Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 182004
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
304 PM CDT THU AUG 18 2016

.SHORT TERM...(This evening through Friday)
Issued at 304 PM CDT Thu Aug 18 2016

The chances of strong to severe storms, as well as chances of
rain, have diminished for the Northland through early this
evening. A storm complex that was in the southern Red River Valley
as of early this morning, moved into central Minnesota, including
the southern forecast area, this afternoon. The complex, as well
as its extensive cloud cover, ate away at and/or prevented the
build up of instability across much of the forecast area, thereby
limited the potential for strong to severe storms, let alone any
showers.

As of 3 pm this afternoon, a complex of thunderstorms was moving
across the south central forecast area to the east. The storms
were associated with a shortwave trough moving through the region,
with radar trends clearly showing a vortex near the Moose Lake
area. Much of the Northland had cloudy skies because of the
overcast cirrus associated with the storm complex. A cold front
stretched from far northwest Ontario to the eastern Dakotas and
was approaching the Northland from the north and west.

The storm complex could continue to move east across the southern
forecast area this afternoon, possibly resulting in small hail,
frequent lightning, and heavy rain to some areas. Another round of
showers and storms is possible this evening and overnight when the
cold front moves through the Northland, combined with other
possible shortwaves lifting through the Northland in the west-
southwest flow aloft, but lowered pcpn chances compared to the
previous forecast.

North-northwest flow on Friday will begin to usher in cooler air
into the Northland in the wake of the passing cold front. Daytime
heating amidst the relatively cool and humid air should help
develop broken/overcast cumulus by the early afternoon. Additional
showers and weak thunderstorms are possible, mainly in the more
humid post-frontal area across northwest Wisconsin into the Pine
County are of Minnesota, which could be aided by passing
shortwaves. The 12Z NAM12 is an outlier, showing much more robust
pcpn than other models because it seems to stall the cold front
across the southern forecast area. Leaned on the drier other
models, such as the GFS, ECMWF, Canadian, and SREF. High
temperatures should be in the middle to upper 70s.

.LONG TERM...(Friday night through Thursday)
Issued at 304 PM CDT Thu Aug 18 2016

In the extended the focus will initially be on the positively
tilted trough axis at 500 hPa digging and deepening from the
eastern ND into MN. Late Sunday morning/afternoon the trough will
become negatively tilted as it exits the Upper Midwest and pushes
into the central Great Lakes as shown by the latest
NAM/GFS/ECMWF/GEM. Decided to stick with the latest GFS/ECMWF/GEM-
NH for Saturday, which develops a broad area of low pressure along
a baroclinic zone over southern WI/eastern IA. The latest 12Z NAM
is an outlier at this point with a very strong area of low
pressure developing farther to the north. Will need to continue to
monitor future guidance to see if things trend in this direction.
Saturday will be cloudy and breezy out of the north/northeast with
scattered showers an some isolated thunderstorms. Due to the cool
northwest flow aloft, cooler than normal temperatures are expected
with readings in the 60s.

High pressure will build in behind the departing system. This
will bring drier air into the region. Aloft, winds will become
westerly which will advect milder air into the region. High
temperatures will be in the 60s to low 70s. Flow will become
southwesterly as the high builds into the central Great Lakes on
Monday. This will bring a return to normal temperatures for Monday
and slightly above normal temperatures for Tuesday with readings
around 80.

Good agreement from the latest GFS/ECMWF for Tuesday/Wednesday as
a trough digs into the Northern Plains from western Canada. Ahead
of the trough a warm front is expected to lift northwards on
Tuesday, which trigger some showers and thunderstorms. A trailing
cold front will keep shower and thunderstorm chances for
Wednesday/Thursday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1230 PM CDT Thu Aug 18 2016

The main concern during the TAF period is the thunderstorm
potential at all terminals. Still somewhat uncertain on the
evolution of things this afternoon due to the early morning MCS
that developed in the eastern Dakotas. Synoptically, a cold front
will slide southeastward from northwest Minnesota into northwest
Wisconsin late tonight. This will trigger showers and storms.
Ceilings will generally remain in the VFR range this afternoon,
but if a heavier shower/storm moves over a terminal will see
ceiling and visibility reductions range from MVFR to IFR or lower
per the latest NAM/GFS/HRRR. Most confident in the thunderstorm
potential at KBRD/KHYR/KDLH. Less certain at KINL/KHIB as cloud
cover from the morning MCS has reduced the amount of instability
to develop, but still included VCTS as the front should provide
enough forcing for storms to develop despite the lower
instability.

Expect showers and storms to continue into the overnight as the
front slides through. Ceiling/visibilities lower to the MVFR/IFR
range tonight with fog developing. Expect most of the thunderstorm
activity to remain at or ahead of the cold front with more
stratiform rain/showers behind the front. Still expect showers or
storms around at KDLH/KHYR from 12Z until 18Z with MVFR or lower
conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  63  75  56  64 /  40  30  40  60
INL  56  74  55  66 /  30  10  20  40
BRD  63  74  57  64 /  40  20  30  50
HYR  64  76  58  64 /  50  50  60  60
ASX  64  75  59  66 /  50  40  60  60

&&

.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...Grochocinski
LONG TERM...WL
AVIATION...WL



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