Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 251603 AAA

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1103 AM CDT Sat Mar 25 2017

Issued at 1051 AM CDT Sat Mar 25 2017

Easterly flow off Lake Superior looks to continue through the rest
of the day today. The drizzle/freezing drizzle that was observed
via radar from Duluth northeast towards Silver Bay has dissipated
this morning, so cut back on the POPs a bit. The 25.12z NAM is
still indicating some drizzle still possible due to this easterly
flow, so maintained only slight chance POPs for now in this area.

The biggest adjustments were made in the sky cover as this low-
level stratus deck seems to be maintaining itself rather well.
What little breaks in sky cover across our northwestern counties
we had this morning has since filled in. Soundings indicate this
stratus deck should persist through the day, so went a bit more
pessimistic on sky cover through the afternoon and evening.


.SHORT TERM...(Today through Sunday)
Issued at 346 AM CDT Sat Mar 25 2017

A ridge of high pressure will stretch from northern Ontario into
the Northland today while low pressure advances northeastward
through the middle Mississippi Valley. The position of these
surface features is conducive to strong northeast winds over
western Lake Superior. The strong winds will push inland around
the Twin Ports and along the North Shore today keeping temps cool
with generally overcast skies. A mix of drizzle and snow flurries
have been reported overnight and was supported by radar echoes
from KDLH. Expect drizzle or freezing drizzle to continue this
morning from the Twin Ports and Cloquet northward toward the Iron
Range and northeast into the Arrowhead. Clearing to our northwest
was attempting to push into Koochiching County at 3 AM, but the
stubborn low stratus was hanging on. Think the western portions of
the forecast area should see a few breaks in the clouds today
before the stratus shield from the approaching surface low brings
grey skies back into the picture tonight.

As the southern low moves closer to the Northland tonight, a
broad arc of showers will move across Wisconsin and into northeast
Minnesota. Precipitation types will be tricky. Surface
temperatures will be near freezing with the top of the cloud
bearing layer warmer than -10 C, limiting the potential for ice
crystal seeding. Rain or freezing rain seem to be the favored
precipitation types, while sleet cannot be entirely ruled out. In
either case, ice accumulation on untreated/diluted surfaces seems
likely. Roads and bridges may become slippery, especially over
portions of Price, Ashland, and Iron Counties. The potential for
freezing rain continues across Bayfield and Douglas Counties and
for portions of northeast Minnesota. Overnight temperatures are
forecast in the low 30s in northwest Wisconsin and around 30
degrees along the North Shore and in the Twin Ports. Confidence in
temperatures isn`t especially high, which precludes the issuance
of headlines for the wintry precipitation. There is a good chance
rain will be the dominant precip type overnight. Areas that do
experience the freezing rain should see ice accumulations less
than one-tenth of an inch with the majority of the area picking up
a thin glaze up to five one-hundredths. Temperatures will slowly
warm on Sunday changing precipitation back to rain.

.LONG TERM...(Sunday night through Friday)
Issued at 346 AM CDT Sat Mar 25 2017

A series of upper level shortwaves will affect the forecast area
Sunday night and Monday. Pieces of energy will moves across the
region and interact with a surface low lifting northeastward from
the southern Great Lakes Sunday night, to the eastern Great Lakes
by Monday afternoon. Thermal profiles suggest a wintry mix of
P-Types Sunday night and early Monday morning before changing to
all rain by mid-morning. High pressure based in Canada will cover
the region from Monday afternoon through Tuesday night. Models
begin to diverge Wednesday through Friday. The ECMWF has a
sharpening upper trough that will move across the forecast area
Wednesday night, followed by a large cutoff low that will drift
northward from the Texas panhandle, reaching the Great Lakes
Friday night. The GFS drags a stronger upper trough across the
region Wednesday night, followed by upper level ridging. The GEM
keeps the Wednesday night trough farther north in Canada, while
taking the aforementioned large cutoff low into the region much
faster than the ECMWF. The surface features are all diverging
during this time as well. Used a model blend to account for these
differences, thermal profiles and their affect on P-Types.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 626 AM CDT Sat Mar 25 2017

High pressure will be in the vicinity of the terminals through
much of the forecast. This will allow an easterly flow to continue
with MVFR clouds for much of the forecast. Latest satellite shows
a clearing trend working over western Lake Superior. If this trend
persists, VFR is possible at all terminals but HYR. Have tried to
time this into the forecast. After 06Z, some light rain will begin
to move towards the terminals from south to north through the end
of the forecast. Confidence is low on when this rain will occur
and have a VCSH mention. INL should remain rain free.


DLH  35  29  37  30 /  20  50  40  20
INL  43  28  44  28 /   0  10  10  10
BRD  44  31  43  32 /   0  30  20  10
HYR  44  33  41  31 /   0  50  40  40
ASX  38  31  37  30 /   0  60  50  40


LS...Small Craft Advisory until 4 AM CDT Sunday for LSZ121-140>148.



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