997
FXUS63 KDLH 221121
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
621 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Periods of rain and some thunderstorms continue through the
weekend.

- More showers and storms are possible Monday late-afternoon into
early Tuesday morning. Some strong to severe storms are possible.

- Active weather with rain and thunder chances persist through next
week with occasional breaks of sunshine.

&&

.DISCUSSION...
Issued at 423 AM CDT Sat Jun 22 2024

Main concerns this morning is for convection and potential for
heavy rainfall in the forecast. Currently, a weak surface low is
over Iowa, with a east-west oriented boundary extending from
Nebraska across Iowa along the WI/IL border. VWP data shows a 40
knot low level jet impinging upon this boundary, explaining the
broad area of showers and storms extending from Iowa into
southern WI and southeast MN. We also have some weaker showers
over northwestern MN, but these appear to be associated with a
weak shortwave moving across that area. Hi res models are
generating an expanding area of showers and storms mainly over
northwest Wisconsin this morning as it gradually pushes east,
right on the nose of the low level jet. They keep generating
some bands that move up into the Twin Ports and nearby areas,
but this is sitting on the far northern fringe of where we may
get thunder, up until mid morning today before it pushes east
for the remainder of the morning. A potent shortwave will move
across the area this afternoon and early evening, and we should
build sufficient instability and deep layer shear for new
thunderstorm development. For now it appears the instability
will be the limiting factor, with only enough for general
thunder chances, but not enough for severe storms. However, most
of the southern CWA should get some afternoon and evening
storms, with the precipitation potential decreasing to the
north. Northeast winds today along with temperatures already on
the cool side will keep high temperatures in the upper 60s to
mid 70s for most of the area. The northeast winds will put the
"cooler by the lake" into reality today, with temperatures along
the Lake Superior shoreline not getting any warmer than the low
60s. Another shortwave will bring shower and storm chances to
the forecast area late tonight and Sunday, again with enough
CAPE for general thunder chances but not enough for severe
storms.

Our next time period of concern is Monday and Monday night,
with a surge of warm air pushing a surface boundary to over the
forecast area, with heat, humidity and significant instability
to the south, and sufficient shear for strong to severe storms.
SPC has us in a day 3 outlook, as well as the CSU severe weather
probability, which support what we`re seeing in the
deterministic model runs. Models are generating some pretty
incredible instability in the warm sector on Monday, and since
it`s not limited to the NAM, it might actually get pretty
significant. While we will have to wait and see on these
details, this might be another active evening of convection. We
currently have max temperatures in the upper 70s to mid 80s, and
would not be surprised to see slowly increase as we get closer
in time to this event. Shower and storm chances continue into
Tuesday and Tuesday night with cyclonic flow continuing behind
the main trough axis for Monday evening. The warmer than normal
temperatures continue into Tuesday, with highs rising into the
80s once again, which is 5 to 10 degrees above normal for both
days. A ridge of high pressure should slide across the area on
Wednesday and Wednesday night for a drier day with cooler
temperatures, especially as compared to Monday and Tuesday.

Precipitation chances return for Thursday into Friday as a
fairly large upper level trough axis moves across the area.
While timing and strength is not in very good agreement at this
point, the ensembles at least show some flavor of this upper
level trough moving through the area late in the work week,
perhaps continuing into the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 620 AM CDT Sat Jun 22 2024

Rain with embedded thunder is spreading into the area this
morning, and will then spread east this morning. For now it
appears the lowest conditions are expected for KBRD, KHYR and
KDLH, with IFR ceilings for a broad area, and MVFR visibilities
where the heaviest showers pass. MVFR conditions can be expected
for KHIB, but conditions to remain VFR for KINL today. These
lowered ceilings to linger through this afternoon and evening,
with some sites returning to VFR by 00z this evening. Rain
chances move back in from the northwest after 00z for KINL. Fog
may also affect some MN terminals after 06z with MVFR
visibilities.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 423 AM CDT Sat Jun 22 2024

Northeast winds to increase today, with gusts of 20 to 25 knots
for several hours from late morning through the afternoon,
before decreasing once again for this evening. These winds will
help build waves into the southwest arm of the lake, and have
continued the Small Craft Advisory that has been issued for
today from Taconite Harbor through to Saxon Harbor, including
the Apostle Islands. Winds decrease for tonight, allowing waves
to diminish as well. Conditions on the lake do not get
significant again until Monday with the stronger weather system
moving through, once again producing stronger northeast winds
into the southwest arm of the lake, causing building waves and
potentially hazardous conditions.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Beach Hazards Statement through this evening for MNZ037.
WI...Beach Hazards Statement through this evening for WIZ001.
MARINE...Small Craft Advisory until 7 PM CDT this evening for
     LSZ142>148-150.

&&

$$

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