541
FXUS63 KDLH 191135
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
635 AM CDT Sun May 19 2024

.KEY MESSAGES...

- Our next chance of precipitation moves in tonight through
  Monday. A few mainly elevated thunderstorms may bring locally
  heavy rainfall.

- Slight Risk >15% for severe storms on Tuesday as a rapidly
  deepening low pressure system moves toward and across the
  Northland Tuesday through Wednesday.

- The active weather pattern continues through next weekend
  with precipitation chances returning for Friday through
  Saturday.

&&

.DISCUSSION...
Issued at 504 AM CDT Sun May 19 2024

Today should be a generally quiet and warm day, with high
temperatures generally in the 70s. Cooler than yesterday, but we
will have a gradual increase in clouds through the day, a
cooler start this morning and shallower mixing. We will have
some warm air advection that sets in aloft which is likely to
help those clouds increase and bring some virga showers into the
area this afternoon. However, the very dry low level RH values
will help delay the arrival of precipitation that reaches the
ground until much later this afternoon or even tonight. Have
included some sprinkles for today in advance of the main wave of
precipitation. This is being driven by a weak shortwave in
combination with a surge of moisture and an inverted trough at
the surface. This system should bring us at least some light
precipitation over a large portion of the Northland, along with
a 75% probability or greater of getting a quarter inch or more
over northwest Wisconsin. Once this band of precipitation moves
through on Monday, we should get a short break in the active
weather Monday night.

Tuesday into Wednesday is the time frame we are most concerned
with, as a much stronger upper level shortwave pulls out of the
Rockies and develops a surface low over western Kansas Monday
night which drives northeast across the western Great Lakes
Tuesday night. This much stronger system will combine with
another surge of Gulf moisture to produce a period of very busy
weather for the Northland Tuesday through Wednesday. Tuesday
evening we should develop a narrow window of instability with
sufficient shear to produce strong to severe storms Tuesday
afternoon and evening, mainly over northwest Wisconsin. SPC has
put us into a slight risk of severe weather on the day 3
outlook, which is well supported by what I see in the model
guidance this morning. This system is also likely to generate
generous rainfall amounts with that Gulf moisture feed, and the
GFS is showing precipitable water values of over 1.25", which is
over the 90th percentile, almost to the climatological max for
this date. WPC has put us into a slight risk of excessive
rainfall, and we will have to watch for localized flooding
issues Tuesday night into Wednesday. This system exits the area
Wendesday night, leaving us with some lingering shower activity
into Thursday. We are also looking at some much cooler
temperatures for Wednesday into Thursday, with highs both days
down into the 50s to low 60s.

We get only a short break in the active weather Thursday before
it appears we get another upper level shortwave that moves
across the Upper Midwest through the end of the work week into
next weekend. Models are still showing some pretty large
variations in timing, track and strength of this system, so can
not say much more than we have precipitation chances through
this time frame with warmer temperatures on Friday followed by a
cool down into the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 635 AM CDT Sun May 19 2024

VFR conditions are expected for most of this TAF period.
Southwest winds of less than 10 kts early this morning will pick
up to 10-15 kts in the 15z-21z time frame today, then decrease
again after 22z. A low pressure system will push high clouds
into the area from the west, with cloud bases slowly lowering
through the afternoon and evening. Showers and isolated
thunderstorms will begin to affect the terminals around 03z,
with ceilings slowly lowering to MVFR for KBRD around 09z, with
KINL, KHIB and KDLH by 12z. Visibilities for KBRD also drop to
MVFR around 09z. KDLH may also get lower visibilities with east
winds off Lake Superior.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 504 AM CDT Sun May 19 2024

Southwest winds will gradually increase over the lake today,
with gusts of 25knots for several hours. This will cause
conditions hazardous for Small Craft from late morning through
the early evening for the North Shore north of Grand Marais. The
winds will decrease once again this evening, then gradually
back into the southeast overnight tonight. Monday winds will
become northeast as a low pressure system approaches the area,
but generally remain in the 10 to 15 knot range through Monday
and Monday night. Winds begin a gradual increase on Tuesdsay as
another low pressure system approaches and then moves across the
area through Wednesday. It looks like we will need another
Small Craft Advisory for much of the lake, with a small risk of
gales Tuesday night into Wednesday.

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 6 PM CDT this
     evening for LSZ140.

&&

$$

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