Area Forecast Discussion
Issued by NWS Duluth, MN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

FXUS63 KDLH 151732

Area Forecast Discussion
National Weather Service Duluth MN
1232 PM CDT Sun Apr 15 2018

.SHORT TERM...(Today through Monday)
Issued at 422 AM CDT Sun Apr 15 2018

Light snow continues to fall over portions of the Northland as of
4 AM this morning, with a few breaks in between snow bands. The
intensity and areal coverage of the snow is expected to increase
through the day today as the strongest lift associated with this
early spring system lifts northward and moisture increases. The
NAM and RAP model soundings both indicate deeper saturation
occurring through the morning today, leading to favorable
dendritic snow growth. Moreover, persistent northeast flow over
Lake Superior will provide very strong winds, with 25 to 35 mph
sustained winds and gusts up to 50 mph possible. These strong
winds, combined with increasing snow, will lead to very hazardous
travel conditions for today. Reduced visibilities down to one-
quarter mile or less is expected, along with snow-covered roads,
in these areas.

Regarding headlines for today, the biggest changes is to extend
the Lakeshore Flood Warning through 00z tonight, as we will
continue to see strong northeast winds, leading to continued
flooding along lakeshore areas and possible damage to structures.
Also, due to increased concern for strong winds at the head of
Lake Superior, decided to expand the Blizzard Warning to include
Douglas county. Confidence isn`t high enough to expand to include
Duluth as the model guidance indicates the strongest winds will
remain just south of Duluth, but the Superior area and points east
into Bayfield county should see a period of blizzard conditions.
There was also thought of expanding the Blizzard Warning to Iron
county, where heavy snow accumulations are anticipated, but due to
weaker winds over much of the county, decided that the threat was
too marginal to include Iron at this time. Still, some blizzard-
like conditions are possible there.

With increasing moisture in the low-levels expected, chances of
lake enhanced snow is also expected, so we have increased the
QPF/snow amounts for areas downstream of the flow over northwest
Wisconsin and adjacent areas of Lake Superior. There is the
possibility for lake enhanced snow to portions of the North Shore,
including Two Harbors and Silver Bay. Due to the increased risk of
lake enhancement in these areas, the Winter Weather Advisory was
upgraded to a Winter Storm Warning. Overall, areas in the Winter
Storm Warnings can expected between 7 to 10 inches of snowfall
through Sunday night, with the heaviest amounts still expected
over Bayfield, Ashland, and Iron counties in northwest Wisconsin
due to the strongest lift going through this area (per the Thaler
QG omega values) and lake enhancement expected. These areas could
see accumulations between 12 to 18 inches.

Light snow will linger along Lake Superior through the evening
hours tonight as the remnant forcing will linger, but eventually
weaken. The mesoscale models indicate that snow will wind down
over much of the area Monday morning, but linger over the Lake
Superior snowbelt region as winds shift from northeast to a
northerly direction during this time. Chances of lake effect snow
will remain over the South Shore as the north winds continue
through the day Monday.

.LONG TERM...(Monday night through Saturday)
Issued at 343 AM CDT Sun Apr 15 2018

Monday night, the synoptic snow comes to an end with lingering
lake effect snow continuing for the south shore of Lake Superior
into Tuesday and even Tuesday night. Monday night through Tuesday
night the upper level pattern will be blocky with the strong upper
low associated with the storm moving over the eastern Great
Lakes, a new upper low developing over the Rockies, and a narrow
ridge over the central CONUS. The ridge shifts over the forecast
area Tuesday night, turning winds to the east and shutting off the
south shore lake effect snow machine. Temperatures also warm up
some for Tuesday, warmer than for the last couple days, but still
below normal with the mid level warm air advection going on and
perhaps some glimpses at sunshine.

Tuesday night a strong wave ejects out of the western upper low and
moves out across the Central Plains on Wednesday.  Some models are
keeping this system far enough south to not affect the forecast
area, but others bring enough warm air advection in aloft to bring
some precipitation to the southern third or so of the forecast area
Wednesday and Wednesday evening.  With early morning lows in the
20s, as the precipitation moves in during the morning it may produce
some freezing rain, but as temperatures warm up it turns to all
rain, then back to a rain/snow mix Wednesday evening before ending.
Have kept pops mainly in the chance category for now, but we may
very well be looking at another event where the low level dry air
eats away at the northern flanks of this storm, keeping it out of
our area.

The weather then turns fairly quiet for the rest of the week, even
as yet another strong upper low moves across the Rockies.  Models
are keeping this storm well to our south, but would not be surprised
to see shifts in the track of this one considering what has been
happening in the short term.  Temperatures gradually warm through
the late week and weekend, but this may be trended towards
climatology too much and we should expect some colder days in there
as well.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1230 PM CDT Sun Apr 15 2018

The massive Spring storm will continue to affect the Northland
throughout the period, although the effects will be most
pronounced today and tonight. The system will gradually lose its
grip on the region overnight and especially on Monday. Strong
northeast winds will gradually become north as well, as the storm
pulls off to the east. Widespread IFR/LIFR will give way to
IFR/MVFR overnight and VFR to MVFR on Monday. Overall, the trend
will improve from west to east.


DLH  28  20  35  20 / 100 100  20   0
INL  35  21  38  20 /  30  50  30   0
BRD  31  21  40  21 /  80  90  10   0
HYR  29  23  33  20 / 100 100  40  20
ASX  28  24  33  23 / 100 100  70  50


WI...Lakeshore Flood Warning until 7 PM CDT this evening for

     Winter Storm Warning until 7 AM CDT Monday for WIZ004.

     Winter Storm Warning until 10 PM CDT this evening for WIZ006>009.

     Blizzard Warning until 7 AM CDT Monday for WIZ001>003.

MN...Winter Weather Advisory until 7 AM CDT Monday for MNZ011-012-019-

     Lakeshore Flood Warning until 7 PM CDT this evening for MNZ020-

     Winter Storm Warning until 7 AM CDT Monday for MNZ020-037.

     Winter Storm Warning until 10 PM CDT this evening for MNZ038.

     Winter Weather Advisory until 10 PM CDT this evening for

LS...Gale Warning until 4 AM CDT Monday for LSZ121-140>148.



AVIATION...DAP is the U.S. government's official web portal to all federal, state and local government web resources and services.