482
FXUS63 KDLH 061752
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1252 PM CDT Sat Jul 6 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms are ongoing this afternoon
  and are expected through Sunday evening. A few storms may be
  strong over northwest Wisconsin Sunday afternoon and evening.

- Diurnal rain and storm chances persist through much of next
  week.

- High water persists across the Rainy River Basin and a Flood
  Advisory is in effect through early next week. See the summary
  at www.weather.gov/dlh/RainyRiverBasin for more information.

&&

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

A ridge of surface high pressure extended northeast from the
central Plains into northeast Minnesota early this morning.
Skies were generally clear and areas of fog are expected through
sunrise. Weak flow was found aloft with the latest RAP analysis
indicating a ridge aloft through 400 mb. GOES-East water vapor
imagery revealed a weak lobe of vorticity over north-central
Minnesota and adjacent areas of northwest Ontario as of 09Z. A
shortwave trough was located over eastern Montana, eastern
Wyoming, the western Dakotas, and the Nebraska Panhandle.

High temperatures today will be similar to Friday with values
in the upper 70s to low 80s. The seasonal temperatures, combined
with cool air aloft, and ample moisture, will lead to isolated
to scattered thunderstorm development this afternoon and
evening. MLCAPE of 500-1250 J/kg is forecast by late afternoon.
Weak flow near the ground and aloft will result in upright
convection, at least initially. As storms collapse, additional
development will occur along resultant outflow boundaries. Cold
pool mergers will eventually support more persistent convection.
Weak deep layer shear and modest lapse rates will limit the
severe weather potential. Brief torrential rainfall is likely
with the storms and there is a small risk of pea to half-inch
diameter hail.

Storms should subside this evening as instability is consumed.
Attention then shifts to the shortwave trough approaching from
the west. A weak southerly LLJ is forecast to develop overnight
and a few models rejuvenate convection over central and
northern Minnesota during the 07-10Z timeframe. Elevated CAPE
from parcels lifted from the 925 to 850 mb layer may find
500-1000 J/kg to work with.

Additional showers and storms are expected over central and
southern Minnesota as the shortwave trough advances into western
Minnesota during the early morning hours. As the trough passes
eastward across the region, shower and storm chances will
persist through the day. Deep layer shear increases over
northwest Wisconsin during the afternoon and there is a
potential for a few stronger thunderstorms. The risk of severe
storms may be locally enhanced over northwest Wisconsin by a
remnant MCV which will likely develop from the nocturnal
convection over the Dakotas early this morning. There will be a
low, but not zero, tornado potential and a small chance of one
inch hail. Mid-level lapse rates of 6.5 to 7 degC/km and high
freezing levels will limit the hail potential. Downbursts with
wind gusts of 40 to 60 mph will be possible considering the
somewhat dry mid to low levels.

Weak flow and relatively cool air aloft will persist through
much of the upcoming week. Look for diurnal chances of showers
and storms each day with temperatures on the warm side of the
seasonal normal range. Wednesday and Thursday have the lowest
chances of precipitation through next 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 440 AM CDT Sat Jul 6 2024

Offshore winds this morning turn southwesterly away from the
shoreline. A relaxed pressure gradient will persist over the
waters into early next week with wind speeds of 3 to 12 knots.
Winds will back northeasterly on Sunday. There are slight
chances of afternoon and evening storms each day. Winds will
back southwesterly again for Monday and remain relatively light.

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...Huyck
AVIATION...NLy
MARINE...Huyck
HYDROLOGY...Levens