Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 210525

Area Forecast Discussion
National Weather Service Duluth MN
1225 AM CDT SUN AUG 21 2016

.SHORT TERM...(This evening through Sunday)
Issued at 332 PM CDT Sat Aug 20 2016

A deep upper trough over Minnesota this afternoon continued to
move east and was deepening a surface low that was located over northern
Lake Michigan as of 20Z. Strong forcing was associated with these
features and was leading to plenty of showers and a few
thunderstorms this afternoon. Pressure falls ahead of this low
were around 3.5MB over the last 3 hours with rises around 1MB. The
low will continue to deepen as it moves off to the northeast,
reaching the southern portion of James Bay by 12Z Sunday. Showers will
be widespread into late afternoon then gradually diminish
overnight, lasting the longest over northwest Wisconsin. A few
thunderstorms will also be possible. Rainfall has varied greatly
across the CWA today with 1 to 2 inches in spots over northern
Minnesota and 1 to 1.5 inches over northwest Wisconsin, mainly
from the Hayward area to to Sand Island on east. Much of the
guidance agrees that the highest amounts of new rainfall tonight
will be over portions of northern Wisconsin with an additional half
to 1 inch expected from from this evening through Sunday morning.
There could be locally higher amounts as well. Some locally
heavier rainfall is also possible over northern Minnesota into
this evening, especially over the Arrowhead.

Some showers may linger over portions of northwest Wisconsin Sunday
morning but then a ridge of high pressure will build into the
area. Partly to mostly sunny skies are expected with highs in
from the upper sixties to lower seventies.

.LONG TERM...(Sunday night through Saturday)
Issued at 332 PM CDT Sat Aug 20 2016

Summary: A warming trend early this week will see temperatures climb
well into the 80s by Tuesday, but a cold front could bring
showers and storms Tuesday night and Wednesday, followed by cooler
weather for the middle of the week.

A broad upper level ridge over the western US/Canada, as of Sunday
evening, will build east into the central US/Canada into Tuesday,
resulting in a building dome of very warm air across the Northern
Plains and Upper Midwest. A warm front, associated with a low in
western Canada, will be just north of Minnesota Sunday night and
Monday morning, where there could be some showers and storms near or
just north of the front. The Northland will already be in the
breezy, warm southerly flow (well south of the warm front) on
Monday. The 850 hpa temperatures will likely build to around 14 to
17 degrees Celsius, but the GFS is even warmer with 15 to 20
degrees. Sunshine and the southerly breeze should promote
considerable heating, so nudged the forecast towards the warmest
model guidance, with highs forecast to reach the lower 80s (save for
the North Shore due to the southerly flow, which should only see

A strong southwesterly low level jet will develop Monday night as
the warm air continues to build into the region and as low pressure
develops in the northern High Plains. Most of the models are dry, or
nearly dry, for Monday night, but the GFS is indicating some
elevated convection for the night into early Tuesday, so have some
low pcpn chances in the forecast. The surface southerly breeze, and
any cloud cover, will bolster the overnight lows. Leaned on the
warmer model guidance, such as the ECMWF, for lows, with a forecast
in the lower 60s.

Tuesday is expected to be the culmination of the warming trend. The
South-southwest flow aloft will advect 850 hpa temperatures of 18 to
22 degrees celsius over the Northland. A cap from the warm air aloft
will likely suppress convection and cloud cover, and since
temperatures will already start relatively warm Tuesday morning,
suspect the warmer model guidance is on the right track. It should
be a gusty day (20 to 25 mph, at least) as a low and its cold front
move east across the Dakotas. The highs will likely build well into
the 80s, especially across the western forecast area. Used a blend
with a weighting towards the GFS, which appears to be the warmest of
the available guidance. Forecast is for low 80s across the eastern
forecast area, ranging to the upper 80s across central to northern
central Minnesota, where the humidity will result in heat indices in
the 90s.

A potent upper level low over south central Canada, which will be
associated with the approaching surface low in the Dakotas, will
begin to catch up with the surface low Tuesday night. The Northland
will experience increasing upper level support for convection
Tuesday night due to the falling heights from the approach upper
low, as well support from the trough/cold front moving into the
Northland from the west. There is a good chance of elevated
overnight convection, tapping into the warm and humid southerly low
level jet. The GFS indicates there could be up to a few thousand
J/kg of most unstable CAPE overnight, but deep layer wind shear
looks fairly weak until behind the cold front. Therefore,
thunderstorms are probable overnight, but the threat of severe
weather is limited by the trailing wind shear. The precipitable
water values around 1.5 to 1.75 inches will promote brief heavy rain.

Much cooler weather will build into the Northland Wednesday and
Wednesday night in the wake of the passing front, with high
temperatures dropping to the 60s for Thursday. There could be
showers Wednesday and Thursday as the upper level low/trough moves
through the region.

High pressure and sunnier skies will return Friday. Highs should
rebound to the lower 70s


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1225 AM CDT Sun Aug 21 2016

Stratus is lingering over KHYR and is close to KDLH and KHIB. This
is expected to continue to slide east over the next few hours.
KHYR, KBRD, KHIB and KDLH, having had a fairly significant amount
of rainfall in the last 24 hours is likely to develop fog
overnight, with LIFR visibilities expected. KINL will remain mainly
MVFR, though some temporary lower visibilities are possible.
Conditions to return to VFR after 13z, which continues then until
the end of the TAF period.


DLH  53  81  63  84 /   0   0  10  10
INL  52  84  61  87 /  20  10   0  10
BRD  55  84  65  88 /   0   0  20  10
HYR  49  81  63  84 /   0  10  20  10
ASX  52  84  64  87 /   0  10  20   0


.DLH Watches/Warnings/Advisories...
LS...Small Craft Advisory until 10 AM CDT this morning for LSZ121-146-

     Small Craft Advisory until 4 PM CDT this afternoon for LSZ148.



LONG TERM...Grochocinski
AVIATION...LE is the U.S. government's official web portal to all federal, state and local government web resources and services.