599
FXUS63 KDLH 110536
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1236 AM CDT Fri Jul 11 2025

.KEY MESSAGES...

- Spotty showers and thunderstorms through tonight along with
  some fog developing overnight.

- Showers and thunderstorms are expected at times Friday and
  Friday evening. A few strong to severe storms are possible
  along with heavy rain that could lead to localized flooding.

- Occasional rain chances into next week with potential for
  thunderstorms on Tuesday.

&&

.DISCUSSION...
Issued at 1255 PM CDT Thu Jul 10 2025

This afternoon and tonight:

An initial round of showers and storms this morning has capped off
convection from developing this afternoon for the most part. Storms
had been largely redeveloping along their outflow boundaries. CAMs
have had a really hard time keeping up with this activity, and with
a similar favorable instability but low wind shear environment
expected to persist into tonight, the forecast confidence for
additional showers and thunderstorms is rather low. We should have
continuing warm air advection and we already have plenty of moisture
in place (PWATs around 1.0"-1.5"). The question of where the cap may
bust in and around our region is still in question, and without much
for organized fronts around until we get a cold front Friday
evening, we can expect more of the same shower and storm activity
through tonight. This means that spatial coverage of any
showers/storms should be generally isolated, but anything that pops
off could develop an outflow boundary that could kick off more
storms around it. But right now, it looks like the best instability
(MUCAPE ~2-3 kJ/kg) may confine itself to north-central Minnesota,
thus giving that area the best chance (~60%) for storms later this
evening into tonight. With wind shear topping out around 15-25 kt,
severe threats are going to be limited to some brief large hail and
maybe some gusty winds (a ~5% chance isolated threat, per SPC
outlooks).

Another thing we`ve been observing with this morning`s storms is
some pretty hefty rainfall rates around or perhaps slightly
exceeding an inch per hour as storms that form (with plenty of
moisture to work with) simply aren`t moving very fast. WPC has
outlined a marginal risk for rainfall exceeding flash flood guidance
through tonight. In other words, while flooding is generally
unlikely, there`s ~5% chance that any storms that form could produce
some localized minor flooding.

Friday and Saturday:

Going into Friday, a bit of rinse and repeat with the storm chances
except that we will have a bit more of a focus for convection out
ahead of the slowly approaching cold front from the northwest. Shear
looks to remain on the low side, but instability should remain in
place and PWATs may increase a bit to around 1.5" to nearly 2.0". We
also might have a brief window Friday late afternoon and early
evening where there could be a brief collaboration between
increasing wind shear just ahead of the cold front and lingering
instability to increase chances for severe weather slightly. There
may be enough dry air aloft to promote the large hail threat and
perhaps some damaging winds. It`s tricky to say how big of hail
there could be since there are going to be some conflicting
ingredients, like high freezing heights (hail melts more as it
falls) but also plenty of instability (up to 2-3 kJ/kg; makes for
bigger hail aloft). Uncertainty in how much moisture entrainment
there will be also lends uncertainty in potential hail size, but all
things considered, perhaps up to around 1.5" in diameter could be
possible in the largest of storms. Any that do form to this
intensity should be pretty short-duration with the low wind shear
though.

Rainfall in general should be a bit more widespread with higher
moisture and pre-frontal forcing. At this time, there are not any
high signals in the models favoring substantial rainfall totals
(e.g. NBM probabilities for 2"+ are only up to ~10%). That
said, what we`ve observed with storms this morning is that where
they do form, they are certainly capable of dropping a lot of
water. Thus, a nonzero threat for flash flooding does exist. WPC
currently has upgraded most of the region to a slight risk for
rainfall exceeding flash flood guidance (~15% chance). Localized
minor flooding is possible, and if there is an area of storms
that develops and persists, then there could still be potential
for rainfall totals upwards of 3-4". There is very low
predictability of where or if this will happen, even at this
short time window, so for now, keep an eye on the forecast and
monitor conditions Friday afternoon and evening in case such a
scenario plays out somewhere in the Northland.

Showers and storms should decrease in overall coverage and
intensity Friday night as diurnal instability goes away and the
front passes through. It`s still looking like we could see some
wraparound showers and perhaps some non-severe storms on
Saturday with a trough passing through overhead, though drier
air filtering in may limit this potential. Any lingering showers
or storms are not expected to produce substantial rain.

Sunday into next week:

Broad but low amplitude ridging develops going into Sunday, so
it`s looking like a largely quiet weather day, and also a bit
warm with highs in the 80s. There are some hints that a weak
trough could pass through around Monday night into Monday
morning, bringing some shower/storm chances, but not all models
are on board with this. A warm air advection regime looks like
it`ll persist going into Tuesday, then maybe an upper-level
trough with a cold front going into Wednesday. Tuesday might be
a day to watch for some storm potential with increasing
moisture, instability, and shear. It`s too early to say if there
could be any severe weather, but this looks to be the next best
chance in the near future after Friday`s storms. Some cooler
temperatures may follow Wednesday into Thursday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1229 AM CDT Fri Jul 11 2025

Fog at HIB has formed, and visibilities should be up and down
for the remainder of the night. Conditions should largely remain
MVFR/IFR, but have added a TEMPO since this terminal in
particular has a habit of reaching below minimums. Fog is also
possible further east at DLH and HYR. Some AWOS`s in northwest
Wisconsin have seen some MVFR visibilities before clearing
again, so have that in a TEMPO for HYR as well. Storms are
expected again today, and a cold front will move through later
today, with the highest probabilities for storms as it passes.
However, there will be plenty of fuel for storms to initiate
ahead of time, so cannot rule that out. PROB30s have been added
where storms could form ahead of the cold front. Models are
hinting at fog again tomorrow night where there is rainfall, and
will be reflected in the next TAF set at 12Z.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 334 PM CDT Thu Jul 10 2025

Expect occasionally breezy east to northeast winds through
around sunset. Gusts up to 15 to 20 kt are possible at times,
but are expected to decrease quickly early this evening. Winds
are expected to become more light and variable on Friday, though
predominantly remaining northeasterly. Periods of rain and
thunderstorms are expected, mainly in the afternoon and evening
hours, which could lead to gusty and erratic winds at times.
Other hazards include heavy rain, cloud to water lightning, and a
small chance for large hail. After a cold front passes through
Friday night, winds are expected to shift to westerly to
southwesterly. Some gusts up to 15 to 20 kt are possible on
Saturday as well as Sunday.

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...JDS
AVIATION...KML
MARINE...JDS