat Jul 6 2024

Scattered general thunderstorms and numerous showers are ongoing
along the Iron Range, in the Arrowhead and southwestward into
the Brainerd Lakes and east-central Minnesota. Expect wind gusts
to 25 knots, pea size hail and very localized half-hour or so
durations of high intensity rainfall creating IFR visibility.
Ceilings are expected to largely remain MVFR with these showers.
These largely diurnal showers and storms decrease in coverage
after 03Z this evening with areas of fog expected at some
terminals. Another round of rain showers from 09Z onward
associated with a weak low pressure lifts from south to north
through 15Z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 300 PM CDT Sat Jul 6 2024

Isolated thunderstorms within a half-mile of the shoreline may
occur into this evening along the North Shore, but impacts would
be limited to a brief period of moderate rain, lighting strikes
within a few miles of the shorelines and erratic wind gusts to
20 knots through mid-evening today. A weak low pressure moves
into the Northland from the Dakotas later tonight and brings
another round of showers and isolated storms to the area early
Sunday morning. Winds shift to easterly over the lake Sunday
afternoon and could gust around 15 knots at the head of the lake
Sunday late afternoon and evening. Sunday afternoon may feature
a locally strong thunderstorm along the South Shore, but chances
are only around 10% at this time. Light winds and thunderstorm
chances last into Monday as well.

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

&&

.HYDROLOGY...
Issued at 440 AM CDT Sat Jul 6 2024

A Flood Advisory continues across portions of the Rainy River
Basin, extending as far east as Lac La Croix and as far west as
the Rainy Lake outlet. Lingering high water from rains in June
continue across the Rainy River Basin. Headwaters gauges on the
Kawishiwi River, Basswood River, and Lake Vermilion have crested
and are slowly but surely coming down (Lake Vermilion falling
at a rate of a measly quarter inch a day). The Vermilion River
is also beginning to fall once again, after taking a turn
upwards after a second round of heavy rains at the beginning of
July. This has allowed the lake level increases on Crane Lake to
slow considerably, nearly flatlining just above minor flood
stage. Lac La Croix levels continue to increase though, the
product of not only the high water from the Basswood River but
numerous Canadian tributaries coming out of the Quetico as well.
Latest data suggest that inflow and outflow are nearly meeting
on Lac La Croix, which could help levels begin to crest soon.

All this high water has led to some decent rises on downstream
lakes, notably Namakan/Kabetogama (Nam/Kab) lakes (minor
flooding ongoing), as well as levels beginning to increase on
Rainy Lake (still within rule curves). Per the latest IJC water
level bulletin, dam operators are working to maximize outflow
through the basin. However, the sheer volume of water moving
through the basin will still result in additional rises on these
lakes. As water levels upstream crest and begin to come down,
rates of rise on Nam/Kab should begin to slow and eventually
crest. We`ve already seen the rates of rise begin to demonstrate
signs of slowing. From July 1 to 3rd, Nam/Kab Lakes were rising
at 2- 2.5" per day, but have recently slowed to 1-1.5"/day in
the last 48 hours or so. General guidance suggest peak levels on
Nam/Kab could be possible this coming week, but that is
uncertain. As is usual for this basin, water will move slowly
and recessions will happen at glacial speeds. Additional
rainfall may cause brief rises in tributaries and extend the
period of high water in core lakes.

Boaters should expect high water, potentially hidden underwater
hazards, and strong currents in constricted areas. Generally
light winds are expected, except for possible brief erratic
gusts out of thunderstorms, so wave heights should remain fairly
minimal. The Flood Advisory is in effect through Wednesday, but
may need to be extended based on observed conditions.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...None.

&&

$$

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