Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 271702 AAB

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1202 PM CDT SAT AUG 27 2016

Issued at 1202 pm CDT Sat Aug 27 2016

Rather significant upper level trof axis continues to approach the
region late this morning, with two lobes of forcing for ascent
evident in WV satellite imagery. The initial lobe continues to
translate northeastward across east central MN and northwest WI,
producing an area of light to moderate rain. Meanwhile, the
secondary area of forced ascent, associated with the deepening mid
level trof axis, is now moving into northwest MN, and is
associated with a persistent area of showers/TStorms.

The upper trof is forecast by all available short range guidance
to move steadily eastward across northern Minnesota through this
evening, and areal coverage of TStorms is expected to increase
rapidly over the next several hours. While the severe threat
appears to be rather low overall, there is a narrow axis of better
destabilization extending across the western sections of the DLH
CWA, and with 40-50 knots of deep layer shear, a couple of strong
or marginally severe storms cannot be entirely ruled out through
this evening as the lobe of strongest forcing moves across the


.SHORT TERM...(Today through Sunday)
Issued at 353 AM CDT Sat Aug 27 2016

An upper level trof was moving into the western Dakotas at 08Z with
embedded pieces of energy cruising through the western Great Lakes.
The southwest flow aloft is helping to raise the amount of
moisture/cloud cover into the forecast area. This is resulting in
some high based showers/sprinkles attempting to dot the landscape
this morning. Meanwhile, surface high pressure was centered over
northeast Wisconsin with a ridge axis over the area.

The upper trof will reach western Minnesota by 00Z/7pm with those
pieces of energy lifting northeastward through the area on the
southwest flow aloft. Meanwhile, the surface high remains nearby.
Will see the opportunity for showers increase this morning, with
some thunderstorms possible in the afternoon. The bulk of the rain
will fall over northeast Minnesota where the best source of moisture
is located, as well as better forcing. Northwest Wisconsin will be
dry for most of the day after the early morning showers.

The upper trof moves through northern Minnesota this evening and
lifts into Ontario later tonight. Have the highest pops over the
northern third of the forecast area this evening as the trof crosses
overhead. Lower pops farther south and into northwest Wisconsin. As
the upper trof reaches Ontario, the forcing remains ahead of the
trof and in the immediate vicinity. The moisture diminishes through
the evening with the surface high still nearby. Have some small pops
right along the Canadian border for any lingering showers.

On Sunday, upper level ridging begins to build across the region
with the surface high in the vicinity. However, the models are
allowing for a small vorticity maximum to scoot through the area as
the upper flow becomes westerly. There is just enough instability to
warrant a mention of thunderstorms in the afternoon over the
southern half of the forecast area.

.LONG TERM...(Sunday night through Friday)
Issued at 353 AM CDT Sat Aug 27 2016

Seasonable to slightly warmer than usual temperatures as August
comes to an end with a chance for showers and storms early in the
week...dry mid-week...then chances for precipitation returning late-
week into the weekend.

Sunday night into Monday a warm front lifting into the Northland
will result in a chance for showers and storms, with chances coming
to an end as a cold front moves through from west to east Monday
night. With an upper high to the southeast and a mid-level shortwave
trough approaching from the west, moderate warm air advection Sunday
into Sunday night will aid in the large-scale forcing for Sunday
afternoon/evening convection, but the real driver for widespread
precipitation will likely be a strong low level jet that ramps up
overnight aiding in sustained convection. Elevated instability will
be on the order of 1500-3000 j/kg, and while deep layer shear could
be only 20-30 knots due to weaker mid and upper level winds, the low
level jet combined with the moderate to potentially extreme
instability through a deep column could produce some strong storms.
This is evident especially in the GFS which has an odd donut of
omega around a convective complex it develops Sunday night. Last
few runs of the NAM are not as aggressive with the convective
development, but it seems if the steep mid level lapse
rates/elevated instability can advect this far north combined with
the warm front, any storms that develop could be strong to severe.

Ahead of the cold front Monday highs will reach the low 80s, likely
the warmest day of the forecast period, with dew point values
approaching 70. Cold front moves through Monday night leading to
clearing skies. Sunny skies Tuesday/Wednesday then mostly sunny
Thursday as a broad area of high pressure builds across the upper
Midwest in response to a mid-level longwave ridge across Canadian
Prairie building eastward. Highs in the 70s through the mid-week.

This ridge axis crosses the Northland Friday morning with clouds
increasing due to increasing low/mid level moisture and warmer air
moving in from the southwest at low/mid levels. Chance for showers
and storms increases Friday, with the better chance for precipitation
on Saturday as a warm front builds into the region from the west.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 636 AM CDT Sat Aug 27 2016

VFR conditions will persist through the TAF period with occasional
rain showers through the day. In the afternoon a few thunderstorms
are possible at BRD...HIB...and INL...which could produce heavy
rain rates that briefly lower visibility to MVFR or worse. This
evening skies gradually clear from west to east with fog
developing...potentially reducing visibility to a mile or less at
some sites. Winds light out of the south-southeast today...near
calm tonight.


DLH  69  55  75  61 /  60  60  30  50
INL  68  53  77  61 /  80  60  20  60
BRD  71  57  80  66 /  70  60  30  30
HYR  72  57  79  63 /  60  30  30  40
ASX  72  58  77  63 /  30  40  20  30


.DLH Watches/Warnings/Advisories...

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