417
FXUS63 KDLH 211133
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
633 AM CDT Sat Sep 21 2024

.KEY MESSAGES...

- Scattered to numerous showers and thunderstorms this morning
  over portions of the Northland. The storms are not expected to
  be severe this morning.

- Additional thunderstorms will develop this afternoon into the
  evening as a cold front moves through the region. Strong to
  severe storms will be possible, mainly over portions of
  northwest Wisconsin.

- Cooler temperatures develop Sunday into Monday then they will
  warm a few degrees through the week. A mostly dry period is
  expected Sunday through late week.

&&

.DISCUSSION...
Issued at 319 AM CDT Sat Sep 21 2024

A low level jet, as seen at 850mb, of 35 to 45 knots is
forecast by the RAP from eastern South Dakota into central
Minnesota. Area VWPs support this forecast as seen at KFSD/KMPX.
The warm air advection and convergence with the low level jet
has caused showers and thunderstorms to expand in coverage
early this morning with a larger area from around Walker south
and east toward Siren, WI. This is more widespread than the CAMS
and much of the guidance is struggling this morning. We`ve
increased POPs quite a bit and pushed chances this morning
further north and east and increased values using the low level
jet as guidance. Additional short term adjustments will likely
be needed over the next few hours and we`ll monitor radar
closely.

The bulk of these showers/storms should either lift north and
east or diminish later this morning as the low level jet
continues north and east. A shortwave, as seen on water vapor
imagery, will move from the northwest North
Dakota/Manitoba/Saskatchewan border early this morning into
northwest Minnesota by early afternoon then continue
east/northeast brushing northern parts of Minnesota. A surface
cold front will also push east today through central to northern
Minnesota by early afternoon and through far eastern Minnesota
and far northwest Wisconsin by late afternoon finally clearing
the rest of northwest Wisconsin early to mid evening.
Instability will build this afternoon ahead of the front,
especially from east- central Minnesota into northern Wisconsin
with PWAT values rising to around 1.3". Deep layer shear will be
30-35 knots with mid-level lapse rates from 7-7.5 C/km. These
parameters along with the forcing from mainly the cold front
will be enough to produce some strong to severe thunderstorms
from mid to late afternoon through about 02Z this evening. SPC
has a marginal risk, 1 out of 5, over parts of northwest
Wisconsin. The main risks are hail to 1 inch in diameter and
damaging wind to 60 mph. The showers/storms will end overnight
with cooler temperatures moving in on gusty west to northwest
winds.

A quiet stretch of weather is expected from Sunday through most
of next week. An upper ridge will move onto the West Coast early
in the week progressing east toward the Northland mid-late week.
A weak shortwave is forecast to move through the region Tuesday,
but it should not produce much for precipitation and we kept
the forecast dry. Nearly all 80 ensemble members of the
ECMWF/GFS keep Tuesday dry. Temperatures will be closer to
normal Sunday/Monday then warm a bit through the week. Some
frost will be possible in spots Sunday night.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 633 AM CDT Sat Sep 21 2024

Scattered showers and a few thunderstorms were occurring across
much of the Northland this morning. They are more numerous and
made it further north and east than earlier expected thanks to
the low level jet. These showers/storms will continue for a few
more hours but should decrease in coverage but may not end
altogether. Low level wind shear will continue at KDLH/KBRD/KHIB
this morning. Some brief dips to low MVFR or even IFR will be
possible in the stronger showers/storms. Additional development
of showers/storms will then occur along a cold front this
afternoon into this evening. A few of the storms may be strong
to severe, especially from east central Minnesota into
northwest Wisconsin. The front will clear northwest Wisconsin
this evening. Winds will switch from southerly ahead to west
then northwest behind the front. Some stronger gusts will occur
both preceding the front and behind.

We will expect some low MVFR ceilings to occur behind the front
but they are not expected to be widespread enough at this time
to add to the forecast. If they were to occur, they`d be most
likely at KINL and KHIB late this afternoon and early evening
and at KHYR this evening.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 319 AM CDT Sat Sep 21 2024

The wind is expected to become easterly for a time today from 5
to 15 knots ahead of a cold front. Winds will switch to west
then northwest behind the front, increasing in speed to 10 to 20
knots with gusts around 25 knots tonight. Thunderstorms will be
possible today into this evening with the main threats cloud to
surface lightning and gusty and erratic wind. We issued a Small
Craft for all areas from Saturday evening into the Sunday
morning.

The wind will be lighter on Sunday, roughly from 10 to 15 knots.

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...Small Craft Advisory from 10 PM this evening to 7 AM CDT
     Sunday for LSZ121-140>142-147-148-150.
     Small Craft Advisory from 10 PM this evening to 4 AM CDT
     Sunday for LSZ143>146.

&&

$$

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