Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 260823

Area Forecast Discussion
National Weather Service Duluth MN
323 AM CDT Thu Apr 26 2018

.SHORT TERM...(Today through Friday)
Issued at 323 AM CDT Thu Apr 26 2018

An active weather pattern will develop over the Northland for
today and Friday, driven by a few mid-level shortwave troughs,
which will bring some measurable precipitation for tonight and
Friday. For this morning, a positively tilted mid-level trough and
an associated cold front will dive southeastward over the region.
Some decent lift will accompany the front due to enhanced low-
level FGEN and a channel of positive vorticity advection (PVA)
along the trough. However, the moisture profile is the big
question regarding precipitation. Both the NAM and RAP model
soundings indicate only a thin corridor of deeper saturation as
the cold front moves through, so the window for precipitation is
rather small. Still think that some chances of precipitation with
this front is reasonable given the lift, so made only small
adjustments to the POPs to better capture the progression of the
front. Precip type should be mostly in the form of rain, but some
snow may mix in along the International Border. Only small rain
accumulations are expected with this front, with up to 0.05"
possible. Otherwise, dry air will quickly move in behind the
front and bring clearing skies from west to east by the afternoon.
Small chances of rain will linger over portions of northwest
Wisconsin this afternoon as the front passes by. Northwest winds
will also pick up behind the cold front, with gusts between 15 to
25 mph. Highs today will range from the upper 40s over the
Minnesota Arrowhead to the middle and upper 50s elsewhere.

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 Wednesday)
Issued at 313 AM CDT Thu Apr 26 2018

The strong shortwave will continue to move southeast across the
western Great Lakes on Friday night, with precipitation generally
ending by Friday evening. Surface high pressure and upper level
ridging will then move into the region on Saturday and Sunday,
bringing much warmer temperatures and dry weather for the upcoming
weekend. This upper level ridge will then start to move eastward
across the Great Lakes on Sunday night and Monday. Southwest flow
from a broad upper level trough in the western states will begin to
send shortwave energy, and increasing moisture into the region by
Monday. As a result, we should see a chance of precipitation from
Sunday night into Wednesday of next week. A few thunderstorms will
even be possible during that time. Highs on Saturday will generally
be in the 50s, with temperatures reaching the 60s on Sunday. The
warm weather will continue on Monday and Tuesday, with highs in the
60s to lower 70s. Lows will be in the 20s across the Northland on
Friday night, but warm into the 30s to 40s for much of the remainder
of the long term period.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1225 AM CDT Thu Apr 26 2018

Water vapor imagery showed an upper level trough moving through
Manitoba late this evening. This trough and a cold front will move
into the Northland later tonight then pass through during the day
Thursday. VFR conditions were occurring this evening but some MVFR
or low VFR ceilings are expected to develop along the frontal
boundary later tonight into Thursday. Some light rain and a possible
wintry mix will be possible as the front moves through. The chance
for rain is expected to be brief, generally a 1 to 3 hour period.
Colder air behind the front may lead to cumulus development Thursday
afternoon keeping clouds around longer, perhaps even some MVFR
ceilings. The wind will turn northwest behind the front and become
gusty due to good mixing.

Another potent shortwave will dive into the area late Thursday
evening and overnight bringing a chance for rain and snow, mainly
after 06Z Friday.


DLH  55  33  47  28 /  40  40  30  10
INL  52  34  47  26 /  20  40  30  10
BRD  59  38  54  30 /  20  10  10   0
HYR  58  29  51  25 /  30  40  40  10
ASX  56  29  45  26 /  40  50  60  10




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