432
FXUS63 KDLH 220924
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
424 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 fromm
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 developmet. 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 /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1255 AM CDT Sat Jun 22 2024

Initial VFR conditions with light east winds of less than 10kts.
Rain with embedded thunder to spread into the area from the
southwest during the early morning, then spread east Saturday
morning. For now it appears the lowest conditions are expected
for KBRD, KHYR and KDLH, with ceilings lowering to IFR and MVFR
visibilities where the heaviest showers pass. MVFR conditions
can be expected for KHIB, but conditions to remain VFR for KINL.
These lowered ceilings to linger Saturday afternoon and evening,
with some sites returning to VFR for the end of the TAF period.
Rain chances move back in from the northwest after 00z for KINL.

&&

.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 Harber 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...None.
WI...None.
MARINE...Small Craft Advisory until 7 PM CDT this evening for
     LSZ142>148-150.

&&

$$

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