Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 130525

Area Forecast Discussion
National Weather Service Duluth MN
1225 AM CDT Tue Mar 13 2018

Issued at 1225 AM CDT Tue Mar 13 2018

Updated below for 06Z Aviation Discussion.

UPDATE Issued at 845 PM CDT Mon Mar 12 2018

Potent short wave is dropping south through Ontario and will reach
northeast Minnesota before midnight. Clouds were trying to form in
the potential vorticity advection ahead of the wave. However,
airmass is very dry as RH has been sparse. Clouds over the
Arrowhead have eroded almost as soon as they develop. In northwest
Wisconsin, lake induced clouds are forming along the south shore
of Lake Superior and moving inland. Cloud bases have been greater
than 5K ft because of the dry air. Still expecting some lake
effect snow, just delayed the timing a bit, with the best chance
still looking to be overnight when moisture in the low levels
improves. Made some minor changes to previous forecast.


.SHORT TERM...(This evening through Tuesday)
Issued at 305 PM CDT Mon Mar 12 2018

For the rest of the afternoon, the stratocumulus cloud field that
has developed from the International Border to the Twin Ports south
over northwest Wisconsin will persist along with gusty northwest
winds, with gusts up to around 30 mph. The boundary layer has mixed
above the 900 mb level, mixing down some stronger winds, which are
expected to weaken by the late evening as the boundary layer
decouples. The stratocu field should linger through the evening
hours as a mid-level shortwave dives southward over the eastern
portions of the region. While the lift associated with the shortwave
is progged to be weak, it should still support chances of lake
effect snow showers over the Lake Superior snowbelt region, thanks
to persistent northerly 1000-850 mb layer flow, and favorable delta-
Ts per the RAP/NAM/GFS models. Delta-T values should drop into the
15 to 20 degree range as the 850 mb level temperatures become
colder. Snowfall amounts should be fairly light, between a few
tenths of an inch up to an inch and a half along the Gogebic Range.
Some flurries will be possible over the Minnesota Arrowhead tonight,
but no accumulation is anticipated. Overnight lows should drop into
the single digits by International Falls to the middle teens over
northwest Wisconsin where cloud cover will linger.

Small chances of lake effect snow will linger through the morning
hours Tuesday before diminishing by the afternoon as surface high
pressure approaches from the northwest. Despite the high currently
situated over southwest Manitoba Canada, it will be a very slow
moving high and is not expected to pass by to our southwest until
Tuesday afternoon. High temperatures should be in the 30s across the
Northland, with upper 30s over the west due to more abundant
sunshine and lower 30s over the east where clouds will linger.

.LONG TERM...(Tuesday night through Monday)
Issued at 305 PM CDT Mon Mar 12 2018

Quiet with no organized systems expected. The only caveat to that is
the 12Z GFS brings a system through Iowa next Tuesday which could
send a precip shield north to the southern portions of our CWA. This
is one solution from the suite of deterministic models trying to
forecast what happens with a deep long wave trough moving into the
PacNW, so some caution is exercised in any solution regarding this

The forecast leading up to this system is largely dry and warmer.
Friday morning may be cool with single digit temperatures under
a good radiational cooling night.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1225 AM CDT Tue Mar 13 2018

VFR conditions are expected through the period with high pressure
building into the terminals. The only exception is at KHYR where
lake-effect clouds will lead to MVFR ceilings moving in around
daybreak Tuesday and then improving to VFR conditions by mid-day.
Any lake-effect snows will not affect the terminal.


DLH  14  34  18  39 /   0   0   0   0
INL   9  37  17  38 /   0   0   0  10
BRD  13  36  17  41 /   0   0   0   0
HYR  17  32  15  41 /   0   0   0   0
ASX  18  31  17  39 /  40  20   0   0




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