221
FXUS63 KDLH 160844
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
344 AM CDT Thu May 16 2024

.KEY MESSAGES...

- Scattered rain showers continue through this afternoon and end
  by this evening, with isolated thunderstorms in northwest
  Wisconsin.

- Warm temperatures in the upper-70s to low-80s are forecast Friday
  areawide and again Saturday mainly in northwest Wisconsin.

- Strong thunderstorms are next possible (20% chance) Saturday
  afternoon and early evening for the Twin Ports, Arrowhead and
  across northwest Wisconsin. Off-and-on periods of scattered
  rain showers and general thunderstorms also this Friday and
  again next week.

&&

.DISCUSSION...
Issued at 343 AM CDT Thu May 16 2024

Mid-level low pressure centered over north-central Minnesota is
producing a band of numerous rain showers across the region early
this morning. Rainfall amounts of 0.25 to 0.5 inches have been
observed in far north-central Minnesota through the pre-dawn hours
today so far. Northeast Minnesota and northwest Wisconsin remain on
track for 0.1 to 0.25 inches through the later morning hours today.

As the low center tracks into the International Border region with
Ontario towards Mid-day today, all frontal-associated precipitation
will have exited the region and wrap-around instability showers last
into this afternoon. Another tenth or two of rain is possible (30-
40% chance) in this late morning to late afternoon time period. A
few rumbles of thunder cannot be ruled out in northwest Wisconsin
and east-central Minnesota this afternoon. These shower and isolated
storm chances wrap up this evening as drier west-northwesterly flow
brings a drier airmass into the Upper Midwest tonight.

Overnight radiational fog may occur (50-60% chance) along and north
of US Hwy 2 and along the I-35 corridor in MN and across northwest
Wisconsin starting closer to Midnight and lasting into early Friday
morning.

Low pressure centered over the southern Canadian High Plains
Thursday night slowly moves eastward into Friday morning. That moves
overhead the Northland Friday morning into midday to allow much more
moist south-southwesterly low-level flow to again increase available
precipitable water per deterministic global guidance. Temperatures
are forecast to increase to 10 to 15 degrees above seasonal normal
values as well for Friday daytime maximum temperatures across the
entire region. A mid-level convergence zone is expected to
create scattered rain and isolated thunderstorms over north-
central to northeast Minnesota Friday afternoon and evening.

The warmest airmass moves over north-central Wisconsin by Saturday
keeping northwest and north-central Wisconsin very warm again to
start the weekend, but temperatures drop 5 to 10 degrees from Friday
for northeast Minnesota. The cold front aloft associated with the
slow moving Canadian low pressure, then centered in Manitoba, aids
in creating the next best chance of stronger storms across the
Northland for Saturday afternoon and early evening. A narrow
corridor of CAPE approaching 600-800 J/kg within a somewhat moist
airmass where mid-level lapse rates approach 8 C/km and aided by 35
to 40 knots of 0-6 km bulk shear create an environment where sub-
severe hail around dime to nickel in size is favored for mainly east-
central Minnesota to the Twin Ports and into the Arrowhead, also
including all of northwest Wisconsin. Wind gusts from outflows could
also approach 50 mph with a dry layer up to 800 mb.

As the storm chances end early Saturday night as the low pressure
pulls well into northeast Ontario, surface to low-level high
pressure builds into the Upper Midwest by Sunday morning. Dry
conditions are expected for Sunday with temperatures remaining
around 10 degrees above normal across all counties.

Ensemble guidance early next week is in fair agreement on some sort
of Colorado Low pressure moving through the High Plains into the
Upper Midwest to bring back rain and thunderstorm chances by Sunday
night into Monday, but the track on deterministic guidance is highly
variable. The main point is the off-and-on wet/showery weather
pattern with near or above normal temperatures persists into next
week as well.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1235 AM CDT Thu May 16 2024

An area of rain showers moves through the Northland creating
MVFR visibility within band. Trailing IFR to MVFR ceilings build
in behind the main rain band today and last into the afternoon
hours at most terminals, longest in the Arrowhead and Minnesota
Borderlands this evening. A wind shift to southeasterly to
southerly to westerly occurs today between 15-21Z from west to
east. While VFR ceilings prevail this evening, there is a 30-40%
chance of radiation fog building over the region after 03Z
Friday and lasting past this TAF period into early Friday
morning.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 343 AM CDT Thu May 16 2024

Sustained easterly winds 10-20 knots today keep elevated wave
heights around 4 feet through late this afternoon so the
southwestern arm Small Craft Advisory was extended in time into
today and a new Advisory was issued for the North Shore. Winds shift
to west-southwesterly behind a passing front this afternoon and into
the evening as remaining 2-3 foot swell diminished overnight. Marine
fog may setup (60% chance) tonight, but any coverage on dense fog
potential is quite uncertain still. Easterly winds once again
increase to 10-20 knots Friday afternoon, but wave heights are
forecast to remain less than Advisory criteria.

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 AM this morning to 4 PM CDT this
     afternoon for LSZ141-142.
     Small Craft Advisory until 4 PM CDT this afternoon for
     LSZ143>145.

&&

$$

DISCUSSION...NLy
AVIATION...NLy
MARINE...NLy