Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 260849
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
349 AM CDT FRI AUG 26 2016

.SHORT TERM...(Today through Saturday)
Issued at 349 AM CDT Fri Aug 26 2016

After a chilly morning with lows in the 40s in some areas and patchy
fog skies will be mostly sunny today as high pressure builds in
across the upper Midwest. Increasing clouds and showers possible
late tonight into Saturday. Temperatures remaining on the cool side
for late August with highs in the upper 60s to low 70s today and
tomorrow and lows in the 50s tonight.

On the synoptic scale an area of high pressure centered over the mid-
Mississippi river valley this morning will gradually build eastward
towards the Great Lakes today. At upper levels of the atmosphere an
upper high will be centered over central Appalachia today while a
shortwave trough across southern Saskatchewan/eastern Montana
approaches from the west. This will all result in southerly flow at
low to mid levels today, bringing some milder air into the upper
Midwest, warming up from 850mb temps around +6 to +8C this morning
to +10 to +12C by 00z this evening. Skies will initially be mostly
sunny, but with steep low level lapse rates from diurnal heating
expect a bit of fair-weather cu developing by the late morning/early
afternoon, similar to the central Dakotas today. More clouds
towards the evening as the shortwave trough approaches from the west
with a large area of mid-level moisture currently over the central
and northern high plains advecting towards the mid to upper
Mississippi river valley.

Precipitation may begin late Friday night across north-central
Minnesota in the warm air advection regime, but the better large-
scale forcing doesn`t really arrive until Saturday when the best PVA
happens. While there is a chance for rain across the entire
Northland Saturday, there are really two separate areas with the
best chances for precip. First, across north-central to northeast
Minnesota (mainly along and northwest of the Iron Range) showers and
storms are expected to move in from the west in the afternoon after
initiating across the Red River Valley in the morning, with strong
large-scale forcing and a bit of an EML advecting in from the west
resulting in a chance for some embedded thunderstorms. Second,
showers and thunderstorms will develop across the eastern central
Plains into the mid-Mississippi valley late today into tonight along
a warm frontal zone. This area of convection will then advect north,
possible impacting parts of northern Wisconsin by Saturday. However,
best instability would be further south, resulting in a low to nil
chance for thunderstorms Saturday afternoon. The margin of error for
the best chances for precip from both of these sources is wide
enough that the entire area has a chance for rain Saturday.

.LONG TERM...(Saturday night through Thursday)
Issued at 349 AM CDT Fri Aug 26 2016

Saturday evening the strong shortwave and associated convection will
sweep northeast out of the region, leaving mainly showers for the
rest of the night. Have maintained some fairly high pops in the
evening time frame, but reduced them to slight chances or less for
after midnight.  We should have at least a short period of quiet
weather Sunday morning, but during the afternoon and evening there
is potential for new thunderstorm development over central Minnesota
that should also sweep northeast across the forecast area Sunday
night and linger into Monday. Models are picking up on the
instability that develops for Sunday afternoon, but not all are
developing convection as the shear and trigger look weak with a cold
front still out over the Dakotas.  Have used the GFS more in
developing this convection, but have kept pops to slights and small
chance pops.  Convection continues on Monday and Monday night with
the cold front that pushes through during the day and early evening.
We finally get a break in this active weather pattern for Tuesday as
a ridge of high pressure builds across the area.

Uncertainty gets larger into the middle of the week as an upper
level ridge builds over the high plains, which should push an 850mb
baroclinic zone across the region for convection to develop upon.
Have had to keep chance pops going through the remainder of the
forecast period with that feature in place through the end of the
week and various shortwave sliding down the northwest upper level
flow interacting with it.  We will continue our relatively warm
pattern with near to above normal temperatures through the
extended.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1231 AM CDT Fri Aug 26 2016

A surface trof has been fairly stationary over northeast MN tonight.
This trof and and an upper level shortwave have kept clouds over
much of northeast MN. Models point to the clouds diminishing through
10Z. Held onto the mention of fog temporarily occurring at all sites
but DLH as the wind subsides. MVFR visibilities are possible with the
fog. Otherwise, VFR through the forecast.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  71  54  68  54 /   0  30  60  50
INL  73  55  68  52 /   0  40  60  40
BRD  72  57  71  56 /   0  50  50  30
HYR  71  54  69  55 /   0  30  70  30
ASX  71  54  71  57 /  10  20  60  40

&&

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

$$

SHORT TERM...JJM
LONG TERM...LE
AVIATION...LE/GSF



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