FXUS63 KDLH 240807
Area Forecast Discussion
National Weather Service Duluth MN
307 AM CDT Tue Oct 24 2017
.SHORT TERM...(Today through Wednesday)
Issued at 307 AM CDT Tue Oct 24 2017
The surface low center over northern lower Michigan continues to
deepen early this morning. This has resulted in a tight pressure
gradient over the forecast area. Gusty winds prevailed everywhere.
Plenty of clouds covered the region, but some clearing looks to be
arriving over the far western edge of the forecast area. However,
there are more clouds upstream in Canada that appear to be on the
move toward the region. Cold air advection underway and combining
with embedded impulses dropping south through the area on the
northerly flow aloft to generate some showers/sprinkles, mainly east
of U.S. Highway 53 in Minnesota and Wisconsin. Surface temps are all
above freezing, but some very light snow showers being reported in
Ontario at Dryden and Sioux Lookout. Will keep the mixed precipitation
wording through the morning. The surface low slowly moves northward
through the day, but the pressure gradient over the region relaxes
and the cold air advection ends by late morning, then warm air
advection begins in the afternoon. The winds will diminish in the
afternoon. Any snow that falls will not accumulate today. Max temps
today in the upper 30s over the Arrowhead with 40s elsewhere.
A brief break in the precipitation occurs in the early evening as the
Michigan low departs and allows a ridge axis to move overhead. By
06Z Wednesday, a potent short wave trof digs into the region and
moves across the Northland overnight. Its associated surface low
will quickly cross the area as well. This clipper will drop a quick
burst of mixed precipitation over much of the region. Only the
Brainerd Lakes region north to Cass Lake appear to miss out on this
round. We could see a couple tenths of an inch of snow overnight,
along and east of U.S. Highway 53.
The clipper departs by noon on Wednesday as upper level and surface
ridging build into the area. Some light mixed precipitation is
possible over the eastern Wisconsin forecast area in the morning
before ending. No snow accumulations are expected and rainfall
amounts will be light. Max temps will be warmer than Tuesday, with
40s and 50s expected.
.LONG TERM...(Wednesday night through Monday)
Issued at 307 AM CDT Tue Oct 24 2017
The focus in the extended period continues to be on a low pressure
system that will bring rain or snow to the Northland as early as
Wednesday night but more so Thursday into Friday.
The models are in fair agreement on the overall trend but still
differ enough to keep confidence lower than average on snowfall
amounts. An upper trough with stronger shortwave will move into the
Northern Plains Wednesday night with a surface low centered near the
MN/ND/MB border region at 12Z Thursday. Low level temperatures will
be will warmer ahead of the low with 850MB temperatures remaining or
warming to at or above 0C Wednesday night into Thursday morning. Low
level temperatures will cool through the day due to evaporative and
dynamic cooling affects. A mix, or at times just snow will occur
Wednesday night into Thursday morning and again later Thursday
afternoon over northern Minnesota. The low will weaken some Thursday
night as it moves east to southeast with model consensus having the
surface low over eastern Wisconsin by 12Z Friday. The GFS remains
most bullish on QPF amounts and we did not buy into those amounts
yet. The precipitation will switch to snow for most areas Thursday
night then become more of a mix by Friday afternoon for most areas.
Consensus also shows the precipitation diminishing over portions of
northeast Minnesota by Friday afternoon but continuing over much of
northwest Wisconsin and far eastern Minnesota. There will be lake
and terrain enhancement to the precipitation, especially along the
South Shore into Friday night. Due to uncertainty in the models,
forecast snow amounts remain challenging. A change in the track of
the low or an error of a few degrees in the low level temperature
forecast could have big impacts on expected snowfall. Given those
caveats, the best chance at a few inches of snow appears to be over
the Arrowhead and along portions of the South Shore where some lake
effects will occur.
As the low pulls away from the region Friday night, snow will
continue to be possible over northwest Wisconsin, especially in the
snowbelt region where additional accumulation is possible.
The rest of the period will feature weaker systems and a few
opportunities for light precipitation. Temperatures will be below
normal with coolest highs on Saturday.
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1220 AM CDT Tue Oct 24 2017
A strong low pressure system stalled over northern lower Michigan
will intensify over the next several hours and then move northeast
into Ontario after 21Z. This is going to produce strong north
winds across the terminals, gradually increasing to maxima between
12Z and 18Z for most sites, with gusts in the 25 to 30 knot
range. Winds should diminish significantly in the 22Z-02Z time
range, with some sites even dropping below 10kts by 03Z. MVFR
stratus over most of the terminals should spread to affect even
KBRD through 11Z, with gradual improvement to VFR by 19Z.
.PRELIMINARY POINT TEMPS/POPS...
DLH 43 33 47 37 / 10 40 10 10
INL 42 31 46 34 / 10 50 10 70
BRD 46 37 52 39 / 10 10 0 10
HYR 45 32 49 35 / 60 30 10 0
ASX 45 33 48 33 / 70 30 20 10
WI...Wind Advisory from 7 AM this morning to 6 PM CDT this evening
MN...Wind Advisory until 6 PM CDT this evening for MNZ020-021-037.
Wind Advisory from 7 AM this morning to 6 PM CDT this evening
LS...Gale Warning until 10 PM CDT this evening for LSZ121-140>143-
Gale Warning until 10 AM CDT this morning for LSZ144-145.
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