269
FXUS63 KDLH 142347
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
647 PM CDT Fri Jun 14 2024

.KEY MESSAGES...

- Showers and thunderstorms will develop across the Northland
  Saturday into Saturday night. The threat for severe storms is
  low but there may be heavy rain in spots, mainly over
  northwest Wisconsin.

- More thunderstorms expected Sunday into Sunday night with the
  potential for strong to severe storms, most likely for
  portions of the Northland that are south of the Borderlands
  and Iron Range. Heavy rain will also be a threat.

- A wet pattern will continue next week with the potential for
  both severe storms and heavy rain leading to flooding. The
  Monday/Monday night period is looking like the best chance for
  very heavy rainfall.

&&

.DISCUSSION...
Issued at 318 PM CDT Fri Jun 14 2024

Tonight...

Upper ridging and surface high pressure will move through and
east of the Northland tonight into Saturday. Dry conditions are
expected for most tonight with a few showers possibly making it
into far western portions of the Northland late.

Saturday into Saturday night...

Showers and thunderstorms will increase in coverage from
southwest to northeast Saturday into Saturday night with
persistent warm air and moisture advection occurring along with
forcing from a shortwave. A low level jet at 850MB is forecast
to increase to 40-50 knots Saturday evening. Instability
Saturday will be limited but will build to 200-800 j/kg Saturday
night. A few stronger storms are expected to develop into
northwest Wisconsin late Saturday night. The storms will be
capable of producing heavy rain with PWAT values around 1.75",
in the 90-99th percentile.

Sunday into Sunday night...

Showers and thunderstorms may be ongoing Sunday morning as a
shortwave exits the area. A cold front will be just entering our
western area Sunday afternoon and a warm and moist airmass will
exist ahead of it. We have highs in the eighties with dewpoints
from the mid-sixties to around seventy. PWAT values will again
be around 1.7" and MUCAPE values will rise to 1500-3000j/kg.
There is also adequate shear in place ahead of the front along
with mid-level lapse rates from 7-8c/km. The convective
parameters are favorable for severe storms Sunday
afternoon/night. However, forcing will be limited with
subsidence in the wake of the exiting shortwave occurring in the
late morning afternoon. 500MB heights will also be rising
Sunday afternoon/night. Convergence along the front is not
particularly strong either. If a few storms do develop, then
severe weather will be possible given the shear/CAPE in place.
If enough storms do develop, heavy rain may also occur given
the moisture in place and with deep southwest flow aloft which
will become nearly parallel to the surface boundary.

Monday into Monday night...

A greater threat for heavy rain and flooding will occur Monday
into Monday night. The surface front will return north as a warm
front, moving into northern Minnesota Monday night, and deep
southwest flow aloft will continue to be nearly parallel to it.
FGEN will strengthen during the day with increasing southerly
flow south of the front which backs on the cooler side of the
front. The theme of this forecast continues to be the presence
of high PWAT air and values around 1.8" are expected which are
in the 90-99th percentile. Instability isn`t real impressive
over the Northland but the forcing and moisture will make up
for that and there is a greater pool south. Strong southerly
low level flow, high moisture, and some instability are all
supportive of multiple rounds of strong to severe thunderstorms.
I`m getting more concerned that very heavy rain may occur which
may lead to flash flooding and possibly longer term flooding of
rivers/streams. The ECMWF ensemble forecasts a 20-40% chance
for rainfall of 2"+ just Monday/Monday night over parts of
central to northern Minnesota. There will likely be localized
even higher amounts due to training strong thunderstorms.

Tuesday through Friday...

Southerly flow aloft on Tuesday will continue but a shortwave
will push a cold front into the Northland Tuesday into Tuesday
night. Warm and moist air will remain in place ahead of the
front with shear/instability/moisture all supportive of strong
to severe storms and more heavy rain.

Wednesday looks be the driest day of the period with the front
moving just east and south of the Northland and weak high
pressure over northern Minnesota.

Confidence in the forecast beyond Wednesday is lower than
average and we continue to have chances for showers/storms
Thursday/Friday.

Summary...

Much of the Northland has seen rainfall much above normal since
mid-May. There will be plenty of moisture available with PWAT
values in the 90-99th percentile developing this weekend and
lasting into at least next Tuesday. There will be several
rounds of thunderstorms that occur this weekend into at least
Tuesday night with a severe and heavy rain threat. Concerns are
growing that very heavy rainfall may occur Monday into Monday
night leading to flooding.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 647 PM CDT Fri Jun 14 2024

VFR conditions are expected to persist through the forecast
period. There is a small chance (<10%) of fog developing at DLH
overnight. Some of the high-resolution models develop fog inland
from Lake Superior at DYT and SUW, possibly spreading west to
COQ and perhaps up the hill to DLH overnight.

There`s a small chance a few showers may persist from the
convection over the Dakotas overnight and may move over INL,
BRD, and HIB in the 09Z to 15Z time frame. Chances are low, less
than 20 percent. Even if the showers persist, VFR ceilings and
visibility are expected with the light rain.

Weak large-scale ascent along and north of a warm front will
bring rain chances to the terminals late Saturday afternoon,
generally after 21Z. Rain chances improve after 16.00Z for
Saturday evening.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 318 PM CDT Fri Jun 14 2024

Easterly winds will be at or less than 15 knots tonight into
Saturday but they are expected to back to more southerly along
parts of the South Shore tonight.

East to southeast winds will occur Saturday night into Sunday
from 10 to 20 knots. There will be a chance for thunderstorms
Saturday night into Sunday.

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...Melde
AVIATION...Huyck
MARINE...Melde