winter forecast 2019-20: cold comes early but leaves mid-January

[Roger Smith]

Here's a brief summary of my research findings for the 2019-20 winter LRF.

This looks like being a "front-loaded" winter that changes from a cold eastern regime in Nov-Dec and possibly early January, to a very mild eastern regime for later parts of January and most of February. This trend would likely continue into March, so a lot of the traditional storm opportunity period for the east coast may be removed from play. However, a front-loaded winter can produce its own brand of memorable winter weather too. 

Expect the circulation to be dominated by high amplitude ridge-trough coupling with a gradual retrograde component that will cause the mid-winter reversal. 

The first part of the winter will see frequent incursions of very cold air into the Midwest, Ohio valley, southeastern U.S. and east coast. The storm track will likely run up the coast at times and sometimes from the eastern Gulf to the Great Lakes. Some heavy snowfalls are likely in the eastern half of the U.S. in November and December. Out west it should be relatively dry with a little less than normal coastal rain and mountain snow in general. 

Around early to mid January this pattern will retrograde allowing the storm track to shift to the plains states towards the upper Great Lakes. Temperatures will rebound to above normal values and there could be a blowtorch effect for the east coast at times. Heavy snow in this phase (mid-Jan into Feb-Mar) would be most likely from higher parts of the desert southwest into northern NM, Colorado then northeast to Minnesota. This part of the winter might see anomalous cold, dry spells over the PNW and western Canada with diminished coastal rainfall and some mountain snows but not enough to reach normal values. Analogues include (Jan) 1932, 1937 and 1950, 1968 and 1969, 1986 and 1990..

This pattern might relax at times to allow modified cold to seep into the Midwest and Great Lakes, setting up a secondary storm track from Missouri to upstate New York. This would not cut off the mild air from the coast but might lead to heavy mixed falls inland from Kentucky to northern New England. 

Because the energy level will be high for storm development, some memorable storms could occur. During the colder first half of the winter one or two very heavy snowfalls might be expected in the I-95 corridor. Major blizzards might be encountered later in the winter in the central and northern plains states.

Looking forward to the other forecasts and won't be too surprised if there would be quite a range of options, as the high-amplitude factor means high risk-reward in terms of placement of features and evolution. In other words, confidence not rated as high going into this, but that's the scenario that my research model has indicated. 

Best bet for winter storm on the east coast is Dec 25-26. Best bet for record highs in the warmer portion of winter is mid to late February.

[raindancewx]

I used different analogs, but I agree on the mid-winter warm up for the East. The years I picked had the NAO negative in December, neutral in January, then positive February.

More generally, the big warm Sept-Oct periods in the East usually feature some kind of late warm up in winter it seems like.

My pure analogs are actually very cold in December, but I think it will be warmer (somewhat) in the East with Nino 4 near record warmth than the raw blend.

I also agree on a pattern with some huge storms - I think there are somewhere between 3-5 historic storms Nov-Mar nationally, it's just where? Dorian, the recent record blizzard in the NW a few weeks ago, and the relatively rapid shifts in temperature profiles in the Fall all hint at it. I think the culprit for the cold shifting positions is likely the changes in the PDO. It appears to be heading negative, with the cold ring next to Alaska developing around a warm tongue east of Japan right now. The Modoki El Nino look right now is also likely to break down, which favors the West later, as you say.

[raindancewx]

I wanted to bump this - Roger's idea of an eastern blowtorch mid-January from mid-October looks quite good. The MJO going into phase five at high amplitude should be good for NM/CO snow pack at least in mid-January.

On 10/16/2019 at 9:22 PM, raindancewx said:

I used different analogs, but I agree on the mid-winter warm up for the East. The years I picked had the NAO negative in December, neutral in January, then positive February.

More generally, the big warm Sept-Oct periods in the East usually feature some kind of late warm up in winter it seems like.

My pure analogs are actually very cold in December, but I think it will be warmer (somewhat) in the East with Nino 4 near record warmth than the raw blend.

I also agree on a pattern with some huge storms - I think there are somewhere between 3-5 historic storms Nov-Mar nationally, it's just where? Dorian, the recent record blizzard in the NW a few weeks ago, and the relatively rapid shifts in temperature profiles in the Fall all hint at it. I think the culprit for the cold shifting positions is likely the changes in the PDO. It appears to be heading negative, with the cold ring next to Alaska developing around a warm tongue east of Japan right now. The Modoki El Nino look right now is also likely to break down, which favors the West later, as you say.

Here is what the US looks like to date..."before" the warm part of the pattern arrives. As I've noted elsewhere, the model pattern (CFS/Canadian/CPC) for January 2020 in the US looks a lot like mid-Sept to mid-Oct...as I hinted at 10/16.

Nashville: (8.0 x 31) + (3 x 11.3) / 34 --> +8.3F

Billings: (6.6 x 31) + (3 x 12.3) / 34 --> +7.1F

Chicago: (6.3 x 31) + (3 x 13.0) / 34 --> +6.9F

Kansas City: (6.4 x 31) + (3 x 12.3) / 34 --> 6.9F

Jacksonville: (5.4 x 31) + (3 x 9.7) / 34 --> +6.3F

Atlanta: (5.9 x 31) + (3 x 7.3) /34 --> +6.0F

Detroit: (5.0 x 31) + (3 x 13.0) / 34 --> +5.7F

Amarillo: (5.0 x 31) + (3 x 5.0) / 34 --> +5.0F

New Orleans: (4.0 x 31) + (3 x 10.3) / 34 --> +4.6F

Seattle: (3.9 x 31) + (3 x 6.2) / 34 --> +4.1F

Salt Lake City: (3.6 x 31) + (3 x 5.5) / 34 --> +3.8F

Denver: (3.7 x 31) + (3 x 3.3) / 34 --> +3.7F

Pittsburgh: (3.0 x 31) + (3 x 10.7) / 34 --> +3.7F

Richmond: (3.0 x 31) + (3 x 9.5) / 34 --> +3.6F

Houston: (3.2 x 31) + (3 x 6.0) / 34 --> +3.4F

Boston: (2.5 x 31) + (3 x 13) / 34 --> +3.4F

San Francisco: (2.9 x 31) + (3 x 3.0) / 34 --> +2.9F

Oklahoma City: (2.3 x 31) + (3 x 7.0) / 34 --> +2.7F

San Diego:(2.2 x 31) + (3 x 2.4) / 34 --> +2.2F

Philadelphia: (1.2 x 31) + (3 x 5.5) / 34 --> +1.6F

Albuquerque: (1.3 x 31) + (3 x -2.2) / 34 --> +1.0F

Flagstaff: (-0.2 x 31) + (3 x -4.0) / 34 --> -0.5F

[LibertyBell]

11 hours ago, raindancewx said:

I wanted to bump this - Roger's idea of an eastern blowtorch mid-January from mid-October looks quite good. The MJO going into phase five at high amplitude should be good for NM/CO snow pack at least in mid-January.

Here is what the US looks like to date..."before" the warm part of the pattern arrives. As I've noted elsewhere, the model pattern (CFS/Canadian/CPC) for January 2020 in the US looks a lot like mid-Sept to mid-Oct...as I hinted at 10/16.

Nashville: (8.0 x 31) + (3 x 11.3) / 34 --> +8.3F

Billings: (6.6 x 31) + (3 x 12.3) / 34 --> +7.1F

Chicago: (6.3 x 31) + (3 x 13.0) / 34 --> +6.9F

Kansas City: (6.4 x 31) + (3 x 12.3) / 34 --> 6.9F

Jacksonville: (5.4 x 31) + (3 x 9.7) / 34 --> +6.3F

Atlanta: (5.9 x 31) + (3 x 7.3) /34 --> +6.0F

Detroit: (5.0 x 31) + (3 x 13.0) / 34 --> +5.7F

Amarillo: (5.0 x 31) + (3 x 5.0) / 34 --> +5.0F

New Orleans: (4.0 x 31) + (3 x 10.3) / 34 --> +4.6F

Seattle: (3.9 x 31) + (3 x 6.2) / 34 --> +4.1F

Salt Lake City: (3.6 x 31) + (3 x 5.5) / 34 --> +3.8F

Denver: (3.7 x 31) + (3 x 3.3) / 34 --> +3.7F

Pittsburgh: (3.0 x 31) + (3 x 10.7) / 34 --> +3.7F

Richmond: (3.0 x 31) + (3 x 9.5) / 34 --> +3.6F

Houston: (3.2 x 31) + (3 x 6.0) / 34 --> +3.4F

Boston: (2.5 x 31) + (3 x 13) / 34 --> +3.4F

San Francisco: (2.9 x 31) + (3 x 3.0) / 34 --> +2.9F

Oklahoma City: (2.3 x 31) + (3 x 7.0) / 34 --> +2.7F

San Diego:(2.2 x 31) + (3 x 2.4) / 34 --> +2.2F

Philadelphia: (1.2 x 31) + (3 x 5.5) / 34 --> +1.6F

Albuquerque: (1.3 x 31) + (3 x -2.2) / 34 --> +1.0F

Flagstaff: (-0.2 x 31) + (3 x -4.0) / 34 --> -0.5F

How do you think the horrendous events occurring in Australia and the record warmth in the waters north of there will impact your forecast going forward?  Even more extreme warmth than you expected?

 

[Roger Smith]

I assume you are asking raindancewx that question, but from my point of view it would not change the outlook.

My timing was a bit off, the warming trend in the east began around mid-December rather than early in January.

That mid-month reversal happened in other years, notably 1875, 1889, 1936, 1949 and 1964. Most of those were followed by very mild Januaries and first half of Februaries in the east. A general trend towards colder than normal weather late February and March could be noted in those same years. 

January 1950 was particularly warm in the east and set records in the 70s on the east coast towards the end of the month (25th-26th). Although the lead-in was somewhat different, 1905-06, 1908-09 and 1915-16 as well as 1966-67 converged on the same late January warm signal. Most of those turned a lot colder in February.

I think the odds are pretty good that winter 2019-20 will feature a core warm spell with bookend cold periods, and the second phase of cold might be fairly potent when it does arrive. Temperatures in the western Canadian arctic have been running colder than average, so there is a source region available. (-40 at YCB recently).

[raindancewx]

I've been looking at 1905-06 & 1936-37 a fair bit. The Fall of 1949 had a record warm November in the SW (65.9F high here...5300 feet up - remarkable), with no moisture, so I think the MJO must have been pretty different, since we had a very wet November regionally, with near normal to cold temperatures. The 1905 November had record precipitation here - not just for November...any month. Since 1892.

As far as January matching mid-Sept to mid-Oct goes, and using that period as a model match, it looks pretty good so far. The CFS/Canadian both trended to a colder look than in the second image. If you buy that mid-Aug to mid-Sept looked like Dec, and that mid-Sept to mid-Oct looks like January, then the middle of the US should get very cold in February if it is to mimic Oct 16-Nov 15. That cold air will break out of Western Canada at some point, just don't think it will fully push into the South.

 

[LibertyBell]

11 hours ago, Roger Smith said:

I assume you are asking raindancewx that question, but from my point of view it would not change the outlook.

My timing was a bit off, the warming trend in the east began around mid-December rather than early in January.

That mid-month reversal happened in other years, notably 1875, 1889, 1936, 1949 and 1964. Most of those were followed by very mild Januaries and first half of Februaries in the east. A general trend towards colder than normal weather late February and March could be noted in those same years. 

January 1950 was particularly warm in the east and set records in the 70s on the east coast towards the end of the month (25th-26th). Although the lead-in was somewhat different, 1905-06, 1908-09 and 1915-16 as well as 1966-67 converged on the same late January warm signal. Most of those turned a lot colder in February.

I think the odds are pretty good that winter 2019-20 will feature a core warm spell with bookend cold periods, and the second phase of cold might be fairly potent when it does arrive. Temperatures in the western Canadian arctic have been running colder than average, so there is a source region available. (-40 at YCB recently).

If you want to look at relatively recent winters with similar patterns, one to consider would be 2005-06.  That one had cold and snow in the first 10 days to 2 weeks in December followed by warmth that lasted right through January.  We went back to snow and cold again by mid February.

The following winter, 2006-7, was similar, but with less snow and more mixed precip after the mild pattern broke.  The cold that followed after was actually historic in its longevity (the first three weeks of April were colder than the first three weeks of January! It hit 70 on the 11th anniversary of the Jan 96 blizzard but did not hit 70 in April until the last week!)

These very mild patterns seem to last from 6-8 weeks before they break.  An exception to this was 1989-90, when the mild pattern lasted for three months. 2011-12 was another exception.  But weren't those high solar years and we're currently near a minimum?

If we follow the regular 6-8 week rule the mild pattern should break around Feb 20.....

 

[LibertyBell]

11 hours ago, Roger Smith said:

I assume you are asking raindancewx that question, but from my point of view it would not change the outlook.

My timing was a bit off, the warming trend in the east began around mid-December rather than early in January.

That mid-month reversal happened in other years, notably 1875, 1889, 1936, 1949 and 1964. Most of those were followed by very mild Januaries and first half of Februaries in the east. A general trend towards colder than normal weather late February and March could be noted in those same years. 

January 1950 was particularly warm in the east and set records in the 70s on the east coast towards the end of the month (25th-26th). Although the lead-in was somewhat different, 1905-06, 1908-09 and 1915-16 as well as 1966-67 converged on the same late January warm signal. Most of those turned a lot colder in February.

I think the odds are pretty good that winter 2019-20 will feature a core warm spell with bookend cold periods, and the second phase of cold might be fairly potent when it does arrive. Temperatures in the western Canadian arctic have been running colder than average, so there is a source region available. (-40 at YCB recently).

1966-67 would probably be on the extreme end of what one can expect- that was one amazing book end winter that won out by its sheer duration and became historic- somewhat like 2014-15?  1966-67 stands out compared to other book end winters because we actually got a major snowstorm down here in December, before the mild pattern ensued.  I was compiling a list of winters that seem to match what you're looking for, with varying lengths of mild periods book ended by cold on either side to varying degrees, that I've experienced.  Here are the ones that snapped back to cold:

1989-90 (very briefly and very late, in early April, with snow!)

1996-97 (mostly in New England, big bookend winter in Worcester and interior Mass., the April snowstorm was a mild bust down here.)

1997-98 a renegade snowstorm as winter was ending

2005-06 and 2006-07 I already discussed these in an earlier post

2014-15 I hesitate to even include this because the snap back to snow and cold was SO extreme and lasted so long, somewhat like 1966-67.

2015-16 almost as extreme as 1966-67 but the warmth came in earlier (December) and so did the cold- we had a 30" + snowstorm on Jan 20th and below zero lows for Valentine's Day!  JFK became only the second location (besides Norfolk, VA) to experience a 40" snowfall season with an average winter temp above 40F!

The last three winters were also somewhat bookend winters (2016-17, 2017-18 and 2018-19).  The first two were more extreme than the last one.

*the number of book end winters seems to be on the increase, perhaps due to the abnormal warming in the Pacific and Indian Oceans?

 

 

 

[Roger Smith]

Well I'm old enough to remember the winter of 1966-67, in southern Ontario it was quite a wild ride (I was operating a backyard weather station about 30 miles west of Toronto at that time as a high school senior). November 1966 was very mild and rainy. There was a brief cold spell with a strong arctic high in early December then it warmed briefly to about 60 F. Following that most of late December was rather cold with some snow, not a lot. January 1967 turned very mild in stages, culminating in some record highs on 23rd and 25th. The second of these was again near 60 F. At this point the ground had thawed out and all the previous moderate snow cover was gone. The famous Chicago snowstorm came along the next two days, at my location it was a mixture of rain, sleet, ice pellets and heavy snow with thunder and lightning, quite a storm (we were supposed to write our SAT exams one of those days and it was postponed for a month as a lot of people couldn't get into school). The onset of much colder weather was very fast, after another snowfall of about 7" in early February, it turned bitterly cold and never warmed up much at any point until late March. There was another strong arctic high and record cold morning temperatures on March 17th and 18th. After that it warmed up quite rapidly and records (since broken) were set on the first two days of April. I would think that was one of the most variable winters on record in the region. From what I've seen of the stats from 1905-06 and 1949-50, they ran quite similar in many aspects (I am not quite that old).