Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 140529

Area Forecast Discussion
National Weather Service Duluth MN
1229 AM CDT Mon Aug 14 2017

Issued at 1228 AM CDT Mon Aug 14 2017

Updated aviation section below for 06Z TAF TAF issuance.


.SHORT TERM...(This evening through Monday)
Issued at 347 PM CDT Sun Aug 13 2017

Short term concern will be chances for showers late this afternoon
through Wednesday.

Current surface analysis shows rain showers across most of the
area south of a line from Lake Winnie to the Twin ports. Most rain
amounts have been less than a tenth of an inch with around a
quarter of an inch in Cass and Crow wing counties. These showers
are associated with a surface low pressure trough moving through
the forecast area. The main batch of rain will move off to the
east this evening and the trough moves east.

A low pressure area will move into SW MN by Monday morning and
move along the surface trough. This will keep the chance for rain
showers across NW wi and from the Twin Ports to Pine City during
the day on Monday. There is some weak cape (500-700) tonight and
tomorrow so will have an isolated thunderstorm in the the grids
tonight and Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 347 PM CDT Sun Aug 13 2017

The main concern for the long range is timing several rounds of rain
and thunderstorms, and the potential for heavy rainfall Tuesday
night and Wednesday.

A relatively active week is shaping up across the long term. At the
start of the period Monday night an Omega Block will be located over
the North American continent with anchoring low pressure over
northern Quebec and the Canadian Rockies. A high-amplitude ridge
aloft will be found from the central Plains north into Nunavut.
Several shortwave troughs will ride across the southern periphery of
the block during the week bringing periodic chances of showers and
thunderstorms to the Northland. The entire blocking pattern is
forecast to drift eastward with the western upper low opening to a
progressive wave by Friday morning. The first shortwave will push
into the region Tuesday afternoon and slowly migrate northeast
across the Upper Midwest through Thursday morning. The next trough
will arrive Friday afternoon and depart on Saturday.

The first shortwave trough appears to be the strongest with the best
support. Strong poleward moisture transport will increase
precipitable water values into the 1.5 to 2 inch range by late
Tuesday night. The slow forward progress of the upper low will keep
light to moderate rainfall in the picture from Tuesday evening
through Wednesday evening. The best conditions for excessive
rainfall develop late Tuesday night through early Wednesday
afternoon. In consultation with neighbors, have decided to raise
POPs well above the consensus guidance and into the likely to
categorical range between 06Z Wednesday through 00Z Thursday.

The rain departs as the upper low exits late Wednesday night. A few
isolated showers may loiter over eastern portions of our forecast
area, from the Arrowhead to north-central Wisconsin, through
Thursday morning. The drier period will be short-lived with the next
shortwave trough approaching Thursday night. Shower chances tick
upward on Friday morning and continue into Saturday. A this
juncture, confidence in placement and timing is rather low, so have
elected to maintain the low-chance consensus POPs with this package.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1228 AM CDT Mon Aug 14 2017

An area of low pressure will continue to move eastward into the
region overnight. As it does, it will bring rain showers and
perhaps an isolated thunderstorm for the rest of the night and
into Monday. Low clouds and visibilities have been slow to develop
so far this evening, but we should continue to see further
deterioration of CIG`s and VSBY`s as the night wears on. Some MVFR
and even IFR conditions will be possible later tonight and on
Monday morning. We should then see a gradual improvement in
conditions by Monday afternoon, as the low pressure system pulls
off to the east.


DLH  54  70  53  74 /  60  30   0  10
INL  51  77  51  78 /  30  10   0  10
BRD  55  72  54  75 /  50  20   0  20
HYR  55  70  53  78 /  60  60  10  10
ASX  56  72  53  75 /  50  50  10  10




SHORT TERM...Stewart
LONG TERM...Huyck/Stewart
AVIATION...DAP is the U.S. government's official web portal to all federal, state and local government web resources and services.