Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 302006
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
306 PM CDT FRI SEP 30 2016

.SHORT TERM...(This evening through Saturday)
Issued at 306 PM CDT Fri Sep 30 2016

Summary: Persistent easterly flow from Lake Superior will
maintain a similar weather pattern into Saturday. Marine stratus
will surge back inland this evening and overnight, only to linger
again Saturday morning before dissipating for inland areas
Saturday afternoon, but remaining over the Lake. Low temperatures
will again fall into the 40s tonight, and lower to middle 60s are
expected Saturday afternoon.

A large, vertically-stacked area of low pressure over Kentucky
will wobble its way north to Indiana/Ohio by Saturday, while a
ridge of surface high pressure will continue to extend from Quebec
through northern Ontario into Minnesota. This pattern will
maintain light easterly flow across the Northland, which will be
relatively humid because of the moisture contribution from Lake
Superior.

The Northland saw stratus from Lake Superior spread to most of
the Northland last night and early this morning, only to linger
well into the day. The Lake is fairly warm, with a surface
temperature in the low 50s, while temperatures inland fell into
the 40s last night. The relatively warm and humid air from the
lake easily clouded over as it ran over the cool air inland. The
stratus gradually dissipated through today to result in most areas
clearing, but it remained over Lake Superior and slightly inland
downwind of the Lake, such as near the shores of the Twin Ports
and Ashland. The overall weather pattern will not be changing to
any significant degree into tomorrow, so it looks like the
Northland is stuck in repeat mode. The HRRR has been handling the
stratus the best amongst the models, and it has the marine stratus
surging back inland this evening and overnight. Increased the
cloud cover forecast for tonight and tomorrow with a heavy
influence from the latest HRRR runs. Other models support/suggest
the marine stratus moving back inland tonight for most areas, too,
such as the 950 hpa RAP RH and the local WRF.

The Northland saw visibilities come down overnight due to the
stratus, but there were few observations meeting true fog (less
than 1 mile). Tonight will likely be similar. However, there could
be some spots with foggier conditions wherever the stratus is low
enough, such as in higher terrain, so have patchy fog moving
inland tonight.

The model soundings are indicating a brief period of deepening
stratus from near the Twin Ports into the Arrowhead, near and
shortly after dawn tomorrow. The GFS even has a little
precipitation. Added patchy drizzle for this area because it looks
like the stratus layer might be deep enough to squeeze out a
little moisture.

Bands of cloud cover from the upper-level low will swing west
into the southeast forecast area late today into early Saturday,
and it might produce some very light rain for the far southeast
forecast area, near Prentice and Ogema.

.LONG TERM...(Saturday night through Friday)
Issued at 306 PM CDT Fri Sep 30 2016

The forecast area will remain positioned between low pressure
rotating to our south near Chicago, and high pressure anchored
to the north over Ontario into next week. The flow will turn
southerly and strengthen through the beginning of next week as the
next low pressure system advances into the Dakotas.

Latest runs of the GFS/ECM are in surprisingly good agreement with
the low that will impact the region next week considering its
out on day 5 and beyond. The long wave trough, with closed 500hPa
low, is projected make landfall on the western coast Sunday, then
migrate east across the central US and into the Northern Plains by
Wednesday. This track will allow for a warm front to lift over the
region early in the week, bringing a surge of warm gulf air along
with a chance for showers and thunderstorms with it. Once the low
passes over the western Lake Superior region and cold air
advection makes a return for the upcoming weekend, a much cooler
airmass with 850hPa temps well below zero will dive into the
Northland. This may be our first shot at light snow accumulations
along the borderland.

However, suspect overall timing of the long wave trough and
associated stacked low/precipitation chances will be slower than
currently in forecast. This is due to model bias of typically
progressing closed systems too fast, as well as the impact of the
tropical storm approaching the east coast during this time; which
the GFS and ECM are showing large differences with.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1249 PM CDT Fri Sep 30 2016

The fog and LIFR ceilings slowly eroded through the morning, with
only KINL still being impacted into this afternoon. Elsewhere
vfr conditions with mostly sunny skies will prevail for remainder
of the day. Expect low clouds and areas of fog to redevelop
overnight. Wrap around mid level clouds, associated with an area
of low pressure to our south, will also lift into the forecast
area overnight and linger into Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  49  61  46  63 /   0  10   0   0
INL  44  66  47  69 /   0   0   0   0
BRD  48  65  46  69 /   0   0   0   0
HYR  49  66  45  66 /   0   0   0   0
ASX  49  61  47  64 /   0   0   0   0

&&

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

$$

SHORT TERM...Grochocinski
LONG TERM...Graning
AVIATION...Graning



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