Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 272211

Area Forecast Discussion
National Weather Service Duluth MN
511 PM CDT Thu Oct 27 2016

.SHORT TERM...(This evening through Friday)
Issued at 353 PM CDT Thu Oct 27 2016

Clouds are the main concern for the next 24 hours as the surface
ridge we had over the area slides off to the southeast, and a low
develops over eastern Montana and pushes northeast to our north on
Friday. This is producing a wing of warm air advection to push
across the forecast area from southwest to northeast this
afternoon and tonight. Unfortunately most of this WAA is going to
happen above our current inversion, likely only reinforcing the
saturated inversion that is trapping a bunch of stratus over the
area. I expect that after dark the stratus we have now is only
going to expand again, despite a late afternoon lull that we`re
going to have in the next few hours. That extra cloud cover and
the warm advection is going to keep our temperatures much warmer
than they have been the last couple mornings, and some sites up in
the mid 40s. There may also be some showers with as strong as the
warm air advection is, but there is a lot of uncertainty with
these and really only have confidence along the Canadian border
where I have put some small POPs. Friday the cold front begins to
push in our direction, keeping us in the warm airmass. Clouds may
be difficult to clear once again as the boundary layer remains
underneath a strong inversion, but we might manage to clear out of
it in the southern fringes of the forecast area and have a large
gradient from north to south in both cloud cover and temperatures
Friday. Initial thoughts are that it will be too dry over the
entire column to get much in the way of showers, but cannot rule
them out have have kept the small chance POPs going, mainly in
the afternoon.

.LONG TERM...(Friday night through Thursday)
Issued at 511 PM CDT Thu Oct 27 2016

The main focus for the long term is rain or shower chances with
two passing shortwaves Friday night through Sunday and the
eventual arrival of a stronger storm system early next week.

Fairly active pattern shaping up for the long term and models
seem to have a good handle on the details this afternoon. A
shortwave trough will move through northern Ontario and the Upper
Midwest Friday evening through mid-afternoon Saturday. Moisture
will be limited with this feature, with Pacific flow expected and
whatever vapor the trough can carry with it across the Rockies.
Think we`ll see a pretty robust band of stratus and light rain
north of the surface low. Winds may pick up over Lake Superior
ahead of the low and then quickly veer northeast behind the
system. The increasing wind speeds may result in hazardous
conditions for smaller vessels.

A second weak shortwave trough will move through the Central
Rockies and into the Midwest Saturday afternoon and evening. This
feature will also be moisture-starved, resulting in mainly clouds
and a few showers along my southern zones. Raised POPs above
consensus toward the ECMWF/GFS, which matched up better with my

A brief period of ridging will build across the region late
Saturday night through Sunday. A broad area of surface high
pressure will quickly scoot across the area. Think we will have
trouble scrubbing the low-level moisture out of the Northland so
trended toward partly cloudy/partly sunny sky for Sunday into
Sunday night.

By Sunday afternoon a shortwave trough rotating southeast out of
Alaska will kick the persistent longwave over the western US
eastward toward the Plains. Southwesterly return flow will develop
as the surface and upper ridging shift eastward. Even so, there
are concerns about the amount of moisture advection available for
this approaching trough by the time it reaches the Upper Midwest.
The longer period of Pacific moisture advection should result in a
broader precipitation shield than any of the earlier systems. GFS
is much stronger and deeper with lee cyclogenesis than either the
GEM or ECMWF. However, these three models are in better consensus
than yesterday afternoon. The GFS is a bit slower and farther
south, while the GEM/ECMWF are stronger than yesterday. Content
with a consensus approach for timing and location. Stronger GFS
still seems a bit aggressive with limited moisture and latent heat
release. Will need to keep an eye on this evolution during the
next 72 hours. A stronger, deeper low may result in a swath of
accumulating snow for portions of the Upper Midwest, including
northern Minnesota. If the weaker trend continues, expect mainly
rain as a p-type.

After Monday night model solutions diverge. Didn`t deviate from
the consensus blend due to low confidence with wide envelope of


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 211 PM CDT Thu Oct 27 2016

IFR/MVFR conditions are expected for the majority of this forecast
period. Stratus trapped near the surface by high pressure passing
overhead will be reinforced tonight with another area of low
pressure moving into the region. Ceilings may briefly lift to VFR
for a few hours this afternoon and tonight. In general, confidence
in improving conditions is low, so maintained the general
IFR/MVFR trends. Look for light rain showers or drizzle to
redevelop for most terminals tonight as additional lift and
moisture move in with the approaching low. Forecast soundings
suggest the boundary layer will decouple overnight with a very
weak inversion developing. At the top of the inversion, which also
seems to be the top of the low stratus layer, wind speeds will
increase. Drizzle is favored at all sites until stronger lift
arrives later overnight, due to turbulent mixing along the top of
the stratus layer. Ceilings should lift back into MVFR once again
late Friday morning as low-level mixing erodes the inversion.
Overall confidence in this forecast package is average.


DLH  42  58  46  49 /  10  10  10  10
INL  42  55  42  44 /  30  10  20  20
BRD  44  64  46  49 /   0   0  10  20
HYR  41  62  48  52 /   0  10  10  30
ASX  40  62  48  52 /  10  20  10  20




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