411
FXUS63 KDLH 172344
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
644 PM CDT Tue Sep 17 2024

.KEY MESSAGES...

- Muggy, much above normal temperatures persist through the week,
with the hottest temperatures and highest dewpoints through
Thursday.

- Scattered showers and thunderstorms are possible today into
Wednesday, primarily across north-central MN and the MN Arrowhead.
Some severe storms are possible Thursday with a passing cold front.

- Seasonable temperatures may return through the weekend and
  into next week.

&&

.DISCUSSION...
Issued at 329 PM CDT Tue Sep 17 2024

Another hot and muggy day has developed across the Northland with
southwesterly flow bringing temperatures in the 80s and dewpoints in
the mid 60s. A front draped just north of the border continues to
spur areas of thunderstorms, but much of the CWA was clear this
morning. A few areas of cumulus fields have developed early this
afternoon, out of which some afternoon showers and an isolated
thunderstorm are possible. With as much moisture as we have hanging
around at the moment, some small areas of heavy rain are possible if
thunderstorms develop but coverage should be very minimal.
Overnight, an area of showers may develop along the front edge of a
zippy LLJ building along a frontal zone. These showers are most
likely over north-central and northeast Minnesota and are generally
expected to dissipate through the morning as the support from the
LLJ wanes.

Wednesday, a stacked upper level low is progged to push out of the
Rockies and into the northern Plains and southern Manitoba, dragging
a cold front over the Upper Mississippi and northern Great Lakes
Wednesday afternoon and through the day Thursday. Along this front,
a narrow corridor of 1000-1500 J/kg of MLCAPE, up to 40 knots of
bulk shear, and steep lapse rates is expected to build, which could
be enough to spur a some scattered severe thunderstorms. CAMs and
global models generally suggest two different periods of possible
storms, one in the morning with elevated convection along the
overnight LLJ, and the second in the afternoon and early evening
from the combination of a front and surface-based instability. The
second is the more likely candidate for any severe storms. Morning
showers could lead to some widespread mid to high clouds which leads
to a little uncertainty regarding the potential for afternoon
convection to redevelop. However, synoptic forcing is good and may
be enough to overcome a lack of instability. Currently, the SPC has
portions of the Northland outlooked in a Slight risk (level 2 out of
5), but there is still some discrepancy on frontal placement by
Thursday afternoon, with the latest suite of models being slightly
more progressive with the front and initiation of afternoon storms.
In addition to the severe threat, some quick downpours and locally
heavy rain is possible, thanks to our very moist environment.
However, no widespread heavy rainfall coverage is expected.

Beyond Thursday, the Northland finds itself stuck between a high
pressure over the southern Plains and an upper level trough bearing
down from Canada. Embedded within that all could come some cut off
lows and shortwave troughs. This should generally bring some cooler
temperatures to the region, but our current above normal temperature
situation may dally on it`s way out, with high temperatures not
expected to reach their climatological normal of high 60s until
Sunday. All the action in the upper levels may also keep chances for
rainfall around. However, global ensembles have backed off slightly
in their widespread washout precipitation chances they were showing
a couple runs back, so there could be some sunshine scattered in
there as well.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 644 PM CDT Tue Sep 17 2024

Thunderstorms over Ontario this evening are expected to continue
to slide east tonight. Additional storms may form near the
northwest MN/Manitoba/Ontario intersection this evening, which
may affect KINL overnight. Have included some VCTS/VCSH groups
for now, but anticipate needing to make adjustments to it. VFR
conditions expected through the TAF period, though some fog is
possible in the early morning if wind drops to less than 5kts.
Strong south-southwest winds around 2kft are expected to cause
LLWS to develop this evening for the MN terminals, with speeds
of 35-40knots, which then diminish again by 12z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 329 PM CDT Tue Sep 17 2024

Through Wednesday, expect a similar wind pattern as the last couple
days. Southerly winds along the South Shore turn and become onshore
for the Twin Ports and North Shore, with some gusts of 10-15 knots
possible in the afternoon. Thursday, slightly strong south to
southeast winds are possible, sustained around 10-15 knots and some
gusts near 20 knots in the Twin Ports and Chequamegon Bay. Some rain
showers and thunderstorms are possible Thursday, which may contain
strong winds and some larger hail in the afternoon and evening.
Friday, expected southwesterly winds with some strong afternoon
gusts behind Thursday`s cold front.

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

&&

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

&&

$$

DISCUSSION...Levens
AVIATION...LE
MARINE...Levens