Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 242033

Area Forecast Discussion
National Weather Service Duluth MN
333 PM CDT Wed May 24 2017

.SHORT TERM...(This evening through Thursday)
Issued at 333 PM CDT Wed May 24 2017

A ridge of high pressure covers the forecast area at 19Z. However,
plenty of cloud cover was found over the area as well thanks to some
700-400mb differential vorticity advection over the region. Some
clearing has occurred along the north shore of Lake Superior from
BFW to Grand Portage. Some sprinkles are possible late this
afternoon across north central Wisconsin as the aforementioned
vorticity moves over this area.

The ridging remains over the region tonight. Expect some fog to form
this evening in northwest Wisconsin and then spread into northeast
Minnesota later tonight. Of the current cloud cover, some
dissipation is forecast this evening. However, there will be enough
clouds expected to linger over the region to keep the temps up a bit

On Thursday, the ridging will be in the vicinity on the eastern
third of the forecast area in the morning and expect no
precipitation. Some minor model differences begin to show up in the
afternoon with regards to the onset of the rain, and departure of
the ridge. GFS/ARW/NAM are driest, ECMWF wettest, and NAM between.
Used a blend for pops and timing of the onset of the rain in the

.LONG TERM...(Thursday night through Wednesday)
Issued at 333 PM CDT Wed May 24 2017

Initially in the extended a low amplitude ridge will build from the
Upper Midwest Thursday evening into central Great Lakes by Friday
evening. While a cutoff upper level system moves eastward across
central Canada. The cutoff will slowly move southeastward into
eastern Manitoba/western Ontario by Saturday afternoon. The
cutoff then will rotate eastward across Ontario through the
weekend and into early next week per the latest GFS/GEM/ECMWF.
Due to the cutoff, multiple shortwaves will eject into the
Northland. Expect scattered showers to linger around the region for
much of the period with occasional thunderstorms. Based on the
GFS/ECWMF and NAM expect the best chances for thunderstorms Friday
afternoon, Sunday afternoon and Monday afternoon as there is a few
hundred to 1000 joules of MUCAPE coupled with strong shortwaves
moving through. Cannot completely rule out a few isolated storms on
Saturday, but the forcing aloft is fairly weak in addition to only a
few hundred joules of MUCAPE to work with. Due to this, held off
from including a thunder mention on Saturday.

The next chance of dry weather comes mid to late next week with a
ridge building in from the west. There are still some discrepancies
between long range guidance, with the GFS bringing the high in much
faster than the ECMWF/GEM. More inclined to lean on the
slower ECMWF/GEM solution as the GFS tends to push out cutoff
systems too quickly.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1207 PM CDT Wed May 24 2017

Weak surface ridge to the northeast will slide away through the
period as a trough of low pressure approaches from the west. There
are currently a few showers with the more robust cu field over
mainly the northern portion of the area, so a brief shower or few
sprinkles can`t be ruled out, but ceilings have climbed into the
VFR range pretty much everywhere at this point. We will see some
warm advection associated with that feature work into the western
portion of the area toward the end of the period, with an increase
in mid/high clouds. KHIB could see a slightly lower deck toward
the tail end of the period, but still looks to be VFR. The LAMP
guidance is bullish on some low ceilings overnight for many
locations, but don`t see much in the raw output from the various
guidance to support it, and previous forecasts also didn`t buy
into the idea. So, left any mention of that out of the forecasts
for now.


DLH  39  60  46  64 /   0  20  40  40
INL  40  67  51  68 /   0  20  40  40
BRD  44  68  52  72 /   0  20  30  20
HYR  39  70  51  70 /   0  20  40  40
ASX  36  60  45  66 /   0  20  30  40




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