Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 152009
AFDDLH

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

.SHORT TERM...(This evening through Monday)
Issued at 309 PM CDT Sun Apr 15 2018

Snow and blizzard conditions continue today with dangerous to near
impossible travel conditions across northwest Wisconsin and parts of
northeast Minnesota, including the Twin Ports. While no time is
great for a blizzard, the timing of this storm on a Sunday and
mainly wrapping up tonight should mean few people will venture out
on to the roads and road crews should be able to get the upper hand
against the weather in time for the Monday morning commute. Some
snowfall will linger into the day Monday but overall new snow
accumulation will be limited - the main focus is today/tonight.

On the synoptic scale the upper low associated with this spring
storm is centered over southern Iowa per RAP and 12z upper air
sounding analysis. Over the next 24 hours the upper level longwave
trough axis becomes negatively tilted with a 120-150 knot southerly
jet ahead of it, resulting in height falls over the lower Great
Lakes region. The surface low currently over the Ohio RIver Valley
will track north, with the deep moisture that has advected across
the Tennessee and Ohio valleys today being transported around the low
to the Upper Great Lakes region, supporting a continued supply of
deep moisture. This afternoon water vapor channel imagery from GOES-
16 vividly depicts this moisture transport process - while there has
been a brief break in the precipitation over parts of northern
Wisconsin today, the moisture transport continues to help saturate
low and mid levels of the atmosphere. This will come together as the
broad-scale lift intensifies today and tonight due to both the mid-
level PVA as the mid-level closed low tracks eastward and weak warm
air advection at low levels.

In addition to the broad-scale pattern, lake-enhanced bands of snow
are anticipated due to very favorable low level winds producing a
long fetch over Lake Superior. While temps aloft are somewhat
marginal (barely meeting the -12C to -19C ideal difference between
air and water temp) and there is some concern about the speed of the
low level winds producing too much turbulence to support long-last
bands, the plentiful low level moisture, broad scale lift already in
place, and very little directional shear is good enough to produce
locally higher snowfall amounts. At this point wind directions look
to favor more of a western Douglas county to eastern Carlton county
band, but this should shift west or east, or we could even see a few
different bands develop late today/tonight as winds shift to become
more north-northeasterly. Along the north shore today there may also
be a bit of terrain-driven enhancement along the ridge of higher
elevations.

.LONG TERM...(Monday night through Sunday)
Issued at 309 PM CDT Sun Apr 15 2018

The strong storm system will continue to move slowly east of the
region on Monday night and Tuesday. Some lingering snow showers will
be found across eastern portions of the region Monday night, and
along the south shore on Tuesday. A couple inches of snow will be
possible across the Gogebic Range of mainly Iron county. Otherwise,
Tuesday is shaping up to be a fairly quiet day with some sunshine
across most of the area. The long range models continue to show a
low pressure system moving across the Central Plains on Wednesday
and Wednesday night, but only indicate a small chance of
precipitation across our area. After Wednesday night, strong upper
level ridging will move into the mid section of the country. This
ridge will bring dry weather for the period from Thursday into
Sunday. Temperatures will warm from the upper 30s to lower 40s on
Tuesday, to the 50s on Friday, Saturday and Sunday. Overnight lows
will generally be in the 20s throughout the period.

&&

.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.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  21  35  20  39 / 100  20  10   0
INL  19  38  20  43 /  50  30   0   0
BRD  20  40  20  43 /  90  10   0   0
HYR  23  33  20  40 / 100  40  20   0
ASX  22  33  23  38 / 100  70  40  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Lakeshore Flood Warning until 7 PM CDT this evening for
     WIZ001>004.

     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-
     021.

     Lakeshore Flood Warning until 7 PM CDT this evening for MNZ020-
     037.

     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
     MNZ034>036.

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

&&

$$

SHORT TERM...JJM
LONG TERM...DAP
AVIATION...DAP



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