Area Forecast Discussion
Issued by NWS Duluth, MN

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124
FXUS63 KDLH 211745
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1245 PM CDT Sat Sep 21 2019

.SHORT TERM...(Today through Sunday)
Issued at 219 AM CDT Sat Sep 21 2019

A very messy day ahead with a lot going on. First off, dense fog
is lingering around Lake Superior and the adjacent shoreline.
Opted to raise a dense fog advisory for the shoreline as fog
conditions continue to be persistent per satellite imagery and
webcams. With northeast winds expected to continue through the day
- do not expect much change at least through the morning hours.

On the western edges of the forecast area, an unstable air mass
will move showers and thunderstorms through the area from west to
east today, perhaps many times as a slow moving upper level trough
and associated low pressure system pinwheel through the region.
This system will provide multiple waves of energy that are
expected to cause storms to repeatedly develop and cross today.
Some of these storms may be severe as CAPE / shear profiles align
this afternoon. Short term models are all over the board with the
convective mode and evolution which makes deciphering the best
solution difficult. Overall, think the threat can be any and/or
all of the following: large hail, damaging winds, isolated
tornadoes, lightning, and heavy rain which may lead to flooding.
The flooding concern is more in the western portions of the
forecast area where the heaviest rain is expected with lesser
chances east of a line extending from Hibbing to Hinckley while
the severe threat is largely Duluth westward.

Luckily for our forecast area the rich moisture field, which has
ingested remnants of Imelda, should largely pass overhead and run
into forcing to the west of our forecast area largely leaving the
area unscathed. Still would keep an eye on the far western
portions of the area from Brainerd to Intl Falls as current radar
is showing heavy rainfall and a slow eastward progression with
upwind propagation vectors showing a slow southerly motion. This
precip mass should dissipate as it moves into our forecast area
as the low level forcing that is causing this will drift northward
today. Still quite concerning that the moisture transport across
the region is so incredibly high.

After the waves of precipitation today that will occur at various
times across the area, believe there will be a marked downtrend in
precip coverage after midnight - leaving Sunday as a mostly dry
day with temperatures climbing into the 60s.

.LONG TERM...(Sunday night through Friday)
Issued at 219 AM CDT Sat Sep 21 2019

The extended period will feature a few opportunities for showers
and a few thunderstorms and will start out mild then trend cooler.

An upper level trough will be over the region Sunday evening but a
ridge will move in briefly on Monday, passing east Monday night. Dry
conditions are expected Sunday night into Tuesday morning. A faster
upper level flow will develop Tuesday sending an upper trough back
into the region along with a cold front. The upper trough will bring
chances for showers and thunderstorms Tuesday afternoon and evening.
Monday and Tuesday will be the warmest days of the period with highs
in the mid sixties to lower seventies.

The upper trough will linger into Wednesday and cooler air will
sweep in behind the front Tuesday night into Wednesday. Showers will
linger Wednesday into Wednesday night. It will be breezy Wednesday
with highs from the upper fifties to mid sixties.

The upper level pattern will shift from the upper trough to
southwest flow aloft by late Thursday into Friday. There could be
some showers on Thursday but we expect most areas will be dry. Rain
chances will increase Friday as an area of low pressure affects the
region.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1246 PM CDT Sat Sep 21 2019

MVFR ceilings for a time this afternoon before a broken line of
showers and storms move across all terminals this afternoon into
the early evening, which will cause periods of IFR ceilings and
MVFR or worse visibility due to heavy rainfall rates. Clouds then
clear out partially this evening leading to a period of VFR
conditions in the wake of the storms, but MVFR fog/stratus will
then develop late tonight at most sites, with a period of IFR or
worse fog possibly at DLH and HIB towards Sunday morning.
Conditions should improve to MVFR or VFR by mid Sunday morning.
Strong winds out of the south to southwest at 10 to 15 knots with
gusts around 25 knots this afternoon, becoming southwest to west
around 10 knots overnight into Sunday.

&&

.MARINE...
Issued at 1005 AM CDT Sat Sep 21 2019

Wet and foggy conditions tonight, with fog lingering along the
north shore through this evening and a chance for a few rounds of
showers and thunderstorms today, some of which could be strong to
severe around the Twin Ports. Precipitation ends tonight, then dry
Sunday and Monday, but some fog may return Sunday night. Wind
direction will become south- southeasterly today at 10 to 15
knots, increasing in strength and becoming southwesterly late
tonight at 15 to 20 knots, then becoming westerly and weakening to
10 to 15 knots on Sunday afternoon. Weak west winds then linger
Sunday night through Monday at around 5 knots or less.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  71  53  65  47 /  80  60  10   0
INL  73  53  62  46 /  90  40  30  10
BRD  75  54  67  48 /  80  10   0   0
HYR  74  55  67  47 /  70  70  10   0
ASX  77  56  69  47 /  70  50  10  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Dense Fog Advisory until 10 PM CDT this evening for LSZ140>143.

&&

$$

SHORT TERM...Wolfe
LONG TERM...Melde
AVIATION...JJM
MARINE...JJM



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