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261
FXUS63 KDLH 292345
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
645 PM CDT THU SEP 29 2016

.SHORT TERM...(This evening through Friday)
Issued at 340 PM CDT Thu Sep 29 2016

Despite a broad area of high pressure across the Upper Midwest, much
of northern Minnesota and parts of northwest Wisconsin are under a
stubborn cloud deck trapped within an inversion. Still, it looks
like late today this inversion should somewhat mix out resulting in
clearing across parts of the region, though by that point the high
pressure will departing to the north. Tonight clouds return as the
abundant boundary layer moisture condenses, resulting in a stratus
deck. While this still looks to be the coolest night of the week,
the cloud cover will limit lows to the mid 40s, though some spots
across the MN Arrowhead could fall to the low 40s if skies are not
as cloudy as currently anticipated. MOS guidance has been
consistently cooler with lows close to freezing in some runs, but
looking at the actual text bulletin, it appears MOS might not be
taking into account the stratus we expect to develop.

The upper level low responsible for all this low level moisture -
currently over the Tennessee Valley - decides to take a visit back to
the Great Lakes this weekend, and as it approaches from the
southeast, low level winds will be out of the east tonight into
Friday. This will result in the dry slot evident on water vapor and
visible satellite imagery to build into the Northland, finally
resulting in what should be a mostly sunny afternoon across the
Northland. Temperatures will be warmer with highs in the mid to
upper 60s, except near Lake Superior and especially in the Twin
Ports and along the south shore where winds off the lake will limit
highs to the upper 50s to near 60.

.LONG TERM...(Friday night through Thursday)
Issued at 340 PM CDT Thu Sep 29 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. This will keep majority of the Northland dry
through the weekend. The exception will be a chance for light rain
possibly pushing as far north as the Park Falls area in northern
Wisconsin Saturday.

The resulting pressure gradient will allow for east winds to prevail
across the Northland through the weekend. 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 00Z TAFS through 00Z Friday evening)
Issued at 645 PM CDT Thu Sep 29 2016

High pressure centered just north of Lake Superior with a ridge
extending southwest through Minnesota will only move slightly
north through the period. VFR ceilings over northeast Minnesota
are expected to continue to slowly diminish per the latest RAP and
satellite supports a slow clearing trend. However, MVFR and IFR
ceilings are expected to expand in a persistent easterly flow. Fog
will also be possible tonight and we have a mention in the TAFs
later tonight into Friday morning. The lower ceilings and fog are
expected to lift Friday morning leading to VFR conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  43  60  49  62 /   0   0   0   0
INL  43  65  45  66 /  10   0   0   0
BRD  46  68  47  66 /   0   0   0   0
HYR  44  65  47  63 /   0  10  10  10
ASX  47  57  50  61 /  10  10  10  10

&&

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

$$

SHORT TERM...JJM
LONG TERM...Graning
AVIATION...Melde