Just out of curiosity, is that what happened in 2009. We had those two storms that year on 1/20 and 2/3 respectively and then got very mild for several weeks, then had that winter storm on 3/1-2 followed by a couple days of 25-30 degree below average temperatures
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Pattern Jammin January 2023
- Thread starter Goose88
- Start date
Webberweather53
Meteorologist
Yes, that's actually what happened. I think if we get a SSWE here, it makes -NAO/-AO on the RMM regression composites much more likely in late Feb-early March.
What exactly is a SSWE and how does it affect us?
I had always wondered but couldn’t find anything doing my own research. Thanks to you and @Webberweather53 for the info. That storm crushed us in Western Gaston County.
Basically, if the stratosphere splits or stretches due to sudden warming and couples with the troposphere, it can send down some colder sourced air to the lower heights. However, even if that happens, there's no guarantee that we'll have much impact, especially during a La Nina. And, this process would take about 3-4 weeks to impact us. However, I wouldn't mind having a SSWE in the cards late Feb/Mar as the Pacific circles out of the warm phases.
Thank you. As I’ve been reading your posts about how you think these next few weeks might go, that February to early March keeps coming up in my head. Ironically enough that was also a time period in which a LaNina was breaking down and of course about to head towards an El Niño… something that I’ve read may happening now as this La Niña continues to break down.
Webberweather53
Meteorologist
If this week's -NAO continues to trend a lot stronger than forecast like it has the last day or two, we could see more rapid coupling/downward propagation of zonal wind + temperature anomalies into the troposphere/lower stratosphere.
Aside from making late Jan's pattern better, getting more -NAO the next 2-3 weeks could also pay dividends down the road. This -NAO showing up on the models now is something to keep an eye on, even if you're looking a month or more down the road.
accu35
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@Webberweather53 should I take that 300 hour control run and run with it?
griteater
Member
The highlighted is what killed us in Feb / Mar 2018. The SSW occurred on Feb 12, 2018. A nice, west-based NAO developed right at the beginning of March. Northern NC and VA got hit multiple times that March even though the Pacific pattern was poor as the MJO was running thru the warm phases (3-4-5-6). It would likely be the opposite this time if one were to occur in early Feb, as the MJO should be in the colder phases in late Feb into early March
MJO in late Feb and March 2018...
LukeBarrette
im north of 90% of people on here so yeah
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So if I’m understanding correctly the SSW coupled with cold MJO phases could make it very cold late Feb and into March?The highlighted is what killed us in Feb / Mar 2018. The SSW occurred on Feb 12, 2018. A nice, west-based NAO developed right at the beginning of March. Northern NC and VA got hit multiple times that March even though the Pacific pattern was poor as the MJO was running thru the warm phases (3-4-5-6). It would likely be the opposite this time if one were to occur in early Feb, as the MJO should be in the colder phases in late Feb into early March
MJO in late Feb and March 2018...
griteater
Member
Ifs and buts and candy and nuts. A lot of people hate to even discuss SSWs. In fairness, a lot has to happen to get SSWs to affect the pattern like we want it. First, you need the actual SSW to occur. Right now, it's still way out in time in the modeling, but the pattern precursors for SSWs are present over the next 10 days (Bering Sea and Greenland troughing / Urals and Scandi ridging) and the 10mb zonal wind forecasts in the polar cap show significant weakening upcoming. But if one occurs, the weakness in the zonal winds needs to downwell from the stratosphere into the troposphere (if the AO/NAO are already negative when the SSW is occurring as Webb mentioned, then you wouldn't really need to have it downwell, as there would already be weakness in the troposphere). But the SSW gives you the best chance at seeing a more robust, extended period of -AO/-NAO (no guarantees of course). The MJO cold phases is just that...a better shot at western ridging when the MJO is in the cold phases. So, yes, these 2 could both act to encourage a colder pattern for us in late Feb / early March if the stars align
Assuming that the expected SSW occurs, is it unheard of for it to propagate down much quicker than the usual +-30 days? Say something like 10-20 days?
griteater
Member
The SSW in the 20-21 winter occurred on Jan 4, 2021. This is a good example of the troposphere already being in a -NAM phase (i.e. -AO) when the SSW occurred, so the effects of the SSW were very quick...essentially just acting to continue to foster the -AO / -NAO environment.
The NAM (Northern Annular Mode) is essentially the AO, but it includes both the troposphere and stratosphere. The warm colors here (negative values) indicate the occurrence of -NAM
Webberweather53
Meteorologist
I finally found the paper I read the other day that talks about S2S ECMWF model biases during weak vortex/SSWEs & how the model tends to underestimate the U wind response at short lead times prior to SSWEs.
Seems more likely than not we're at least going to see a "weak vortex" event (where the zonal wind at 10hpa & 60N is < 5ms-1 vs < 0ms-1 for a full fledged major sudden stratospheric warming event).
https://wcd.copernicus.org/articles/4/81/2023/
Webberweather53
Meteorologist
The SSW in the 20-21 winter occurred on Jan 4, 2021. This is a good example of the troposphere already being in a -NAM phase (i.e. -AO) when the SSW occurred, so the effects of the SSW were very quick...essentially just acting to continue to foster the -AO / -NAO environment.
The NAM (Northern Annular Mode) is essentially the AO, but it includes both the troposphere and stratosphere. The warm colors here (negative values) indicate the occurrence of -NAM
Yeah just another reason why we gotta watch how the -NAO evolves in week 2 on the models.
Webberweather53
Meteorologist
Also, just to reinforce @griteater's post
This is from White et al (2018):
"The Downward Influence of Sudden Stratospheric Warmings: Association With Tropospheric Precursors"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7440399/
"Further, Black and McDaniel (2004) observed that the determination of the DW (downward) propagation of a SSW depended on the pre-existing tropospheric state; in the case of NDW (non downward) -propagating events, the troposphere was already in a positive northern annular mode (NAM or +NAO)-like state that acted to mask the DW (downward) stratospheric influence. In the case of DW (downward)-propagating (stratospheric warming) events, the troposphere was already in a negative NAM (or -NAO)-like state, although slightly out of phase, latitudinally, with the canonical NAM."
I.e. getting a -NAO near the onset of a sudden stratospheric warming event (SSWE) is a critical factor in determining whether the SSWE actually impacts the troposphere.
Hence, trends like this matter a lot, not just for guiding the chances of us seeing a winter storm in late January, but also in this situation, seemingly small errors like this in week 2 forecast could actually have the potential impact the overall pattern at least through March. This -NAO in the extended range could be a wildcard/throw a wrench at things if it goes unchecked & we trend even more to it the next several days.
Interesting times ahead
This is from White et al (2018):
"The Downward Influence of Sudden Stratospheric Warmings: Association With Tropospheric Precursors"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7440399/
"Further, Black and McDaniel (2004) observed that the determination of the DW (downward) propagation of a SSW depended on the pre-existing tropospheric state; in the case of NDW (non downward) -propagating events, the troposphere was already in a positive northern annular mode (NAM or +NAO)-like state that acted to mask the DW (downward) stratospheric influence. In the case of DW (downward)-propagating (stratospheric warming) events, the troposphere was already in a negative NAM (or -NAO)-like state, although slightly out of phase, latitudinally, with the canonical NAM."
I.e. getting a -NAO near the onset of a sudden stratospheric warming event (SSWE) is a critical factor in determining whether the SSWE actually impacts the troposphere.
Hence, trends like this matter a lot, not just for guiding the chances of us seeing a winter storm in late January, but also in this situation, seemingly small errors like this in week 2 forecast could actually have the potential impact the overall pattern at least through March. This -NAO in the extended range could be a wildcard/throw a wrench at things if it goes unchecked & we trend even more to it the next several days.
Interesting times ahead
Broken024
Member
GFS throwing us a bone this morning
Don't fall for it. It will pull a Lucy on you Charlie ?