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Pattern February Discussion Part II

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by the 19th there isn't any cold in the US .#marchwillsaveus
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The major EC storm showed up again on this run. H5 looks amazing!

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Get the track of low coming from southern FL and riding the coast with cold air blasting down...BINGO!

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that storm later in the gfs run is some kind of massive, it's warm, but boy is it massive.

maybe we get lucky and it trends colder, but if not, perhaps it's a future severe weather event?
 
GeorgiaGirl said:
that storm later in the gfs run is some kind of massive, it's warm, but boy is it massive.

maybe we get lucky and it trends colder, but if not, perhaps it's a future severe weather event?
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Yeah webber has been all over the pattern around the 20th. It's starting to look more and more severe like

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The system is done if you're wanting Wintry. Sorry.

Lets get into 70F + for the rest of Winter/into early Spring and be happy. when I changed my avatar, I meant it. Spring is here.
 
pcbjr said:
Webb - in all seriousness here - given the deep Pac tropics we've been seeing, and despite all of the relatively good teleconnections we've seen off and on this winter (and really generally "good" the next week to 10 days), what if the AO and NAO and EPO were positive, the PNA negative - all in all just the opposite of a "textbook" cold, could the whole thing work in "reverse" and actually cause cold in the SE? I hope this makes sense - if not, PM me and we'll get into it deeper, but this is right up your alley! Phil
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Yeah, it makes sense, but keep in mind these teleconnections are descriptors not necessarily forcings upon the ambient pattern. Teleconnections such as the NAO, AO, PNA, EPO, WPO, etc. were created in an attempt to provide a more simple description of the myriad of coupled, extremely complex, non-linear forcing-feedback-responses in the ocean-atmosphere system, otherwise it would be fairly difficult to glean much useful information from looking blankly at a weather map, satellite picture, etc, however they also have their pitfalls especially if they're misrepresented... Although the canonical tropical-extratropical teleconnections are changing due to low frequency Hadley Cell expansion, the classical relationships still largely hold up imo. Wrt if we had a +AO/+NAO/-PNA/+EPO during a non-NINO February, we would be more likely to be above normal, but that's far from guaranteed considering that even a collection of teleconnections still lend an incomplete description of the overall pattern because they inherently constitute only the primary modes of variability, sometimes the expression of less significant and relatively more rare, subordinate modes dominates the picture...

Now, of the years that featured a +AO/+NAO/-PNA/+EPO in February, 1910, 1937, & 1967 were at or below normal here in the SE US, with February 1967 producing a large snowstorm over east-central NC on February 9th-10th.
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February 9-10 1967 NC Snowmap.png


Here's a February teleconnection snowfall table I made for Raleigh (1895-present), teleconnection combinations that result in a snowfall anomaly that's greater (less) than + (-) 1 standard deviation from the rest of the values in the table are denoted in blue (red).
Interestingly, the WPO is liable to have the largest impact on snowfall in RDU, and this is evidenced by the fact that the WPO holds the highest and lowest index averages for monthly snowfall. Another intriguing aspect from this is that I found no change between a -AO and +AO, a -WPO coupled with a +AO and/or -PNA is actually favorable for snow, and a -AO/+NAO is the least favorable teleconnection configuration for snowfall in RDU. This actually makes sense because a -AO/+NAO combination is often indicative of cold air draining away from North America and into Eurasia instead...

RDU Snowfall Teleconnection Table Feb.png
 
Shawn said:
The system is done if you're wanting Wintry. Sorry.

Lets get into 70F + for the rest of Winter/into early Spring and be happy. when I changed my avatar, I meant it. Spring is here.
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I'm waving the white flag, no need to get false hope for a 10 day storm at this point, besides after this mess of a winter, I'm ready for spring. Just try again in December.
 
Lol, the canadian brings what appears to be a hybrid, shallow warm core subtropical cyclone out of the southern Gulf of Mexico and Yucatan near the end of its run into the SE US. Ugh, it's too early for hurricane season but tbh we probably have a better chance w/ a hurricane in the winter than snow at this rate..
 
Webberweather53 said:
Yeah, it makes sense, but keep in mind these teleconnections are descriptors not necessarily forcings upon the ambient pattern. Teleconnections such as the NAO, AO, PNA, EPO, WPO, etc. were created in an attempt to provide a more simple description of the myriad of coupled, extremely complex, non-linear forcing-feedback-responses in the ocean-atmosphere system, otherwise it would be fairly difficult to glean much useful information from looking blankly at a weather map, satellite picture, etc, however they also have their pitfalls especially if they're misrepresented... Although the canonical tropical-extratropical teleconnections are changing due to low frequency Hadley Cell expansion, the classical relationships still largely hold up imo. Wrt if we had a +AO/+NAO/-PNA/+EPO during a non-NINO February, we would be more likely to be above normal, but that's far from guaranteed considering that even a collection of teleconnections still lend an incomplete description of the overall pattern because they inherently constitute only the primary modes of variability, sometimes the expression of less significant and relatively more rare, subordinate modes dominates the picture...

Now, of the years that featured a +AO/+NAO/-PNA/+EPO in February, 1910, 1937, & 1967 were at or below normal here in the SE US, with February 1967 producing a large snowstorm over east-central NC on February 9th-10th.
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Here's a February teleconnection snowfall table I made for Raleigh (1895-present), teleconnection combinations that result in a snowfall anomaly that's greater (less) than + (-) 1 standard deviation from the rest of the values in the table are denoted in blue (red).
Interestingly, the WPO is liable to have the largest impact on snowfall in RDU, and this is evidenced by the fact that the WPO holds the highest and lowest index averages for monthly snowfall. Another intriguing aspect from this is that I found no change between a -AO and +AO, a -WPO coupled with a +AO and/or -PNA is actually favorable for snow, and a -AO/+NAO is the least favorable teleconnection configuration for snowfall in RDU. This actually makes sense because a -AO/+NAO combination is often indicative of cold air draining away from North America and into Eurasia instead...

View attachment 77
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Eric,
Great stuff! I had just done a study of the PNA and EPO on days when ATL was getting major SN/IP since 1948. I found 16 of them. The avg. daily PNA was +0.4 (median +0.7) while the avg EPO was in the -30's. I posted this recently. I was next going to do AO & NAO.

Some time back I did find that several big RDU SN were when the NAO &/or AO were suprisingly + (like 1973 & 1988) though I didn't do a thorough analysis to see what the average AO/NAO was for all major SN there.
 
RollTide18 said:
I'm waving the white flag, no need to get false hope for a 10 day storm at this point, besides after this mess of a winter, I'm ready for spring. Just try again in December.
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Don't think you want to count on next winter to bring you any glory. VERY preliminary long range pac temps are indicating a weak to moderate El Nino setting up right at the coast of S America which is seldom if ever good for winter in the East or South USA.
 
MichaelJ said:
Don't think you want to count on next winter to bring you any glory. VERY preliminary long range pac temps are indicating a weak to moderate El Nino setting up right at the coast of S America which is seldom if ever good for winter in the East or South USA.
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So we just cancel next winter before this crappy winter is over with...Sounds smart to me...


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So, the Euro is still showing the track of low further north while the track of low is about 50 miles south on the GFS. The models should start to come into more of an agreement any day now. This winter, models have very little skill beyond 4 days.

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