Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 171202 AAA
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
702 AM CDT Sun Sep 17 2017

.UPDATE...
Issued at 703 AM CDT Sun Sep 17 2017

Update for new 12Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Monday)
Issued at 429 AM CDT Sun Sep 17 2017

A pair of surface low centers were near the forecast area at 07Z.
One in the southeast corner of Manitoba, the other over Lake
Superior. A trof connected the two and was located right along the
international border. A cold front extended through northwest
Wisconsin from the Lake Superior low. Clouds were lifting to the
North from southern Minnesota toward northwest Wisconsin.
Meanwhile, plenty of low clouds were found over the area with more
developing just to the West and were moving into the forecast
area. Even with this cloud cover, low level drier air was working
its way across the region as dewpoints were dropping from the 60s
near the cold front, to the 40s over the western edge. This was
thanks to high pressure that was building into the area with the
center currently in western South Dakota. This high will drift
over southern Minnesota by late afternoon. Will see a gradual
clearing trend through the day. Max temps will be quite a bit
cooler today with 50s north, and 60s south.

The high will waft over to north central Wisconsin late tonight.
This puts the forecast area into a return flow pattern overnight.
Moisture will be advecting into the region late tonight and clouds
will be on the increase as a result. Warm air advection will also
be occurring tonight and will help to keep minimum temps in the
40s.

Even through the high will be near eastern Lake Superior through
the day, an upper level short wave trof moves into the region in
the afternoon. The moisture profile is not very deep, until late
afternoon, but with cold air advection from the south moving into
the area, will see some showers develop by late morning over the
western and southern edges of the forecast area. The shower chance
increases over the southern portion of the forecast area in the
afternoon and northwest Wisconsin, while diminishing over the
north. Model differences in the potential for QPF and placement
were handled by using a blended approach. No thunder is expected
due to the lack of instability. Max temps will be around 60 over
the Arrowhead, with lower to middle 60s elsewhere.

.LONG TERM...(Monday night through Saturday)
Issued at 429 AM CDT Sun Sep 17 2017

Mid-level ridging expected to bring relatively quiet conditions
Monday night and Tuesday transitioning to a more active regime
Tuesday night through the end of the period.

A deep longwave trough is forecast over the Intermountain West
Monday evening with a mid-level ridge over the western Great Lakes
and the Canadian Prairies. As high pressure departs to the east
Monday night and Tuesday, the building ridge aloft should be
sufficient to keep a dry forecast for the Northland. South to
southeasterly winds are expected and wind speeds will increase
during the day as the pressure gradient tightens between the
departing ridge and developing low pressure over southern Alberta.
The southeasterly breezes will work to keep much of northeast
Minnesota a little cooler thanks to the influence of Lake
Superior. Elsewhere, temperatures will trend a little warmer with
highs from the low 60s in the Arrowhead to near 70 degrees in
central and north-central Minnesota, and much of northwest
Wisconsin.

A strong cold front will advance eastward into Minnesota Tuesday
night associated with a strong shortwave trough rotating through
the Northern Plains and into northwest Ontario. The combination of
falling heights and convergence along the front should be able to
set off numerous showers and thunderstorms. The best signal for
storms is over western Minnesota and will spread into the
Northland overnight and Wednesday morning. High pressure will
build quickly behind the front Wednesday afternoon and a
strengthening mid-level ridge over the eastern United States will
keep conditions relatively quiet until Thursday evening. Southerly
flow over the nation`s midsection will pump progressively warmer
air and additional moisture into the Northland late in the week.
Look for unseasonably warm temperatures in the middle 70s to low
80s by Friday, 10 to nearly 20 degrees above normal. Another round
of showers and thunderstorms is expected Friday through the
weekend as a quasi- stationary front sets up across the region.
Several shortwave troughs will ride along the boundary and rich
southerly flow in the boundary layer and mid-levels will support
successive rounds of rain and thunderstorms. By Sunday most of the
instability will be located south and east of the CWA with
showers expected.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 703 AM CDT Sun Sep 17 2017

Stubborn MVFR ceilings will linger over much of the area through
mid-morning at least before clouds break up with high pressure
building in. Strong west winds will continue as the pressure
gradient tightens over the Northland. Winds will gradually subside
late this afternoon or this evening as the ridge axis moves into
the area. A warm front will push into the region this evening
bringing a chance of rain showers into BRD and HIB late in the
forecast period. Opted to handle with VCSH for now due to
substantial amount of dry air between the cloud bearing layer and
the surface.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  58  46  61  49 /   0   0  20  10
INL  54  41  64  46 /   0   0  10  10
BRD  62  46  65  50 /   0   0  20  10
HYR  62  43  63  49 /   0   0  40  20
ASX  63  44  64  48 /   0   0  30  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 10 PM CDT this evening for LSZ121-
     140>148.

&&

$$

UPDATE...Huyck
SHORT TERM...GSF
LONG TERM...Huyck
AVIATION...Huyck



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