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000
FXUS63 KDLH 240547
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1247 AM CDT Sun Sep 24 2023

.DISCUSSION...(This evening through Friday)
Issued at 345 PM CDT Sat Sep 23 2023

Key Messages:

1. Moderate to heavy rain around 1 to 2 inches (locally higher
possible) is expected through early Monday for many areas,
especially around the Brainerd Lakes and North Shore. There could
be some localized flash flooding issues.

2. There is a marginal chance for strong to severe thunderstorms
this evening around the Brainerd Lakes. Large hail and gusty winds
are the main threats.

3. Gusty east to northeast winds on Sunday may create a high risk
for rip currents.

4. The weather may trend warmer and drier in the mid-to-late parts
of next week.

Current Weather Synopsis:
Several waves of cyclonic vorticity are spiraling through the
region this afternoon, producing areas of mainly synoptically-
forced light to moderate rain. It is currently falling across the
International Border, North Shore, and north-central Wisconsin.
Rainfall along the North Shore has been the most persistent this
afternoon as it is enhanced by upslope flow along the terrain.
This is pretty well defined on radar stretching from the higher
elevations around the Twin Ports and areas northeast where rain
continues to redevelop over the same areas. Elsewhere, skies are
cloudy and there are some areas of fog, especially around the
Brainerd Lakes region. This general pattern is expected to
continue through about sunset.

Tonight through Sunday:
Surface low pressure currently located over southwestern Minnesota
is expected to move very slowly and eventually occlude over that
general area for the rest of the weekend. Warm air advection and
an attendant occluded front are expected to bring another more
organized band of rain into the region from the south and west.
Some convection is expected with this, as an MCV has already
developed this afternoon in more unstable air around the MN/IA
border, and is expected to move north through the evening. There
are two primary hazards expected as a result tonight and Sunday,
which will be described in more detail below.

Severe Weather this evening:
A marginal to slight risk for severe thunderstorms has been drawn
up by the SPC for much of central and southern Minnesota through
tonight, with a sliver of this marginal risk including the
Brainerd Lakes region. The threat for severe weather in the
Brainerd Lakes has been trending downward, but still remains
nonzero. The best instability and corresponding convection is
expected to remain south, where it is currently developing this
afternoon with warmer surface temperatures and greater instability
around 1k J/kg. As the MCV moves north along the occluded front,
it will move into a more stable airmass and the timing will also
coincide with the loss of daytime heating. These two factors
result in a decreasing chance for severe weather later this
evening. However, factors still in place that favor severe weather
include a strengthening low-level jet around sunset and a narrow
area where just enough surface-based instability could persist to
produce some isolated strong to severe storms. If any storms do
develop, large hail (up to 1" in diameter) and gusty winds (up to
60 mph) are the main threats. Timing for any strong/severe storms
is expected to be around sunset to midnight.

Moderate to heavy rain and flash flooding concerns:
With PWAT values maxing out at the top of climatology, plenty of
synoptic forcing and a bit of convective forcing possible tonight
through Sunday, the potential for heavy rain remains in place. The
best synoptic forcing is expected around the Brainerd Lakes
tonight and also terrain-enhanced forcing along the North Shore.
In the past 24 hours, the highest rainfall amounts just over an
inch have been observed along the North Shore with radar estimates
suggesting that totals to around 1.5" or so may have occurred. So
far, rainfall rates have not been high enough to produce any known
flooding. This rain has been mostly a net positive thus far given
the drought conditions over the region. Rainfall rates are likely
to remain less than 1" per hour, as the HREF suggests, but any
convection or prolonged orographic enhancement could lead to some
localized flash flooding concerns. The best chances for any heavy
rainfall rates will be tonight for the Brainerd Lakes and Twin
Ports/North Shore, then lingering into Sunday along the North
Shore where bands of rain are expected to persist the longest. As
of now, confidence remains low that flooding will become much of
an issue, but with several variables at play that could come
together briefly to produce heavy rain, the threat of localized
flash flooding can`t be ruled out.

Additional hazards through Sunday:
Winds from the southeast to northeast are expected to remain gusty
through Sunday. Gusts from 25 to 35 mph are expected for much of
the region. Strong northeast winds may also result in dangerous
rip current conditions around the Twin Ports once again on Sunday.

With plenty of moisture in the area through the weekend, fog will
be possible both night and day. Widespread dense fog isn`t
currently expected, especially for areas that have the highest
chances for seeing higher rainfall rates, but some locally dense
fog can`t be ruled out at times.

Monday and Tuesday:
The occluded low pressure system is expected to sit and spin over
the region early this week, keeping clouds around and bringing
reinforcing bands of light to moderate rain. Any flooding threats
are expected to end by the end of the day Sunday, but lingering
rain may add up to several tenths of an inch for many areas Monday
and Tuesday. Despite the gloomy weather that will result, this
should produce a bit of drought relief (though not enough to end
the drought).

Wednesday through Friday:
Ridging from the west may finally push the closed low to the east
Wednesday morning. A few lingering showers may be possible, but a
trend towards drier weather is expected for the end of the week. A
return to southerly flow may bring some warmer temperatures as
well.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1245 AM CDT Sun Sep 24 2023

Seeing mainly MVFR/IFR ceilings and some MVFR visibilities across
the region with the exception of VFR conditions in HYR as of the
06Z update. The vertically stacked low pressure is centered near
the MN/ND/SD border, which should result in MVFR to IFR ceilings
and visibilities in the region throughout most of the TAF period.
HYR should deteriorate to MVFR conditions towards mid-morning.
Ceiling are expected to back into IFR to LIFR over much of
Minnesota this evening into tonight, while improving to MVFR/VFR
over NW Wisconsin.

Winds will continue at 10 to 15 kt out of the east to southeast
through the TAF period, with some gusts up 25 to 30 kt,
particularly near BRD through the current overnight hours, then
over the Iron Range and North Shore of Lake Superior this
afternoon. Gusts should weaken to 15 to 20 kt tonight.

Showers and a few embedded thunderstorms continue through the
period with the best chances now through this morning.

&&

.MARINE...
Issued at 932 PM CDT Sat Sep 23 2023

Gusty east winds will continue through the overnight hours at 20
knots with gusts to 25 knots. As a result, waves will be 2 to 5
feet from the Outer Apostle Islands into the Twin Ports and along
the North Shore. Due to the elevated winds and waves a Small Craft
Advisory has been issued.

Showers and isolated thunderstorms are expected through the
remainder of the weekend into the first part of the week. Cloud to
water lightning is possible and no severe weather is expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  55  60  54  62 /  90  90  60  70
INL  55  61  51  65 /  70  80  40  40
BRD  58  64  54  65 /  90  70  80  80
HYR  56  63  52  68 /  70  80  40  60
ASX  57  65  54  69 /  60  80  40  50

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 1 AM CDT Monday for LSZ140-146-147-
     150.

     Small Craft Advisory until 4 AM CDT Monday for LSZ141>145.

&&

$$

DISCUSSION...JDS
AVIATION...Rothstein
MARINE...KSE