153
FXUS63 KDLH 201921
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
221 PM CDT Thu Jun 20 2024

.KEY MESSAGES...

- Some light showers will continue over NW WI this afternoon and
  evening before a brief dry period on Friday morning. Then
  chances for showers and thunderstorms return for most of the
  weekend.

- The potential for heavy rainfall has shifted south with the
  latest model trends and just clips NW WI with more than an
  inch with amounts decreasing to the north.

- Severe storms are possible Monday afternoon into Tuesday
  morning.

&&

.DISCUSSION...
Issued at 220 PM CDT Thu Jun 20 2024

In a bit of a lull at the moment with a few showers crossing
over NW WI with not much QPE. Precipitation is expected to
completely stop overnight before a surge of moisture arrives
Friday as a warm front slowly lifts and stalls over NW WI.

A pool of PWATs above 2.0" will reside just south of this warm
front (over the Twin Cities), but models have been trending
towards keeping this to the south. This makes a bit of sense
given that the LLJ is more southwesterly and not too strong.
Meanwhile the shear environment and CAPE pools are also located
more to our south and are progged to remain along this eventual
quasi-stationary boundary. Eventually a surface low develops and
will act to force this system out of the region by Saturday
evening. While thunderstorms are possible throughout the
transition of this system, the best chance for any organized and
strong to severe storms is Saturday afternoon across NW WI
where CAPE briefly increases to 1000 J/kg in a fairly weak shear
environment. The HREF indicates the heavy rain potential largely
keeps just south of our forecast boundary with MPX. The overall
trend in guidance has been to push the heaviest QPF axis south
after a long period of being consistently over our area. While I
think we have low probabilities of heavy rain, it`s conceivable
that things still could change in the opposite direction, so
it`s best to keep an eye on the forecast.

On Sunday, a shortwave drops south from Canada giving some
potential for thunderstorms over the Minnesota Arrowhead. May
have a few strong storms with this feature with CAPE over 1000
again and 0-6km shear broaching 30 knots. This feature does have
a little upper level jet max sneaking through which could help
with forcing.

The better chance in the forecast period for severe weather
arrives on Monday afternoon/evening (and possibly even
overnight) as an EML washes out over our area with high values
of shear > 40 kts and plenty of CAPE. Again PWATS inch up
towards 2.0" as strong low level flow converges from the Gulf
and also from the northern Great Plains. Upper level flow lags a
little behind the surface heating curve, but may help to keep
things going into the overnight hours.

Afterwards a blob of dry and colder air slides south cooling
temperatures and giving a break from convective weather for a
few days.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1221 PM CDT Thu Jun 20 2024

Lower flight cats will nose in from the south overnight and
really make their way north after 12Z as a warm front
approaches. Could be some thunderstorms embedded in the
advancing nimbostratus. High confidence in IFR or lower
conditions but lower confidence in northward extent of these low
flight cats. Winds generally remain light ( less than 10 knots )
and easterly.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 220 PM CDT Thu Jun 20 2024

Light east winds gusting to less than 20 knots will be here
until Saturday morning when they build to 25 knots. Waves will
also increase in response to the stronger winds.

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...Wolfe
AVIATION...Wolfe
MARINE...Wolfe