Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 250619
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
119 AM CDT Fri Sep 25 2020

.UPDATE...
Issued at 118 AM CDT Fri Sep 25 2020

Issued a Dense Fog Advisory for much of east-central Minnesota,
the Twin Ports, and most of northwest Wisconsin. Light low level
easterly flow will allow for dense fog to continue for much of the
night and early morning hours before it gradually lifts after
sunrise.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 431 PM CDT Thu Sep 24 2020

Persistent mid and low level clouds are covering the majority of
the Northland this afternoon, and could thin or dissipate in some
areas this evening. Tonight, warm and moist air should get
transported inland from Lake Superior, increasing chances for
widespread fog close to the lake, and thinner further inland. This
fog is expected to last through mid morning tomorrow.

Tomorrow morning, a shortwave should move into the Northland,
progressing southeast throughout the day. Northwest Wisconsin is
under a marginal risk for severe weather tomorrow, with isolated
severe storms embedded along the cold front. Though there is also a
sufficient cap in the early evening that could inhibit substantial
convection, with MUCAPE values between 500-1500 J/kg and sufficient
bulk shear around 50 kts, any convection that does initiate could
include strong winds and large hail. These showers and storms are
expected to exit to the east by late tomorrow night.

.LONG TERM...(Saturday through Thursday)
Issued at 431 PM CDT Thu Sep 24 2020

Saturday morning our CWA should see a break from the rain before
another round of precipitation moves though with a warm front from
a shortwave trough in the Dakotas. The low pressure associated
with this trough is expected to move east-northeast through the
upper Midwest, bringing cooler temperatures due to post-frontal
northwest flow. A small shortwave immediately following the first
should keep chances for showers and thunderstorms higher through
Sunday.

Sunday night into Monday, another upper level trough deepens into
central CONUS, causing below average temperatures to settle in the
Northern Plains. The GFS and ECMWF are hinting at a low level
shortwave moving southeast from Canada and into our area on Tuesday,
though the GFS has the low moving southeast through our CWA while
the ECMWF has it staying in Canada as it moves east. Which path
it takes will affect precipitation amounts in our southern-most
counties.

As we go through the rest of the work week, the upper level low will
settle in eastern Canada. Numerous shortwaves associated with the
low should produce nearly constant chances of showers through
Thursday, though uncertainty is high this far out in the forecast.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 118 AM CDT Fri Sep 25 2020

The main concern for tonight is dense fog, which will keep
IFR and occasionally LIFR conditions prevailing through the early
morning at DLH/HIB/HYR. There is some uncertainty on visibility at
BRD as the pressure gradient will be tightening up through the
morning, possibly allowing for visibilities to improve some there.
But, even if visibilities improve, ceilings will remain IFR at all
terminals through at least 13Z. LLWS is possible through the
morning at BRD/INL as a low level jet strengthens. Visibilities
will improve to VFR at all terminals after 13Z this morning, but
with warm air advection through the morning and then an
approaching short wave trough and cold front during the afternoon,
ceilings will remain MVFR/IFR for most of the day. As the
trough/front pass through, showers and thunderstorms are possible
with temporary visibility restrictions not out of the question. A
period of VFR ceilings/visibilities is possible this evening
following the cold front, but fog and low clouds may develop later
at night.

&&

.MARINE...
Issued at 943 PM CDT Thu Sep 24 2020

Winds have decreased some this evening but it`s taking the waves
longer to subside. We did cancel portions of the Small Craft
Advisory, north of Silver Bay and east of Bayfield with the rest
remaining until midnight. The wind will be 15 knots or less for
most areas later tonight into Saturday and waves should be 4 feet
or less. There may be some fog tonight, dense in spots. A cold
front will cause thunderstorms to occur Friday and some could be
strong to severe, mainly in the afternoon and evening hours. Large
hail and damaging winds will be possible. More thunderstorms will
be possible on Saturday into Saturday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  50  69  49  67 /  10  50  10  30
INL  51  66  46  66 /  10  80  10  50
BRD  54  71  50  69 /  10  30  10  20
HYR  54  77  50  71 /   0  50  40  30
ASX  51  77  51  72 /   0  60  50  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

UPDATE...JDS
SHORT TERM...Huyck/Kossen
LONG TERM...Huyck/Kossen
AVIATION...JDS
MARINE...Melde


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