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Pattern Freezing Ferocious February

Kylo said:
Could this be the third February in a row without any accumulating snow for Raleigh. We might have had a trace in 2016 and 2017 but nothing accumulating that I recall. February is our peak snow month and to potentially go three February’s in a row would be disappointing. Still holding out hope for last week of February but it’s getting tough to hope when the global ensembles look this rough.
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There was a dusting of snow in Raleigh in February 2016 on the 14th-15th but yea next to nothing pretty much.
February 14-16 2016 NC Snowmap.jpg
WSI Radar Feb 14 2016 845pm.gif
 
ForsythSnow said:
I'm not. I hope we have a non-existent severe season. Haven't had major lines that do major damage in a long time and I'd like to keep it that way for some time. As far as hurricane season, how about you help write the wiki articles and keep them up to date, especially when we have multiple storms at once. Trying to track all of them and update them last year was a pain and still isn't complete. :confused:
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Lol, your doing a great job of keeping up with that stuff. I dont wish for anyone to get hurt or anything buy this is a weather forum for all types of weather events. You got to take the good with the bad, i love extreme weather weathe, from snow, ice, to hurricanes and severe weather. Its a passion of mine. I do love my winter season but here lately in the past few years ive grown into the severe season as a interest to me to learn. Just take a break from WIKI if its to much and enjoy weather life.;)
 
Folks, I know I'm stating the obvious but just as the case for any one index, being in a favorable MJO phase for SE cold (like phase 8) doesn't even come close to guaranteeing colder than normal in the SE. What it has done is AVERAGE colder than normal once the 43 years of days in phase 8 are averaged out just like phases 4 and 5 have averaged warmer than normal. It isn't anywhere near 100% colder (warmer) than normal in phase 8 (4 & 5). It is more like 55%/30%/15% of the days are cold/norm/warm (warm/norm/cold). So, there are way more than enough days that are either near normal or even the opposite of "the expected" to even try to depend on MJO.
 
We should see a downwelling Kelvin wave show up on the CPC subsurface analysis and hovmoller plots in the next week or two, the easterly trade winds have completely collapsed all the way to the International Dateline thanks to this MJO pulse.
u.total.30.5S-5N.gif
 
GaWx said:
Folks, I know I'm stating the obvious but just as the case for any one index, being in a favorable MJO phase for SE cold (like phase 8) doesn't even come close to guaranteeing colder than normal in the SE. What it has done is AVERAGE colder than normal once the 43 years of days in phase 8 are averaged out just like phases 4 and 5 have averaged warmer than normal. It isn't anywhere near 100% colder (warmer) than normal in phase 8 (4 & 5). It is more like 55%/30%/15% of the days are cold/norm/warm (warm/norm/cold). So, there are way more than enough days that are either near normal or even the opposite of "the expected" to even try to depend on MJO.
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Larry,
100% and thanks for pointing it out for board-wide consumption.
It (MJO) is just one tool to look at.
Too bad the rest of the tools in the shed are rusty and need some cleaning ... (AO looks to be going neutral at best, and the PNA, though positive, is also hanging on for dear life).
That's not to say that PH 8 MJO, a -AO and a +PNA guarantee anything, but that combo does make playing the dealer a little more enticing ... ;)
Best!
Phil
 
tennessee storm said:
i been a huge severe weather fan since 11 years old...intrigued by the super 74 outbreak april...been amateur chasing since early 80s ... were surely over due for active season... hoping no one gets hit... but midsouth way over due for large scale event... i be posting more as spring draws closer....
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As much as I don’t want to see severe I do believe you are correct that we are way overdue for a big outbreak.
 
Well hopefully something big happens at the end of the month, feeling a little bummed that my area missed out on all that early potential. Even though it’s only been four years, it feels like a freaking lifetime ago since Columbia, SC has had a winter storm. STILL clinging to hope, trying to stay positive. Late February 2004 was a historic winter storm for SC, mainly the upstate. But still a good example that you can get big dogs in late February. March 2009 was suppose to be a big one here in Columbia, but we got dry slotted instead and the upstate got the heavy snow.
 
Webberweather53 said:
We should see a downwelling Kelvin wave show up on the CPC subsurface analysis and hovmoller plots in the next week or two, the easterly trade winds have completely collapsed all the way to the International Dateline thanks to this MJO pulse.
View attachment 3785
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Webb,
Below is an MDA file that includes a 11/7/2017 write-up done by MDA mets on the correlation of winter temp anomalies for the E 2/3 of the US to MJO amplitude. This was based on an 11 year dataset of years with similar SSTs to the last 2 winters. In general, they found that weaker MJO amps averaged colder than stronger ones in the E 2/3 of the US overall for these 11 winters. They told me that the stronger MJOs tended to cause a stronger N Pac jet that tended to result in more zonal flow, which cut off the NW flow from the Arctic. Keep in mind that their analysis was based on only 11 years (out of 43 I assume) with similar SSTs. They didn't analyze the other winters. That's not to say that they wouldn't have found something similar for those but we don't know.

Edit: Unfortunately, the file is 1.3 MB, which is too large to load. So, here is a copy of the text:

"Northern Hemispheric and tropical sea surface temperatures feature a similar spatial spread of anomalies as observed a year ago, so we ask if there is anything we learned about the MJO last year that can be applied again for the upcoming winter. One notable factor from last winter was just how strong the MJO was, especially in February when the MJO had an average amplitude of 2.3 in a month which was record warmest by a large 47 GWHDDs. A large part of the second half of January also featured a strong MJO signal and periods of record warmth. Oppositely, colder periods in mid-December and early to mid-January were observed with a weak MJO signal. Taking those considerations, we test whether other years with a similar sea surface temperature regime as is current are consistent in this regard. The maps below highlight the data, which only considers the ampli-tude of the MJO and not the phase in which the signal resides. These suggest a similar theme with a weaker signal allowing for colder air into the Eastern Two-Thirds while the strong MJO dates were broadly warmer. This is a consideration to be had as we go forward, on top of the phase that the signal resides."
 
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Webberweather53 said:
We should see a downwelling Kelvin wave show up on the CPC subsurface analysis and hovmoller plots in the next week or two, the easterly trade winds have completely collapsed all the way to the International Dateline thanks to this MJO pulse.
View attachment 3785
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I assume this could potentially flip the ENSO for summer/fall/winter? We have had two snowy ninos in 15 years, which is interesting to think about. I always consider ninos more conducive for snow in the SE but it’s been Nina’s by far the past 20 or so years. Atleast for Raleigh.
 
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Get the shorts ready
5aae0f8ea0b405f541e7cd5488de464f.jpg


Sent from my SM-J320VPP using Tapatalk
 
GaWx said:
Webb,
Below is an MDA file that includes a 11/7/2017 write-up done by MDA mets on the correlation of winter temp anomalies for the E 2/3 of the US to MJO amplitude. This was based on an 11 year dataset of years with similar SSTs to the last 2 winters. In general, they found that weaker MJO amps averaged colder than stronger ones in the E 2/3 of the US overall for these 11 winters. They told me that the stronger MJOs tended to cause a stronger N Pac jet that tended to result in more zonal flow, which cut off the NW flow from the Arctic. Keep in mind that their analysis was based on only 11 years (out of 43 I assume) with similar SSTs. They didn't analyze the other winters. That's not to say that they wouldn't have found something similar for those but we don't know.

Edit: Unfortunately, the file is 1.3 MB, which is too large to load. So, here is a copy of the text:

"Northern Hemispheric and tropical sea surface temperatures feature a similar spatial spread of anomalies as observed a year ago, so we ask if there is anything we learned about the MJO last year that can be applied again for the upcoming winter. One notable factor from last winter was just how strong the MJO was, especially in February when the MJO had an average amplitude of 2.3 in a month which was record warmest by a large 47 GWHDDs. A large part of the second half of January also featured a strong MJO signal and periods of record warmth. Oppositely, colder periods in mid-December and early to mid-January were observed with a weak MJO signal. Taking those considerations, we test whether other years with a similar sea surface temperature regime as is current are consistent in this regard. The maps below highlight the data, which only considers the ampli-tude of the MJO and not the phase in which the signal resides. These suggest a similar theme with a weaker signal allowing for colder air into the Eastern Two-Thirds while the strong MJO dates were broadly warmer. This is a consideration to be had as we go forward, on top of the phase that the signal resides."
Click to expand...

Thanks for the explanation I appreciate it a lot, it's a little clearer to me what they're getting at but I still have some lingering issues and questions. I don't disagree whatsoever with the notion that stronger W Hem-Pacific MJO events intensify the Aleutian low that floods the continent w/ mild air but what about Indian Ocean/ E Hem events. Surely yes stronger forcing can strengthen the teleconnection to a trough over the Rockies but this can entice more anticyclonic wave breaking over Alaska and the NE Pacific that loads North America w/ Siberian air. You also have to keep in mind that the MJO is only describing a very small fraction of the total variance of convective activity in the tropics, there's a host of other waves (Kelvin, Rossby, TD-type waves, MRG waves (which are important for WP typhoons) and indices which provide vastly differing opinions on the MJO due to different filtering techniques (which the RMM doesn't use, bandpass filtering is utilized to describe the MJO but there's no smoothing of the data to eradicate high frequency spectral noise that can leak &/or saturate the MJO's bandwidth), EOF weights (wind is weighted more in RMM than the VPM/OMI, this also makes the RMM noisier), and emphasis of variables (OLR for the OMI developed by Kiladis et al, & VP200 from Ventrice and others.). Have these results been verified via bootstraping, Montle carlo, or randomized resampling and iterated tens of thousands of times over in NWP models that can adequately describe the MJO and the extratropical circulation response & feedbacks? (I know however this isn't particular easy given most models have a COD bias w/ the MJO (besides the GEFS in the WP/W Hem among other things). Should be intriguing to see how the MJO responds to this stratospheric warming event in the N Hem (if significantly at all), these can further amplify an MJO event by accelerating the upward branch of Brewer Dobson Circulation over the equator and thus decreasing the tropopause/lower stratosphere temps which for large-scale convection as well as intensifying the Planetary Waves in the winter hemisphere. See my post from this time last year on this topic where I not only delve into this relationship but link to several studies that discuss how stratospheric warming events can and have influenced subsequent MJO activity.
http://southernwx.com/community/threads/february-discussion-part-ii.110/page-32#post-16927
 
Here's the snow/ice accumulation map for today's in-situ CAD event, sleet/freezing rain occurred as far SE as Charlotte, Albemarle, Mebane, and Roxboro, significant ice accumulations were confined to the far western piedmont, and snow was observed as far SE as Wilkesboro & Mt Airy in the extreme NW piedmont and foothills, the northern mountains picked up about 1-2" of snow. Most locations changed over to rain before the precipitation ended.
February 4 2018 NC Snowmap.png
 
Having a little back and forth with Judah Cohen on Twitter if anyone is interested:


You can read his tweets and replies to see what he thinks.

Here’s a tweet I made on Jan 23 of the possibility of a PV split and the two analog years. My only correction I’d make as Cohen pointed out to me was that Jan 1991 was a displacement (Feb 1 1991 was a split)....Obviously folks remember Jan 1985.




It will be interesting to read his blog post tomorrow. I imagine he will lean heavily on 1985 event as it was also a Nina and East based QBO year, so more alike. Either way, two splits with one big sister vortex over North America, two different solutions — which is why you can’t write off Feb (let alone winter)....yet. Maybe we’ll get a nice blend


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Jon, the PV splits you referenced were both in January. You don't think the potential outcome of a split in February would be different? Not as cold, etc
 
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