Webberweather53
Meteorologist
If this lead-lag relationship holds firm we’d be looking at a big cold outbreak across the continent in late Dec. Til then the pattern seems generally nice even with cutters in the near term.
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Wintry Winter 2018-19 Discussion
- Thread starter Snowfan
- Start date
If this lead-lag relationship holds firm we’d be looking at a big cold outbreak across the continent in late Dec. Til then the pattern seems generally nice even with cutters in the near term.
I wish we'd start to see a stronger signal for a ridge in SW US. That, combined with AN heights in eastern Canada would give the SER the boot and allow for some cold air to drain into the SE. With the fairly continuous wave train, we'd get a chance at a storm. Unfortunately, I keep seeing troughing showing up there. It's smoothed out in the means, but it's there.
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SnowNiner
Member
Getting a cold outbreak in late December would coincide just right with the start of our snow season IMO. Maybe a week or two early but with the decent patterns that have been showing, I'd think very doable. We may just need to be patient for a few more weeks.
Yep. If we can peak around New Years then we are sitting pretty especially with seasonal models pointing towards a cold and stormy February. I’m picking up what Webb is putting down.
B
Brick Tamland
Guest
I always go back to this regarding snow in the Raleigh area.
Winter months in NC that average a negative NAO see a significant increase in snow days.
Our results found that a negative NAO combined with a positive ENSO phase (El Niño) resulted in the most snow days on average, with an increase of 25% (or more) in snow days for all four winter months.
A positive NAO combined with a negative ENSO (La Niña) resulted in the greatest decrease in average snow days. This is due to a lack of cold air (results of a typical positive NAO), and less active subtropical jet stream (results of a typical La Niña).
NAO had the most significant impact on snow days. Even in winter months that featured La Niña conditions (typically warm and dry), combined with a negative NAO, only February saw a decrease in snow days, which suggests that the NAO has a more direct influence on NC snowfall than ENSO. The reason behind this is that the NAO directly impacts the large scale atmospheric pattern over the eastern U.S. on a daily timescale, whereas the ENSO pattern indirectly effects the eastern U.S. atmospheric pattern by altering global circulations, and does so on monthly to seasonal timescales.
https://climate.ncsu.edu/climate/patterns/nc-snowfall
Winter months in NC that average a negative NAO see a significant increase in snow days.
Our results found that a negative NAO combined with a positive ENSO phase (El Niño) resulted in the most snow days on average, with an increase of 25% (or more) in snow days for all four winter months.
A positive NAO combined with a negative ENSO (La Niña) resulted in the greatest decrease in average snow days. This is due to a lack of cold air (results of a typical positive NAO), and less active subtropical jet stream (results of a typical La Niña).
NAO had the most significant impact on snow days. Even in winter months that featured La Niña conditions (typically warm and dry), combined with a negative NAO, only February saw a decrease in snow days, which suggests that the NAO has a more direct influence on NC snowfall than ENSO. The reason behind this is that the NAO directly impacts the large scale atmospheric pattern over the eastern U.S. on a daily timescale, whereas the ENSO pattern indirectly effects the eastern U.S. atmospheric pattern by altering global circulations, and does so on monthly to seasonal timescales.
https://climate.ncsu.edu/climate/patterns/nc-snowfall
Broken024
Member
Excellent analysis brickI always go back to this regarding snow in the Raleigh area.
Winter months in NC that average a negative NAO see a significant increase in snow days.
Our results found that a negative NAO combined with a positive ENSO phase (El Niño) resulted in the most snow days on average, with an increase of 25% (or more) in snow days for all four winter months.
A positive NAO combined with a negative ENSO (La Niña) resulted in the greatest decrease in average snow days. This is due to a lack of cold air (results of a typical positive NAO), and less active subtropical jet stream (results of a typical La Niña).
NAO had the most significant impact on snow days. Even in winter months that featured La Niña conditions (typically warm and dry), combined with a negative NAO, only February saw a decrease in snow days, which suggests that the NAO has a more direct influence on NC snowfall than ENSO. The reason behind this is that the NAO directly impacts the large scale atmospheric pattern over the eastern U.S. on a daily timescale, whereas the ENSO pattern indirectly effects the eastern U.S. atmospheric pattern by altering global circulations, and does so on monthly to seasonal timescales.
https://climate.ncsu.edu/climate/patterns/nc-snowfall
Jon
Member
I always go back to this regarding snow in the Raleigh area.
Winter months in NC that average a negative NAO see a significant increase in snow days.
Our results found that a negative NAO combined with a positive ENSO phase (El Niño) resulted in the most snow days on average, with an increase of 25% (or more) in snow days for all four winter months.
A positive NAO combined with a negative ENSO (La Niña) resulted in the greatest decrease in average snow days. This is due to a lack of cold air (results of a typical positive NAO), and less active subtropical jet stream (results of a typical La Niña).
NAO had the most significant impact on snow days. Even in winter months that featured La Niña conditions (typically warm and dry), combined with a negative NAO, only February saw a decrease in snow days, which suggests that the NAO has a more direct influence on NC snowfall than ENSO. The reason behind this is that the NAO directly impacts the large scale atmospheric pattern over the eastern U.S. on a daily timescale, whereas the ENSO pattern indirectly effects the eastern U.S. atmospheric pattern by altering global circulations, and does so on monthly to seasonal timescales.
https://climate.ncsu.edu/climate/patterns/nc-snowfall
Yes.
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Double yes.
ForsythSnow
Moderator
What year was this? Sorry to ask, but was this for other states too?
Thanks
This is a H5 composite from all single day 6"+ storms at RDU.
Were there any 6”+ snows in December??
ForsythSnow
Moderator
Oh okay, I see now. I would think this setup benefits more than just RDU as well. Probably SC mainly, but who knows since there have to be some overrunning events in there.
Here's the full list:
20000125
19790218
19690301
19581211
19670209
19550119
19800302
19660126
19830324
19880107
19600309
19630226
19840206
20101226
19480201
19600302
20020103
Two were in December (19581211, 20101226). There are some events that I didn't capture if they spanned multiple days, but the point is still the same overall in regards to the pattern evolution for the RDU "big dogs".
Definitely. As you can see from the list, some of these were major events for many here.
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Wow, I did not realize December significant snowfall at RDU was that rare. Only two in the last 100+ years of record? You'd think the second coldest month of the year would have a significant portion of the snowfall but that does not seem to be the case. Even March, which averages about 10 degrees warmer than December on average, has more snow historically!
I wonder what makes snow so much more likely when we get to January. It seems like every time there is a South snowstorm in December RDU is always unlucky (except for maybe 2010).
In fairness, I'm only looking back to 1944, but I think for RDU it's often the lack of significant snow cover to the north (not going to be as much of a problem this December!), which allows the air masses to moderate too much to support the big storms and also just the seasonal progression of the jet stream, which obviously on average shifts further south as winter progresses. Another factor could also be the warmer SSTs in December as compared to March for the strong coastal lows. There's been some whopper storms -- even recently -- in December that even the Triad scored and RDU whiffed on like 2009.
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Kylo
Member
From that list 13/17 comes after Jan 25th. I don’t get it either why that period is more conducive.
That was also the case, to an extent, last December. Much of the Deep South saw several inches of snow but RDU get stuck in 33 degree rain for at least six hours. I don't think RDU will have much of a chance for any snowfall until at least mid-December, but knowing climatology I wouldn't be surprised if December is measurable snow-free even if it turns out on the cool side of normal.In fairness, I'm only looking back to 1944, but I think for RDU it's often the lack of significant snow cover to the north (not going to be as much of a problem this December!), which allows the air masses to moderate too much to support the big storms and also just the seasonal progression of the jet stream, which obviously on average shifts further south as winter progresses. Another factor could also be the warmer SSTs in December as compared to March for the strong coastal lows. There's been some whopper storms -- even recently -- in December that even the Triad scored and RDU whiffed on like 2009.
Webberweather53
Meteorologist
The December "snow hole" at RDU looks to be due largely to internal variability (i.e. random) rather than some other large-scale physical reason. The biggest snowstorm to hit the triangle since 1895 in December struck in 1958, producing 12-15"+ just one county to the SE
December 1896 generally followed suit.
The heavy snows in December 1930 missed one county to the NW, if that, mixing w/ IP is what lowered totals near Raleigh, Durham had more than twice as much due to more snow vs IP.
December 1989 missed way to the SE and dropped up to 20" near Wilmington.
In essence, this looks like a long string of bad luck and I doubt there's enough big samples even going back a century or more to say anything substantiative about if there's something physical driving this local minimum in maximum storm-total snowfall in the Triangle during December.
December 1896 generally followed suit.
The heavy snows in December 1930 missed one county to the NW, if that, mixing w/ IP is what lowered totals near Raleigh, Durham had more than twice as much due to more snow vs IP.
December 1989 missed way to the SE and dropped up to 20" near Wilmington.
In essence, this looks like a long string of bad luck and I doubt there's enough big samples even going back a century or more to say anything substantiative about if there's something physical driving this local minimum in maximum storm-total snowfall in the Triangle during December.
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Webberweather53
Meteorologist
I will add though the same probably can't be said about underlying statewide variability. I can definitely agree that the 2nd half of the winter season, even as temperatures warm, we see more big winter storms per capita than we do in the front half of the season & the largest snowstorms in March are larger than the biggest storms in December in NC despite the fact that the overall winter storm climatologies are roughly similar for both months. Why these non-linearities and apparent discrepancies exist is definitely a topic of discussion, and there are various hypothesis that exist to explain it, but I'm actually curious to what extent this exists in NC, how significant the differences are, is there a lot of regional variation, & if there have been any forced or internal (random) changes in this relationship over the last several decades or so?