Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211733
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1233 PM CDT Thu Sep 21 2017

.UPDATE...
Issued at 1233 PM CDT Thu Sep 21 2017

Updated for the new 18Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Friday)
Issued at 407 AM CDT Thu Sep 21 2017

A quiet day is on tap with high pressure over the Northland.
Temperatures will start cool across the area, but as the ridge
axis pushes east of the area, southerly return flow will bring
much warmer air by late this afternoon. Strong warm advection in
the 925 to 850 mb layer, along with increasing moisture profiles,
should bring a few more clouds into the picture by late this
afternoon into this evening. Several of the high resolution CAMs
feature showers or thunderstorms moving into the southern CWA this
evening. Think that approach is plausible so have continued a
broad-brushed chance of showers and thunderstorms spreading
northward with time tonight. Showers and storms may intensify as
the nocturnal LLJ strengthens late tonight. There are questions as
to how far north the LLJ will push with some models producing
strong convection in Ontario, while other guidance farther south.
Continued the increase in probabilities overnight with the concept
of one or two lines of storms moving through the area. Increased
POPs for Friday morning as the showers/storms exit the area to the
northeast.

Strong warm air advection will continue on Friday leading to
near- record high temperatures for much of the Northland.
Afternoon temperatures from the upper 80s to near 90 degrees are
possible over northwest Wisconsin and much of central and east-
central Minnesota with middle 70s along the International Border.
The warmth will recharge the atmosphere after the early morning
convection and instability will increase through the afternoon.
The chance of thunderstorms returns to the picture late in the day
over far northern Minnesota, along the International Border.

.LONG TERM...(Friday night through Wednesday)
Issued at 407 AM CDT Thu Sep 21 2017

A wet period is in store for much of the Northland Friday night
into early next week. Portions of the Northland will also see
temperatures much above normal Saturday into Monday.

A longwave trough over the western CONUS early in the period will
only make slow progress east into Monday with a moist southerly
flow through a deep layer over the region. Plenty of moisture will
move into the area with PWAT values forecast between 1.5 inches
and 1.7 inches by Saturday. These values are near all time highs
recorded at KINL. A frontal boundary will move slowly east and
south over the Northland Friday night and remain over or near the
region into early next week. Showers and storms will occur as a
result of the front, plentiful moisture, and several shortwaves
moving through in the southerly flow aloft. The chance for rain
will be highest over north/northeast Minnesota Friday night
through Monday with chances decreasing into northern Wisconsin.
There will be a few opportunities for heavy rainfall through
Sunday night and there will be growing concerns for some flooding.
In addition to the heavy rain threat will be chances for severe
storms into Friday night, mainly over our Minnesota zones.

Temperatures will be well above normal Saturday into Monday,
especially over northwest Wisconsin where highs Saturday will be
into the eighties. Far north central Minnesota will see cooler
highs under more clouds and higher chances for rain.

As the upper trough moves further east Monday into mid week, the
low and surface front will shift further north and east gradually
lessening the chance for rain by Tuesday and into Wednesday.
Temperatures will also cool quite a bit during this time.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1233 PM CDT Thu Sep 21 2017

Northeast MN and northwest WI might have widespread sunny skies
and warm, breezy southeast flow as of early this afternoon.
However, a strong low-level jet stream will develop this evening
as low pressure approaches the region from the west. This jet
will develop showers and storms across the region and bringing
deepening low-level humidity, which will translate to lower
ceilings. Strong and cooler flow from Lake Superior may actually
result in lower ceilings and visibility at KDLH and areas near the
Lake first. Expect a transition to widespread IFR to LIFR
conditions by early Friday. Some of the storms overnight could be
strong to severe. The strong jet will result in periods of
significant low-level wind shear. Ceiling and visibilities
will slowly improve Friday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  67  59  81  65 /   0  60  50  50
INL  73  58  75  60 /   0  40  50  70
BRD  74  66  87  64 /  10  60  20  50
HYR  77  67  89  68 /  10  60  60  30
ASX  71  62  90  66 /   0  60  60  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement until 8 PM CDT this evening for WIZ001.

MN...Beach Hazards Statement until 8 PM CDT this evening for MNZ037.

LS...Small Craft Advisory until 10 PM CDT this evening for LSZ146-147.

     Small Craft Advisory until 5 AM CDT Friday for LSZ142>145.

     Small Craft Advisory from 4 PM this afternoon to 5 AM CDT Friday
     for LSZ140-141.

     Small Craft Advisory from 4 PM this afternoon to 10 PM CDT this
     evening for LSZ121-148.

&&

$$

UPDATE...Grochocinski
SHORT TERM...Huyck
LONG TERM...Melde
AVIATION...Grochocinski


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