Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 092230
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
530 PM CDT Thu Apr 9 2020

.UPDATE...
Issued at 525 PM CDT Thu Apr 9 2020

Updated Marine for recent ship observation.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 342 PM CDT Thu Apr 9 2020

Steep low level lapse rates aligned with moisture resulting in
CAPE in the dendritic growth zone have been the primary cause of
the erratic weather today and copious number of snow showers. A
lot of cellular convection has spawned from this combination and
the added rotational energy from an upper level trough sagging
southward has contributed as well. In addition to the steep lapse
rates causing convection and eventually snowfall, they are also
contributing to the gusty winds with deep layer mixing - though
the moderate surface pressure gradient hasn`t helped this cause
either. Luckily, winds aloft aren`t too strong. The NAM suggests
at least some activity looks to continue over the MN Arrowhead
into this evening, so have left higher PoPs there and in our NC WI
counties.

Models move these steep lapse rates off to the east by late
tonight which should put an end to the shower activity as high
pressure moves overhead. This should keep the weather quiet
through Friday night.

.LONG TERM...(Saturday through Thursday)
Issued at 342 PM CDT Thu Apr 9 2020

A large system will impact the Midwest during the Sunday-Monday
timeframe with chances for accumulating snow for parts of the
region. Otherwise, the remainder of the extended will be generally
quiet and cool.

A surface cold front will work through the Northland for Saturday
and may bring a few light showers before the front washes out over
northwest Wisconsin. However, with weak forcing in place, have
continued to keep a dry forecast in place. Highs Saturday will reach
into the 40s to middle 50s before cooler air moves into the region
Saturday night in the wake of the front.

The next system will begin to take shape Saturday night with low
pressure developing in eastern Colorado as a longwave trough moves
through the Rockies. A warm front will then set up along a
temperature gradient extending from the Central Plains into the
western Great Lakes. Gulf moisture will be drawn northward ahead of
this low Sunday as the low moves to the northeast. Models track this
low into Iowa Sunday morning then near Lake Michigan Sunday night
and into northern lower Michigan on Monday. While this track keeps
the bulk of the system to our south and east, some snow showers will
be possible, especially across northwest Wisconsin. The best chance
for any accumulating snow currently will be across Iron and Price
Counties Sunday night into Monday. However, with daytime highs in
the 40s and lows in the 20s, expecting rain during the day with snow
overnight. All areas look to be breezy as the low will deepen and
set up a tight gradient across the region for Sunday and Monday.
Snow showers may then linger into Tuesday as a secondary upper
trough rotates through the region. Highs Sunday will reach into the
upper 30s and lower 40s with readings Monday and Tuesday in the 30s.
Weak high pressure will move through on Wednesday before another
system approaches for Thursday per the GFS while the ECMWF and GEM
remain dry. Temperatures then start to warm by Thursday with highs
in the 40s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1246 PM CDT Thu Apr 9 2020

A mix of VFR and MVFR conditions are currently in place across the
terminals this afternoon as low pressure spins to our northwest
and brings scattered rain and snow showers to the region. These
showers will remain possible through early evening before the loss
of daytime heating brings an end to them. Brief visibility
reductions to MVFR or even IFR will be possible with the stronger
showers. Confidence is low on reaching IFR visibilities based on
current radar trends, so have only gone MVFR at BRD and
HYR. Ceilings will remain a mix of MVFR and VFR into this evening
before becoming all VFR overnight as high pressure begins to build
in. Gusty northwest winds will remain possible through sunset as
well with gusts to 20 to 30 knots possible at times.


&&

.MARINE...
Issued at 525 PM CDT Thu Apr 9 2020

At 450 CDT a ship near Taconite Harbor reported sustained
northwest winds at 34 knots. Wind speeds along the North Shore
near Taconite Harbor have been increased to account for this
observation.

Gusty northwest winds will slowly diminish overnight, lasting
longest along the South Shore. Gusts to 20 to 30 knots will be
possible, mainly this evening and highest along the Bayfield
Peninsula. Waves of 2 to 4 feet will be possible this evening
along the northern Bayfield Peninsula as well. Small Craft
Advisories remain in effect into tonight across all the nearshore
waters of western Lake Superior. Winds Friday will be
northwesterly in the morning at 5 to 15 knots and slowly turn
southerly through the day and diminish to 5 to 10 knots. Waves
Friday will be around 2 feet or less. Winds Saturday morning will
be southeasterly as high pressure passes to the southeast and then
become northwesterly as a cold front moves through. Wind speeds
will be around 5 to 15 knots through the day with waves around a
foot or less.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  24  46  30  50 /  10   0   0  10
INL  19  48  28  45 /  10  10  10  10
BRD  24  49  31  51 /   0   0   0  10
HYR  25  48  31  55 /  10   0   0  10
ASX  27  46  31  53 /  30   0   0  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 AM CDT Friday for LSZ121-146>148.

     Small Craft Advisory until midnight CDT tonight for LSZ140>145.

&&

$$

UPDATE...KL
SHORT TERM...Wolfe
LONG TERM...BJH
AVIATION...BJH
MARINE...BJH


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