Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 180824
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
324 AM CDT Tue Jul 18 2017

.SHORT TERM...(Today through Wednesday)
Issued at 320 AM CDT Tue Jul 18 2017

As of early this morning, there was a surface cool front
stretching from a low over Hudson Bay down through north-central
and northwest Minnesota, and through the Dakotas to a low in
central South Dakota. Surface high pressure was lee of the Rocky
Mountains in Canada and extending down to the border area between
North Dakota and Canada. There were some thunderstorms near the
cool front near the Bigfork area of north-central Minnesota.

Showers and thunderstorms will be possible this morning, primarily
near the cool front, as the front steadily works its way south and
east through the Northland. Some models are also suggesting there
may be some overnight convection along an elevated stationary
front farther south, generally from the Brainerd Lakes region to
the Twin Ports and far northern Wisconsin. The 20 to 30 knots
within the low-level jet may be just enough forcing up against
this elevated front to trigger those storms. Also, complicating
matters for precipitation chances this morning are the subtle
nature of shortwaves moving through the region. Hard to detect
waves may be able to trigger some showers and storms. In summary,
the precipitation chances, while low, are a bit liberally spread
across much of the forecast area this morning.

A warm day will develop with highs reaching the upper 70s and low
80s. The front will work its way into northwest Wisconsin this
afternoon, and a more prominent shortwave trough will move in from
the west. The extra forcing from this wave, combined with
destabilization from daytime heating along and near the cool
front, will likely develop showers and thunderstorms from east-
central Minnesota through northwest Wisconsin during the afternoon
through evening. The environment will likely feature 1000 to 2000
J/kg of mixed layer CAPE, 25 to 35 knots 0-6km deep layer wind
shear, and precipitable water values of 1.5 to nearly 2 inches
across the southeast forecast area, especially areas of Pine,
Sawyer, and Iron Counties. This environment will support
multicellular thunderstorm development, but perhaps some
supercellular storms. The more organized cells will be capable of
large hail and damaging winds, and all the storms are capable of
heavy downpours of rain. Some areas in northwest Wisconsin could
get ponding of water from training storms.

The front and storms will exit to the south of the forecast area
by late this evening, and the high pressure will build into the
Northland. Expect a clear, calm, and cool night. Overnight will
mostly be in the low to middle 50s, but northern Minnesota could
get some upper 40s.

The high pressure will shift east of the Northland Wednesday
afternoon, and it will help to maintain a fairly sunny day across
the Northland for much of Wednesday. Some models are indicating
showers and storms developing in the Dakotas and western Minnesota
during the afternoon, which might affect areas just west of the
Brainerd Lakes by the very late afternoon. Highs will be in the
upper 70s and lower 80s.

.LONG TERM...(Wednesday night through Monday)
Issued at 320 AM CDT Tue Jul 18 2017

A west-northwest upper level flow will be over the region to
start the period with a thermal gradient and pool of higher CAPE
and PWAT values located just south of our CWA. A shortwave will be
moving through the fast flow aloft and showers/storms will be
possible Wednesday night over mainly the south half of the CWA
including all of northwest Wisconsin. The showers/storms will end
for most areas Thursday and highs are expected in the eighties for
most areas.

A chance for more showers and storms will occur late Thursday
night into Friday over portions of the Northland as additional
shortwaves will continue to move through the quasi-zonal flow
aloft. Highs Friday will range from the upper seventies to lower
eighties for most areas.

A stronger upper trough will move southeast toward the Northland
late Friday night and will slow continuing to affect parts of the
region into Sunday. A surface low will develop ahead of the wave
and draw higher moisture north. Storm coverage will be at a
minimum Friday evening but is expected to increase later Friday
night as the upper wave continues east-southeast and the low level
boundaries move into the Red River Valley to western Minnesota
area by 12Z Saturday. Storms will continue to develop and move
across the Northland Saturday diminishing Saturday night. Some
strong storms will be possible Friday night into Saturday. Expect
highs Saturday in the lower to middle seventies over far northern
areas to upper seventies to lower eighties from the Brainerd Lakes
into northwest Wisconsin.

Showers/storms will linger into Sunday over mainly northeast
Minnesota into northern Wisconsin, then high pressure will bring a
dry period into early next week. Highs Sunday will be cooler in
the upper sixties over the Arrowhead to the seventies elsewhere.
Monday`s highs will be in the seventies as well.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1205 AM CDT Tue Jul 18 2017

Early this morning a cold front was over northwestern MN. Showers
and perhaps a few storms are possible overnight and Tuesday ahead
of the front. The front should be entering northwest Wisconsin by
noon tomorrow. The heaviest storms are expected Tuesday afternoon
along and ahead of the front.

In the meantime, there will be periodic light fog at the
terminals tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  79  56  80  59 /  30  10   0  20
INL  79  51  79  56 /   0   0   0  10
BRD  79  55  82  62 /  30   0  10  40
HYR  81  54  84  61 /  70  20   0  50
ASX  82  56  83  59 /  50  10   0  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...Grochocinski
LONG TERM...Melde
AVIATION...CLC



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