Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211651
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1051 AM CST Sat Jan 21 2017

.UPDATE...
Issued at 1025 AM CST Sat Jan 21 2017

Have just finished a round of updates and have made some headline
decisions. Of note, air temperatures everywhere have risen to
freezing or above. Road surface temperatures are the tricky part.
In the Arrowhead, they are still below freezing, with above
freezing temperatures elsewhere. Thus, with the precipitation
moving in from the south I expect new icing only in the Arrowhead.
Elsewhere, the rain may even help melt the icing that is on roads
from the last 24 hours of mixed precipitation. However, we are
very near thresholds for all of these items and would not be
surprised to see some small changes cause icing to develop once
again. This is most likely to happen this evening when
temperatures drop again, but will have to make that call later
this afternoon or early evening. For now it seems icing should be
limited to the tip of the arrowhead and have decided to put a new
winter weather advisory for that area out until tomorrow morning,
and let the rest of the area drop for now. Fog is still at it`s
worst for Duluth and up the North Shore, which should continue as
long as we have this onshore flow off the slightly warmer lake in
this already very moist atmosphere and then moving up the terrain
ridge. Have extended the fog advisory into this evening when winds
should turn more northerly and at least stop the convergent flow
along the terrain ridge that is enhancing the fog development.

&&

.SHORT TERM...(Today through Sunday)
Issued at 248 AM CST Sat Jan 21 2017

Wintry mix of drizzle/freezing drizzle/rain/snow continues across
portions of the Northland this morning as a mid-level wave
progresses northward. Not everyone will see precipitation this
morning as the more robust forcing eventually moves off to the
north. Fog is also expected to continue through this morning as a
moist airmass remains overhead. Snow melt due to temperatures at or
above freezing today and light winds will also support fog
development tonight. Another mid-level shortwave will translate
through southeast MN and western WI this morning, which will make
its way into the Northland. The latest synoptic guidance is showing
some good mid-level positive vorticity advection (PVA) and
isentropic lift associated with this system, which looks to be
maximized over northwest WI. So, have more likely PoPs through
northwest WI into the MN Arrowhead through the afternoon and into
tonight. Precipitation types look to be more rain and drizzle this
afternoon, except for some cooler temperatures adjacent to Lake
Superior will support more wintry mix p-types. The potential for
some slick roadways will continue for today, especially this
morning, as temperatures may be near freezing, with the most likely
area of icing being in the Arrowhead. Snow and ice accumulation are
expected to be light, except for perhaps up to one inch of snow
accumulation along the higher elevation areas of the North Shore
Saturday evening into Sunday morning as winds remain easterly during
this time.

Chances of precipitation will linger through Sunday morning as the
shortwave moves off to the north and pivots over the Arrowhead
region. This looks to keep the PVA around through this period, which
would support the chance PoPs. The PoPs then turn to more slight
chances as the shortwave eventually moves off to the north.
Temperatures are expected to remain in the upper 30s and lower 40s
today and Sunday, so some areas of fog are expected to continue
through the day Sunday.

.LONG TERM...(Sunday night through Friday)
Issued at 248 AM CST Sat Jan 21 2017

The extended period will see a gradual shift toward cooler
temperatures compared to the very mild conditions that have been in
place for the past few days.

An upper trough will move through the Northland Sunday night into
Monday with a weak surface ridge developing on Monday as the main
energy moves just east of the region. There will be a continued
chance for light precipitation Sunday night with chances ending from
south to north on Monday. The lack of deep moisture will lead to a
mix of drizzle, freezing drizzle, and light snow. Any accumulation
is expected to be very light. Lows Sunday night will be in the upper
twenties to lower thirties with highs rebounding to 35 to 40 on
Monday.

A lack of organized lift Monday night and Tuesday will lead to
mainly dry conditions with some small chances for light
drizzle/light freezing drizzle/light snow in spots. Highs Tuesday
will again be in the mid to upper thirties.

A stronger shortwave and low pressure system will track across the
central/southern Plains Tuesday toward the eastern Great Lakes by
Wednesday evening. The GFS is a bit further north with the track
compared to the ECMWF. This system will bring a chance for mainly
snow to the Northland Tuesday night into Wednesday morning with the
highest chance over northwest Wisconsin. Given the current track is
well south of the region, snow accumulation looks to be light with
accumulations remaining less than 3 inches. A shift in the track
will impact snow amounts so if you have travel plans Tuesday
night/Wednesday remain up to date on the forecast.

Colder air will move over the Northland Wednesday as northerly winds
develop behind the low. We have periodic chances for light snow late
in the period with chances highest along portions of the South Shore
due to lake processes there. Some accumulation will occur as
northwest winds will continue for several days. High temperatures
Friday/Saturday will be mainly in the twenties.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 546 AM CST Sat Jan 21 2017

A moist and unseasonably warm airmass will remain over the
Northland through the period leading to LIFR/IFR conditions. A
shortwave was moving out of Iowa into southern Minnesota this
morning with an area of heavier precipitation associated with it.
Areas of drizzle/freezing drizzle will occur both prior and after
this area of precipitation moves through the region. Rain or snow
may occur with the heavier precipitation, mostly likely impacting
KHYR.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  37  33  37  31 /  60  50  30  20
INL  37  30  37  27 /  30  40  30  20
BRD  37  31  38  30 /  50  30  20  20
HYR  39  33  40  31 / 100  40  20  20
ASX  40  33  40  31 /  60  60  20  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Winter Weather Advisory until 10 AM CST Sunday for MNZ011-012-
     019>021.

     Dense Fog Advisory until 9 PM CST this evening for MNZ020-021-
     037.

LS...None.
&&

$$

UPDATE...LE
SHORT TERM...JTS
LONG TERM...Melde
AVIATION...Melde



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