Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 261954
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
254 PM CDT Thu Apr 26 2018

.SHORT TERM...(This evening through Friday)
Issued at 229 PM CDT Thu Apr 26 2018

With the ongoing event in Superior, Wisconsin, main concern for
tonight will be the winds for the dispersion of smoke. Northeast
winds 10 to 15 mph becoming light and variable after sunset. Winds becoming
southwest around 5 mph after midnight. Winds will shift to the
west around 8 AM, then north by late morning, winds 10 mph gusting
to 17 mph. Winds in the afternoon will switch out of the
northeast at 10 mph, gusting to 15 mph.

A very short break from the clouds and precipitation will occur
this evening before a more potent shortwave trough will quickly
dive southward from Manitoba Canada overnight. This shortwave
looks to have better lift associated with it, per the Thaler QG
omega progs. Deeper moisture will persist for longer with this
shortwave compared to the one for this morning, so precipitation
efficiency will be more robust with this second wave. The thermal
profiles indicate a mix of precip types, primarily a mix of rain
and snow due to 925 mb low-level temperatures dipping to near zero
degrees. The best chances of snow accumulation will be over the
Minnesota Arrowhead and points southeast into northwest Wisconsin.
Forecast snow accumulation through Friday morning will be light,
with only up to one inch possible, which is consistent with the
SREF ensemble mean values in these areas, although these values
may even be too high still due to above freezing surface
temperatures per MNDot RWIS stations. Some lingering PVA and low-
level saturation will linger some chances of precipitation into
Friday afternoon, when precipitation types will be in the form of
rain. There may even be a rumble of thunder in northwest Wisconsin
due to increased instability due to steepening low-level lapse
rates. MUCAPE values are generally around 50 J/kg, so only put in
a slight chance of thunder in the forecast.

.LONG TERM...(Friday night through Thursday)
Issued at 229 PM CDT Thu Apr 26 2018

A mild and dry weekend followed by numerous chances for rainfall and
even a few thunderstorms next week. Sunny with highs in the 50s to
near 60 on Saturday, 60s to near 70 Sunday. It will also be very dry
through the weekend with relative humidity values falling to 20 to
30 percent on Saturday, though lack of much wind with the high
pressure nearly centered over the region will mitigate a fire
weather risk, but on Sunday stronger southerly winds combined with
again low relative humidity values could lead to a higher risk for
fires to spread easily. These drier conditions also mean that while
the days will be warm, lows on Friday night and Saturday night will
be on the chilly side in the 20s to near 30 Friday night, mid 20s to
mid 30s on Saturday night. Increasing clouds Sunday night into
Monday with an increasing chance for precipitation (all rain)
through Monday and Tuesday, with a chance for a few storms Monday
evening into Tuesday.

On the synoptic scale a broad mid/upper level longwave ridge will
build from the Rockies into the Midwest through the weekend, with an
upper low/mid-level longwave trough then deepening across the
western states late in the weekend. At low levels a broad area of
high pressure will build across the Upper Great Lakes/Upper Midwest
on Saturday, gradually building to the southeast towards the work
week. As the surface high builds east of the Northland,
south/southwesterly flow at low levels will result in warm and moist
air advecting into the region at low levels. An broad warm frontal
zone tracks across the Upper Midwest Monday into Monday night which
could result in showers and even a few thunderstorms. The best
chance for widespread precipitation and thunderstorms will be on
Tuesday when the Northland will be within the warm sector ahead of a
cold front and there will be decent elevated instability in place.
The cold front will track from north to south of out Canada into the
Upper Great Lakes on Tuesday into Tuesday evening which could result
in showers and storms, with guidance currently depicting the best
conditions for precip north and west of the Iron Range. In addition
to the precip, confidence is high in very strong south-southwest
winds ahead of the cold front on Tuesday with gusts perhaps
approaching 45 mph for areas south of Highway 2 in east-central MN.
Beyond the cold front temperatures a cooler northwest flow pattern
settles in for the rest of the work week, resulting in temps falling
back to near-normal values.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1253 PM CDT Thu Apr 26 2018

VFR conditions will prevail through the day. Northwest wind 10 to
15 knots with gusts to 20-25 knots through the afternoon,
diminishing tonight. MVFR ceilings increase from south to north
across northeast Minnesota late tonight into Friday as a light
rain/snow mix develops, impacting INL/HIB and possibly DLH. A
brief period of low level wind shear is expected at BRD late
tonight between around 09z and 11z.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  34  51  28  51 /  40  30  20   0
INL  33  46  25  57 /  40  30  10   0
BRD  38  53  30  58 /  10  10   0   0
HYR  31  53  24  52 /  40  40  10   0
ASX  30  51  26  48 /  50  50  10   0

&&

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

$$

SHORT TERM...LE/WM
LONG TERM...JJM/Stewart
AVIATION...JJM


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