February 2011 Thoughts: Another 'Atypical' La Niña Month

[donsutherland1]

Ottawa Blizzard,

IMO, February will likely feature more snowfall than January in Ottawa (probably 40 cm - 60 cm), though light and moderate events will likely account for the snowfall. February should also see one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal.

[donsutherland1]

DS -- How about storm tracks and setups? Do you think we'll see a classic one where everyone cashes in instead of these tight gradients and a stone's throw from 2 inches to 2 feet?

PSUHazletonWx,

I suspect there is a chance of a more classic system that impacts a much larger area than has been the case so far this winter. The best prospect for such a system might be toward the end of the colder pattern. Certainly, I hope that central and western PA/eastern Ohio Valley, Upstate New York, southern Ontario, and southern Quebec will get a chance to see a substantial snowfall this winter. I empathize with all those who have had to watch as storms bypassed them so far.

[JBG]

Joe Bastardi seems to be hinting at a major arctic outbreak for around Valentine's Day. He showed a map of the tropopause and how there's warming over the pole and how this can hint at a big arcti outbreak down the road. Interestingly, he showed a map and said that the current situation (over the pole) looks similar to how it looked on December 20,1993. We all know what happened after that. He made a comparison to the January 3-23,1994 period, which, in keeping with his style, was one of the most extreme periods of arctic weather in recent decades.

With Lake Erie frozen, and I'm sure a good deal of the other Great Lakes frozen, any hope for a repeat of February 9, 1934?

[Ottawa Blizzard]

With Lake Erie frozen, and I'm sure a good deal of the other Great Lakes frozen, any hope for a repeat of February 9, 1934?

That would be interesting. I doubt if Ontario will freeze though. i think that onl yhappened twice in the past century: 1934 and 1994

[A-L-E-X]

PSUHazletonWx,

I suspect there is a chance of a more classic system that impacts a much larger area than has been the case so far this winter. The best prospect for such a system might be toward the end of the colder pattern. Certainly, I hope that central and western PA/eastern Ohio Valley, Upstate New York, southern Ontario, and southern Quebec will get a chance to see a substantial snowfall this winter. I empathize with all those who have had to watch as storms bypassed them so far.

Don, do you see it as getting much colder for a sustained period behind the progged rain storm for next week?

[Ottawa Blizzard]

Brett Anderson of accuweather today opined that it could b either rain or snow up in my neck of the woods, but that the "coldest air of the season by far" would follow by the middle of next week.

[donsutherland1]

Don, do you see it as getting much colder for a sustained period behind the progged rain storm for next week?

It's too soon to speculate on p-type or track. Much colder air should follow the system.

[pcbjr]

Don,

Into at least early Feb I see what that the AO and NAO are progged to do (go +), and the PNA looks like its sliding. Temporary or the start of a longer (warmer) trend?

Thoughts? Implications (as if a +AO, +NAO, and neutral PNA takes much gray matter to comprehend - just maybe you see something the untrained eye doesn't)?

[Snow Wizard]

Perhaps our time is coming in the West. The latest PNA forecast shows slight negative by the second week of Feb with a solidly negative EPO.

[NortheastPAWx]

PSUHazletonWx,

I suspect there is a chance of a more classic system that impacts a much larger area than has been the case so far this winter. The best prospect for such a system might be toward the end of the colder pattern. Certainly, I hope that central and western PA/eastern Ohio Valley, Upstate New York, southern Ontario, and southern Quebec will get a chance to see a substantial snowfall this winter. I empathize with all those who have had to watch as storms bypassed them so far.

Thanks DS.

We can only hope. Next week's may be a good one.

[Ottawa Blizzard]

Ottawa Blizzard,

IMO, February will likely feature more snowfall than January in Ottawa (probably 40 cm - 60 cm), though light and moderate events will likely account for the snowfall. February should also see one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal.

Don, are you expecting one of those arctic intrusions to come next week? (Jan. 31-Feb. 6th) It's already looking to be cold again come Sunday and Monday!

[Yes_Probably_Maybe_No]

Where art thou -NAO?

GFS strat charts indicate slight ridging along the east coast at 100hpa. 10 and 30 hpa charts indicate some warming over the pole but most of the warming is in Alaska.

ECM showing some real impressive warming soon to happen at those levels as well.

Don't see much signs of a -AO/-NAO any time soon though.

[gil888]

Where art thou -NAO?

GFS strat charts indicate slight ridging along the east coast at 100hpa. 10 and 30 hpa charts indicate some warming over the pole but most of the warming is in Alaska.

ECM showing some real impressive warming soon to happen at those levels as well.

Don't see much signs of a -AO/-NAO any time soon though.

I think you can blame some of the shift on the change in the MJO, with the first intrusion into "el nino" territory in quite some time. Perhaps in 2-3 weeks things will come back to how they have been, but with the MJO becoming more active, I feel a lot less confident about the -NAO returning than I did. A significant stratospheric warming would help a lot to making sure that nasty SE ridge doesn't return.

[am19psu]

I think you can blame some of the shift on the change in the MJO, with the first intrusion into "el nino" territory in quite some time. Perhaps in 2-3 weeks things will come back to how they have been, but with the MJO becoming more active, I feel a lot less confident about the -NAO returning than I did. A significant stratospheric warming would help a lot to making sure that nasty SE ridge doesn't return.

With the wavenumber-2 CHI anomaly setting up next week, none of the MJO analogs are going to work. But if you think about where the latent heat release will lead to ridges, doesn't it make sense that we'll end up with a -EPO and an east-based -NAO? I don't actually know, just throwing ideas out.

[Whacker77]

I live in Louisville and never thought I would feel so left out of the snow bonanza with almost 16 inches of snow for the season. Sadly, it's a bit frustrating to watch watch the east coast get slammed with big storm after big storm while I keep cleaning two inch coatings off the driveway. It seems the pattern this season has been to see periods of crazy blocking and cold followed by an east coast storm that relaxes the pattern for a brief moment before reloading. Down here in the lower Ohio Valley, we're hoping just one storm hits with a massive arctic outbreak before it's too late. Hey, a man can dream can't he.

[Snow Wizard]

I think you can blame some of the shift on the change in the MJO, with the first intrusion into "el nino" territory in quite some time. Perhaps in 2-3 weeks things will come back to how they have been, but with the MJO becoming more active, I feel a lot less confident about the -NAO returning than I did. A significant stratospheric warming would help a lot to making sure that nasty SE ridge doesn't return.

To me that SE ridge sounds very sweet indeed! I think the NW is finally going to get a turn this winter.

[A-L-E-X]

To me that SE ridge sounds very sweet indeed! I think the NW is finally going to get a turn this winter.

I dont think a SE Ridge has any affect on weather in the NW unless its out somewhere in the middle of the country However, the forecast I told you about awhile ago seems to be coming true with regards to February. I wonder if the March forecast of a return to strong blocking like we've seen in some other La Nina winters (1956 among them) will hold true also.

[Mallow]

I dont think a SE Ridge has any affect on weather in the NW unless its out somewhere in the middle of the country However, the forecast I told you about awhile ago seems to be coming true with regards to February. I wonder if the March forecast of a return to strong blocking like we've seen in some other La Nina winters (1956 among them) will hold true also.

The SE ridge has a huge impact on us here in the NW, actually.

With amplification offshore, one might expect a deep trough to dig over the Pac NW... but without a SE ridge, troughs have a hard time digging southward, and instead swing southeastward (or pinch off to the west under the blocking ridge ). This prevents cold air bottled up in SW Canada from making significant headway into the Pac NW. In these situations, how far south the cold air penetrates is a huge question, and often Bellingham, WA is the only place that wins out. Sometimes, the cold makes it to Seattle, and less frequently to Portland. We've seen the former two scenarios a couple times this winter already.

With a SE ridge, the cold air can dig southward much more easily, putting the entire Pac NW into the ice box.

[pcbjr]

I hate the SE ridge!

[A-L-E-X]

The SE ridge has a huge impact on us here in the NW, actually.

With amplification offshore, one might expect a deep trough to dig over the Pac NW... but without a SE ridge, troughs have a hard time digging southward, and instead swing southeastward (or pinch off to the west under the blocking ridge ). This prevents cold air bottled up in SW Canada from making significant headway into the Pac NW. In these situations, how far south the cold air penetrates is a huge question, and often Bellingham, WA is the only place that wins out. Sometimes, the cold makes it to Seattle, and less frequently to Portland. We've seen the former two scenarios a couple times this winter already.

With a SE ridge, the cold air can dig southward much more easily, putting the entire Pac NW into the ice box.

Thanks, your words created a great mental image and I can totally see what youre saying. Basically, the feedback mechanism isnt just a west-east thing, it's east-west also. BTW, what's the normal annual snowfall of Bellingham? I've always been intrigued by the climate of that city, because of its latitude, nearness to the ocean and its elevation. If the pattern is ripe, they must have some epic snowstorms over there, with high winds and a boatload of moisture coming in from the Pacific. Maybe as much as some of the higher elevations on Vancouver Island?

[Mallow]

Thanks, your words created a great mental image and I can totally see what youre saying. Basically, the feedback mechanism isnt just a west-east thing, it's east-west also. BTW, what's the normal annual snowfall of Bellingham? I've always been intrigued by the climate of that city, because of its latitude, nearness to the ocean and its elevation. If the pattern is ripe, they must have some epic snowstorms over there, with high winds and a boatload of moisture coming in from the Pacific. Maybe as much as some of the higher elevations on Vancouver Island?

Ya, that's pretty much correct. I believe their avg annual snowfall is a foot or better (twice Portland's). And they have had some epic snowstorms, as you said, with the cold air pouring out of the Fraser Valley, and moisture-laden Pacific storms swinging in from the southwest.

We can get similar storms here in Portland due to the Gorge, but much more infrequently, and usually not as heavy.

[donsutherland1]

As January concludes, a brief update on my February thoughts is in order.

1) The AO- regime that I thought would begin to evolve sometime during the first week in February might be delayed. In a worst-case scenario, the timing of its redevelopment could be similar to that of Winter 2000-01. I do believe it will develop, but weak ensemble support with only a few members negative after the first week in February suggests some caution.

2) The EPO- regime could end as the calendar approaches mid-February.

3) The PNA could go negative at least for a time beginning near the end of the first week in February.

What all this means is that the EPO-/PNA+ regime that has kept the eastern U.S. generally cold and will likely lead to a very cold first 10 days of February will be coming to a close. Without strong AO blocking, the prospect of a thaw beginning around mid-month will be heightened. By that time, the coldest air will no longer be located on our side of the Hemisphere and the East's old nemesis the southeast ridge could be taking hold.

4) As I continue to expect AO blocking to develop albeit later than I had initially thought, I suspect that the thaw will be of a 2 week or so variety. It won't mark the end of winter.

Even legendary winters have a period or periods of relaxation.

Winter 1740-41 is one such example. The Pennsylvania Historical Society described that winter as follows:

The winter of 1740-1, was long remembered as “the winter of the deep snow;” it lay from four to five feet deep, from Christmas to the beginning of March. The crust on its surface was so firm as to bear horses and sleds. It is said that those who cut down trees this winter for fuel, were surprised in the spring, to see stumps standing six and seven feet high.

Yet accounts from New London, CT revealed a snowstorm that changed to rain on February 20, "sloppy weather" and rain on the 22nd, "not exceedingly cold" on the 23rd, more rain on the 26th, and "fair & thawing" with a southwest wind on the 28th. The southwest wind on the 28th marked the approach of a strong cold front. Afterward, a renewed period of cold weather with several snowstorms set in.

In short, even taking into consideration the possible mid-month thaw, I believe the Middle Atlantic region, New England, Ohio Valley/Great Lakes, Northern Plains and Central Plains will likely feature colder than normal readings for the month. The Pacific Northwest, Southern Plains, and probably the Gulf Coast into the Southeast will probably wind up on the milder side of normal, though a cold shot, especially in the Pacific Northwest is possible when the PNA goes negative. The magnitude of a coming cold discharge into the Southern Plains and Texas could reduce prospects of milder anomalies there.

Storminess should generally persist. February will likely feature above-to-much above normal snowfall in the northern Mid-Atlantic region and southern New England. Philadelphia, Newark, New York City, Providence, and Boston will likely see above normal to excessive snowfall for the month. February will likely feature more snowfall than January in Ottawa and similar amounts to January in Toronto. A KU-type snowstorm cannot be ruled out.

February will likely feature one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal. Toronto could be a shade warmer, but should see one or more -20°C (-4°F) minimum temperatures. Single digit lows should occur on one or more days in such cities as Philadelphia, New York City, and Boston and a subzero low in any of those cities is not out of the realm of possibility. Such cold shots are presently modeled, especially on the GFS.

[Scarlet Pimpernel]

As January concludes, a brief update on my February thoughts is in order.

1) The AO- regime that I thought would begin to evolve sometime during the first week in February might be delayed. In a worst-case scenario, the timing of its redevelopment could be similar to that of Winter 2000-01. I do believe it will develop, but weak ensemble support with only a few members negative after the first week in February suggests some caution.

2) The EPO- regime could end as the calendar approaches mid-February.

3) The PNA could go negative at least for a time beginning near the end of the first week in February.

What all this means is that the EPO-/PNA+ regime that has kept the eastern U.S. generally cold and will likely lead to a very cold first 10 days of February will be coming to a close. Without strong AO blocking, the prospect of a thaw beginning around mid-month will be heightened. By that time, the coldest air will no longer be located on our side of the Hemisphere and the East's old nemesis the southeast ridge could be taking hold.

4) As I continue to expect AO blocking to develop albeit later than I had initially thought, I suspect that the thaw will be of a 2 week or so variety. It won't mark the end of winter.

Even legendary winters have a period or periods of relaxation.

Winter 1740-41 is one such example. The Pennsylvania Historical Society described that winter as follows:

The winter of 1740-1, was long remembered as “the winter of the deep snow;” it lay from four to five feet deep, from Christmas to the beginning of March. The crust on its surface was so firm as to bear horses and sleds. It is said that those who cut down trees this winter for fuel, were surprised in the spring, to see stumps standing six and seven feet high.

Yet accounts from New London, CT revealed a snowstorm that changed to rain on February 20, "sloppy weather" and rain on the 22nd, "not exceedingly cold" on the 23rd, more rain on the 26th, and "fair & thawing" with a southwest wind on the 28th. The southwest wind on the 28th marked the approach of a strong cold front. Afterward, a renewed period of cold weather with several snowstorms set in.

In short, even taking into consideration the possible mid-month thaw, I believe the Middle Atlantic region, New England, Ohio Valley/Great Lakes, Northern Plains and Central Plains will likely feature colder than normal readings for the month. The Pacific Northwest, Southern Plains, and probably the Gulf Coast into the Southeast will probably wind up on the milder side of normal, though a cold shot, especially in the Pacific Northwest is possible when the PNA goes negative. The magnitude of a coming cold discharge into the Southern Plains and Texas could reduce prospects of milder anomalies there.

Storminess should generally persist. February will likely feature above-to-much above normal snowfall in the northern Mid-Atlantic region and southern New England. Philadelphia, Newark, New York City, Providence, and Boston will likely see above normal to excessive snowfall for the month. February will likely feature more snowfall than January in Ottawa and similar amounts to January in Toronto. A KU-type snowstorm cannot be ruled out.

February will likely feature one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal. Toronto could be a shade warmer, but should see one or more -20°C (-4°F) minimum temperatures. Single digit lows should occur on one or more days in such cities as Philadelphia, New York City, and Boston and a subzero low in any of those cities is not out of the realm of possibility. Such cold shots are presently modeled, especially on the GFS.

Thanks, Don, for this well-posed and reasoned outlook. Sounds reasonable to me. Couple of questions I have, if I may. First, you have been suggesting for some time now that you expect the blocking to return sometime during February, though currently the ensembles aren't overly enthusiastic about that so far. Is this based on your research with extreme December blocking correlating with a return of the block in February, or do you expect some kind of stratospheric warming to kick it off, or a combination of both of those? Perhaps something the ensembles and models have not been able to sniff out yet. Secondly, you suggest a relative thaw or relaxation in the pattern for a couple of weeks in February, after about the 10th. That makes sense from what I've seen. Problem is, 2 weeks beyond that and we're pretty well near the end of the month, and in the DC region that's getting awfully close to the realistic end of chances for good snow events for the season, barring an unusually cold end to February and beginning of March. It's happened of course...is this kind of what you're implying here, as you say "it won't mark the end of winter" (in reference to the relative thaw/relaxing of the pattern)? Unless you were refering mostly to places farther north.

Upcoming storm for mid-week, though it will pretty much be rain around here (maybe some ice to start), is quite interesting to me all the same. I grew up in northeast Ohio, and this could be one of those blockbuster midwest/Ohio Valley storms where they get well over a foot. Which is really kind of unusual around there in a synoptic scale storm. Seems similar to the Valentine's Day storm in 2007 almost.

[donsutherland1]

Always in Zugzwang,

The idea of a returning AO- regime is based on the historic experience associated with severe to extreme December AO- regimes. The modeled stratospheric warming, now looking much less impressive (and such events are poorly modeled relative to other meteorological developments, as much more research remains to be done). Hence, the timing of the redevelopment of an AO- regime looks to be delayed.

DCA could wind up colder than normal during the period running from the end of February into mid-March. Snowfall prospects are more problematic. But a number of La Niña events saw Washington, DC pick up 6" or more March snowfall (1910-11, 1922-23, 1933-34, 1942-43, and 1998-99). Fading La Niña events in 1891-92 and 1908-09 brought more than 10" snowfall in March to Washington, DC. So the thaw should not bring an end to Washington's chances for additional snow. Needless to say, as noted in this thread, the highest chances for above normal snowfall (February and perhaps into March) remains Philadelphia northward.

[Scarlet Pimpernel]

Always in Zugzwang,

The idea of a returning AO- regime is based on the historic experience associated with severe to extreme December AO- regimes. The modeled stratospheric warming, now looking much less impressive (and such events are poorly modeled relative to other meteorological developments, as much more research remains to be done). Hence, the timing of the redevelopment of an AO- regime looks to be delayed.

DCA could wind up colder than normal during the period running from the end of February into mid-March. Snowfall prospects are more problematic. But a number of La Niña events saw Washington, DC pick up 6" or more March snowfall (1910-11, 1922-23, 1933-34, 1942-43, and 1998-99). Fading La Niña events in 1891-92 and 1908-09 brought more than 10" snowfall in March to Washington, DC. So the thaw should not bring an end to Washington's chances for additional snow. Needless to say, as noted in this thread, the highest chances for above normal snowfall (February and perhaps into March) remains Philadelphia northward.

Thanks again, Don...appreciate your quick response! That's informative and makes perfect sense. There definitely have been some decent late February and early March snows here in DC even recently (and even after a relatively warm period). Not necessarily "blockbusters", but heck, in March 2009 we got a pretty good moderate event and that was likewise a Nina (though not as strong as this one). I've heard several around this area that say you can realistically expect snow chances through about the Ides of March, which kind of sounded hokey but in my experience that's actually not too bad an estimate most of the time.

[uncle W]

As January concludes, a brief update on my February thoughts is in order.

1) The AO- regime that I thought would begin to evolve sometime during the first week in February might be delayed. In a worst-case scenario, the timing of its redevelopment could be similar to that of Winter 2000-01. I do believe it will develop, but weak ensemble support with only a few members negative after the first week in February suggests some caution.

2) The EPO- regime could end as the calendar approaches mid-February.

3) The PNA could go negative at least for a time beginning near the end of the first week in February.

What all this means is that the EPO-/PNA+ regime that has kept the eastern U.S. generally cold and will likely lead to a very cold first 10 days of February will be coming to a close. Without strong AO blocking, the prospect of a thaw beginning around mid-month will be heightened. By that time, the coldest air will no longer be located on our side of the Hemisphere and the East's old nemesis the southeast ridge could be taking hold.

4) As I continue to expect AO blocking to develop albeit later than I had initially thought, I suspect that the thaw will be of a 2 week or so variety. It won't mark the end of winter.

Even legendary winters have a period or periods of relaxation.

Winter 1740-41 is one such example. The Pennsylvania Historical Society described that winter as follows:

The winter of 1740-1, was long remembered as “the winter of the deep snow;” it lay from four to five feet deep, from Christmas to the beginning of March. The crust on its surface was so firm as to bear horses and sleds. It is said that those who cut down trees this winter for fuel, were surprised in the spring, to see stumps standing six and seven feet high.

Yet accounts from New London, CT revealed a snowstorm that changed to rain on February 20, "sloppy weather" and rain on the 22nd, "not exceedingly cold" on the 23rd, more rain on the 26th, and "fair & thawing" with a southwest wind on the 28th. The southwest wind on the 28th marked the approach of a strong cold front. Afterward, a renewed period of cold weather with several snowstorms set in.

In short, even taking into consideration the possible mid-month thaw, I believe the Middle Atlantic region, New England, Ohio Valley/Great Lakes, Northern Plains and Central Plains will likely feature colder than normal readings for the month. The Pacific Northwest, Southern Plains, and probably the Gulf Coast into the Southeast will probably wind up on the milder side of normal, though a cold shot, especially in the Pacific Northwest is possible when the PNA goes negative. The magnitude of a coming cold discharge into the Southern Plains and Texas could reduce prospects of milder anomalies there.

Storminess should generally persist. February will likely feature above-to-much above normal snowfall in the northern Mid-Atlantic region and southern New England. Philadelphia, Newark, New York City, Providence, and Boston will likely see above normal to excessive snowfall for the month. February will likely feature more snowfall than January in Ottawa and similar amounts to January in Toronto. A KU-type snowstorm cannot be ruled out.

February will likely feature one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal. Toronto could be a shade warmer, but should see one or more -20°C (-4°F) minimum temperatures. Single digit lows should occur on one or more days in such cities as Philadelphia, New York City, and Boston and a subzero low in any of those cities is not out of the realm of possibility. Such cold shots are presently modeled, especially on the GFS.

nice post as usual Don...We have not had a real thaw except for the first of January and a brief one on the 20th...usually when we don't see a good thaw like we saw last January it usually comes in February...If the blocking comes back strong again more record wintry weather will happen...If not we still can see a return to wintry weather after a big February thaw like 1947-48 and 1993-94 had...

[Snow Wizard]

No question the model and index forecasts continue to look fabulous for the NW to fianlly cash in on this La Nina. Today's 12z GFS shows what would be a truly historic cold period for the West if it verifies. We totally deserve it after the crapfest we have seen so far!

[Feb]

No question the model and index forecasts continue to look fabulous for the NW to fianlly cash in on this La Nina. Today's 12z GFS shows what would be a truly historic cold period for the West if it verifies. We totally deserve it after the crapfest we have seen so far!

If i could some how control the weather i would make sure you see at least two weeks of sub zero weather and 15 feet of snow if that would make you stop bitching and mucking up Mr Sutherland's threads.

[Snow Wizard]

If i could some how control the weather i would make sure you see at least two weeks of sub zero weather and 15 feet of snow if that would make you stop bitching and mucking up Mr Sutherland's threads.

I certainly didn't intend to do that. I will try to refrain from adding the negative commentary to my posts. I do think that if the East was seeing a really lame El Nino winter there would be a whole lot of complaining going on though.

[Feb]

I certainly didn't intend to do that. I will try to refrain from adding the negative commentary to my posts. I do think that if the East was seeing a really lame El Nino winter there would be a whole lot of complaining going on though.

Hey Snow Wizard. You would have enjoyed JB's long ranger video today. He said starting around Valentine's Day Winter returns to the PNW for about a 3-4 week period. While you chill, the east warms up big time. A false spring as he put it since winter will return sometime in March and for the NE it will be an ugly spring.