2013 Fall Medium Range Discussion

[wxmx]

I am clearly in the minority, so what I am missing that everyone has locked in the -NAO for so long? I'm just not seeing it, but you, HM, and some energy mets I talk to are all on board with it (I can see a -NAO through like Feb 25 or so, but I'd think it should relax toward neutral after that).

Feb 25th sounds about where it would be near it's min according to most ensembles. Signal is pretty strong in model world. Euro, GFS and GGEM ensembles have ridging near Davis straits for most of the rest of the month. Yeah, I think it should relax towards neutral past it's min(it wouldn't be a min otherwise ), but my assessment is that residual ridging should linger over NE Canada for an extended period of time, including the first week of March.

 

Edit: Synoptically, the Scandinavian ridge should reinforce the -NAO as it retrogrades west, which is a common occurrence in this pattern, that would certainly aid in the longevity of the -NAO episode.

[wxmx]

Just looked at 0z ensembles guidance, and consensus is astounding.

 

 

[donsutherland1]

Yesterday, I noted in #597 that even as the CFSv2 has recently been suggesting a warm month in the Northeast (cold in the Pacific Northwest), my emerging pool of analogs is more mixed in the East. The idea of cold in parts of the west is well-supported in the early pool. However, in the East, there's less consensus on warmth.

 

Today's run of the CFSv2 has shifted a little and is indicated that cool anomalies might prevail in the Mid-Atlantic region in March. The last four runs of that model are below:

 

 

At this point, the details are not very important. What is important is that the changing outcomes in parts of the East might reflect the uncertainty among the early pool of analogs.

 

Looking at some of the drivers, there is now a split in the guidance concerning the MJO. Some guidance shows the MJO moving into Phases 4 and 5 and basically stalling out toward the end of February. Other guidance maintains the MJO's progression. What happens could have a significant impact on the temperature anomalies. For example, last March saw the MJO in Phases 4, 6, and 7 for 21 days. March 2012 was the warmest March on record in the CONUS. 

[Mike.Ventrice]

Yesterday, I noted in #597 that even as the CFSv2 has recently been suggesting a warm month in the Northeast (cold in the Pacific Northwest), my emerging pool of analogs is more mixed in the East. The idea of cold in parts of the west is well-supported in the early pool. However, in the East, there's less consensus on warmth.

 

Today's run of the CFSv2 has shifted a little and is indicated that cool anomalies might prevail in the Mid-Atlantic region in March. The last four runs of that model are below:

 

 

At this point, the details are not very important. What is important is that the changing outcomes in parts of the East might reflect the uncertainty among the early pool of analogs.

 

Looking at some of the drivers, there is now a split in the guidance concerning the MJO. Some guidance shows the MJO moving into Phases 4 and 5 and basically stalling out toward the end of February. Other guidance maintains the MJO's progression. What happens could have a significant impact on the temperature anomalies. For example, last March saw the MJO in Phases 4, 6, and 7 for 21 days. March 2012 was the warmest March on record in the CONUS. 

 

Thanks Don for your insights! I know Paul Roundy's MJO projections suggest that we will be observing a high amplitude MJO event over the Maritime Continent into the West Pacific by March 5-10, siding with some of the dynamical model guidance that 'stalls' the MJO in phase 5. I'm tracking a 1.5 sigma convectively coupled atmospheric Kelvin wave over the equatorial Atlantic that once moves over the Indian Ocean, should fuel the fire for some intense convection later next week that should amplify the MJO signal currently over the IO.

 

Some new 925 hPa temp anomaly maps I have on my page... we saw some pretty cold temperatures over much of the CONUS, centered about the Midwest-northern plains region.

 

 

Last week, we've observed a bit of a warm up over much of the southern and interior U.S. with the coldest air shifting over southeastern Canada, nosing down into the Northeast.

 

 

 

Looking a map of the entire globe, these are some of the strongest negative temp anoms over the entire globe.

 

 

It's been mostly a headache trying to figure out what's in store for us during the upcoming month. I'm still on board for warmer than average conditions over much of the southeast, and well below temps over the west- the wild card is the northeast with that pesky -NAO blocking pattern set up. I think that blocking pattern may begin to break down, or drift southward over the NE during the next few weeks promoting warmth but then again.. who knows.

[thenewbigmack]

Thanks Don for your insights! I know Paul Roundy's MJO projections suggest that we will be observing a high amplitude MJO event over the Maritime Continent into the West Pacific by March 5-10, siding with some of the dynamical model guidance that 'stalls' the MJO in phase 5. I'm tracking a 1.5 sigma convectively coupled atmospheric Kelvin wave over the equatorial Atlantic that once moves over the Indian Ocean, should fuel the fire for some intense convection later next week that should amplify the MJO signal currently over the IO.

Hey Mike, thanks for your input as well regarding the MJO! I've recently had an obession for the MJO and have been doing as much research as possible, including reading through all of the discussions on here. I'm curious what kind of life span you think this current wave will have? Do you feel the interaction with the CCKW will fire up the convection and propagate further east than models currently show?

 

As you've pointed out, using Paul Roundy's MJO projections, it appears convection dies off once it reaches the western Pacific then convection starts forming over the eastern IO during the 2nd week of March. I'm curious if you know whether Pauls MJO projection is calculated any different than this one below? Thanks for your time!

 

[Mike.Ventrice]

Hey Mike, thanks for your input as well regarding the MJO! I've recently had an obession for the MJO and have been doing as much research as possible, including reading through all of the discussions on here. I'm curious what kind of life span you think this current wave will have? Do you feel the interaction with the CCKW will fire up the convection and propagate further east than models currently show?

 

As you've pointed out, using Paul Roundy's MJO projections, it appears convection dies off once it reaches the western Pacific then convection starts forming over the eastern IO during the 2nd week of March. I'm curious if you know whether Pauls MJO projection is calculated any different than this one below? Thanks for your time!

 

 

Hi BigMack, the convection over the West Pacific is tied to the passage of a convectively coupled atmospheric Kelvin wave, so once that passes, we can expect more of a suppressed state to settle back in. The bulk of the MJO signal is still over the Indian Ocean so as that CCKW over the Atlantic superimposes with the active MJO over the IO, we might expect a surge in convection during that time (probably over the eastern IO).

 

Those plots you posted are the total OLR anomaly (not dissected into individual wave components). If you go to his MJO filtered OLR anomalies, you can see more of a continuous eastward propagation of convection from the Indian Ocean to the Maritime.  But yeah, Paul's forecast is suggesting a pretty potent MJO event over the Maritime and West Pacific regions during early-to-mid March... The convection signal will die off as the MJO passes the warm pool regions, so negative OLR anomalies will die off near the Dateline (probably towards the latter half of May). The MJO signal will most likely continue in upper level circulation, however. This is also a time where the global wind oscillation should kick in and we will be in more of an 'el nino' state, followed by a negative trend in global angular momentum anomalies... suggestive of a more active weather pattern towards the end of March, probably more so early April... just in time for the beginning of the U.S. severe weather season.

[donsutherland1]

Thanks Don for your insights! I know Paul Roundy's MJO projections suggest that we will be observing a high amplitude MJO event over the Maritime Continent into the West Pacific by March 5-10, siding with some of the dynamical model guidance that 'stalls' the MJO in phase 5. I'm tracking a 1.5 sigma convectively coupled atmospheric Kelvin wave over the equatorial Atlantic that once moves over the Indian Ocean, should fuel the fire for some intense convection later next week that should amplify the MJO signal currently over the IO.

 

Some new 925 hPa temp anomaly maps I have on my page... we saw some pretty cold temperatures over much of the CONUS, centered about the Midwest-northern plains region.

 

 

Last week, we've observed a bit of a warm up over much of the southern and interior U.S. with the coldest air shifting over southeastern Canada, nosing down into the Northeast.

 

 

 

Looking a map of the entire globe, these are some of the strongest negative temp anoms over the entire globe.

 

 

It's been mostly a headache trying to figure out what's in store for us during the upcoming month. I'm still on board for warmer than average conditions over much of the southeast, and well below temps over the west- the wild card is the northeast with that pesky -NAO blocking pattern set up. I think that blocking pattern may begin to break down, or drift southward over the NE during the next few weeks promoting warmth but then again.. who knows.

Very nice discussion and charts. It will be interesting to see if the NAO- develops and then is sustained.

[uncle W]

Very nice discussion and charts. It will be interesting to see if the NAO- develops and then is sustained.

while the AO is falling slowly the NAO is rising slowiy the last few days...Typical for this winter...Both are forecast to be negative in the near future...

[donsutherland1]

Some quick thoughts...

 

1. The weekend system that is likely to develop somewhere off the Southeast coast and then rapidly intensify as it heads north-northeastward is likely to develop too far offshore to pose much of a threat to the Mid-Atlantic and southern New England regions. A period of accumulating snow is likely across eastern Long Island and eastern New England. However, the GFS has probably been forming the storm too close to the coast and remains an outlier at this point.

 

2. Much of the rest of February is likely to be blocky. Some guidance supports the development of a strong NAO-/AO- regime. Hence, especially if the MJO maintains its progression forecast to take it through Phases 4 and 5 in coming days, the pattern could become more conducive toward a more widespread East Coast snowfall than appears likely this weekend.

 

3. The development of blocking supports the idea showing up in some analogs that March is not a slamdunk for warmth in the east. March is likely to be cold in the West. The East remains uncertain and there are colder analogs in the mix. In the meantime, the CFSv2 has continued to shift toward a colder outcome in the East.

 

[Heisy]

Hey Don, I was bored today and was looking at past 500mb patterns for snowstorms. I started off with March 1958 and it kind of resembled what the EURO is showing for the L.R. Do you see any similarities? 

[donsutherland1]

Hey Don, I was bored today and was looking at past 500mb patterns for snowstorms. I started off with March 1958 and it kind of resembled what the EURO is showing for the L.R. Do you see any similarities? 

Highzenberg,

 

I don't believe there are any real close matches for the forecast pattern. However, given the forecast teleconnection indices, perhaps the February 1987 storm, which focused its heaviest snows from Washington, DC to Philadelphia might be the closest match.

 

 

Much can change between now and the possible storm signaled on the ECMWF. Interestingly enough, the 1987 event occurred when the MJO was in Phase 6 and the GFS ensembles forecast the MJO to speed through Phases 4-5 into Phase 6 (albeit the low amplitude circle) by the time the possible event takes place. What is worrisome on the MJO front is that some of the guidance is now slowing the MJO's progression down and leaving it in Phase 5 (not a good one for KU storms in February or March). As the 1987 event was more of a regional storm rather than a more widespread Mid-Atlantic and New England storm, it might be the kind of event that has occurred in Phases 4 and 5.

[Mike.Ventrice]

Highzenberg,

 

I don't believe there are any real close matches for the forecast pattern. However, given the forecast teleconnection indices, perhaps the February 1987 storm, which focused its heaviest snows from Washington, DC to Philadelphia might be the closest match.

 

 

Much can change between now and the possible storm signaled on the ECMWF. Interestingly enough, the 1987 event occurred when the MJO was in Phase 6 and the GFS ensembles forecast the MJO to speed through Phases 4-5 into Phase 6 (albeit the low amplitude circle) by the time the possible event takes place. What is worrisome on the MJO front is that some of the guidance is now slowing the MJO's progression down and leaving it in Phase 5 (not a good one for KU storms in February or March). As the 1987 event was more of a regional storm rather than a more widespread Mid-Atlantic and New England storm, it might be the kind of event that has occurred in Phases 4 and 5.

Models were too bullish on a convectively coupled atmospheric Kelvin wave which is why it was propagating the MJO signal too fast. I think they are beginning to get a better handle on the MJO mean progression, where by the end of week two should be in a phase 5 regime. Been meaning to ask, what is a "KU" storm?

[andyhb]

Models were too bullish on a convectively coupled atmospheric Kelvin wave which is why it was propagating the MJO signal too fast. I think they are beginning to get a better handle on the MJO mean progression, where by the end of week two should be in a phase 5 regime. Been meaning to ask, what is a "KU" storm?

 

Acronym based off of "Kocin-Uccellini". They were the ones that came up with the Northeast Snowfall Impact Scale, major winter storms in the Northeast that register on the scale (especially higher end ones) seem to be synonymous with "KU", if I'm on the right track.

[donsutherland1]

Models were too bullish on a convectively coupled atmospheric Kelvin wave which is why it was propagating the MJO signal too fast. I think they are beginning to get a better handle on the MJO mean progression, where by the end of week two should be in a phase 5 regime. Been meaning to ask, what is a "KU" storm?

That's a storm of a magnitude similar to those listed in Paul Kocin's and Louis Uccelini's Northeast Snowstorms.

[Mike.Ventrice]

Thanks guys

[thunderbolt]

i though you guys ( mike don adam wxmx ) would find this interasting about the mjo and nao correlationhttp://www.cerfacs.fr/globc/links/presentation/Sieste_cassou_2008.pdf

[usedtobe]

i though you guys ( mike don adam wxmx ) would find this interasting about the mjo and nao correlationhttp://www.cerfacs.fr/globc/links/presentation/Sieste_cassou_2008.pdf

 

Thanks for posting it. 

[donsutherland1]

i though you guys ( mike don adam wxmx ) would find this interasting about the mjo and nao correlationhttp://www.cerfacs.fr/globc/links/presentation/Sieste_cassou_2008.pdf

Many thanks for the link. I look forward to reading it.

[Mike.Ventrice]

i though you guys ( mike don adam wxmx ) would find this interasting about the mjo and nao correlationhttp://www.cerfacs.fr/globc/links/presentation/Sieste_cassou_2008.pdf

Awesome, thanks for sharing this.

[Heisy]

Hey Don & others, with the recent model runs going away from showing any KU potentials in the 7-8 day range do you see any other periods that could offer any hope? 

[donsutherland1]

Hey Don & others, with the recent model runs going away from showing any KU potentials in the 7-8 day range do you see any other periods that could offer any hope? 

 

Although I'm not sure that there will be another KU snowstorm this winter, there may be some chance of such a development. For example, 1960 remains in the pool of March analogs based on ENSO and teleconnections. Moreover, the MJO won't remain in Phases 4 and 5 indefinitely.

 

The CFSv2 is now forecasting colder than normal conditions across the Mid-Atlantic and Southeast for March. New England comes up on the warm side of normal, probably on account of strong blocking. The idea is not too far from what is showing up on the analog cases based on ENSO and the teleconnections, which had been showing a higher probability of cold even when the CFSv2 was very warm.

 

If the analog pool does not change much, Philly will probably finish the winter with more then 10" seasonal snowfall (closer to 20" if a KU storm occurs), NYC could be close to 25", and Boston could be near or even above 50". To date, seasonal snowfall figures for those cities are as follows:

 

Boston: 40.8"

New York City: 18.8"

Philadelphia: 7.0"

[CoastalWx]

Morch cancel, at least the first half.

[JamieOber]

Morch cancel, at least the first half.

Oh? What came in to cancel it? Euro Weeklies? 

[CoastalWx]

Oh? What came in to cancel it? Euro Weeklies? 

 

Every piece of guidance. It might not be teens, but a good part of the country will be near to below I think. Certainly not like last year. Good pattern for the srn plains too with drought easing precip..although they need a hell of a lot of rain and snow.

[am19psu]

-NAO ftw? Or models just not handling organized tropical convection properly? I actually don't know the answer.

[Mike.Ventrice]

-NAO ftw? Or models just not handling organized tropical convection properly? I actually don't know the answer.

 

You got me... You start to think of how much an impact the previous Northeast blizzard and subsequent storm may have had on the extra-tropical flow regime. I'm sure a lot of mass was transported to the north, which consequently built the -NAO blocking ridge... something MJO-type composites would not catch onto. The question is how long does this blocking ridge stay in place, and why does the Northeast Pacific ridge deteriorate during next week and beyond? It might be a combination of the models missing tropical-extratropical linkages and underestimating convective heating which built the -NAO ridge we are seeing in today's forecast.

 

Signs still point to a warmer March over much of the Northeast... which I think may begin to materialize during the second week of March.

[Srain]

Fairly good agreement via the ensembles in the 6-10 day range that certainly is noteworthy.

 

[am19psu]

NAEFS combo looks better than the Euro to me. I don't have any clue what would be forcing a +PNA pattern.

[donsutherland1]

The latest CFSv2 forecast is now remarkably similar to what is showing up in the analog cases based on ENSO-teleconnections for March.

 

 

It should be noted that the analog cases are better at illustrating areas of cold-warm anomalies than magnitude. The base climate regime of 1981-2010 is not the same as the earlier climatic base from which a number of the analog cases have been drawn.

 

Top 3 cases showing up: 1960, 1965, and 2006. 2006 has been declining in weight recently.

 

FWIW, the current mix of analog cases suggests the potential for a snowy March in parts of the Mid-Atlantic region and New England. The Ohio Valley, southern Ontario and southern Quebec would likely seek their most snowfall in March since 2011.

 

March snowfall for select cities based on the analog cases (weighted for frequency of cases):

 

Boston: 9.7" (snowiest since 2009)

Cleveland: 10.8" (snowiest since 2011)

Montreal: 26.0 cm/10.2" (snowiest since 2011)

New York City: 7.2"  (snowiest since 2009)

Toronto: 21.7 cm/8.5" (snowiest since 2011)

Washington, DC: 6.8" (snowiest since 1999); excluding 1960: 2.2" (snowiest since 2009)

 

Analog cases should not be used for making precise estimates of snowfall. What the above figures are useful in illustrating is the big picture idea that March could be snowier than usual in the Mid-Atlantic and New England regions and that the Ohio Valley and parts of southern Canada should see a much snowier March than last winter.

[uncle W]

The latest CFSv2 forecast is now remarkably similar to what is showing up in the analog cases based on ENSO-teleconnections for March.

 

 

It should be noted that the analog cases are better at illustrating areas of cold-warm anomalies than magnitude. The base climate regime of 1981-2010 is not the same as the earlier climatic base from which a number of the analog cases have been drawn.

 

Top 3 cases showing up: 1960, 1965, and 2006. 2006 has been declining in weight recently.

 

FWIW, the current mix of analog cases suggests the potential for a snowy March in parts of the Mid-Atlantic region and New England. The Ohio Valley, southern Ontario and southern Quebec would likely seek their most snowfall in March since 2011.

 

March snowfall for select cities based on the analog cases (weighted for frequency of cases):

 

Boston: 9.7" (snowiest since 2009)

Cleveland: 10.8" (snowiest since 2011)

Montreal: 26.0 cm/10.2" (snowiest since 2011)

New York City: 7.2"  (snowiest since 2009)

Toronto: 21.7 cm/8.5" (snowiest since 2011)

Washington, DC: 6.8" (snowiest since 1999); excluding 1960: 2.2" (snowiest since 2009)

 

Analog cases should not be used for making precise estimates of snowfall. What the above figures are useful in illustrating is the big picture idea that March could be snowier than usual in the Mid-Atlantic and New England regions and that the Ohio Valley and parts of southern Canada should see a much snowier March than last winter.

1960 is the coldest March after 1916...If the last three days weren't warm it would have ended colder...The blizzard on the 3-4th is an alltime favorite...Now March 1965 looks like a more reasonable analog...it had some wet snow on St Patty's day and 1-3" on the 20th or 21st...