443
FXUS63 KDLH 120952
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
452 AM CDT Fri Jul 12 2024

.KEY MESSAGES...

- Seasonably warm temperatures persist through the weekend.

- Several rounds of storms possible Saturday morning through
  Monday. Some storms may be severe and damaging wind gusts are
  the main hazard. Heavy rainfall may lead to localized
  flooding.

- Temperatures cool down though remain seasonable Tuesday
  through the end of next week.

&&

.DISCUSSION...
Issued at 452 AM CDT Fri Jul 12 2024

One more relatively quiet day ahead before thunderstorm chances
return late tonight through the weekend. A broad area of high
pressure was in place at the surface over the Great Lakes early
this morning. In contrast with the surface ridge, and upper
level low and associated trough were found over Michigan into
northeast Ontario while a ridge extended from southwest
Minnesota into northwest Ontario north of Lake Superior. Farther
west, the first of several shortwave troughs stretched from
Manitoba into central South Dakota. Farther north into the
Canadian Prairies, several clusters of thunderstorms were
observed from Pickle Lake, ON to portions of central and
southern MB, to near Saskatoon, SK. We can consider those storms
a preview of what`s ahead for the northern Plains and Upper
Midwest this weekend.

The eastward propagating shortwave trough over the Dakotas and
Manitoba will kick the ridge and upper low farther east today.
One more day of relatively quiet weather is on tap with mostly
sunny to partly cloudy skies. There`s a slight chance (less than
20%) a few showers or perhaps a storm develops over northwest
Wisconsin later this morning as a ribbon of vorticity and a
pocket of slightly cooler 700 mb temps passes overhead. A lake
breeze is expected once again today and should provide enough
low-level convergence to generate isolated to scattered storms.
High temperatures will trend a degree or two warmer for many
areas with highs in the middle 80s to low 90s. Lake breeze-
induced showers and storms will gradually weaken with the loss
of instability this evening.

Attention then shifts to tonight and the first of several
rounds of storm chances. Storm modes, location, and timing will
all be dependent on the evolution of previous rounds of
convection. There are a wide variety of solutions offered by the
models going forward and I won`t dive into all of them.

Storms this afternoon may redevelop on the leftover outflow
boundary from this morning`s convection over southern Manitoba
or they may develop along the stationary front farther west over
Saskatchewan. Either scenario features storms quickly
coalescing into one or more MCS and propagating southeastward
into northern Minnesota tonight or early Saturday morning.
MUCAPE of 1500-3000 J/kg is forecast overnight over northwest
Minnesota and eastern North Dakota, so there will be plenty of
instability to work with.

Storms will gradually weaken overnight as they advance
southeastward early to late Saturday morning. Several solutions
reinvigorate storms during the afternoon over portions of
central Minnesota or northwest Wisconsin subsequently pushing
farther southeast out of the Northland. Storms will likely
redevelop Saturday afternoon over eastern North Dakota and
northwest Minnesota, perhaps along the remnant outflow boundary
from the earlier convection. Strong instability with MLCAPE of
3000-4000 J/kg is forecast by late afternoon with 25-35 knots of
0-6 km bulk shear. A few supercells are possible in this
environment, particularly for storms which form along the
remnant outflow boundary. Large hail and a small risk of
tornadoes will be the main threat initially. Cold pool mergers
should lead to upscale growth into an MCS with the risk changing
to mainly damaging wind gusts of 60 to 70 mph. Heavy rainfall
will be possible in both scenarios. The resultant MCS is
forecast advance southeastward with time into northwest
Wisconsin by evening.

We may see a break in storm chances during the day Sunday.
Another round of storms is forecast Saturday night into early
Monday morning. Storms may redevelop over southern Saskatchewan,
eastern Montana, and western North Dakota then propagate east-
southeast into the Northland. There will be a chance of damaging
wind gusts and heavy rain with those storms, should they
persist and move into our area.

Confidence in temperatures is highest today, ahead of the
convection. Highs Saturday and Sunday remain on the warmer side
of average for mid-July, and are highly dependent on whether
showers/storms and cloud cover loiters over the Northland in the
wake of earlier convection. Highs are currently forecast in the
middle to upper 80s with a few 90s possible. If clouds remain
in place, expect temperatures to be several degrees cooler than
forecast.

A cold front will move southeastward across the Northland on
Monday bringing an end to storm chances and cooler temperatures.
Temperatures will begin to warm up again late in the week,
although staying near normal.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1236 AM CDT Fri Jul 12 2024

Light winds are forecast tonight with clear skies. Areas of fog
may develop before 12Z. HIB and HYR are most likely to see fog,
although BRD and INL have a chance of reduced visibility as
well. VFR conditions are expected for the daylight hours Friday.
Showers and storms may affect BRD, INL, and HIB early Saturday
morning after 13.06Z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 452 AM CDT Fri Jul 12 2024

Light winds will continue over western Lake Superior today and
tonight, generally less than 10 knots. A little fog may develop
near the Twin Ports and in smaller bays and harbors before
sunrise. Fog will dissipate quickly after sunrise. There is a
small chance of a few thunderstorms moving over the waters
Saturday morning and another chance of storms Saturday night.
Storms may be strong and wind gusts over 40 knots are possible.

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

&&

.HYDROLOGY...
Issued at 330 AM CDT Wed Jul 10 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. This advisory remains in effect through
Friday, but as levels in waterways further east crest, it may be
trimmed in its areal extent prior to expiring. However, for
areas further west, the Advisory may need to be extended in
time. Lingering high water from rains in June continue across
the Rainy River Basin. The Vermilion River continues to fall.
This has allowed the lake level increases on Crane Lake to slow
considerably, with lake levels having flattened out in the last
12 hours, likely having reached its crest. Lac La Croix levels
are cresting and should begin to slowly recede through this
week.

All this high water continues to lead to steady rises on
downstream lakes, notably Namakan/Kabetogama (Nam/Kab) lakes
where minor flooding continues, and on Rainy Lake where levels
have just exceed the rule curve. Past events have shown there is
a lag between the crest at Lac La Croix and the crest on
Namakan lake of anywhere from 3 to 10 days (the longer coming
from events when rain fell around peak waters). As water levels
upstream crest and begin to come down, rates of rise on Nam/Kab
should begin to slow and eventually crest, possibly by late this
week or this weekend. Rates of rise have slowed to 1-1.5"/day
over the weekend and in the last 24 hours there was only about a
0.5" rise on Kabetogama/Namakan as inflows are decreasing.
Until peak, another 2.5-7 inches of rise could be possible
(estimate, not an official forecast), with the high end of that
range probably being a worst case scenario. This could bring
Nam/Kab just over 1120 feet with a peak level somewhat similar
to the high water during the summer of 2014. This is still 2
feet or more below the high water levels of Spring 2022 - we
are nowhere close to that level of flooding and extreme rises
to that point are currently not expected. As is usual for this
basin, water will move slowly and recessions will happen at
glacial speeds with some flavor of high water possibly
continuing through the month. However, peak should happen sooner
rather than later, based on latest observations. 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 (including
submerged docks), 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.

&&

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

&&

$$

DISCUSSION...Huyck
AVIATION...Huyck
MARINE...Huyck
HYDROLOGY...Levens/Rothstein