Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 191640 AAC
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1140 AM CDT SUN JUN 19 2016

.UPDATE...
Issued at 1140 AM CDT Sun Jun 19 2016

Quite impressive storms along the canadian border this morning
continue to translate eastward along the low level
thermal/moisture gradient at the nose of the low level jet. very
impressive cores aloft with 65+dbz to above -30C level/43 kft and
supercell updraft structure resulted in quite a few reports of
golf ball/tennis ball size hail across northern Koochiching
County. It appears as though the surface warm front is in the
process of jumping north as full sun and heating is allowing for
shallow morning inversions to rapidly mix out, so the threat of
additional intense updraft development appears to have shifted
into Ontario between Quetico Provincial Park and Thunder Bay for
the rest of the morning/early afternoon. Although we will still
have to monitor the International Border area closely from the
Boundary Waters to Grand Portage as additional development remains
possible on the south/southwest flank of the ongoing convection
just on the other side of the border.

Our focus now shifts to the redevelopment of strong/severe TStorms
along the approaching cold front this afternoon and evening. Most
short range guidance is keying on the 4-5 PM time frame for
sustained initiation along or just west of an axis from Lake
Vermilion/Grand Rapids/Brainerd. The large scale environment will
be characterized by ~3000 j/kg CAPE and 40+ knots of deep layer
bulk shear. CAM/HiRes guidance suggests that the mode for the
first few hours should trend toward discrete storms, and any
supercells will be capable of very large hail (up to baseballs),
and damaging wind gusts. The latest near-surface mass fields are
also a bit more concerning for the tornado potential as well, with
somewhat longer 0-1 km hodographs and stronger near-surface shear
that previous runs, especially over NE MN 21-00z time frame.
Eventually, activity should grow up scale into a squall line, with
the potential for a more widespread wind threat east of I35 into
the evening.

&&

.SHORT TERM...(Today through Tonight)
Issued at 356 AM CDT Sun Jun 19 2016

At 345 AM...Surface high pressure was centered over the eastern
United States, and it was helping to provide clear skies and very
light wind speeds across the Northland. However, high clouds were
spreading into the Northland from the west, which were associated
with a thunderstorm complex over north-central North Dakota and
southern Manitoba. The storm complex was associated with a surface
low in western North Dakota and a shortwave trough lifting through
northern North Dakota and southern Saskatchewan/Manitoba. A subtle
warm front stretched from the area of low pressure east and south
across the Northern Plains into Minnesota.

Early this morning...The majority of the models suggest the storm
complex will track east-northeast into northwestern Minnesota,
southeast Manitoba, and northwest Ontario. There is some sense to
this since the low is lifting northeast and the warm front is
lifting north, and the storm complex will attempt to feed on the
warm/humid air on the cool side of the warm front. Also, the
latest radar trends show the southern-most cluster of storms
tracking slightly to north as it moves east. While indications are
for it to mainly miss our forecast area, it could clip the far
northwest forecast area, including the International Falls area,
this morning around 7 AM to 9 AM. If it does, the main threats will
be damaging winds and brief torrential rain.

This morning and early this afternoon...Cloud cover will continue
to spread into the Northland as the storm complex approaches from
the west. Expect most of the cloud cover to dissipate or move out
of the forecast area by early this afternoon as a subtle upper
level ridge shifts into the Northland in the wake of the passing
low and shortwave trough in Canada, and as the warm front lifts
into Canada. Strong south-southwesterly winds will quickly develop
today, ushering warm and humid air into the region ahead of the
cold front, associated with the low moving into Canada, approaches
from the west. There is good model agreement that there will be
widespread 15 to 20 mph sustained wind speeds with gusts of at
least 25 to 35 mph. The rap, nam, and gfs soundings have 30 to 40
knots of flow in the mixing layer, so gusts could be
substantially higher, but was not confident to forecast above 35
mph yet. May need to increase the gusts later in the shift.
Temperatures are expected to climb well into the 80s for all but
the far North Shore, which should only get 70s because of the
southerly flow from Lake Superior. The dew point temperatures will
climb to the upper 60s, so the combination of the heat and
humidity will make it feel close to 90 degrees for most areas. The
southwest flow will cause downslope warming for the Twin Ports
shoreline, so increased the temperature far above models to the
upper 80s.

Late this afternoon and this evening...There is an enhanced risk
of severe weather for the Northland. There will be falling heights
across the Northland as a potent upper level low and its trough
move east of the Rockies into southern Manitoba and North Dakota.
The falling heights will be providing synoptic lift across the
Northland. The lift should be sufficient to develop thunderstorms
along the cold front in northeast Minnesota by late this
afternoon or this evening when the capping breaks. These storms
will tap into an environment with mixed layer cape up to around
2500 J/kg, deep layer (0 to 6 km) wind shear of 40 to 50 knots,
strong westerly upper-level steering flow, strong southwesterly
low- level (25 to 30 knot 0.5 km wind speeds) inflow, and
precipitable water values of 1.75 to 2.0 inches. This environment
will likely favor supercell development at the onset of activity,
and those storms will be capable of large hail, damaging winds,
frequent lightning, and torrential rainfall. The storm types may
transition to a more linear complex in the evening as outflow from
the multiple storms organize and reinforce the cold front,
transitioning the main threat to damaging winds for northwest
Wisconsin.

The greatest threat for severe weather appears to be the
southwest forecast area, including the Brainerd Lakes, Aitkin,
Cloquet, areas, and the Interstate 35 corridor from Pine City to
Duluth. There could be brief flash flooding if the storms are able
to train, but otherwise think the storm movement should be quick
enough to prevent any single storm remaining on any particular
location for very low.

Tonight...There could be lingering storms across the far southeast
forecast area around midnight, but the storms should exit a few
hours before dawn. Cooler and much less humid air will build into
the Northland in the wake of the cold front. There should be a
clearing trend overnight from the northwest. Temperatures will
drop to the upper 50s and lower 60s.

.LONG TERM...(Monday through Saturday)
Issued at 356 AM CDT Sun Jun 19 2016

By Monday all the Northland will be in a post cold frontal
situation with much cooler air coming in on very strong northwest
flow. One more upper level short wave embedded in the cyclonic
flow will graze northern MN with some spotty morning showers.
otherwise...it will be dry but very breezy. With steep lapse rates
in the cold air advection, there will be mixing from about 6k
feet, mixing down winds of 30 kts.

In the upper levels the omega block across much of the U.S. will
keep the region dry through mid week with seasonal temperatures in
the 70s. However...by Thursday the extended models are hinting at
another upper level short wave riding across the ridge over the
High Plains, and affecting the Northland late in the week with a
round of showers and storms. There are still some timing
differences between the GFS and ECMWF with the GFS faster and
stronger, but the general idea is similar.

The for the weekend, a deep low will be making landfall on the NW
Pacific coast and ride through the ridge over the weekend,
pointing to a stormy weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1232 AM CDT Sun Jun 19 2016

A warm front stretched from North Dakota east into northern
Minnesota late this evening and will continue to lift north
overnight. A low level jet will develop overnight and may cause
some additional showers and thunderstorms to form, mainly along
and north of Highway 2. Fog will be possible again, but we do not
expect it to be as widespread as Friday night. A complex of strong
to severe storms over northwest North Dakota and southeast
Saskatchewan will continue to move east overnight making it into
KINL around or shortly after 11Z. These storms will continue east
through the morning and will be capable of producing strong winds.
The storms may stretch further south but we limited the mention to
KINL at this time.

A cold front will then be the focus for more storms Sunday
afternoon into Sunday evening and these storms could be quite
strong producing large hail, damaging winds, and frequent
lightning.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  88  58  75  50 /  40  70  10  10
INL  84  56  71  48 /  80  30  20  10
BRD  89  60  77  53 /  60  70  10   0
HYR  87  60  79  51 /  10  60  10   0
ASX  86  62  76  51 /  10  60   0  10

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...Small Craft Advisory until 7 PM CDT this evening for LSZ142>146.

&&

$$



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