179
FXUS63 KDLH 270606
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
106 AM CDT Thu Jun 27 2024

.KEY MESSAGES...

- Widespread moderate to locally heavy rainfall may return
  Thursday night and ends Friday midday. The heaviest rainfall
  is most likely near and north of the Iron Range into the
  Arrowhead of far northern Minnesota.

- Isolated severe thunderstorms in north-central Minnesota late
  Friday afternoon and evening may (5% chance) move into
  northeast Minnesota through early Friday night.

- Residual showers Saturday in northeast Minnesota give way to a
  dry Sunday before the next round of moderate to locally heavy
  rainfall is forecast to return Monday into Monday night.

&&

.DISCUSSION...
Issued at 211 PM CDT Wed Jun 26 2024

Satellite imagery shows the partly sunny skies that are being
observed across the Northland today as a few elevated showers
associated with a very weak mid-level disturbance in Ontario
north of Superior moves eastward. Not seeing any indications on
surface observations nor forecast model soundings for this dry
boundary layer to even support more than a few hundredths of an
inch in highly isolated locations in the Arrowhead and
Borderlands today so kept with only `Sprinkle` mention in the
forecast for now through 10 PM today.

Clearing diurnal skies after sunset tonight under surface high
pressure and a low to mid-level high-amplitude ridge axis
tonight create fair radiational cooling conditions in the
Northland. Areas of fog are expected tonight, mainly in the I-35
corridor and across northwest Wisconsin into early Thursday
morning. A few cold spots in inland north-central Wisconsin
(mainly Price County and far southern Iron County in this case)
could (10-20% chance) drop down to 39 F by early Thursday
morning. There are zero concerns for frost, but just a note on
the seasonally cool temperatures (10 degrees below normal low
temperatures on the low side of this forecast).

After a dry Thursday daytime, a warm front lifts east-
northeastward from the Northern Plains into north-central
Minnesota Thursday evening. Precipitation chances increase
around sunset for the Brainerd Lakes region first, with
northwest Wisconsin closer to the 3-6 AM hours early Friday
morning. The moist southerly advection provides the next chance
for widespread moderate (mainly northeast Minnesota) to light
(northwest Wisconsin) rainfall for that early Thursday night to
Friday morning daylight hours. Locally heavier rainfall is most
likely (50-70% chance) near and north of the Iron Range in
northeast Minnesota. There is a 10-20% chance of exceeding 2
inches of rainfall in the Borderlands, with around an inch
favored (50-70% chance) from Grand Rapids to Silver Bay and
northward. This rainfall scenario is the most favored (60%
chance) solution, but there is also a possibility (40% chance)
that the warm front lifts even further northward into Ontario
and Manitoba to only leave even the Iron Range northward with
moderate rainfall (0.25 to 0.75 inches).

An instability axis is expected to setup in northwest Minnesota
Friday afternoon, with somewhat favorable mid-level lapse rates
aligning along the instability axis to support some isolated
severe weather threat into north-central Minnesota by the late
afternoon to evening hours. Model forecast soundings show a
disorganized shear environment though and CAPE maximized around
800 J/kg in that area of around 7 C/km lapse rates. This setup
creates concerns for not much more than scattered strong to
near-severe thunderstorms for the Brainerd Lakes to western Iron
Range locations into the late evening hours. The furthest east
locations for strong thunderstorms currently look to be along a
line from Silver Bay to Ely and westward. As the mid- level
instability axis shifts into northwest Wisconsin Friday night, a
few strong elevated storms may persist into inland northwest
Wisconsin, but confidence is very low on that scenario at this
point.

Lingering showers behind the cold frontal passage in the
Arrowhead are favored (40-60% chance), but severe thunderstorms
would not be expected for those weekend plans. A dry Sunday and
first part of Monday yields to the pattern of moderate to
locally heavy rainfall returning for the Monday PM. Long-range
ensemble guidance is in low to moderate agreement for a 30%
chance of around a half inch to one inch of rainfall again next
Monday and Monday night.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 106 AM CDT Thu Jun 27 2024

VFR ceilings with northwest winds of 5 kts or less are expected
for the terminals through at least 00z this TAF period. Fog is
possible at several terminals with MVFR/IFR visibilities, but
confidence is not very high and have included TEMPO groups for
several sites between 09z and 12z. Showers and storms along to
spread in from the southwest after 00z, with MVFR conditions
moving in after 02z for KBRD.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 211 PM CDT Wed Jun 26 2024

Northeast winds around 10 knots or less are ongoing this
afternoon and shift northwesterly Thursday morning. Those
northwesterly winds then shift southerly Thursday afternoon,
except northeasterly into the southwestern arm. Thunderstorm
chances build back into the region Thursday night and last into
Friday afternoon. Heavy rainfall Friday over the North Shore may
(20% chance) produce locally dense fog.

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...NLy
AVIATION...LE
MARINE...NLy