raindancewx

Good start after a quiet October in New Mexico outside of one major rain event in SE NM very early in the month.

2004 is probably a good analog to November. If I had done Fall analogs, 1994, 2004, 2012, 2017, 2018 as a blend would have been pretty good. But I don't really see it lasting into winter. All the components are there - MJO matches 1994, 2004, 2018. The cool east is there with 2017 included. The temperature profile in the US looks like where Oct 2019 is going. The PDO is neutral. The IOD is positive. The coolness east of South America is there, with the gulf stream very warm off the East Coast. It's relatively low solar too. 2014 doesn't exactly look like 2019 in October...despite somewhat similar MJO progression...it makes sense since 2014 was a basin-wide El Nino in October. Only off by 10 or 20 degrees in the NW...but you know New England is destined to see snowmaggedon again. 2004 isn't as different in October as 2019, but it's still kind of north/south backwards, just a 2014 v. 2019 is east/west backwards.

Bye bye Modoki? Nino 1.2 has warmed up above 20.0C - so the PDO likely will remain positive, at least slightly for Nov-Apr. El Nino development is around a month slower than last year so far. But October Nino 3.4 reading is up to about 27.3C now. That's El Nino level, even using the 26.75C CPC uses for October as Neutral. Subsurface warmth is up again too. It looks like the subsurface heat for 100-180W could be around +0.6 or +0.7 - that is similar to October 2004 & October 2014. Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 25SEP2019 20.0-0.5 24.8-0.1 27.2 0.5 29.7 1.1 02OCT2019 20.0-0.6 25.1 0.3 27.2 0.5 29.7 1.0 09OCT2019 19.7-1.0 24.8-0.1 27.1 0.4 29.5 0.9 16OCT2019 20.6-0.2 25.3 0.4 27.5 0.8 29.7 1.1 26SEP2018 20.2-0.3 25.5 0.6 27.3 0.6 29.3 0.6 03OCT2018 21.3 0.7 25.6 0.7 27.4 0.7 29.5 0.8 10OCT2018 21.1 0.4 25.6 0.7 27.3 0.6 29.5 0.9 17OCT2018 21.1 0.3 25.9 1.0 27.6 0.9 29.6 0.9

There is a fairly strong signal in the years I like for a big snow storm around Nov 20 for New Mexico, likely parts of Colorado too. The pattern in ocean temperatures kind of looks like 2004 which I believe had some big storms in November. if I had done fall analogs, 2004 would have made the cut, I just don't like it for winter. 2012 is actually pretty good for Fall too. November might be something like a blend of 1994, 2004, 2012, 2017, 2018 and then the 2012/2017 will vanish from relevancy for winter from rapid cooling. 1994/2018 will likely fall off too once the MJO match in October wanes a bit. The blend matches reality fairly well for temps - cold West/warm East (and the warmth by end of Oct will be a lot less than now even int he SE like in the blend), and then the West is fairly warm in Nov, with average or slightly wetter than average precipitation. The blend respects the warm Atlantic, positive IOD, warm tongue east of Japan relative to cooler waters by NA to some degree, with extensive cold on both sides of South America. We'll see.

It's not exact, but in some ways we're about a month behind the development of the El Nino last year. The cold by South America was mostly defeated by this point last year. But...it was still there in September 2018. The Oct 2019 pattern by South America looks a bit like the blend of Sept/Oct 2018.

This is what I had for snow nationally in my winter outlook - but I think for Colorado after a quick start there is something of a break until late winter. My snow map was fairly good last year. Montana and Virginia did better than I thought, and I should have had an elevation component for the West last year since the valleys in NM were much closer to average than the mountaintops everywhere.

Large area of +1C to +2C heat has filled into Nino 3.4 during the last month. With the surface readings over 27.0C in October...that's enough for Nino 3.4 to stay warm for a while. The cold in Nino 3 (90W-150W) is just about gone now too, although Nino 1.2 is still going to take a while to warm (maybe til December).

Pretty sure the IOD was positive last year too by Fall anyway, although not as much as this year. The Jamstec has it falling off later. The main thing with the IOD is it is a way to keep relatively high pressure over Australia, which helps the SOI stay negative or neutral.

The (relatively) cold backwards C by the Alaskan Coast around that blotch of warmth is a pretty canonical -PDO, especially with the warm waters east of Japan. 2014 was the opposite - super warm by the coast of Alaska, and cold east of Japan. Will the -PDO ish look now last all winter? I kind of doubt it. Just because Nino 1.2 falling below 20.0C in October is a leading indicator that the PDO will fall. It did on the weeklies. But now it looks like it will warm up. So it probably reverses, at least somewhat, by December or January. Even with the El Nino last year, the Nov-Apr PDO only recovered to +0.5 from +0.3 in 2017-18. With a weaker El Nino this year, it could easily be closer to 0. The trend has been down. I think the PDO is weak enough that the SE ridge won't get squashed or destroyed for any length of time, and when the subtropical jet is strong, and the SE ridge is strong, that is the best shot at major storms (cut offs) for where I am, as the two battle it out. Nov-Apr PDO 2013 0.38 2014 2.07 2015 1.70 2016 1.06 2017 0.30 2018 0.51 With the NAO negative, the winter -PDO correlations seem to work about perfectly for October so far.

Looking back at what the Weather Channel forecast in August for Fall really gives some sense of how difficult this winter may be to nail. They really were quite close on September, I'd give it a B- (from mid-Aug), but their October forecast is going to be fairly opposite, with the very warm South, somewhat warm NE, and very cold NW. I don't really get why they expected the pattern to flip so quickly? I know its gotten colder since the early days of October when it was in the mid-90s as far as Philly...but still. I generally find their forecasts verify better than say, CPC or Weatherbell, and they're definitely better than WXRISK or Accuweather.

Nate Mantua PDO value came in today: https://oceanview.pfeg.noaa.gov/erddap/tabledap/cciea_OC_PDO.htmlTable?time,PDO Sept 2019: +0.41 Aug 2019: +0.38 Sept 2018: +0.09 I believe October will be substantially lower than September, but we will see.

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.

Not quite as warm as last year....but pretty close now in Nino 3.4. I think the Jamstec is too cold in the SE, but I'm broadly on board with what it has. A Modoki El Nino (ish) with a neutral or -PDO (colder right by Alaska for SSTs, with a warmer tongue east of Japan. I really struggle with places in the mid-south going from +8 to +12 in October, after a warm September, to a very cold winter like the model shows. The Jamstec is a bit drier than I am in the Rockies (I think we're near to slightly above average, it has near- to below).

Just for reference: Nino 3.4 is now very close to last year. K - 273.15 = C for reference. So the 27.0C is orange, because it is 0.5C or more above the 1951-2010 October average in Nino 3.4

At the end of the day, you can try to forecast a season using two basic methods: 1) Find predictive variables and guess what they will do (this seems to be what most of you do). That will work most of the day, but you'll get situations like last year, where 1963 matches on most of the variables that are predictive but end up completely different by ignoring weather clues, like the super hot October 1963 compared to the very cold October 2018. My analog system, prior to incorporating weather matches had 1963 as a top three match last year...but it fell off to like 15th with weather included in Fall. (2018-19 was 27.40C in Nino 3.4 for DJF, 1963-64 was 27.35C in Nino 3.4 for DJF) 2) Find predictive variables. With the predictive variables find a blend that matches the weather for a long-period, with the variables and weather still heading in the "correct" direction together going forward. This is what I try to do. I'm really looking forward to seeing the forecasts this winter - there are so many more things that can go wrong this winter compared to last winter: 1) Solar - there is a non-negligible chance of a rapid increase by mid-2020 2) PDO - it looks like it is heading more Neutral, and maybe legitimately negative, but it also may snap positive. My analogs assumed near neutral, on either side. People see the Blob and think "2013" but US weather really hasn't matched well to 2013 at all since Summer. October has been a bit closer, but I think it is a case of two trains passing each other from opposite directions. In 2013-14, the PDO was warming from years of being in the predominantly negative phase. In 2019-20, it is cooling from years of being in the predominantly positive phase. 3) ENSO structure. Modoki El Nino since September. But Nino 1.2 is losing the cold pool below it, Nino 4 warm pool below it is moving east. 4) NAO. Pretty rare historically to have any streaks <=-0.3 more than four months, less than 2% of all possible outcomes. October is negative. November probably will be too. 5) SOI under -10 in September is like a ~95% El Nino indicator for winter. For what its worth, the new Jamstec (October) does have an El Nino Modoki look continuing in winter, with a cold East. The dry slot from TX to MI, with New England and the West Coast warm is pretty much what I had in my forecast.

Nino 1.2 is currently under 20.0C in October on the weeklies. The monthlies usually come in warmer for Nino 1.2...still, if the month finishes under 20.0C in Nino 1.2, a -PDO is likely for winter. Since 1950, 17/18 years with a <20.0C Nino 1.2 in October have finished with a -PDO for Nov-Apr. With an El Nino forming, that can be an incredible pattern nationally. The temperature pattern for October (super cold NW / super hot SE) is consistent with the PDO correlations to winter when the PDO is negative. This is the composite for when the PDO finishes under 0 for the Nov-Apr period, in an El Nino (it is the same idea - cold West / mild East if you use only 1950+ years)

The first map is a correlation map, so the yellow/green colors mean positive correlation, i.e. when the PDO is negative the NW is cold. The blues/purples mean negative correlation, so when the PDO is negative, the SE is warm. The opposite is also true, positive PDO means cold south (negative correlation), positive PDO means cold northwest (positive correlation). The cold ring of waters by Alaska and then the warm tongue of waters east of Japan - that is the canonical -PDO image

I'm starting to think the PDO may drive the pattern this year. The October split so far, very hot SE, very cold NW, is consistent with a -PDO in winter if you look at the correlation map I posted in the ENSO thread. The zones that are most correlated are currently the hottest/coldest so far. The cold ring forming by the Alaskan coast surrounding the warm tongue east of Japan is the canonical -PDO look. Really aren't any recent El Ninos (27.0C+ Nino 3.4) regimes with a -PDO, but it has happened. Nino 1.2 is under 20.0C for October to date on the weeklies (19.85C). In 18 <20.0C Nino 1.2 Octobers, 17/18 the PDO finished below 0 on average from Nov-Apr, and the highest value was in 2005-06 at +0.14. Generally speaking, a -PDO favors a cold NW, a neutral PDO favors a cold Central, and a positive PDO favors a cold SE in winter. In 2017, the weeklies were ~19.5C for October in Nino 1.2, but the monthly data came in at 20.2C. So this may all be moot anyway, since I base stuff off the monthlies. Blending the PDO in Mar-Aug with Nino 1.2 SSTs in October is highly predictive, and the best match for that looks to be 1996/1988 averaged together for the PDO, for -0.1 for Nov-Apr. That's for a 20.0C October Nino 1.2 after a +0.83 Mar-Aug PDO. If the PDO hadn't been +0.8 in Mar-Aug, I think the -0.5 PDO depicted below for a 20.0C Nino 1.2 in October would be about right. When the PDO is warm mid-year, and then Nino 1.2 is very cold in October, you look for Nov-Apr to be more negative generally (so in 2017-18, with the cold Nino 1.2, we went from +0.6 Mar-Aug to +0.3 for Nov-Apr).

My take on the very cold NW/very hot SE this October is that the PDO is going negative. Look at where the biggest anomalies v. the correlations are (granted, they are for winter, but with the NAO negative its a pseudo winter pattern now). Blending Nino 1.2 in October (currently under 20.0C on the weeklies) with the PDO in Mar-Aug (+0.83) to match 2019, you have to pick something like 1988-89 and 1996-97. I've hindcasted this method, it's remarkably strong as a predictor once Nino 1.2 is known in October. Analog PDO M-A Oct 1.2 PDO N-A 1988 0.86 19.81 -0.60 1996 1.06 20.31 0.38 Blend 0.96 20.06 -0.11 2019E 0.83 20.00 ??? This was the blend I used to estimate the PDO last year. Year Oct 1.2 PDO M-A PDO N-A 1963 20.96 -0.75 -0.88 2002 21.39 -0.24 1.69 2004 21.16 0.57 0.47 2004 21.16 0.57 0.47 Mean 21.17 0.03 0.44 2018 21.13 0.07 0.51

All fear the PDO? The JISAO update isn't in for September yet, but the severe cold in the NW and severe warmth in the SE are both showing up in the zones that correlate highest to the PDO for winter. The cold ring by Alaska hasn't been there in a long time but it is trying to form.

The cold pool near Peru is starting to surface so Nino 1.2 and Nino 3 cooled this week. Nino 3.4/4 were down a tiny bit. Against 1951-2010 averages in Nino 3.4, 27.0C is +0.5C, but CPC uses 26.75C, the 1985-2014 average, for Nino 3.4. Either way, Nino 3.4 for October is at borderline El Nino conditions - 27.15C or so, pending the rest of October...but lots of warmth below the surface is set to come up shortly. Nino1+2 Nino3 Nino34 Nino4 Week SST SSTA SST SSTA SST SSTA SST SSTA 18SEP2019 19.1-1.3 24.2-0.6 26.5-0.2 29.3 0.6 25SEP2019 20.0-0.5 24.8-0.1 27.2 0.5 29.7 1.1 02OCT2019 20.0-0.6 25.1 0.3 27.2 0.5 29.7 1.0 09OCT2019 19.7-1.0 24.8-0.1 27.1 0.4 29.5 0.9 You can see that if we pop up to 27.15C or so in October, it's fairly close to the top 10 warmest Octobers already (27.58C is 10th since 1950). Nino 3.4 for the past three weeks has more or less caught up to 2014-15 at this point, but 2014-15 was much warmer in Nino 3/1.2 and colder in Nino 4. At this time of year, Nino 1.2 tends to lead what the PDO will do - so the very warm Nino 1.2 in 2014 preceded the +2.07 PDO reading for Nov-Apr. 17SEP2014 21.0 0.7 25.2 0.4 27.2 0.5 29.4 0.8 24SEP2014 21.2 0.8 25.4 0.5 27.1 0.4 29.3 0.6 01OCT2014 21.7 1.1 25.4 0.5 27.1 0.3 29.2 0.5 08OCT2014 21.3 0.6 25.5 0.6 27.1 0.4 29.1 0.5

I went with a fairly snowy cold season for parts of the Plains, West and Northeast this year. Not many areas of the US came in with less than 75% of average snow. For New Mexico, the "average" snowline seems to be 7,000-8,000 feet - areas above that level will be snowier than average. The ocean temperature pattern globally in early October is pretty close to opposite of what the 2016-17 winter ended up, essentially a Modoki El Nino instead of a Modoki La Nina. If it was truly opposite to 2016-17, maybe it'd be severely cold in the Southeast, but I have the cold somewhat to the Northwest of the South. I do think with Atlanta and areas west of it currently 10F above normal in October after a hot September that a lot of nights in the South will be pretty cold as the warm air is replaced by cold/dry air. Longer term, the subsurface heat is draining in Nino 4 to some extent, and the wave of ocean heat is moving East, so you'll see less of a Modoki look as Nino 4 cools and Nino 1.2 warms. The PDO also looks like it is going to go negative for at least a little while which is not great for cold in the Southeast.

Definitely an idealized Modoki El Nino look for the past month, but the warm waters do seem to be pushing east into Nino 3 now. The areal extent of the cold to the east is thinning. You can also see the PDO going negative to some extent as the warm ring moves away from Alaska and the tongue that should be cold east of Japan in a positive PDO, is very warm. 1953-54 had a 23.25C DJF seasonal reading in Nino 1.2 - so I have that in my analogs to incorporate the very cold waters by Peru that will take a bit longer to warm up than Nino 3.

I've done data mining on the NAO and the winter tendency will tend to match a year with similar April-May transitions AND similar March-Sept transitions. Years with those tendencies that match 2019 are 1990, 1993, and 2016 among recent years - all positive NAO winters. However, my winter analogs do imply one winter month will see a -NAO, despite the other two months being positive or neutral. Independently, Apr-May and Mar-Sept are both r-squared around 0.1 for predicting the NAO, but blended together correctly it is stronger than that. On the monthly NAO data, 1975 was a good match to last year for Apr-May, Mar-Sept, and it was a positive NAO winter like last year. There is also some tendency long-term (r-squared around 0.2) for Box C cold in the Modoki calculation (waters by the Philippines) to be a leading indicator of the NAO. I've linked to my outlook elsewhere - will be interesting to see how good or terrible it is in a few months.

Nice and dry + cold = very cold lows for the rural areas of the high terrain in New Mexico.