• Member Statistics

    15,856
    Total Members
    7,904
    Most Online
    freestyle
    Newest Member
    freestyle
    Joined
Sign in to follow this  
donsutherland1

Winter Outlook 2018-2019

Recommended Posts

1 hour ago, donsutherland1 said:

Thanks Griteater.

Two factors give me cautious optimism about an ocean-atmosphere coupling at some point in January:

1. The forecast for a decline in the SOI to negative levels

2. The development of a PDO+ in December (daily values)

I don't believe the coupling will be immediate, and it could be preceded by dual Atlantic and Pacific blocking.

Finally, I don't think the Southeast has seen its last snowfall for this winter. Raleigh, Charlotte, Asheville, Greensboro, etc., should see more accumulations. Indeed, I believe Atlanta will experience accumulating snow at some point. 2004, if it provides insight, would be good for eastern North Carolina. Hopefully, places like Cape Hatteras and Wilmington will get a decent snowfall at some point.

 

Makes ya wonder if early December was a precedent...gotta wonder if the south sees more snow than the Mid-Atlantic this year...(more suppressed storms?)

  • Like 1

Share this post


Link to post
Share on other sites

After a record 6 consecutive days in Phase 4 with an amplitude of 2.000 or above, the MJO's amplitude fell to just below 2.000.

Previously, I noted that there were 3 prior Decembers that had 2 consecutive days meeting such criteria: December 2002, December 2006, and December 2015.

What followed in January and the January-February period in terms of the 500 mb patterns also held similarities to an El Niño/EPO-/AO- pattern. Below are the composite 500 mb anomalies for the January and January-February period:

Jan-Feb500mb-Anomalies-MJO12192018.jpg

Whether or not the current remarkable MJO data is providing a signal of significant winter weather ahead remains to be seen. In my view, taken as one piece of a larger puzzle, the signal is a good one.

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Occasionally, extreme MJO signals in one month can provide insight into the atmospheric pattern for the following month at 500 mb. The most extreme signal during November was Phase 4 with an amplitude of 1.8 or above for 4 consecutive days. Based on November cases with an MJO in Phase 4 with an amplitude of 1.8 or above for 4 or more days, one would get the following 500 mb anomalies.

December:

MJODec2018.jpg

Of course, one is not dealing with precision. Indeed, there was one notable difference (circled).

Here's what's being signaled for January and January-February

Jan-Feb500mb-Anomalies-MJO12192018.jpg

The last two runs of the EPS weeklies have been suggesting a move toward the above-depicted patterns.

All said, as December approaches its end, there continues to be reason to look forward to January if one enjoys winter weather (cold and snow), especially in the Great Lakes Region, southern New England, and Middle Atlantic states. The possibility of additional accumulating snow in the Southeast also remains on the table.

  • Like 3

Share this post


Link to post
Share on other sites
On 12/22/2018 at 5:33 PM, AfewUniversesBelowNormal said:

Continuing the theme, there is a +land torque signal in Northern Europe. Analogs show a poleward progression of the warmth. 

m9.gif

P0.png

Now things may finally get interesting for the Eastern 2/3rds. Just need the Pacific to cooperate. 

  • Like 1

Share this post


Link to post
Share on other sites

MJO update...

On December 17, I noted:

The MJO will likely move into Phase 5 at a fairly high amplitude toward the latter part of that timeframe. While some previous guidance had suggested a low amplitude outcome, a low amplitude appears very unlikely to verify over the next 10 days and probably longer.

The MJO moved into Phase 5 on December 18. It has now spent 7 consecutive days in Phase 5. 6 of those 7 days have had an amplitude of 2.000 or above. Overall, the MJO has remained in a very high amplitude.

The average amplitude for December 1-24 is 2.000. That would rank as the 3rd highest December amplitude on record if it is sustained through the remainder of the month. The record high amplitude is 2.181, which was set in 1996.

What this means going forward is that January will likely see a high amplitude MJO predominate. Thus, one should be wary of guidance shifting the MJO into a low amplitude phase until there is strong evidence to support such a move.

Here's how January followed the 10 highest amplitude cases in December:

Average days with an amplitude of 1.000 or above: 24.1
Median days with an amplitude of 1.000 or above: 26.5
Least days with an amplitude of 1.000 or above: 8, 2003
Most days with an amplitude of 1.000 or above: 31, 2004, 2018

Average days with an amplitude of 2.000 or above: 9.5
Median days with an amplitude of 2.000 or above: 10.0
Least days with an amplitude of 2.000 or above: 0, 2003
Most days with an amplitude of 2.000 or above: 25, 2004

Cases with 20 or more days having an amplitude of 1.000 or above: 8/10 (80%)
Cases with 10 or more days having an amplitude of 2.000 or above: 7/10 (70%)

A high amplitude MJO in the colder phases is likely as January progresses.

The MJO will very likely move into Phase 6 sometime in the December 27-30 period. Indeed, despite its MJO guidance which shows the MJO in Phase 5, the forecast 500 mb pattern at 144-168 hours on the EPS closely resembles the kind of Northern Hemisphere pattern that is seen during Phase 6 (high amplitude) in December or January. Some guidance keeps the MJO in Phase 5 until the start of January. Were that to happen, the MJO would spend its longest stretch on record for December or January in Phase 5. The record is 12 days during December 7-18, 1994.

The upcoming forecast period is also complicated by the now developing sudden stratospheric warming (SSW) event. That event could lead to a splitting of the polar vortex. Often, Phase 6 (high amplitude) in December or January is followed within about a week (+/- a few days) with a shift toward colder weather in the East. That first push of cold is typically part of a transition and a brief period of warmth then follows. Afterward, the cold returns and locks in for 2 weeks and sometimes 3. Some cases have featured a bout of severe cold during the sustained 2-3 week cold period.

The split of the polar vortex, should a split occur, could determine whether the cold period is sustained beyond 3 weeks prior to any reloading. 

Share this post


Link to post
Share on other sites

It's interesting how the EC is more so than the American cluster, representational (perhaps) of that theoretical forcing. 

Its almost like the GEFs fights 

  • Like 1

Share this post


Link to post
Share on other sites

This morning, the SOI bounced back into slightly positive values (+1.66) after having its first negative reading since December 9. A positive SOI is atypical for an ongoing El Niño event. The SOI has now been positive for 35 of the last 38 days. During December, the SOI has averaged +9.0. That is on track to be the highest positive December figure on record during an El Niño. During the 1969-70 El Niño, December had a +3.7 SOI average. Since 1950, there were only 3 positive December cases during an El Niño event: 1965, 1968, and 1969. All three cases were followed by -10.0 or below January averages. Despite the return to positive SOI values, the guidance still suggests the development of a sustained period of negative SOI values in coming days. Interestingly enough, all three prior SOI cases also featured severe Atlantic blocking (monthly AO average of -2.000 or below).

The MJO remained in Phase 5, reaching an extreme amplitude of 3.092. The MJO will likely move into Phase 6 sometime in the December 27-30 timeframe.

The ongoing sudden stratospheric warming (SSW) event has now seen stratospheric winds reverse at 1 mb. A reversal at 10 mb is likely to occur in the next day or two. It remains somewhat uncertain whether a reversal at 30 mb will take place.

Back to the near-term, the next two days will see another significant storm bring moderate or greater precipitation to parts of the East and Midwest. By the time the precipitation ends tomorrow night, both Green Bay and Sterling, VA will likely have set new annual precipitation records.

Another storm could bring rain to the Southeast and Middle Atlantic region on New Year's Eve or New Year's Day. There could be some frozen precipitation on the northern edge of the precipitation shield.

 

  • Thanks 3

Share this post


Link to post
Share on other sites
On 12/27/2018 at 8:37 AM, donsutherland1 said:

This morning, the SOI bounced back into slightly positive values (+1.66) after having its first negative reading since December 9. A positive SOI is atypical for an ongoing El Niño event. The SOI has now been positive for 35 of the last 38 days. During December, the SOI has averaged +9.0. That is on track to be the highest positive December figure on record during an El Niño. During the 1969-70 El Niño, December had a +3.7 SOI average. Since 1950, there were only 3 positive December cases during an El Niño event: 1965, 1968, and 1969. All three cases were followed by -10.0 or below January averages. Despite the return to positive SOI values, the guidance still suggests the development of a sustained period of negative SOI values in coming days. Interestingly enough, all three prior SOI cases also featured severe Atlantic blocking (monthly AO average of -2.000 or below).

The MJO remained in Phase 5, reaching an extreme amplitude of 3.092. The MJO will likely move into Phase 6 sometime in the December 27-30 timeframe.

The ongoing sudden stratospheric warming (SSW) event has now seen stratospheric winds reverse at 1 mb. A reversal at 10 mb is likely to occur in the next day or two. It remains somewhat uncertain whether a reversal at 30 mb will take place.

Back to the near-term, the next two days will see another significant storm bring moderate or greater precipitation to parts of the East and Midwest. By the time the precipitation ends tomorrow night, both Green Bay and Sterling, VA will likely have set new annual precipitation records.

Another storm could bring rain to the Southeast and Middle Atlantic region on New Year's Eve or New Year's Day. There could be some frozen precipitation on the northern edge of the precipitation shield.

 

1968-1969 was one of my main analogs and the best ENSO match imo. It was a relatively late blooming modoki that peaked near the cusp of weak-moderate, but had a similarly meager MEI...more representative of a marginally weak modoki, nearly ENSO neutral. Reflective of the struggle of the atmosphere and ocean to couple early on in the season. It also provided the impetus behind my decision to hold off the PNA early on in the season. 

Main difference being less NAO and more PNA in the JM aggregate this year relative to 1969, which was extreme.

  • Like 1

Share this post


Link to post
Share on other sites

The 12/28 MJO data is now in. The MJO remained in Phase 5 for the 11th consecutive day with an amplitude of 2.858. The amplitude is down from the 12/27 adjusted figure of 3.112.

The MJO will very likely move into Phase 6 in coming days at a high to very high amplitude. During the second week of January, it will likely progress into Phase 7. Initially, both the SOI and Arctic Oscillation (AO) will likely remain predominantly positive. However, as the MJO approaches and then moves into Phase 7, the SOI will likely go persistently negative and the AO will also become increasingly negative. The second half of January could see a predominant PNA+/AO- combination.

  • Like 1

Share this post


Link to post
Share on other sites

My winter thoughts are now under review for possible revision...

One of my fundamental assumptions concerned a central Pacific-based El Niño event. The latest weekly ENSO data reveal that the ongoing weak El Niño has largely been and remains a weak basin-wide event. The newest data show a Region 1+2 anomaly of +0.9°C vs. a Region 3.4 anomaly of +0.5°. I am currently reviewing the data for weak basin-wide events and will post any needed update in coming days.

My two ENSO-related assumptions going forward are:

1. The current El Niño event has largely peaked for winter 2018-19 (this doesn't preclude a moderate or stronger El Niño next winter)

2. The current El Niño event will wind up having been a basin-wide event, not a central Pacific-based one

Note: The exercise is about seeing whether there are material implications. An outcome should not be prejudged. The effects for February-March could well be immaterial. I need to examine the data before reaching conclusions.

  • Like 1
  • Thanks 1
  • Haha 1

Share this post


Link to post
Share on other sites

Winter forecast update: A bad forecast...

The latest data suggest that my initial pre-season idea of much above normal snowfall from Washington, DC to Boston will likely be substantially incorrect.

A major premise of the forecast was a central Pacific-based El Niño event. Instead, winter 2018-19 will wind up having seen a predominant very weak, basin-wide El Niño event. February now appears poised to see neutral-warm to very weak El Niño conditions (monthly ENSO 3.4 average of +0.35°C to +0.65°C). The distribution of ENSO region anomalies, their lower magnitude of warmth than what is usually seen during an El Niño event, and the broader extent of warm Pacific SSTAs likely contributed to a lack of coupling between the atmosphere and ocean that is typical with El Niño events. In a sense, winter 2018-19 has been like a neutral-warm winter masquerading as an El Niño winter.

The probability of snowfall of 1" or more in the Middle Atlantic and southern New England areas during these conditions is approximately half that for typical El Niño events.

In the Middle Atlantic region, including such cities as New York, Philadelphia, and Washington, only a small share of 6" or greater February snowstorms occurred when the ENSO Region 3.4 anomaly averaged 0.00°C to 0.69°C during February (1950-2018). In Philadelphia, just 5% of 6" or greater February snowstorms occurred with such ENSO conditions. In Washington, DC, the figure was 6%. In New York City, such conditions were present with 21% of 6" or greater snowstorms, but just 7% of 10" or greater snowstorms.

The spatial distribution of snowfall to date is consistent with a lower snowfall scenario across much of southern New England and the Middle Atlantic region.

Through January 31, Caribou had received a record 111.6" season-to-date snowfall. Only four prior winters registered 90" or more snow through January 31. All four cases featured much below normal snowfall in the northern Mid-Atlantic region.

Through January 31, Boston has received just 2.3" snow. There are seven prior cases where Boston had less than 6.0" snow through January 31. 71% saw < 20" seasonal snowfall in Boston and 86% saw < 15" seasonal snowfall in New York City.

Based on this latest data, my initial snowfall estimates, especially for the Mid-Atlantic and southern New England areas, will very likely be incorrect. More likely are the following amounts:

Albany: 60"-70" (through 2/1: 32.6")
Baltimore: 15"-25" (through 2/1: 10.6")
Binghamton: 95"-110" (through 2/1: 60.3")
Boston: 15"-30" (through 2/1: 2.3")
Chicago: 40"-50" (through 2/1: 33.2")
Detroit: 35"-50" (through 2/1: 21.4")
New York City: 15"-25" (through 2/1: 7.5")
Newark: 15"-25" (through 2/1: 7.3")
Philadelphia: 15"-25" (through 2/1: 7.4")
Providence: 20"-30" (through 2/1: 7.9")
Richmond: 15"-25" (through 2/1: 13.0")
Scranton: 40"-50" (through 2/1: 23.3")
Sterling: 20"-35" (through 2/1: 19.4"
Washington, DC: 15"-25" (through 2/1: 13.8")

What could lead to higher amounts:

1. Prolonged deep blocking (AO of -1.000 or below)
2. The MJO's persistently being in Phases 7, 8, 1, and 2 at a high amplitude
3. The ongoing gradually fading El Niño would strengthen appreciably by the middle of February

What could lead to lesser amounts:

1. The development of a persistently positive AO coupled with a strongly negative SOI
2. The MJO's persistently being in Phases 4, 5, and 6 at a high amplitude
3. The MJO's reaching an amplitude of 2.500 or above for an extended period of time

  • Thanks 1

Share this post


Link to post
Share on other sites
23 hours ago, donsutherland1 said:

Winter forecast update: A bad forecast...

The latest data suggest that my initial pre-season idea of much above normal snowfall from Washington, DC to Boston will likely be substantially incorrect.

A major premise of the forecast was a central Pacific-based El Niño event. Instead, winter 2018-19 will wind up having seen a predominant very weak, basin-wide El Niño event. February now appears poised to see neutral-warm to very weak El Niño conditions (monthly ENSO 3.4 average of +0.35°C to +0.65°C). The distribution of ENSO region anomalies, their lower magnitude of warmth than what is usually seen during an El Niño event, and the broader extent of warm Pacific SSTAs likely contributed to a lack of coupling between the atmosphere and ocean that is typical with El Niño events. In a sense, winter 2018-19 has been like a neutral-warm winter masquerading as an El Niño winter.

The probability of snowfall of 1" or more in the Middle Atlantic and southern New England areas during these conditions is approximately half that for typical El Niño events.

In the Middle Atlantic region, including such cities as New York, Philadelphia, and Washington, only a small share of 6" or greater February snowstorms occurred when the ENSO Region 3.4 anomaly averaged 0.00°C to 0.69°C during February (1950-2018). In Philadelphia, just 5% of 6" or greater February snowstorms occurred with such ENSO conditions. In Washington, DC, the figure was 6%. In New York City, such conditions were present with 21% of 6" or greater snowstorms, but just 7% of 10" or greater snowstorms.

The spatial distribution of snowfall to date is consistent with a lower snowfall scenario across much of southern New England and the Middle Atlantic region.

Through January 31, Caribou had received a record 111.6" season-to-date snowfall. Only four prior winters registered 90" or more snow through January 31. All four cases featured much below normal snowfall in the northern Mid-Atlantic region.

Through January 31, Boston has received just 2.3" snow. There are seven prior cases where Boston had less than 6.0" snow through January 31. 71% saw < 20" seasonal snowfall in Boston and 86% saw < 15" seasonal snowfall in New York City.

Based on this latest data, my initial snowfall estimates, especially for the Mid-Atlantic and southern New England areas, will very likely be incorrect. More likely are the following amounts:

Albany: 60"-70" (through 2/1: 32.6")
Baltimore: 15"-25" (through 2/1: 10.6")
Binghamton: 95"-110" (through 2/1: 60.3")
Boston: 15"-30" (through 2/1: 2.3")
Chicago: 40"-50" (through 2/1: 33.2")
Detroit: 35"-50" (through 2/1: 21.4")
New York City: 15"-25" (through 2/1: 7.5")
Newark: 15"-25" (through 2/1: 7.3")
Philadelphia: 15"-25" (through 2/1: 7.4")
Providence: 20"-30" (through 2/1: 7.9")
Richmond: 15"-25" (through 2/1: 13.0")
Scranton: 40"-50" (through 2/1: 23.3")
Sterling: 20"-35" (through 2/1: 19.4"
Washington, DC: 15"-25" (through 2/1: 13.8")

What could lead to higher amounts:

1. Prolonged deep blocking (AO of -1.000 or below)
2. The MJO's persistently being in Phases 7, 8, 1, and 2 at a high amplitude
3. The ongoing gradually fading El Niño would strengthen appreciably by the middle of February

What could lead to lesser amounts:

1. The development of a persistently positive AO coupled with a strongly negative SOI
2. The MJO's persistently being in Phases 4, 5, and 6 at a high amplitude
3. The MJO's reaching an amplitude of 2.500 or above for an extended period of time

Thanks Don.

I am hopeful for at least 1 good event before winter concludes. Perhaps we can pick out I.e. blizzard of 2006 or 2013.

Share this post


Link to post
Share on other sites
22 minutes ago, EastonSN+ said:

Thanks Don.

I am hopeful for at least 1 good event before winter concludes. Perhaps we can pick out I.e. blizzard of 2006 or 2013.

I do, too. Such an outcome is still possible especially if the pattern evolves toward sustained cold with an active subtropical jet stream after the upcoming warm period.

  • Thanks 2

Share this post


Link to post
Share on other sites

ENSO Regional Anomaly update...

Based on the latest ENSO Region data, the fading El Niño will not begin to resemble a central Pacific-based event this month. It will retain the characteristics of a basin-wide event. Overall, neutral-warm to possibly borderline El Niño conditions will be present.

The latest data is as follows:

Region 1+2 anomaly: +1.0°C (4-week moving average: +0.65°C)
Region 3.4 anomaly: +0.3°C (+0.40°C)

The last time ENSO Region 3.4 had anomalies of +0.50°C was during the week centered around January 16 when that region had an anomaly of +0.50°C.

Key points:

1. Winter 2018-19 saw a weak basin-wide El Niño event.
2. The El Niño has been fading and may well have yielded to generally neutral-warm conditions for the remainder of February.
3. There remains little supporting evidence to contradict that data showing that this event will retain basin-wide characteristics over at least the next several weeks. The month as a whole should feature average anomalies that remain consistent with a basin-wide event.

Share this post


Link to post
Share on other sites

Neutral-warm ENSO conditions continue to persist. For the week centered around February 6, the ENSO Region 1+2 anomaly was +0.30°C and the ENSO Region 3.4 anomaly was +0.40°. For the past 5 weeks, those anomalies have averaged +0.73°C and +0.40°C respectively. A continuation of neutral-warm ENSO conditions will tend to limit opportunities for big Middle Atlantic snowstorms during much or all of February. Larger snowfalls (6" or more) are far more likely across central/Upstate New York eastward across central/northern New England. Caribou will likely continue to pile up its seasonal total, as it continues to run just below the record-setting 2007-08 winter.

Share this post


Link to post
Share on other sites

Seasonal snowfall update:

Revised estimates from February 1 and snowfall through March 6:

Albany: 60"-70" (through 2/1: 32.6"; 3/6: 51.1")
Baltimore: 15"-25" (through 2/1: 10.6"; 3/6: 18.0")
Binghamton: 95"-110" (through 2/1: 60.3"; 3/6: 77.0")
Boston: 15"-30" (through 2/1: 2.3"; 3/6: 26.5")
Chicago: 40"-50" (through 2/1: 33.2"; 3/6: 41.5")
Detroit: 35"-50" (through 2/1: 21.4"; 3/6: 29.3")
New York City: 15"-25" (through 2/1: 7.5"; 3/6: 20.5")
Newark: 15"-25" (through 2/1: 7.3"; 3/6: 21.5")
Philadelphia: 15"-25" (through 2/1: 7.4"; 3/6: 17.1")
Providence: 20"-30" (through 2/1: 7.9"; 3/6: 28.3")
Richmond: 15"-25" (through 2/1: 13.0"; 3/6: 13.1")
Scranton: 40"-50" (through 2/1: 23.3"; 3/6: 31.1")
Sterling: 20"-35" (through 2/1: 19.4"; 3/6: 25.5")
Washington, DC: 15"-25" (through 2/1: 13.8"; 3/6: 16.9")

  • Like 1

Share this post


Link to post
Share on other sites

Update to the Revised Snowfall Estimates:

Albany: 60"-70" (through 2/1: 32.6"; through 4/3: 53.3")
Baltimore: 15"-25" (through 2/1: 10.6"; through 4/3: 18.3")
Binghamton: 95"-110" (through 2/1: 60.3"; through 4/3: 81.0")
Boston: 15"-30" (through 2/1: 2.3"; through 4/3: 27.4")
Chicago: 40"-50" (through 2/1: 33.2"; through 4/3: 41.6")
Detroit: 35"-50" (through 2/1: 21.4"; through 4/3: 31.3")
New York City: 15"-25" (through 2/1: 7.5"; through 4/3: 20.5")
Newark: 15"-25" (through 2/1: 7.3"; through 4/3: 22.0")
Philadelphia: 15"-25" (through 2/1: 7.4"; through 4/3: 17.1")
Providence: 20"-30" (through 2/1: 7.9"; through 4/3: 29.4")
Richmond: 15"-25" (through 2/1: 13.0"; through 4/3: 13.1")
Scranton: 40"-50" (through 2/1: 23.3"; through 4/3: 32.5")
Sterling: 20"-35" (through 2/1: 19.4"; through 4/3: 26.5")
Washington, DC: 15"-25" (through 2/1: 13.8"; through 4/3: 16.9")

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.