February 2011 Thoughts: Another 'Atypical' La Niña Month

[Ji]

Don..do you still expect blocking to return and in what part of Feb or March?

[A-L-E-X]

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.

Snow wiz I hope you get an epic period of snow and cold-- you deserve it after the winter you have had so far. However, around here, el ninos arent usually very good unless their weak. Last year was an anomaly. El ninos like 1994-95, 1997-98 and 2006-07 (mod to strong) usually feature milder than normal weather. If you had me pick, I would chose weak la nina or weak el nino over any other enso. The weaker the signal the better it is for us-- too warm or too cold and we're screwed (usually-- last winter and this winter have both been hugely anomalous.)

[JBG]

In the wake of a storm that dumped a swath of 4” and greater snows across parts of the northern Mid-Atlantic and southern New England regions, the coldest air mass to date is pouring into the East. That Arctic blast should solidify and expand the cold anomalies that have predominated there in non-La Niña fashion.

A convergence of factors suggests that February, typically warm across a wide part of the U.S./southern Ontario/southern Quebec, with cold anomalies generally confined to the West during moderate/strong La Niña events, will defy post-1950 La Niña climatology. Instead, it will likely resemble the “cold” La Niña events that appeared from time to time in the early 19^th century, and then in a remarkable cluster in the early 20^th century.

• Precedent with the 1872-73, 1903-04, 1909-10, and 1916-17 moderate/strong “cold” La Niña cases suggests that February will closely resemble the winter anomalies to date.

• Historic snowfall climatology based on the December snowfall (posted here on December 28, 2010) suggested that New York City should reach or exceed 40” seasonal snowfall and Boston should reach or exceed 50” snowfall. That idea is well on the way to verifying. After today’s snowfall, both cities are on the brink of attaining those figures (Boston: 49.6”; New York City: 36.1”). That historic experience and also snowfall-La Niña experience points to a continuation of above to much above normal snowfall from Philadelphia to Boston.

For example, if one took all the La Niña cases when New York City received November-December snowfall of 8” or more, the following winters show up: 1872-73 (cold moderate/strong La Niña), 1898-99, 1916-17 (cold moderate/strong La Niña), 1933-34, and 1967-68. In 4/5 (80%) cases, New York City picked up 10” or more snowfall in February. Three of those cases saw NYC receive 15” or more snowfall. In 50% of those cases (Boston’s monthly snowfall record does not extend back to 1872-73), Boston picked up 30” or more monthly snowfall. In addition, those winters featured widespread cold in the East. All of those winters featured one or more substantial Arctic blasts in February (something that is showing up on the long-range of the 1/21/2011 12z GFS).

********************

• 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.

Don, any update?

Obviously we're well above 40" in KNYC. Are you still optimistic about February? The NAO doesn't look so great.

[Feb]

JB said this morning that the worst of the winter is over in the east. The storm this weekend will be rain for the east coast, maybe clear back to State College it might rain. It gets cold next week but after that winter goes gang busters in the west for 3-4 weeks.

[donsutherland1]

JB said this morning that the worst of the winter is over in the east. The storm this weekend will be rain for the east coast, maybe clear back to State College it might rain. It gets cold next week but after that winter goes gang busters in the west for 3-4 weeks.

The mid-month (+/- a few days ) thaw is really showing up on the models now. IMO, this modeled thaw is not a false alarm. It will take hold. However, it won't mark the end of winter. Indeed, given how the winter has unfolded, there is a lot of risk in declaring winter's demise with each modeled thaw.

One could see a return to more winterlike conditions as blocking is renewed ala Winter 2000-01 late in February. Even with the thaw, the one or two Arctic shots and generally cool conditions leading up to the thaw should assure that such cities as Philadelphia, New York, Chicago, Boston, and perhaps Washington, DC will wind up cooler than normal for the month as a whole.

During the thaw, there should be more winterlike weather in the West. Some areas that have been starved from winter could receive a consolation prize of sorts with some cold shots and opportunities for snow.

[donsutherland1]

Don, any update?

Obviously we're well above 40" in KNYC. Are you still optimistic about February? The NAO doesn't look so great.

I still believe NYC will likely see 10" or more snowfall for February. I don't believe the thaw will mark the end of winter, but a pause.

[A-L-E-X]

The mid-month (+/- a few days ) thaw is really showing up on the models now. IMO, this modeled thaw is not a false alarm. It will take hold. However, it won't mark the end of winter. Indeed, given how the winter has unfolded, there is a lot of risk in declaring winter's demise with each modeled thaw.

One could see a return to more winterlike conditions as blocking is renewed ala Winter 2000-01 late in February. Even with the thaw, the one or two Arctic shots and generally cool conditions leading up to the thaw should assure that such cities as Philadelphia, New York, Chicago, Boston, and perhaps Washington, DC will wind up cooler than normal for the month as a whole.

During the thaw, there should be more winterlike weather in the West. Some areas that have been starved from winter could receive a consolation prize of sorts with some cold shots and opportunities for snow.

Thanks for the update, Don! Before we get the thaw, do you foresee any big winter events for us, either this weekend or next week?

[donsutherland1]

Don..do you still expect blocking to return and in what part of Feb or March?

Probably last week in February/1st week in March. Similar to the timing of the late winter/early spring 2001 blocking.

[donsutherland1]

Thanks for the update, Don! Before we get the thaw, do you foresee any big winter events for us, either this weekend or next week?

I believe we'll get some accumulations of snow, possibly even a moderate accumulation this weekend. But there is also a risk of at least some rain getting involved in the northern NJ, NYC/southeast NY, Long Island, and coastal CT region.

[golia1w]

Don, I've always enjoyed reading your stuff, and never ventured to ask an imby question before, but if you get a few moments, could you offer up any thoughts for RIC wrt the potential return of blocking late Feb/early Mar. That timeframe is getting awfully late in the game for winter weather this far south, but thought I would inquire anyway.

Many thanks in advance for your insights!

[JBG]

Thanks for the update, Don! Before we get the thaw, do you foresee any big winter events for us, either this weekend or next week?

Probably last week in February/1st week in March. Similar to the timing of the late winter/early spring 2001 blocking.

Wasn't that blocking markedly unproductive south of the MA-NH line?

[donsutherland1]

Wasn't that blocking markedly unproductive south of the MA-NH line?

Only for the March 2001 "near miss" storm. The month, as a whole, was colder than normal in the eastern half of the U.S. Has the timing of the phasing associated with the March 2001 system been a little different, the Middle Atlantic region could have received a crippling snowfall.

[A-L-E-X]

Only for the March 2001 "near miss" storm. The month, as a whole, was colder than normal in the eastern half of the U.S. Has the timing of the phasing associated with the March 2001 system been a little different, the Middle Atlantic region could have received a crippling snowfall.

Besides 2000-01, two other analogs you might want to look at are 1993-94 and 2003-04. I think 2003-04 is a closer match, but in both cases we had a break from mid February to the end of the month and things got going again in March. This is disregarding ENSO and just going by pattern.

[Chris L]

Besides 2000-01, two other analogs you might want to look at are 1993-94 and 2003-04. I think 2003-04 is a closer match, but in both cases we had a break from mid February to the end of the month and things got going again in March. This is disregarding ENSO and just going by pattern.

IF its like 2000-2001, let's hope March will be in our favor this time.

[ORH_wxman]

Wasn't that blocking markedly unproductive south of the MA-NH line?

Boston had 19.2" in March 2001. Just inland had over 30" with over 40" in the hills.

[tamarack]

Boston had 19.2" in March 2001. Just inland had over 30" with over 40" in the hills.

Farmington, Maine had 58.3", most for any month not containing an "F". (And 4th most in 119 yr record.)

[okie333]

JB said this morning that the worst of the winter is over in the east. The storm this weekend will be rain for the east coast, maybe clear back to State College it might rain. It gets cold next week but after that winter goes gang busters in the west for 3-4 weeks.

And remember what happened last time he said winter would be over...

Seriously, that cold air being shown in Canada on the Euro is insane (as per the 500mb heights)... any blocking and it all comes crashing down into the US. In other news, a stratospheric warming is occurring as we speak. I say give it till sometime between the 14th and 21st.

[donsutherland1]

Don, I've always enjoyed reading your stuff, and never ventured to ask an imby question before, but if you get a few moments, could you offer up any thoughts for RIC wrt the potential return of blocking late Feb/early Mar. That timeframe is getting awfully late in the game for winter weather this far south, but thought I would inquire anyway.

Many thanks in advance for your insights!

Golia 1w,

Richmond's best prospects for a return to wintry weather (snowstorm prospects) would be a combination of a negative AO and the GWO's being in Phases 3, 4, or 5.

Since 1950, the overwhelming majority of March snowfalls of 1" or more saw the AO <0 and/or the GWO being in Phases 3, 4, or 5. The benchmark storms were as follows:

March 5-6, 1962: AO at start: -4.302; GWO at start: Phase 4

March 30-April 1, 1964: AO at start: -1.407; GWO at start: Phase 3

March 26, 1971: AO at start: -0.236; GWO at start: Phase 3

March 1-2, 2009: AO at start: +2.296; GWO at start: Phase 5

[donsutherland1]

And remember what happened last time he said winter would be over...

Seriously, that cold air being shown in Canada on the Euro is insane (as per the 500mb heights)... any blocking and it all comes crashing down into the US. In other news, a stratospheric warming is occurring as we speak. I say give it till sometime between the 14th and 21st.

I suspect that thaw will last 1-2 weeks, no more (perhaps not too much longer than the late December-early January one). Already, the 18z GFS is tempering the extent of the thaw.

[A-L-E-X]

Golia 1w,

Richmond's best prospects for a return to wintry weather (snowstorm prospects) would be a combination of a negative AO and the GWO's being in Phases 3, 4, or 5.

Since 1950, the overwhelming majority of March snowfalls of 1" or more saw the AO <0 and/or the GWO being in Phases 3, 4, or 5. The benchmark storms were as follows:

March 5-6, 1962: AO at start: -4.302; GWO at start: Phase 4

March 30-April 1, 1964: AO at start: -1.407; GWO at start: Phase 3

March 26, 1971: AO at start: -0.236; GWO at start: Phase 3

March 1-2, 2009: AO at start: +2.296; GWO at start: Phase 5

Don, that 3/1-2/2009 event really stands out in this list.

[golia1w]

Golia 1w,

Richmond's best prospects for a return to wintry weather (snowstorm prospects) would be a combination of a negative AO and the GWO's being in Phases 3, 4, or 5.

Since 1950, the overwhelming majority of March snowfalls of 1" or more saw the AO <0 and/or the GWO being in Phases 3, 4, or 5. The benchmark storms were as follows:

March 5-6, 1962: AO at start: -4.302; GWO at start: Phase 4

March 30-April 1, 1964: AO at start: -1.407; GWO at start: Phase 3

March 26, 1971: AO at start: -0.236; GWO at start: Phase 3

March 1-2, 2009: AO at start: +2.296; GWO at start: Phase 5

Don,

Thank you for taking the time to look into the data to answer my inquiry. Your willingness to share your knowledge is a great gift to readers like me.

Cheers.

[Ottawa Blizzard]

Don, how does the rest of February look for ottawa in your opinion? Do we have another shot at a 0F day?

By the way, really dissapointed with EC. I really don't believe their 5" total for Ottawa today. I've received 6-8" I think.

[Snow Wizard]

Snow wiz I hope you get an epic period of snow and cold-- you deserve it after the winter you have had so far. However, around here, el ninos arent usually very good unless their weak. Last year was an anomaly. El ninos like 1994-95, 1997-98 and 2006-07 (mod to strong) usually feature milder than normal weather. If you had me pick, I would chose weak la nina or weak el nino over any other enso. The weaker the signal the better it is for us-- too warm or too cold and we're screwed (usually-- last winter and this winter have both been hugely anomalous.)

Things always even out. Even if we don't hit gold this winter, we probably will in the coming years. It still looks like we have a decent shot around Valentines Day.

It seems like weak ENSO is normally better for us also. That having been said there are some stronger La Ninas where we have gotten pounded.

[Snow Wizard]

Farmington, Maine had 58.3", most for any month not containing an "F". (And 4th most in 119 yr record.)

I think February is the only month that does contain an "F".

[Guest Pamela]

Probably last week in February/1st week in March. Similar to the timing of the late winter/early spring 2001 blocking.

Wasn't that blocking markedly unproductive south of the MA-NH line?

Only for the March 2001 "near miss" storm. The month, as a whole, was colder than normal in the eastern half of the U.S. Has the timing of the phasing associated with the March 2001 system been a little different, the Middle Atlantic region could have received a crippling snowfall.

Boston had 19.2" in March 2001. Just inland had over 30" with over 40" in the hills.

It was closer than that...Upton on Long Island measured 19.0" of snow in March 2001.

[donsutherland1]

Don, how does the rest of February look for ottawa in your opinion? Do we have another shot at a 0F day?

By the way, really dissapointed with EC. I really don't believe their 5" total for Ottawa today. I've received 6-8" I think.

February will probably come out cooler than normal at Ottawa. While I don't believe the temperature will stay at or below 0°F for a whole day, there can be some days with minimum temperatures at or below -25°C.

[Srain]

Good morning, Don. We certainly have an very 'Atypical' La Nina Month right now across TX...

[donsutherland1]

Good morning, Don. We certainly have an very 'Atypical' La Nina Month right now across TX...

I fully agree. I am hoping to see Houston pick up measurable snow for a record third consecutive winter.

[Quakertown needs snow]

I fully agree. I am hoping to see Houston pick up measurable snow for a record third consecutive winter.

wild stuff.

[donsutherland1]

Earlier in this thread, I suggested that the coming thaw would likely last 1 to no more than 2 weeks (probably starting around mid-month +/- a few days). Some quick additional thoughts:

1. After mid-month, the EPO is forecast to be declining. I suspect that it will go negative some time in the last week of the month (timing close to February-March 2001), opening the door again for some of the coldest air in the Northern Hemisphere to reload in Canada.

2. The signal for an AO+ is much weaker. Numerous ensemble members have the AO heading negative and/or staying negative prior to mid-month. I believe the redevelopment of blocking will ultimately lead to a strongly negative AO possibly in the last week of the month.

3. The objective analogs centered around 2/4 (GFS ensembles) are: 2/28/1956, 2/20/1976, 3/2/1974, 2/3/1965, 2/6/1979, 2/11/1999, 2/11/1994, 2/6/1959, 2/13/1967, and 2/3/1969. If one runs the composites, one finds:

Day 0 (centered around 2/14): Cool in the northeast, normal/mild in the Mid-Atlantic, warm in the Southeast; AO+

Day 5: The warmth is heading toward a peak with the entire eastern half of the U.S. above normal in temperatures, AO moving toward neutral

Day 10: A sustained cold pattern moves in; AO- and falling

4. Various runs of the operational GFS show colder air moving back toward or into the East at the end of the model's range.

Although the operational GFS might be rushing the cold back, the general idea is that the thaw should be temporary (no more than 1-2 weeks, perhaps around 10 days in duration). It will not be 3-5 weeks in duration, essentially meaning that winter is finished. Seasonal persistence with other "signals" of a dramatic shift in the pattern e.g., late December/early January, where such a shift proved of short-duration also argues for a temporary thaw, not an end to winter. Hence, at this point in time, I have added confidence that cities such as DCA, PHL, NYC, BOS, YOW, YUL, DTW, ORD will have overall cool anomalies for the month. Moreover, even with a "snow pause" in some areas during the lead up to the thaw and during the thaw, above to much above normal monthly snowfall still looks like a strong possibility for PHL, NYC, and BOS (BOS is already above 10" snowfall for the month and very likely en route to > 20" for the month). Finally, for the winter-starved Pacific Northwest, the duration of the thaw and perhaps a few days afterward could offer some periods of wintry weather. However, toward the end of the month (last week?) things could grow milder there.