Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 190947

Area Forecast Discussion
National Weather Service Duluth MN
447 AM CDT WED OCT 19 2016

.SHORT TERM...(Today through Thursday)
Issued at 447 AM CDT Wed Oct 19 2016

At 4 AM, a cutoff low was centered over northeast Manitoba aloft
and two ribbons of were rotating around the upper low; one over
southern Manitoba and northwest Ontario and a second over northern
Minnesota. A surface trough extended east into far northern
Ontario and angling back southwest across eastern Lake Superior
and into the Upper Midwest. A cold/quasi-stationary front marked
the surface trough and stretched from central Upper Michigan
across northwest Wisconsin and central Minnesota to eastern South
Dakota. Behind this boundary an area of stratus has expanded east-
southeastward across northern Minnesota overnight and stretched
from along the North Shore west across the Brainerd Lakes to the
North Dakota/ South Dakota border. The presence of the low
overcast has restricted radiational cooling keeping temperatures
warmer than previously anticipated. There was still a cooling
trend noted in my northwest as cold air advected into the area
behind the front and under the cloud deck. Weak forcing for ascent
was found ahead of the vort max over northeast Minnesota and was
generating scattered showers over portions of northeast Minnesota
and adjacent areas of Lake Superior and northwest Ontario.
Scattered showers were observed on Canadian weather radar imagery
from Dryden and Nipigon, ON. While the echoes were located north
of the International Border, satellite imagery featured some
cooler cloud tops from near Taconite Harbor northeast toward
Thunder Bay. Expect the potential for scattered showers to rapidly
diminish over my northeast Minnesota zones by 11Z.

Upper low will slowly drift farther eastward today and the
surface front will advance southeast out of my forecast area by
late morning. Clouds will linger over much of the forecast area
this morning. My far northern zones will likely hang onto the
clouds for much of the day, as was observed over portions of North
Dakota and the Canadian Prairies yesterday. Farther south, think
the boundary layer should mix deep enough by late morning/early
afternoon for partly cloudy to partly sunny skies. Trended max
temps a few degrees cooler today largely due to the early cloud

A shortwave trough will approach the Northland this evening from
the northwest. This feature is accompanied by a ribbon of
vorticity and will act to deepen the positively titled trough over
the area. Moisture will be somewhat limited this evening, with
clouds expanding southward once again late overnight. Still think
there is a slight chance for scattered showers on the windward
side of the Bayfield Peninsula as the Lake Superior surface
temperatures remain in the upper 40s to low 50s. Weak northwest
winds should result in relatively long parcel residence times over
the short fetch between the North Shore and northern Bayfield
County. Confidence is not very high due to a relatively warm
airmass. With the warm temperatures, saturation mixing ratios are
much higher than later in the season, requiring a greater moisture
flux to initiate precipitation. Rain seems to be the favored
precip type in northern Bayfield County overnight, but a few
snowflakes may mix in late. Trended temperatures slightly cooler
for inland northwest Wisconsin due to expected partly to mainly
clear skies and diminishing winds.

Clouds will increase across the Northland for Thursday with
deepening low pressure aloft and continued cold air advection.
With increasing low- and mid-level moisture over northern
Minnesota and long parcel trajectories over upstream lakes in
Manitoba and northwest Ontario, think there is a potential for a
few rain or snow showers over portions of north-central and
northeast Minnesota Thursday. Due to the dependence on moisture
from upstream lakes, and sensitivity to wind direction, elected to
keep previous shift`s low chance POPs through late afternoon.

Temperatures will trend below normal through the short term, with
Thursday highs a few degrees cooler than today.

.LONG TERM...(Thursday night through Tuesday)
Issued at 447 AM CDT Wed Oct 19 2016

As an upper level trof departs Thursday night, it is replaced by
northwest flow aloft. Mid level and surface ridging build into the
forecast area. This ridging remains in place through Friday. By
Friday night, an upper level shortwave moves over the top of the
ridge. Model differences begin to reveal themselves with their QPF
fields. The NAM/GEM are the most robust and the farthest south
with their QPF. The ECMWF has some QPF in the evening, while the
GFS is dry. A compromise leads to some POPs/QPF that is closer to
the NAM/GEM solutions. There is just enough cold air over the
Arrowhead for a mix of rain and snow late Friday night. No snow
accumulation is expected. The ridging returns for Saturday. Model
differences are quite large for Saturday night. The GFS develops a
surface low in the western Dakotas and deepens it as it lifts into
northeast North Dakota. The GEM keeps the low center in southeast
South Dakota, and the ECMWF does not produce a low center in these
areas, instead its in northwest Ontario. They also disagree on the
location of a shortwave trof and its strength. As a result, the
GFS is dry, the GEM has a strip of QPF late near the Canadian
border, the ECMWF has the most QPF and over a larger area. Used a
blended approach to pops. Primarily rain is expected, but some
snow may mix in again over the Arrowhead. The differences continue
on Sunday and maintained the blended approach. Sunday night and
Monday finds the upper level and surface ridging returning to the
region. The models are pointing to a pattern change Monday night
and Tuesday. The upper ridging attempts to hang tough over the
region, but strong warm air advection on a 45 knot low level jet
will pump warm, moist air back into the region. Showers will
develop over much of the area and last through Tuesday.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1214 AM CDT Wed Oct 19 2016

A trough of low pressure and cold front were moving through the
Northland late this evening with colder air moving in behind these
features. There has been some light showers in spots but those
should be dissipating over the next hour or two. MVFR ceilings were
moving into northern Minnesota and should continue to do so on west
to northwest winds. MVFR ceilings extended through North Dakota into
Montana and southern Saskatchewan. We bring these ceilings into
KHIB/KBRD/KINL and as far east as KDLH overnight into Wednesday
morning. Cyclonic flow aloft and colder air will be over the
Northland Wednesday and should lead to more clouds, especially far
north. The guidance is mixed in how far east and south these MVFR
ceilings occur and how quickly they lift on Wednesday. It`s possible
we may have to hold onto the lower ceilings longer at KBRD and KDLH.


DLH  48  31  43  31 /  10   0   0   0
INL  42  32  41  29 /   0  20  20   0
BRD  49  31  45  31 /   0   0   0   0
HYR  53  31  45  31 /   0   0   0   0
ASX  53  35  44  33 /   0  10  10  10


.DLH Watches/Warnings/Advisories...


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