Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 172351
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
651 PM CDT Thu Oct 17 2019

.UPDATE...
Issued at 651 PM CDT Thu Oct 17 2019

Updated for the 00Z Aviation discussion.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 323 PM CDT Thu Oct 17 2019

Main concern in the short term is gusty winds ahead of a cold front
moving in from the Northern Plains. The front will slide through
much of the CWA late on Friday bringing rain showers.

A ridge will slide from the Mississippi River Valley into the
central Great Lakes by early Friday while a trough digs across the
Intermountain West. This setup will gradually slide high pressure
into the central Great Lakes tonight while a surface low deepens
over Saskatchewan and Manitoba. This will tighten the pressure
gradient over the area which will keep winds up tonight. Cloud
cover will gradually increase from west to east along with
southerly warm air advection as the ridge axis slides to the east
of the area. Bumped up low temperatures from the previous forecast
to account for the higher winds and more cloud cover. Lows range
from the low 30s to the low 40s.

Expect dry conditions through much of Friday with the high to the
east and a cold front approaching from the Dakotas. This will bring
strong southerly winds with sustained speeds of 10 to 20 mph. Gusts
of 25 to 35 mph are also anticipated. If winds mix a little bit
higher there is potential for some 40+ mph gusts. Confidence is high
on the stronger winds, but am not overly certain on the gusts. May
need to be bumped up in future forecast updates if things trend
toward the latest ARW. Temperatures will warmer with readings in the
50s across much of the CWA. A few locations across the south will
see readings in the low 60s.

Precipitation will move in late on Friday into early Saturday as the
cold front slides through. This will bring chances of light rain
from west to east. There are some hints from the ECMWF, GFS and
latest GEM that conditions will be dry. Low temperatures will be in
the 40s.

.LONG TERM...(Saturday through Thursday)
Issued at 323 PM CDT Thu Oct 17 2019

The extended forecast period continues to show a warming trend for
the latter half of this week, with a few rounds of precipitation
possible to bookend the forecast period.

Tuesday night will have gradually diminishing chances of
precipitation, in the form of a rain/snow mix, as an area of low
pressure moves off to the east. This low should be located
approximately over northern Lake Michigan Tuesday evening, with some
cooler air aloft over our region to help support some precipitation,
with possibly some light snow accumulations over northwest
Wisconsin. The better lift associated with this low pressure system
will have departed the region by this time, so precipitation should
gradually diminish. The only exception will be for along the Lake
Superior snow belt region, where some light rain/snow mix will be
possible through Wednesday morning.

High pressure then builds into the region late Wednesday, and
lingers through the day Friday, leading to dry conditions. Despite a
mid-level shortwave diving through the region Wednesday evening, the
column appears to be just too dry to support any precipitation.
Southerly return flow will help warm temperatures back up to closer
to seasonal average for this time of the year, with highs Thursday
into the upper 40s and lower 50s to the middle to upper 50s Friday.

The next chances for precipitation are progged to be Friday night
and Saturday morning as a low amplitude shortwave moves through the
region. Increasing moisture could support some chances of rain
showers, mainly for our eastern portions of the forecast area. The
thermal profile appears too warm to support any snow mixing in with
the rain. There could be a more potent system that could develop for
Sunday night through Monday as a longwave trough will possibly
develop over the Intermountain West states, and support a
strengthening surface low over the region. However, there is much
uncertainty with how this system will evolve, given the differences
in timing and spatial coverage from the GFS, ECMWF, and GEM models.
Precipitation types do appear to remain as all rain at this time
with this system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 651 PM CDT Thu Oct 17 2019

VFR conditions as of issuance time as a ridge of high pressure
slides off to the east of the area. There is a small area of MVFR
stratus along the North Shore north of Silver Bay. This area of
stratus should continue to slowly dissipate this evening, but it
could also expand and spread inland depending on some items that
cannot be measured at this time. Will be watching these clouds in
the next few hours to monitor their development. A developing low
pressure system over the high plains will cause winds aloft to
increase tonight, and expect some LLWS to develop over some of the
MN terminals beginning around 06z, continuing until surface winds
increase in the morning as mixing brings the stronger winds down
in the 12z-15z time range in the morning. So far only KINL, KBRD
and KHIB should be affected, but KDLH may also be affected. This
developing storm system will push high clouds in our direction,
but no lower clouds until after 00z. LLWS is possible again
after 00z as well.

&&

.MARINE...
Issued at 323 PM CDT Thu Oct 17 2019

High pressure will slide into the central Great Lakes tonight and
on Friday while low pressure deepens over central Canada. This
setup will bring increasing southeasterly winds tonight and
tomorrow. The prolonged fetch coupled with increasing winds may
bring a period where conditions are hazardous for small craft late
Friday morning into the afternoon across portions of the North
Shore. Held off from a Small Craft Advisory as conditions are
borderline at this point in time.

Winds will become more westerly late on Friday into early Saturday
as the cold front slides through. Small craft conditions may occur from
Sunday through Tuesday as low pressure moves through the area,
with occasional gale force winds possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  38  57  46  59 /   0  10  40  20
INL  38  57  44  58 /   0  10  40  10
BRD  41  60  43  59 /   0  10  20  10
HYR  37  59  47  60 /   0   0  30  30
ASX  35  60  48  61 /   0   0  30  30

&&

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

$$

UPDATE...LE
SHORT TERM...WL
LONG TERM...JS
AVIATION...LE
MARINE...JS


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