Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211947
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
247 PM CDT Wed Aug 21 2019

.SHORT TERM...(This evening through Thursday night)
Issued at 242 PM CDT Wed Aug 21 2019

Mainly sunny skies and temperatures running below normal today into
Thursday. There will be some clouds in the afternoon each day and
the possibility for a stray shower on Thursday afternoon, but
generally quiet weather with winds out of the northwest 10 to 15 mph
today becoming northeast to easterly at around 5 to 10 mph on
Thursday, strongest along the lakeshore at the head of the lake.
Highs in the mid 60s to near 70 each afternoon while lows will fall
to 40s each night, with a few of the usual cold inland spots falling
into the 30s.

On the synoptic scale an amplified longwave mid/upper level ridge is
moving across the Canadian Prairie east towards the Great Lakes late
this week with an associated broad area of high pressure centered
over Manitoba today and building east into northern Ontario on
Thursday. While this would usually just signal sunny skies for the
Upper Midwest, a broad low over eastern Canada will result in a mid-
level shortwave trough axis moving across the Upper Great Lakes
which combined with some mid-level moisture and the cool air aloft
may lead to a stray shower or two on Thursday. A few lobes of
vorticity rotating around the upper low are already moving across
the region today, clearly evident on water vapor channel imagery,
but on Thursday there will also be additional low level moisture and
slightly cooler temps aloft leading to the possibility for some
isolated showers. Thunderstorms are unlikely, and any shower that
does develop will probably only produce a few hundredths of an inch
of rainfall at most. With the residual moisture in place, clearing
skies and calm winds may lead to areas of fog late Thursday night
into early Friday morning.

.LONG TERM...(Friday through Wednesday)
Issued at 242 PM CDT Wed Aug 21 2019

Seasonable temperatures through the weekend and into next week with
an increasing chance for precipitation late in the weekend into
early next week.

As the area of high pressure builds eastward over the Great Lakes
Friday into Saturday, southerly flow across the Great Plains and
Mississippi River Valley will bring warmer and somewhat richer low
level moisture into the northern Great Plains and Upper Midwest. At
the same time, a very broad longwave trough will develop across the
Canadian Rockies ino the Canadian Prairie with a series of mid-level
shortwave troughs embedded within the otherwise near zonal flow
across the international border. Widespread showers and storms will
develop across the northern Great Plains Friday afternoon and then
again Saturday afternoon within the warm sector of a developing low,
with a fairly sharp pressure gradient over Minnesota leading to
strong southerly winds developing on Saturday and Sunday as the warm
front approaches from the west. There is a low chance for some
diminishing showers and storms to track into north-central Minnesota
on Friday night, but chances are much higher Saturday night into
Sunday as a surface low begins to deepen over southern Manitoba then
track north-northeast up the Manitoba-Ontario border into early next
week. A cold front associated with this low will move across
northern Minnesota and northwest Wisconsin Monday into Monday night,
but the surface low will remain nearly stationary through mid-week,
ever so slowly tracking northeast into far northwest Ontario. This
continued cyclonic flow will result in a continued chance for
precipitation as cooler air advects into the region Tuesday and
Wednesday.

While there will be a low chance for thunderstorms throughout the
weekend into early next week, the airmass in place across the
Northland much of the time will not be particularly unstable, with
the best chance for any storms being on Sunday when the best of the
rich low level moisture moves into northeast MN and northwest
Wisconsin, though limited deep layer shear (around 15 to 25 knots)
due to somewhat weak winds at mid to upper levels will limit the
number of organized storms. The good news is that this pattern
should support a healthy amount of rainfall late-weekend into early
next week - around one to two inches of rainfall is anticipated for
much of the Northland over the weekend and into the middle of next
week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1239 PM CDT Wed Aug 21 2019

VFR conditions will prevail at most sites through the TAF period,
except for INL and HIB where MVFR ceilings are expected beginning
early Thursday morning and lasting into the early afternoon. Winds
out of the northwest today 10-12 knots gusting as high as 20 knots
at times will weaken this evening to become nearly calm, then
become north-northeasterly at around 5 to 10 knots on Thursday.


&&

.MARINE...
Issued at 247 PM CDT Wed Aug 21 2019

No hazardous marine conditions expected through Friday. North wind
5 to 10 knots tonight becoming northeasterly on Friday, with winds
as strong as 10 to 15 knots with gusts approaching 20 knots at
the head of the lake (Two Harbors to Duluth and Duluth to Port
Wing) on Friday. Winds weaken Friday night to around 5 knots out
of the east, then increase to around 5 to 10 knots out of the east
on Friday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  49  66  46  69 /   0   0   0   0
INL  44  65  43  73 /  10  10   0   0
BRD  47  69  47  74 /   0   0   0   0
HYR  47  68  43  73 /   0   0   0   0
ASX  50  67  47  71 /  10  10   0   0

&&

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

$$

SHORT TERM...JJM
LONG TERM...JJM
AVIATION...JJM
MARINE...JJM


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