996
FXUS63 KDLH 171751
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1251 PM CDT Mon Jun 17 2024

.KEY MESSAGES...

- Overall threat for flash flooding has decreased a bit due to
  forecast uncertainty. Heaviest rainfall has shifted north
  since last update and the Flash Flood Watch extended north as
  a result. Today`s severe threat reduced as well.

- A cold front will bring chances for strong to severe storms
  for Tuesday as it works across the region.

- Additional chances for rain and storms this weekend.

&&

.DISCUSSION...
Issued at 540 AM CDT Mon Jun 17 2024

A complex pattern was in place across the central CONUS early
this morning. A large area of low pressure was located over
northern Manitoba with with a cold front trailing into far
northwestern Ontario, far southwestern Manitoba and into North
Dakota. Another area of low pressure was analyzed over northern
Lake Superior with a cold front trailing into northwestern
Wisconsin, southeastern Minnesota and northwestern Iowa before
turning into a warm front across Nebraska. A large area of
showers and thunderstorms was located along and behind this
front from southern and eastern Minnesota into northwestern
Iowa, eastern South Dakota and eastern Nebraska and was moving
east-northeast along the front.

Multiple rounds of showers and thunderstorms are expected to
move along this front today into tonight. CAMs are showing a
break during the midday hours before activity ramps back up
tonight. Overall model trends have backed off on QPF amounts
over the region today and tonight and have shifted the area of
highest QPF further north. A surge of northward moving higher
PWATs are forecast to reach areas along and north of the Iron
Range overnight with values of 1.5-1.8" which would be near the
top of climatology for the date. However, CAMs continue to
struggle in the placement of showers and storms overnight,
although northern areas are favored on the latest HRRR and
NAMNest runs. Rainfall amounts of 0.25-1" are currently forecast
for today and tonight, which is quite a bit lower than our
previous package. WPC has outlined the entire area in a slight
risk for excessive rainfall for today and tonight and given the
reduction in QPF amounts, this seems warranted. Have held on to
the Flash Flood Watch currently in place, but have extended it
north based on the shift in highest QPF to the north. Have left
the southern part in place due to continued uncertainty. A few
stronger storms cannot be ruled out at times today with hail up
to 1" and damaging wind gusts to around 55 mph being possible.
An isolated tornado cannot be ruled out across far southeastern
Sawyer County and southern Price County this evening, but
overall chances for any severe storms is around 10% or less in
this area.

Tuesday will see a Colorado low lift northeastward across the
eastern Dakotas and western Minnesota and drag a cold front
across the region during the evening and overnight hours.
Additional rounds of showers and thunderstorms are expected
through the day with a final push during the late afternoon and
evening hours in association with the front. The heaviest
rainfall looks to occur in areas along and north of the Iron
Range in the vicinity of a warm front during the morning and
early afternoon hours. Another surge of higher PWATs will move
in ahead of the cold front with values over 2" in some spots
which would exceed the climatological max for the day. While
rainfall amounts of 1.5-3" will be possible along and north of
the Iron Range, amounts up to around an inch will be possible
elsewhere. There still remains uncertainty in the where that
warm front will set up and if it remains south of the Iron
Range, the heavy rainfall threat will shift south as well. As
mentioned above, have keep the Flash Flood Watch in place to the
south despite the lower QPF amounts due to this uncertainty.
However, the threat for 3" or rainfall or greater has fallen
below 10% at this time for the entire event. Instability along
the cold front may build to around 1000-2000 J/kg with effective
shear around 35 knots. Given the nearly unidirectional wind
field along the front, quick upscale growth into a line of
storms is expected. This storm mode will favor damaging wind
gusts to around 60 mph and small hail. SRH is forecast to be
over 300 m2/s2, so a few tornadoes will be possible embedded
within the line. As this line pushes eastward into northwest
Wisconsin during the evening hours an overall downward trend is
expected. Some of the severe threat may be tempered if clouds
and rainfall linger through the morning and early afternoon
ahead of the front, but should any breaks in the clouds occur,
temperatures in the 80s and Tds in the low 70s will quickly
build instability.

High pressure will then build in for Wednesday and Wednesday
night giving the region a break from the active weather.
However, the pattern will remain active with additional chances
for showers and thunderstorms for the end of the week and into
the weekend. Temperatures through this period will be near
normal to start with a slow warming trend into the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1250 PM CDT Mon Jun 17 2024

Light rain is moving out of the vicinity of KHYR by 19Z.
Otherwise, expect a period of VFR conditions under some mid/high
level clouds until a batch of rain north of a warm front
currently located over southern MN pushes north into the area
from south to north this evening into tonight, lingering longest
at KINL that will be closer to the low pressure center. Expect
MVFR to IFR ceilings and some reduced visibilities with the
showers and storms this evening and tonight, with some LIFR
ceilings possible on the backside of the rain showers at
KDLH/KHIB late tonight into Tuesday morning, and KINL on Tuesday
morning. LLWS is also expected tonight at the TAF sites given a
low-level jet moving into the region.

Winds out of the east this evening and tonight, gradually
increasing in speed, then turn southerly and gusty on Tuesday.
Daytime gusts on Tuesday could reach up to 20-25 knots in the
morning, and up to 25-30 knots in the afternoon ahead of an
approaching cold front.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 540 AM CDT Mon Jun 17 2024

Periods of showers and thunderstorms will be the primary concern
over the next 48 hours as winds outside of storms remain around
20 knots or less. However, southerly winds Tuesday morning into
Tuesday afternoon may gust to around 24 to 28 knots at the head
of the lake and may lead to a brief period of conditions
hazardous to small craft. Gusty winds to around 40 knots will
be possible in any storms today into Tuesday with higher wind
gusts to around 50 knots possible Tuesday afternoon with a line
of storms.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch through Wednesday morning for MNZ010-011-018-019-
     025-026-033>038.
WI...Flood Watch through Wednesday morning for WIZ001-006-007.
MARINE...None.

&&

$$

DISCUSSION...BJH
AVIATION...Rothstein
MARINE...BJH