Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 150955
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
355 AM CST Sat Dec 15 2018

.SHORT TERM...(Today through Sunday)
Issued at 353 AM CST Sat Dec 15 2018

The generally quiet weather will continue through the weekend with
temperatures continuing their warming trend today, then cooling
for Sunday. A fairly potent shortwave will move across Ontario
tonight and Sunday, but is expected to bring little more than
clouds to the Northland due to a general lack of moisture.
Temperatures are the main concern today, with upstream
temperatures today over South Dakota having reached into the mid
40s to low 50s with the incoming airmass. However, this is
originating in an area where there is no snow on the ground, and
they had full sun while I expect us to have some cirrus overhead
for at least part of the day. Thus, have gone with highs on the
high end of guidance, ranging from the upper 30s to mid 40s. The
potent shortwave moving across Ontario will bring some extra
clouds and a wind switch from south to west tonight, which should
keep temperatures warmer than they have gotten so far this
morning. More cloud cover is expected for Sunday in the wake of
the shortwave, with cold air advection ongoing and a field of
cumulus in the steep low level lapse rates. Some of the high
resolution CAM models have been producing some afternoon showers
over mainly the Arrowhead, but the very considerable dry air we
have should keep any of that from reaching the ground. I did put
in some stronger surface winds, and gusts may be even higher than
what I have. Have also brought temperatures back into the 30s for
all locations, closer to the median guidance values.

.LONG TERM...(Sunday night through Friday)
Issued at 353 AM CST Sat Dec 15 2018

Temperatures remain near to above normal during the long term.
Chance of snow Wednesday afternoon through Thursday and again
Friday night.

Quasi-zonal flow aloft and west to southwest winds in the low-
levels will continue through Wednesday morning. Temperatures will
remain above to much above normal with highs on Monday in the low
20s in the northeast portions of the Arrowhead to near 30 in the
Brainerd Lakes. Highs Tuesday in the low to middle 30s.

A shortwave trough will move eastward across the region Wednesday
and Thursday. The GFS is most aggressive and deepens the trough
over the western Great Lakes while the ECMWF/GEM are more
progressive. Thermal profiles indicate a warm and dry layer aloft
before onset of precipitation. Think the column will cool
sufficiently for mostly snow. Left a mention of rain/snow mix on
the periphery of the chance POPs, where confidence and timing is
a little smaller. May see a brief period of rain or drizzle
before the change to all snow. Temperatures will remain above
normal Wednesday with highs in the low to middle 30s. Cooler in
the wake of the system Thursday with readings in the middle 20s
to low 30s.

Northwest flow returns Thursday night through Friday night with a
colder airmass aloft. H8 temperatures around -10 degrees Celsius
are forecast over western Lake Superior. Availability of upstream
moisture is uncertain with the GFS indicating the greatest amount
of moisture while the ECMWF and GEM are drier. Think there is a
chance of lake effect snow showers through Friday evening in
northwest Wisconsin. Widespread snow chances return Friday night,
but confidence is low. GFS, GEM, and ECMWF all feature distinctly
different solutions with regard to precipitation potential and
other details. Left chance POPs in for that period. Highs on
Friday will be in the upper teens to upper 20s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1127 PM CST Fri Dec 14 2018

Mainly VFR conditions for all TAF sites. However, in the early
morning hours, patchy fog is possible at HYR. Currently, misty
conditions are causing MVFR VSBYS to the south and east of HYR.
Confidence is not high on whether it will reach HYR. On Saturday, as
high pressure moves out of the region, gusty south-southwesterly
flow filters in behind it. This will result in LLWS beginning late
Saturday afternoon into evening for most sites.

&&

.MARINE...
Issued at 1045 PM CST Fri Dec 14 2018

Surface high pressure ridge will pass across western Lake Superior
overnight, with a continued decrease in winds and subsiding waves
and residual swell over the nearshore waters. All small craft
advisories were allowed to expire at 10 PM.

After a brief break in the winds through Saturday morning,
south/southwest winds will increase later Saturday and then become
strong and gusty out of the west and northwest later Saturday
night and Sunday as a weather disturbance and moderately strong
cold front move across the region. Wind gusts are expected to
reach between 30-35 knots over the lake Sunday and perhaps into
Sunday night, and a small craft advisory may once again be needed
for many areas during this time period.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  40  27  35  17 /   0   0   0   0
INL  44  28  31  11 /   0   0   0   0
BRD  42  27  36  16 /   0   0   0   0
HYR  41  26  36  18 /   0   0   0   0
ASX  43  29  38  21 /   0   0   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...LE
LONG TERM...KLH
AVIATION...KC
MARINE...Miller


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