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FXUS63 KDLH 112047

Area Forecast Discussion
National Weather Service Duluth MN
247 PM CST Mon Nov 11 2019

.SHORT TERM...(This evening through Tuesday night)
Issued at 239 PM CST Mon Nov 11 2019

The Lake Superior lake effect machine will continue to generate 
heavy lake effect snow over northwest Wisconsin, specifically over 
Iron county, where a Winter Storm Warning continues overnight 
tonight and into Tuesday morning. So far today, we have received 
reports of snowfall amounts ranging from 5 to 10 inches already, 
with another 3 to 11 inches possible this evening and overnight
over Iron county. The main features supporting this lake effect 
are some bitterly cold temperatures aloft, with northwesterly low-
level flow. A positively-tilted upper-level trough will gradually
track eastward this evening and overnight, with 850 mb 
temperatures ranging from the 20 to 24 degree C below 
zero...sufficiently cold over the relatively warm lake to support 
lake effect snow. These temperatures are actually around 2 to 3 
standard deviations below average for this time of the year! Very 
cold temperatures are also expected overnight, with lows in the 
single digits below zero over most of the region, which would make
tonight the coldest night so far this season. People should dress
appropriately if they plan to venture out and about tonight.

Eventually, a high pressure ridge axis will enter the region early 
Tuesday morning, which will not only bring in drier air with it, but 
also will back winds more southwesterly Tuesday morning. These 
conditions will gradually shut down the lake effect snow over north-
central Minnesota before sunrise, and along Lake Superior later in 
the morning. Southerly return flow will bring in some relatively 
warmer temperatures compared to today for Tuesday, with highs in the 
lower to middle teens. As winds turn more southerly, there could be 
a small chance for some lake effect snow along the tip of the 
Minnesota Arrowhead Tuesday afternoon and early evening. If any snow 
does develop, accumulation amounts should remain very light.

Attention then turns to another chance for light snow early 
Wednesday as a mid-level shortwave trough along with a low-level 
baroclinic zone/frontogenesis band moves across central 
Minnesota. There are some timing differences among the forecast 
model guidance, so it's unclear how quickly this snow will move 
in. In any case, it does appear to move through the region 
Wednesday morning. I have introduced some small PoPs around 12z 
Wednesday to account for the leading edge of this system.

.LONG TERM...(Wednesday through Monday)
Issued at 239 PM CST Mon Nov 11 2019

A gradual transition warming up to near-normal temperatures through 
the work week, with above normal temperatures possible for the 

Mid to late week: A low chance for light snowfall along a cold front 
Wednesday, then at least partially clearing skies into Thursday as a 
broad area of high pressure builds across the Great Plains. Late-
week another strong arctic airmass will approach from the north, but 
will be on a more easterly trajectory towards New England leading to 
increasing clouds and just a very low chance for some snow along the 
international border on Thursday night. An area of high pressure 
builds across Ontario on Friday leading to skies clearing out, with 
a more zonal pattern taking hold at mid/upper levels across much of 
the Great Plains and Canadian Prairie. Highs in the 20s to low 30s, 
with some locations reaching above freezing on Friday depending on 
when the southerly flow develops at low levels as the area of high 
pressure moves off to the east. Lows in the teens - warmer than 
early week but still around ten degrees below normal.

Next weekend: As the high pressure builds eastward, southerly flow 
develops at low levels across the Mississippi River Valley causing a 
warm front to approach the Upper Midwest Friday night into Saturday. 
Initially this warm front will just lead to increasing clouds and 
warmer temps, with a chance for light precipitation developing 
within the warm sector on Saturday. However, a better chance for 
accumulating snow Saturday night as a cold front approaches from the 
northwest. Snowfall amounts in the 1-3 inch range are most likely - 
while there will be fairly good large-scale forcing from an 
approaching mid-level longwave trough and good potential for low 
level moisture from the Gulf advecting in ahead of the cold front, 
the timing for snow falling will be along a fairly short window, and 
the potential for heavy snowfall rates is low. Temperatures will be 
warmer, even a few degrees above normal at times, with highs in the 
mid 30s and potential for some locations to warm up to the low 40s 
on Sunday/Monday. Lows in the mid to upper 20s. 

Beyond next weekend there is typical variability across guidance, 
with occasional chance for snow through the week and temperatures 
currently leaning towards near to perhaps above normal.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1145 AM CST Mon Nov 11 2019

A mix of MVFR and VFR conditions today due to stratus clouds and
lake effect snow from both Lake Superior and many inland lakes
that remain open. Snow is most likely at HIB with periods of IFR
visibility possible in more intense snow bands, but overall
conditions are most likely to MVFR through this afternoon. INL,
DLH, and HYR will also likely see periods of MVFR ceilings this
afternoon with occasional light snow chances. Clouds clear out
this evening from west to east with clear skies expected through
early Tuesday afternoon. Winds will be out of the northwest
gusting as strong as around 20 knots this afternoon, then becoming
weak and variable tonight at around 5 knots or less. Southerly
winds develop on Tuesday morning, but should only be around 5 to
10 knots.


Issued at 239 PM CST Mon Nov 11 2019

Northwest winds 15 to 20 knots gusting to around 25 knots will 
persist through tonight across parts of western Lake Superior, with 
a brief period of even stronger winds possible around the nearshore 
waters of Grand Marais to Grand Portage due to cold air sinking 
along the higher terrain this evening. Overall, a diminishing 
trend in winds after midnight tonight, with winds gradually 
becoming southwesterly through the day Tuesday. By Tuesday
evening, winds will be south-southwest at 15 to 20 knots, causing
building waves and dangerous conditions for small craft along 
parts of the north shore. A Small Craft Advisory is currently in 
effect for portions of the western Lake Superior nearshore zones, 
and after this advisory expires late tonight into Tuesday morning,
another will be needed for parts of the north shore by Tuesday 


DLH  -1  17  10  24 /  60   0  20  30 
INL  -5  18  11  25 /  60  10  10   0 
BRD  -3  19  15  28 /  10   0  30  40 
HYR  -4  18  10  25 /  50   0  20  50 
ASX   3  20  12  27 /  60  20  10  30 


WI...Winter Storm Warning until 9 AM CST Tuesday for WIZ004.

LS...Small Craft Advisory until 4 AM CST Tuesday for LSZ140>142-



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