Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 111145

Area Forecast Discussion
National Weather Service Duluth MN
645 AM CDT Wed Oct 11 2017

Issued at 645 AM CDT Wed Oct 11 2017

Updated aviation section below for 12Z TAF TAF issuance.


.SHORT TERM...(Today through Thursday)
Issued at 332 AM CDT Wed Oct 11 2017

Another dry day on tap for today as high pressure remains in control
over the region. However, clouds will increase this afternoon and
evening as southerly return flow on the western edge of the sfc high
pressure will enhance 850-700 mb layer warm air and moisture
advection. A low-level cloud deck will move in from the south and
eventually spread over the Northland later this evening and
overnight. The western portions of the forecast area could
experience breezy southeast winds late this morning and through the
afternoon as the sfc pressure gradient tightens from the west. The
high-resolution model guidance, such as the NAMNest, ARW, and NMM
models, are all indicating some light activity developing due to the
low-level WAA. Increased PoPs slightly from the previous forecast,
but also increased the areal coverage of this activity due to a lack
of confidence in where precipitation will fall. NAM soundings are
progging a low-level saturated layer of ~5500 ft deep, which should
be sufficient moisture for some rain showers with this activity.
However, the NAM soundings also prog this layer to shrink later
Thursday morning, transitioning rain showers to more drizzle after
12z. Chances of drizzle will persist the longest along the North
Shore of Lake Superior due to persistent on-shore flow, possibly
lasting into the afternoon. This will also keep temperatures cooler
along this area. Today`s highs will range from the lower 50s along
the North Shore, and into the middle to upper 50s elsewhere.

A 35 to 45 kt low-level jet will translate eastward Thursday morning
over the western half of the forecast area as well, and persist
through the day Thursday, so fairly gusty winds could be mixed down
to the sfc from aloft. Gusts over our western forecast area Thursday
could increase into the 20 to 25 kt range, especially from the
Brainerd Lakes north to International Falls. The continued WAA will
bring the warmest temperatures of the upcoming week for Thursday,
with highs ranging from the middle 50s over the Arrowhead region
into the lower 60s west.

.LONG TERM...(Thursday night through Tuesday)
Issued at 332 AM CDT Wed Oct 11 2017

Thursday night and Friday morning we have a cold front that slowly
sweeps through the area, along with a fairly decent upper low that
moves across Manitoba into northern Ontario. The better dynamics
with this system will be to the north, but there should be enough
moisture to spread some stratus along with some precipitation
chances across the area.  Have kept pops low for now as whether we
get showers or not is going to depend on how much moisture is
available, and am not terribly confident in this right now. However,
the cloud cover is going to keep temperatures moderated overnight
and cool during the day, so have mainly 40s for overnight lows and
50s during the day.

Friday night looks like another cold one, with some areas dipping
below freezing overnight.  Have gone on the cold end of guidance as
a ridge axis overhead should allow for decent radiational cooling
even as a decent jet in the southwest flow aloft may spread cirrus
our direction to moderate it.

Our next weather maker spreads into the area Saturday night, and
continues through Sunday night.  A strong upper level trough axis
swings across the central CONUS during the period, with a surface
low tracking from where it develops over Kansas, sweeps northeast
across Iowa and Lake Michigan and then continuing off to the
northeast by Sunday evening.  This should push an initial wave of
warm air advection precipitation across the area Saturday night,
followed by deformation zone precipitation that continues into
Sunday and Sunday night. Models are in fairly decent agreement on
this system, and expect that at some point soon we can raise pops
for this wave.  The big question will be precipitation types. This
storm brings in enough cold air aloft for precipitation to at least
start out as snow aloft, but for most areas the surface will be warm
enough to melt it to rain before getting to the ground.  However,
some locations overnight Saturday night and Sunday night may switch
over to mixed rain/snow or even all snow.  Considering ground
temperatures are still pretty warm do not expect any accumulations,
but snow will be visible falling through the air.  Models do differ
on the ending time, with the ECMWF lingering showers over us Sunday
night and even Monday while the GFS moves the storm quickly off to
the east to leave us dry.  For now have gone drier, which may need
pops for diurnally driven afternoon showers as we get closer to it.

The remainder of the forecast appears relatively dry and quiet with
temperatures slowly warming through the middle of the week.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 645 AM CDT Wed Oct 11 2017

High pressure over the area this morning has produced mainly VFR
conditions. However, radiational fog has developed around KBRD,
which should dissipate by no later than 15z this morning. Stratus
is expected to stream into the area from the south beginning
around 00z, bringing MVFR ceilings initially. These clouds
expected to slowly lower with some sites dropping into IFR after
08z, which should continue through 12z before slowly moving east
and allowing ceilings to improve to VFR once again.


DLH  54  47  59  46 /   0  20  20  20
INL  57  44  62  42 /   0  10   0  20
BRD  55  48  62  44 /   0  20   0  10
HYR  59  49  60  49 /   0  10  10  20
ASX  59  47  62  50 /   0   0  10  20


LS...Small Craft Advisory from 10 PM this evening to 4 PM CDT
     Thursday for LSZ140-141.



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