Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 101736
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1236 PM CDT Thu Aug 10 2017

.UPDATE...
Issued at 1034 AM CDT Thu Aug 10 2017

Update to trim down the POPs in areal coverage as drizzle/rain
showers are mainly confined from just south of Brainerd,
northeastward over the North Shore and Arrowhead region, as well
as adjacent areas of the South Shore. Still continued high-end
POPs, with values between 60 to 100% in many locations along
these areas. Very strong northeasterly flow has prompted the
issuance of a Gale Warning over the nearshore waters from Two
Harbors, MN, southeast to the Twin Ports, and points northeast to
Sand Island, WI. Wind gusts over 35 kts and waves up to 8 feet
have been reported over the open waters of Lake Superior.

The area of low pressure causing the strong winds and rain
showers, which is currently centered over northwest Wisconsin,
will eventually move out of the region later tonight, bringing
this activity to an end. Chances of precipitation should quickly
begin to diminish later this evening and overnight.

&&

.SHORT TERM...(Today through Friday)
Issued at 400 AM CDT Thu Aug 10 2017

The main concerns for the short term are precipitation timing and
amounts today and tonight and temperatures for Friday.

Surface low pressure was centered over east-central Minnesota
early this morning with a swirl of rain showers and thunderstorms
across much of the region. The axis of an upper-level trough of
low pressure stretched from northwest Ontario into eastern South
Dakota. RAP analysis and GOES-16 water vapor imagery indicated a
vort max over west-central Minnesota. The upper trough and surface
reflection will advance eastward across northern Wisconsin and
into Upper Michigan by this evening.

Showers have redeveloped near Brainerd during the past hour, near
the approaching vort max, and rain shower coverage has increased
across much of northern Minnesota and northwest Wisconsin. Hi-
resolution CAM solutions are rather noisy this morning, but all
suggest coverage will continue to increase during the next several
hours. Leaned on a blend of the ECAM and short-term consensus for
POPs and QPF. The heaviest rainfall for the Northland seems to
have occurred from yesterday afternoon through tonight and expect
up to another tenth to one- half inch of rain. A few isolated
locales may see up to three-quarters of an inch. As the low
departs tonight, look for precipitation to wind down to isolated
showers through early Friday morning. High pressure will make a
return by late Friday. Rising heights and weak warm air advection
aloft should limit afternoon convection to cumulus field, with a
very low chance of any rain showers.

Temperatures will be quite cool today with overcast skies and
northerly winds. Winds off the lake will keep lakeshore and inland
areas southwest of Lake Superior in the low 60s. Skies will
gradually clear over Koochiching County and the northwest portion
of the forecast area this afternoon, which should boost
temperatures into the low 70s. Areas farther inland from Lake
Superior should see temps in the upper 60s. Tonight will be chilly
with lows from the upper 40s north to the middle 50s southeast,
climatologically cool locations in northern Minnesota may dip into
the middle 40s. Highs will trend a bit warmer with help from the
August sun with temperatures climbing into the upper 60s to upper
70s.

.LONG TERM...(Friday night through Wednesday)
Issued at 400 AM CDT Thu Aug 10 2017

A mean upper level trough will dominate the weather during the
first part of the long term period, starting with Friday night. By
Friday evening, an upper level shortwave will be making its way
through the central Great Lakes, resulting in a break in the
precipitation across the Northland. Surface high pressure will
build into the region Friday night, with dry weather expected to
continue across the Northland from Friday night through Saturday
night. There is somewhat of a disagreement in the long range
models regarding the weather across the area on Sunday. The ECMWF
indicates the potential for some showers across the Minnesota
Arrowhead by Sunday afternoon, with a few showers or a storm
possible from the Brainerd Lakes into east central Minnesota. The
shortwave that could bring the precipitation to the east central
Minnesota area will then drop southeast on Sunday night. Heights
will build in the Rockies on Sunday night, which will bring more
of a northerly upper level flow into the western Great Lakes
region. The models, especially the ECMWF do indicate some
instability across the Minnesota Arrowhead on Monday afternoon, so
we have added the possibility of a few thunderstorms to that
area. After several days of northwest flow, an upper level ridge
will build into the region from the Rockies by Tuesday. The ridge
will precede the next chance of showers and thunderstorms that are
expected to make their way into the Northland starting as early
as Wednesday, and continuing into Thursday of next week. High
temperatures throughout the long term period are expected to be in
the 70s, with lows ranging from the mid 40s to the mid 50s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1236 PM CDT Thu Aug 10 2017

The rain/drizzle and MVFR ceilings will gradually improve late
today with skies becoming VFR as they generally clear out from
west to east. Tonight MVFR to IFR/LIFR fog is expected to develop
at some sites, mainly at DLH, HIB, and BRD. Confidence is good
that DLH visibility will fall to LIFR levels for a period after
midnight, with less confidence at HIB/BRD. On Friday morning fog
will dissipate after sunrise resulting in VFR conditions at all
sites. North winds generally light today, except at DLH where
sporadic gusts to 15-20 knots are possible out of the northeast
due to stronger winds over western Lake Superior. Winds calm
overnight, then light out of the north again on Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  63  53  73  52 / 100  20   0   0
INL  72  49  76  49 /  20  10   0   0
BRD  69  54  74  53 / 100  20  10   0
HYR  68  55  73  49 /  90  20   0   0
ASX  64  55  72  51 /  90  30  10   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement until 9 PM CDT this evening for WIZ001.

MN...Beach Hazards Statement until 9 PM CDT this evening for MNZ037.

LS...Gale Warning until 4 PM CDT this afternoon for LSZ144>146.

     Small Craft Advisory until 10 PM CDT this evening for LSZ141>143-
     147.

     Small Craft Advisory from 4 PM this afternoon to 5 AM CDT Friday
     for LSZ121-148.

&&

$$

UPDATE...JTS
SHORT TERM...Huyck
LONG TERM...DAP
AVIATION...JJM



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