Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 260509
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1209 AM CDT Sun Mar 26 2017

.UPDATE...
Issued at 926 PM CDT Sat Mar 25 2017

Clouds continue to expand north and west this evening with light
precipitation moving through parts of northern Wisconsin. KPBH
reported light rain for a brief period and area radars show weak
echoes continue to move north. We don`t plan any big changes to
the forecast at this time. There is some concern portions of
Ashland and maybe even Bayfield Counties could get enough freezing
rain to warrant an advisory. Temperatures were from 31 to 36
degrees across those counties and there may be a bit more of a
drop but clouds continue to thicken. We will not add any more
counties to the advisory at this time but continue to monitor
radar/model/observations.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 314 PM CDT Sat Mar 25 2017

Cloud cover is expected to increase again overnight tonight ahead of
a stacked area of low pressure that will be situated over the mid
Mississippi River Valley overnight. A lobe of PVA will eject from
this low pressure system, along with increasing 850-700 mb layer
warm air and moisture advection, will support increasing chances
of precipitation over northwest Wisconsin this evening, and then
from the Brainerd Lakes northeast towards the Minnesota Arrowhead
Sunday morning. East to northeast on-shore winds off of Lake
Superior will continue through the day Sunday, which should advect
some cooler temperatures over land. This may lead to the
development of some patchy fog along the North Shore. Confidence
is not high that any dense fog will develop despite what a few of
the models were progging, including the RAP and HRRR models, and
to a lesser extent - the WRF ARW/NMM models. Cloud cover and
stronger winds due to the favorable fetch should help limit the
fog, but dew point depressions still look favorable. Due to the
cooler temperatures being advected on-shore, still think some
patchy fog is likely, but don`t think it will be dense. Therefore,
introduced patchy fog over the North Shore overnight.

The main concern for the overnight hours will be the precipitation
types overnight. As the PVA and warm air advection arrives, the
thermal profiles are expected to cool. Deepening moisture profiles,
as indicated in the RAP/NAM model soundings, along with cooling sfc
temperatures, will lead to mainly freezing rain across portions of
northwest Wisconsin, with the possibility of snow/sleet mixing in.
The most uncertainty for this forecast comes from the exact
temperature profile as the sfc temperatures will be right at
freezing. Any change in the sfc temperatures, either plus or minus
a degree, will have big changes in p-types. The guidance is
hinting at favorable sfc temperatures for freezing rain along the
higher elevations of the Gogebic Range in Iron county. Due to the
potential for a wintry mix, with freezing rain being the primary
p-type expected, decided to issue a Winter Weather Advisory for
Iron county tonight and into mid Sunday morning until temperatures
warm up. Smaller changes of freezing rain are possible along the
North Shore overnight as well, but the heaviest QPF is expected
over northwest Wisconsin, so not expecting as much ice
accumulation along the North Shore. Ice accumulation in Iron
county could be up to a tenth of an inch, with the greatest
amounts expected in the higher elevations of the Gogebic Range.

Precipitation will transition to all rain late Sunday morning
through the afternoon as the temperatures increase. Temperatures
will remain near or above seasonal averages during the day Sunday,
with decreasing chances of precipitation Sunday afternoon and
evening.

.LONG TERM...(Sunday night through Saturday)
Issued at 314 PM CDT Sat Mar 25 2017

No major storms appear in the offing for the upcoming week, but
there will be periodic chances for light precipitation, both at the
beginning of the period, and again later in the week.

At the beginning of the extended periods Sunday night and Monday,
ongoing light precipitation will be winding down and ending as the
slow-moving upper low over the middle Great Lakes region slowly
pulls away to the east.

As the eastern North American trof axis amplifies a bit early to mid
week, high pressure will strengthen slightly over Canada, and should
be sufficiently strong to push a weak surge of slightly colder air
southward into the western Lakes region Tues-Wed.  This should also
be sufficient to minimize precip chances during this time with
general large-scale subsidence.

Beyond Wednesday, the medium range models have significant
differences in both amplitude and timing of various weak
disturbances that will affect the Northland through the remainder of
the 7 day forecast window, which is also supported by the rather
large spread in the ensemble solution space.  The region should
transition to a slightly warmer airmass with time, but there will
also likely be periodic chances for light precip during the Thursday-
Saturday time range, and it seems likely that there will be at least
a couple of short time windows where light wintry mixed precip will
be possible across the region.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1209 AM CDT Sun Mar 26 2017

An area of surface low pressure was located along the northeast
Missouri and western Illinois border as of late evening. The low
will move northeast toward southern Lake Michigan and southwest
Michigan by early Sunday evening. An upper level disturbance was
also moving through the Northland this evening. These features will
bring a chance for rain, freezing rain, and possibly some sleet to
portions of the Northland, especially over northwest Wisconsin.
Freezing drizzle has also developed further northwest into the
KCOQ/KDLH/KTWM/KBFW areas. Areas of precipitation will be possible
through late Sunday or Sunday evening. Temperatures will warm
through the day so mainly rain will occur. We did keep a mention of
freezing rain at KHYR later tonight. We also have a period of
freezing drizzle at KDLH. The freezing drizzle in the KDLH area may
diminish later tonight as the low level flow weakens off of Lake
Superior possibly warming temperatures and leading to weaker
orographic lift.

Mainly MVFR/IFR conditions will prevail through the period with some
possible VFR conditions developing at KBRD/KINL late in the day or
in the evening hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  30  38  30  46 /  70  50  10  10
INL  29  47  28  48 /   0   0   0  10
BRD  32  45  32  54 /  30  20  10  10
HYR  33  42  31  48 /  60  50  30  10
ASX  32  39  30  45 /  60  50  30  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 9 AM CDT this morning for WIZ004.

MN...None.
LS...Small Craft Advisory until 4 AM CDT early this morning for
     LSZ121-140>148.

&&

$$

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


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