Area Forecast Discussion
Issued by NWS Duluth, MN

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964
FXUS63 KDLH 221126
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
626 AM CDT Tue Aug 22 2017

.SHORT TERM...(Today through Wednesday)
Issued at 321 AM CDT Tue Aug 22 2017

The remnants of a mid-level shortwave will move out later this
morning, which will bring a brief respite to any precipitation
chances this morning. However, as the shortwave departs to the east,
northwest flow aloft will continue, along with some weak cold air
advection. This will support chances of showers and perhaps a small
chance of a thunderstorm late this morning and through the
afternoon, mainly along the International Border and Iron Range
regions. Some of this activity may reach as far south as the Twin
Ports and South Shore regions as well as some of the convective-
allowing models (HRRR and NAMNest) are progging this solution. 850
mb temperatures will fall to the 6 to 8 degree C range, with some
decent instability possible, as MUCAPE values range from a few
hundred up to around 1000 J/kg. 850 mb wind speeds will also
increase, with values between 25 to 35 kts. NAM and RAP model
soundings both indicate some decent boundary layer mixing expected,
which will help to mix down these low-level winds. Moreover,
pressure rises from the west will enhance the sfc pressure gradient.
To account for this, I bumped up the winds a bit more from the
previous forecast package, leaning towards the MOS guidance. Wind
gusts across the Northland could increase up to 25 kts, with
possibly some isolated stronger gusts. Temperatures will be on the
cool side today, with highs ranging from the lower 30s over the tip
of the Minnesota Arrowhead, into the upper 60s and lower 70s further
inland.

Chances of showers and storms will quickly decrease this evening as
diurnal heating diminishes. As such, cloud cover should also
diminish. This, coupled with light winds, will lead to a night of
rather cool temperatures due to radiational cooling. Temperatures
over northern Minnesota could drop to as low as the lower 40s in
some spots. Due to the expected reduction in temperatures,
introduced some patchy fog to the forecast for tonight, mainly from
north-central Minnesota, southeast towards Hayward, WI. Most of the
day Wednesday looks to be dry, but cool, with highs in the mid to
upper 60s. A compact mid-level shortwave trough is progged to then
bring another round of showers to the Northland, late in the day
Wednesday.

.LONG TERM...(Wednesday night through Monday)
Issued at 319 AM CDT Tue Aug 22 2017

The Northland will be under northwest flow aloft through much of the
extended period with high temperatures mostly below normal. There
will be a few opportunities for mainly showers as several shortwaves
move through the region.

A shortwave will move through the region Wednesday night and combine
with low-mid level FGEN to cause a chance for showers during the
evening from the Walker area to the Twin Ports to Hayward and points
south. As those features exit late Wednesday night, high pressure
will nose into the area, bringing dry conditions Thursday and
Thursday night. Mainly dry conditions will continue into Friday as
the high shifts further east. Highs Thursday and Friday will range
from the upper sixties to lower seventies.

A couple more shortwaves will affect the region over the weekend
aiding to knock down the upper ridge with a trough developing over
the region. There will be a chance for showers over the weekend into
early next week with highs Saturday from the upper sixties to lower
seventies warming slightly by Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 626 AM CDT Tue Aug 22 2017

Cyclonic upper level flow will be over the region into this
evening. Conditions varied from IFR to VFR across the Northland
early this morning. Areas of IFR ceilings were occurring from the
Arrowhead south into the Twin Ports area and into parts of
northwest Wisconsin. These ceilings will lift and move out as the
morning progresses. We do expect a cumulus field to form and it
may be MVFR initially but should rise to VFR. Ceilings will be
possible, especially over far northern Minnesota. Showers will
also develop and be most likely over far northern Minnesota.

Ceilings and the showers will dissipate tonight for most areas.
There could be some patchy fog that forms late tonight.

Gusty winds will develop today as mixing deepens through the
morning. The wind will then subside by early evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  70  49  66  47 /  10  10  10  20
INL  67  44  66  41 /  30  20  10   0
BRD  72  47  69  48 /   0   0  10  20
HYR  70  49  67  44 /  10   0   0  20
ASX  71  50  66  46 /  10  10   0  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 10 PM CDT this evening for LSZ146-147.

&&

$$

SHORT TERM...JTS
LONG TERM...Melde
AVIATION...Melde



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