Medium Range Discussion Winter 2011-12

[Ottawa Blizzard]

Euro @day 10 is a caricature of how this winter transpired...exaggerated features and brings you a smile because of how ludicrous it looks. That's a nice omega block. >25C in parts of Ontario and Quebec?

Not unheard of. It hit 25C in Toronto in both March 1945 and 1946.

[bluewave]

It's pretty impressive to see the Euro and GFS indicating the potential for greater that 400m positive 500 mb

height anomalies in the 7-10 day time frame. I guess this is the new March climo.

[Nic]

It's pretty impressive to see the Euro and GFS indicating the potential for greater that 400m positive 500 mb

height anomalies in the 7-10 day time frame. I guess this is the new March climo.

How warm would it be if we had this pattern in July? 90s-100s?

[bluewave]

How warm would it be if we had this pattern in July? 90s-100s?

For March that is about the maximum height anomaly that I have seen here. I know back in early April 2010 the 582 dm line

got north of NYC. About the strongest ridge that I have seen over the lower 48 during the summer has

been 600 dm or a little higher this past summer and in earlier years which produced temps in excess of

100 degrees.

[donsutherland1]

Thoughts on Possible March 19-23, 2012 Outbreak of Heat:

For several days, the computer guidance has strongly suggested the potential for an anomalous outbreak of heat. Such guidance is in good agreement with patterns consistent with the forecast teleconnections. The GFS ensembles are showing 500 mb height anomalies and 850 mb temperatures reaching 2.0 or more standard deviations above normal. 500 mb heights are forecast to reach 300 or more meters above normal in a sizable portion of eastern North America.

If one examines two historic outbreaks of March heat (March 27-30, 1945 and March 27-31, 1998), one finds that the highest anomalies are forecast to be displaced to the north of those associated with the aforementioned cases. As a result, the potential exists for some exceptional readings in southern Ontario and southern Quebec.

At the same time, noteworthy heat could also be felt in parts of the Mid-Atlantic and Northeast region of the U.S. For example, the following range would be 2-3 standard deviations above the March 16-31, 1950-2011 mean high temperature in select cities:

Boston: 67°-77°

New York City: 72°-82°

Philadelphia: 75°-85°

Washington, DC: 79°-89°

At this time, one cannot rule out the possibility of backdoor fronts that could inhibit readings pushing into the higher-end of those boundaries in some areas, but it does appear likely that one or more days would see readings in the mid-70s or above in New York City and possibly Boston and perhaps 80° or above in Washington, DC and Philadelphia. Readings of 21°C to perhaps 24°C (70°F-75°F) on one or two days in Montreal and Toronto are a possibility. In an extreme case, readings could reach into the 80s even into southern New England, while Montreal and Toronto could see peak readings in the 24°C-26°C (75°F-79°F) range.

[Ottawa Blizzard]

Thoughts on Possible March 19-23, 2012 Outbreak of Heat:

For several days, the computer guidance has strongly suggested the potential for an anomalous outbreak of heat. Such guidance is in good agreement with patterns consistent with the forecast teleconnections. The GFS ensembles are showing 500 mb height anomalies and 850 mb temperatures reaching 2.0 or more standard deviations above normal. 500 mb heights are forecast to reach 300 or more meters above normal in a sizable portion of eastern North America.

If one examines two historic outbreaks of March heat (March 27-30, 1945 and March 27-31, 1998), one finds that the highest anomalies are forecast to be displaced to the north of those associated with the aforementioned cases. As a result, the potential exists for some exceptional readings in southern Ontario and southern Quebec.

At the same time, noteworthy heat could also be felt in parts of the Mid-Atlantic and Northeast region of the U.S. For example, the following range would be 2-3 standard deviations above the March 16-31, 1950-2011 mean high temperature in select cities:

Boston: 67°-77°

New York City: 72°-82°

Philadelphia: 75°-85°

Washington, DC: 79°-89°

At this time, one cannot rule out the possibllity of backdoor fronts that could inhibit readings pushing into the higher-end of those boundaries in some areas, but it does appear likely that one or more days would see readings in the mid-70s or above in New York City and possibly Boston and perhaps 80° or above in Washington, DC and Philadelphia. Readings of 21°C to perhaps 24°C (70°F-75°F) on one or two days in Montreal and Toronto are a possibility. In an extreme case, readings could reach into the 80s even into southern New England, while Montreal and Toronto could see peak readings in the 24°C-26°C (75°F-79°F) range.

Don, it'll be interesting to see if, like in 1945, below average temperatures move in for April and May. A frost would be bad news in April.

Also, with a fading La Nina, as in spring 1976, could it be that the northeast has not seen the last of snow? I don't mean a major storm, but an inch or two of snow. Often when one gets an early seen heatwave, it is followed by a major cooldown .

[donsutherland1]

Don, it'll be interesting to see if, like in 1945, below average temperatures move in for April and May. A frost would be bad news in April.

Also, with a fading La Nina, as in spring 1976, could it be that the northeast has not seen the last of snow? I don't mean a major storm, but an inch or two of snow. Often when one gets an early seen heatwave, it is followed by a major cooldown .

I agree. However, at this point, about 60% of my preliminary analogs are showing warm anomalies for April, including in the Toronto-Ottawa areas, though the warm anomalies are less expansive than what had been seen during February and so far during March. A key assumption is that the La Niña gives way to neutral ENSO conditions. The coolest idea that is showing up at present is 1997, but for now 1997 is an outlier. I don't believe the current La Niña will give way to an El Niño conditions during late April as happened in 1997.

[easternsnowman]

I agree. However, at this point, about 60% of my preliminary analogs are showing warm anomalies for April, including in the Toronto-Ottawa areas, though the warm anomalies are less expansive than what had been seen during February and so far during March. A key assumption is that the La Niña gives way to neutral ENSO conditions. The coolest idea that is showing up at present is 1997, but for now 1997 is an outlier. I don't believe the current La Niña will give way to an El Niño conditions during late April as happened in 1997.

We don't want el nino developing too early, look at what happened in 1997!

[donsutherland1]

We don't want el nino developing too early, look at what happened in 1997!

I don't believe we'll see anything like the 1997-98 El Niño, either in terms of an explosive onset during which El Niño conditions were present by late April or magnitude. Aside from the current guidance, a number of additional reasons follow:

1. The PDO went positive in January 1997 and grew increasingly positive. Prior to then a PDO+ also predominated, with only a few weekly negative months. The lowest winter 1996-97 PDO reading was -0.03 (December 1996). The lowest winter 2011-12 PDO was -1.79 (December 2011). The absence of a strong PDO- regime might have been a catalyst for a runaway shift to a strong El Niño. A PDO- may act as a brake so to speak.

2. The SOI had a brief burst of notable negative readings in January (falling to -20.89 on 1/5/97 and then -21.68 on 1/12/97) Afterward, a long period of SOI+ persisted (just 1 of February's 28 days were negative). However, the proverbial dam broke on March 9. The SOI was negative for 21 of the last 23 days in March. In the latter part of the month, it regularly reached new annual lows: -23.08 on 3/23, -23.92 on 3/24, -28.17 on 3/25, -30.50 on 3/26, and -38.04 on 3/27). In contrast, 2012's lowest SOI was -16.86 on January 8. Nothing yet can be said whether the SOI will surpass that reading later this month, but a cautious look at the ensemble guidance seems to suggest that odds are against a 1997-style plunge in the SOI.

3. In March 1997, the SOI averaged -8.5 and the SOI was negative on 65% of the days. To date, the SOI has averaged +5.3 this month and it has been negative on 31% of the days.

4. A period of high amplitude (2 or above) for the MJO commenced on 2/21/1997. The ongoing high amplitude (2 or above) MJO began on 2/28 this year. Each of those cases saw the amplitude remain below 3. On March 8, 1997, a sustained period of super high amplitude (3 or above) began and 21 of the closing 24 (88%) days of March saw the amplitude at 3 or above. That super high amplitude coincided very closely with the severe drop in the SOI (dramatic weakening in the easterlies). The ensemble guidance shows a continuation of the current amplitude regime with no strong support for the onset of a super amplitude regime.

Finally, a caveat remains in order. At this time of year, ENSO guidance has among its lowest verification scores.

[CoastalWx]

It's possible some NE cities will be in the 80s next week. Compressional heating ahead of front and the heat plume of 12C at 850 may make NYC and BOS have the highest temps. As always..BD front may ruin the party, but the potential is there.

Down the road, the weeklies show some ridging developing near AK and Greenland. It's enough to open the door possible to more colder temps and perhaps cutoffs bothering New England area by the end of the month.

[easternsnowman]

I don't believe we'll see anything like the 1997-98 El Niño, either in terms of an explosive onset during which El Niño conditions were present by late April or magnitude. Aside from the current guidance, a number of additional reasons follow:

1. The PDO went positive in January 1997 and grew increasingly positive. Prior to then a PDO+ also predominated, with only a few weekly negative months. The lowest winter 1996-97 PDO reading was -0.03 (December 1996). The lowest winter 2011-12 PDO was -1.79 (December 2011). The absence of a strong PDO- regime might have been a catalyst for a runaway shift to a strong El Niño. A PDO- may act as a brake so to speak.

2. The SOI had a brief burst of notable negative readings in January (falling to -20.89 on 1/5/97 and then -21.68 on 1/12/97) Afterward, a long period of SOI+ persisted (just 1 of February's 28 days were negative). However, the proverbial dam broke on March 9. The SOI was negative for 21 of the last 23 days in March. In the latter part of the month, it regularly reached new annual lows: -23.08 on 3/23, -23.92 on 3/24, -28.17 on 3/25, -30.50 on 3/26, and -38.04 on 3/27). In contrast, 2012's lowest SOI was -16.86 on January 8. Nothing yet can be said whether the SOI will surpass that reading later this month, but a cautious look at the ensemble guidance seems to suggest that odds are against a 1997-style plunge in the SOI.

3. In March 1997, the SOI averaged -8.5 and the SOI was negative on 65% of the days. To date, the SOI has averaged +5.3 this month and it has been negative on 31% of the days.

4. A period of high amplitude (2 or above) for the MJO commenced on 2/21/1997. The ongoing high amplitude (2 or above) MJO began on 2/28 this year. Each of those cases saw the amplitude remain below 3. On March 8, 1997, a sustained period of super high amplitude (3 or above) began and 21 of the closing 24 (88%) days of March saw the amplitude at 3 or above. That super high amplitude coincided very closely with the severe drop in the SOI (dramatic weakening in the easterlies). The ensemble guidance shows a continuation of the current amplitude regime with no strong support for the onset of a super amplitude regime.

Finally, a caveat remains in order. At this time of year, ENSO guidance has among its lowest verification scores.

Thanks Don that is more reassuring! Of course our best hope is for a weak el nino next year.

[Snowstorms]

I don't believe we'll see anything like the 1997-98 El Niño, either in terms of an explosive onset during which El Niño conditions were present by late April or magnitude. Aside from the current guidance, a number of additional reasons follow:

1. The PDO went positive in January 1997 and grew increasingly positive. Prior to then a PDO+ also predominated, with only a few weekly negative months. The lowest winter 1996-97 PDO reading was -0.03 (December 1996). The lowest winter 2011-12 PDO was -1.79 (December 2011). The absence of a strong PDO- regime might have been a catalyst for a runaway shift to a strong El Niño. A PDO- may act as a brake so to speak.

2. The SOI had a brief burst of notable negative readings in January (falling to -20.89 on 1/5/97 and then -21.68 on 1/12/97) Afterward, a long period of SOI+ persisted (just 1 of February's 28 days were negative). However, the proverbial dam broke on March 9. The SOI was negative for 21 of the last 23 days in March. In the latter part of the month, it regularly reached new annual lows: -23.08 on 3/23, -23.92 on 3/24, -28.17 on 3/25, -30.50 on 3/26, and -38.04 on 3/27). In contrast, 2012's lowest SOI was -16.86 on January 8. Nothing yet can be said whether the SOI will surpass that reading later this month, but a cautious look at the ensemble guidance seems to suggest that odds are against a 1997-style plunge in the SOI.

3. In March 1997, the SOI averaged -8.5 and the SOI was negative on 65% of the days. To date, the SOI has averaged +5.3 this month and it has been negative on 31% of the days.

4. A period of high amplitude (2 or above) for the MJO commenced on 2/21/1997. The ongoing high amplitude (2 or above) MJO began on 2/28 this year. Each of those cases saw the amplitude remain below 3. On March 8, 1997, a sustained period of super high amplitude (3 or above) began and 21 of the closing 24 (88%) days of March saw the amplitude at 3 or above. That super high amplitude coincided very closely with the severe drop in the SOI (dramatic weakening in the easterlies). The ensemble guidance shows a continuation of the current amplitude regime with no strong support for the onset of a super amplitude regime.

Finally, a caveat remains in order. At this time of year, ENSO guidance has among its lowest verification scores.

Strong ENSO anomalies occur every 7-10 years and the last strong El Nino was in 2009-10, meaning the next Strong El Nino will most likely occur after 2015. 1997-98 was the last strong Nino before 09-10.

BTW if you observe the latest weeklies, you'd notice decent cooling as the Low Level Easterlies pick up once again.

29FEB2012 27.3 1.1 27.1 0.4 26.4-0.5 27.2-0.8

07MAR2012 26.6 0.4 26.7-0.2 26.4-0.6 27.3-0.8

The Global AAM remains near record lows indicating a La Nina like atmosphere still present globally despite a Weak ENSO anomaly and that maybe a indicator this Nina is not done yet. Latest SOI value is +17.95.

http://www.atmos.albany.edu/student/carl/weather/timeLon/u.anom.30.5S-5N.png

Low Level Easterlies are expected to continue. Lets see what ends up happening thru this Spring. If it does turn out to be a La Nina, 75-76, 00-01 and 56-57 are decent analogues to analyze but two Winters are never alike. The back-back Nina's have killed of the STJ so the prospects of any strong storms will likely be minimal if next year is a Nina unless the MJO progresses a bit more next Winter.

[bluewave]

It's possible some NE cities will be in the 80s next week. Compressional heating ahead of front and the heat plume of 12C at 850 may make NYC and BOS have the highest temps. As always..BD front may ruin the party, but the potential is there.

Down the road, the weeklies show some ridging developing near AK and Greenland. It's enough to open the door possible to more colder temps and perhaps cutoffs bothering New England area by the end of the month.

It's looking like that this will be the first shot at March 80's for several locations since 1998 following that mild winter.

This time around many locations will get to experience one of their warmest Marches to go along with the potential

record daily highs.

[CoastalWx]

It's looking like that this will be the first shot at March 80's for several locations since 1998 following that mild winter.

This time around many locations will get to experience one of their warmest Marches to go along with the potential

record daily highs.

Sometimes these warm shots trend shorter as we get closer to the actual date. The GFS all of the sudden got cold front happy next week. Either way 1-2 very mild -warm days seem possible, but we are a week out here.

[bluewave]

Sometimes these warm shots trend shorter as we get closer to the actual date. The GFS all of the sudden got cold front happy next week. Either way 1-2 very mild -warm days seem possible, but we are a week out here.

It looks like the big expansion of the ridge will at least give us a window of opportunity for a day or maybe more

above 80 before the front comes through. The overall departures are going to be impressive on the month as

there will be 60's and 70's on the other days along with mild overnight lows.

[donsutherland1]

March 24-31, 2012 Thoughts:

The first month of spring appears poised to end on another warm note for much of North America...

Below are the teleconnection anomalies assume ENSO Region 3.4 anomalies in the -0.8°C to -0.2°C range, an AO in the +1.00 to +2.50 range, and PNA in the -0.50 to 0.00 range.

The circled region will likely see warm anomalies based on a combination of ensemble guidance, the observed decadal temperature trends, and persistence.

Finally, it is possible that some cool anomalies could be located, mainly along the West Coast. Alaska and adjacent sections of Canada appear likely to be colder than normal.

[Nic]

March 24-31, 2012 Thoughts:

The first month of spring appears poised to end on another warm note for much of North America...

Below are the teleconnection anomalies assume ENSO Region 3.4 anomalies in the -0.8°C to -0.2°C range, an AO in the +1.00 to +2.50 range, and PNA in the -0.50 to 0.00 range.

The circled region will likely see warm anomalies based on a combination of ensemble guidance, the observed decadal temperature trends, and persistence.

Finally, it is possible that some cool anomalies could be located, mainly along the West Coast. Alaska and adjacent sections of Canada appear likely to be colder than normal.

Hopefully it continues to mid April I do not want to see a April 2007 repeat with 19F.

[donsutherland1]

Today, Seattle picked up 0.9" snow. That another accumulating snow occurred this winter season is consistent with past experience when January experienced a major snowstorm in the Seattle area.

From #658 in this thread:

This morning, in the wake of Seattle's biggest snowstorm in nearly 11 years, the question for the Pacific Northwest is whether there will be any more snow this winter. Odds strongly favor additional snow in and around the Seattle area. Additional snow fell following 8 of the 9 (89%) previous 6" or greater January storms. Additional snow fell in all four previous January La Niña cases. Sometimes, as was the case following the first two storms in January 1950 and first two storms in January 1969, the additional snowfall was significant.

The additional snowfall statistic is now up to 9/10 (90%) cases, including 5/5 (100%) January La Niña cases.

[Snowlover76]

Hopefully it continues to mid April I do not want to see a April 2007 repeat with 19F.

I hope and pray that it ends REALLY FAST!!!

[Geos]

Hopefully it continues to mid April I do not want to see a April 2007 repeat with 19F.

I hope and pray that it ends REALLY FAST!!!

Typically these warmups don't last in March. Freezing temps always happen around here in April. I agree with snowlover - let's have an early end to this warmup and save the warmer air for the last 1/2 of April and May. The 2007 warmup in March was enough to get fruit and other flowering trees to send out buds, only to be frozen off in April. Wasn't much fruit in western Lakes that summer. I remember the neighbors Magnolia tree budding out at the end of the warmup, then the cold came and the buds and petals that had started, fell off onto the fresh 6" of snow we had on the 11th!

0z GFS shows a little taste of winter coming back into the lakes for the 27th and 28th. Maybe even some snow for Minnesota.

[Nic]

Typically these warmups don't last in March. Freezing temps always happen around here in April. I agree with snowlover - let's have an early end to this warmup and save the warmer air for the last 1/2 of April and May. The 2007 warmup in March was enough to get fruit and other flowering trees to send out buds, only to be frozen off in April. Wasn't much fruit in western Lakes that summer. I remember the neighbors Magnolia tree budding out at the end of the warmup, then the cold came and the buds and petals that had started, fell off onto the fresh 6" of snow we had on the 11th!

0z GFS shows a little taste of winter coming back into the lakes for the 27th and 28th. Maybe even some snow for Minnesota.

It can stay in Minnesota. 46 did not get too cold here after the warmup in April just a few nights one 32 degree night that is not too bad. Although north of 1-70 it was probably much worse.That is the best hope at this point the warmup will not end with lows in the mid 20s.

1946-

[Snowstorms]

This warmth is just incredible. Thru yesterday, were only 2.7C away from 1945 and its only the 14th today lol

http://www.weatheroffice.gc.ca/forecast/city_e.html?on-143&unit=i

The fact that our normal high temp is 41F and normal low is 25F is just astounding. The coldest overnight low is 41F LOL.

[Geos]

It can stay in Minnesota. 46 did not get too cold here after the warmup in April just a few nights one 32 degree night that is not too bad. Although north of 1-70 it was probably much worse.That is the best hope at this point the warmup will not end with lows in the mid 20s.

1946-

The western lakes got the brunt of the cold blast that April. There is always freezing temperatures here in April, no matter how warm it is in March. Last several years there has been at least 2 days in May with frost. With regards to the plants, I hope a wind off the lake (at times) will slow down the buds so they don't end up getting damaged later. Of course that won't help plants further west of here.

I guess will have to see what happens. Looks mild through the 25th.

Just noticed this on the 18z GFS.

[donsutherland1]

Update on the Upcoming March 19-23, 2012 Warmth...

The ensemble guidance is still showing 500 mb anomalies and 850 temperature anomalies peaking at 2-3 standard deviations above normal, with the most extreme anomalies being focused on the Great Lakes region, particularly across parts of Michigan into Ontario.

Given the good consistency in the guidance, I still believe that it is likely that one or more days during the timeframe could see readings in the mid-70s or above in New York City and possibly Boston and perhaps 80° or above in Washington, DC and Philadelphia. Readings of 21°C to perhaps 24°C (70°F-75°F) on one or two days in Montreal and Toronto are a possibility. In an extreme case, readings could reach into the 80s even into southern New England, while Montreal and Toronto could see peak readings in the 24°C-26°C (75°F-79°F) range.

The 3/15 0z MEX MOS figures for the maximum temperature are as follows:

Boston: 68° (already in the 2-3 standard deviation above normal range)

Detroit: 75°

Montreal: 65° (18.3°C)

New York City: 70°

Philadelphia: 70°

Toronto: 66° (18.9°C)

Washington, DC: 74°

Windsor: 73° (22.8°C)

The 0z MOS does not yet extend to 3/23. There is also a possibility that the period of exceptional warmth could extend through Saturday, March 24.

[NJwinter23]

Don,

Any thoughts on April? I'm inclined to bring a cooler than average anomaly into the SE for at least the first half of the month, perhaps trending back to normal in the northeast. I'm just not sure if appreciable cold anomalies can make it into the eastern U.S. even if a decent trough returns, due to the exceptional warmth upcoming. I mean, this looks like it could wipe out the snow cover right up to Hudson's Bay. I'm wondering if it could even snow in April across New England.

[donsutherland1]

Don,

Any thoughts on April? I'm inclined to bring a cooler than average anomaly into the SE for at least the first half of the month, perhaps trending back to normal in the northeast. I'm just not sure if appreciable cold anomalies can make it into the eastern U.S. even if a decent trough returns, due to the exceptional warmth upcoming. I mean, this looks like it could wipe out the snow cover right up to Hudson's Bay. I'm wondering if it could even snow in April across New England.

Earlier I took a first look at April. The eastern quarter of the CONUS was above normal, though the Gulf States were normal to cooler than normal. There was a lot of variability among the analogs (~60% warm, 40% cold). I'll have another look at the data early next week. One analog that came up was 1997 (cool almost nationwide), but I don't see the ENSO going warm as rapidly as 1997, so I'm treating that analog as an outlier.

[donsutherland1]

Updated MOS numbers 3/15 12z vs. 3/15 0z:

Boston: 70° vs. 68°

Detroit: 76° vs. 75°

Montreal: 68° (20.0°C) vs. 65° (18.3°C)

New York City: 72° vs. 70°

Philadelphia: 73° vs. 70°

Toronto: 71° (21.7°C) vs. 66° (18.9°C)

Washington, DC: 73° vs. 74°

Windsor: 72° (22.2°C) vs. 73° (22.8°C)

[Ottawa Blizzard]

Updated MOS numbers 3/15 12z vs. 3/15 0z:

Boston: 70° vs. 68°

Detroit: 76° vs. 75°

Montreal: 68° (20.0°C) vs. 65° (18.3°C)

New York City: 72° vs. 70°

Philadelphia: 73° vs. 70°

Toronto: 71° (21.7°C) vs. 66° (18.9°C)

Washington, DC: 73° vs. 74°

Windsor: 72° (22.2°C) vs. 73° (22.8°C)

Don, at this rate, it looks like we could beat 1945 and 1946 for warmth in Toronto. What are your updated thoughts on this?

[donsutherland1]

Don, at this rate, it looks like we could beat 1945 and 1946 for warmth in Toronto. What are your updated thoughts on this?

If Toronto can have a mean temperature of +7.1°C for the remainder of this month, Toronto would eclipse the +5.2°C mean temperature for March 1946. Through March 14, the mean temperature was +2.9°C. Prospects for such an outcome are increasing, as record warmth is possible on a number of upcoming days.

[Ottawa Blizzard]

If Toronto can have a mean temperature of +7.1°C for the remainder of this month, Toronto would eclipse the +5.2°C mean temperature for March 1946. Through March 14, the mean temperature was +2.9°C. Prospects for such an outcome are increasing, as record warmth is possible on a number of upcoming days.

Judging from the outlook for this week, Toronto could be on its way to crushing the 1945 and 1946 records!