raindancewx

Honestly the WPO definition is 50-70N minus 25-40N for 140E-150W. It doesn't look negative for October but what the CFS shows is neutral. You have a mix of strong heights and neutral heights in the north and then consistently low heights to the south. I'm still expecting a mixed bag of WPO conditions in the winter. I don't think its very likely we see the Feb/Mar 2023 type of WPO without a transition to an El Nino. So my guess would be +/= WPO early in winter then =/- later on.

The low Atlantic ACE thing in a September La Nina (it tends to be around 60) is interesting to look at. I know you all like 2022. But we had major cold waves in the West in November. Don't really expect that this year. But I do see evidence for a lot of cold days again (relatively) for a La Nina locally with ACE remaining low. This is mostly because our dew points have been consistently running much lower than in 2022 so lows should get very cold at times. If you notice six of the nine the inactive Septembers for Atlantic ACE in La Ninas tend to follow El Ninos (1983, 1970, 1973, 2016 2007, 1954). You can see that Jan/Feb are the most likely months to see a lot of cold days in a low Sept ACE / 70-130 ACE type hurricane season. September ACE has fairly weak correlations to monthly highs in La Nina here. But it does correlate somewhat strongly with January (r-squared is about 0.3). It's actually been quite a while since we've had a La Nina with an inactive September. In 2022, September was pretty active. October actually looks pretty different from 2022 anyway. It's going to be pretty warm down here if you buy into the models in October. In 2022 it was warmest in the Northwest not the Southwest. The cool/average spot shown on the CFS is also fairly off from 2022 when it was chilly in the South.

Atlantic still has a long way to go to be anywhere near average for ACE. We're running more than 20% below average still and that's after a very fast start. The season after Beryl has been extremely inactive. It's Beryl and then less than 40 ACE otherwise. Isaac & Joyce will both die Sunday/Monday. Neither is going to add very much ACE in the short term. The formula is sustained winds in knots squared measured every six hours (UTC time) divided by 10,000. You're looking at 3-5 ACE per day for another two days or so from those storms. At that point we're around 80 ACE with 94 as average through 9/30. It doesn't look like there is anything that will be strong enough imminently to bump up ACE quick after Isaac dies. So entering October we probably start to fall behind relative to average again. Early October still sees ACE go up by 1 point or so per day. October averages 20-25 ACE so even in a bit of a dead season you should see some tropical activity. My general rule is September + 60 ACE is a pretty safe ceiling. It's very rare to get anywhere near 60 ACE in Oct-Nov. So we're almost certainly looking at 80-140 for the season. Still think we could finish as low as 90 ACE but 100-110 is probably a better bet now. Since 1850 (170+ years) it's like seven hurricane seasons with 60+ ACE for Oct-Nov. Even for the 1991-2020 period which is mostly the warmed up, warm AMO, it's still only 2005, 2016, 2020 (3/30 years) or 10%. The 2016 season had Matthew (cat 5) and Nicole (cat 4) form in late Sept/early Oct and carry on for a while after an inactive start. Matthew was a 4/5 in October for like five days which is nuts. That's probably the best case for those of you who want the hyperactive ACE totals. But I don't expect to see multiple long-duration cat 4+ storms in early October this year.

He's just using the SST matching tool from Tropical Tidbits but this is similar overall to my thoughts on the winter. Haven't written my forecast yet though. I do think the Atlantic ridging will setup somewhat west of where he shows it though. https://www.tropicaltidbits.com/analysis/hsanalog/ I don't like 2017 as an analog - it's the most active September hurricane season since 1850, with low solar and weakly positive PDO conditions. The other years are high solar, and less active hurricane seasons with more -PDO conditions. ACE has to be 50% above normal for the rest of the season to catch up to normal. My rule is ~95%+ of seasons will finish between June-Sept and June-Sept + 60 ACE. To me it's about 50/50 that we'll hit 90 ACE.

Must be a wonderful life you have, with all of your time on the internet spent telling people they are wrong. After all, everyone loves being told they are wrong and stupid all the time.

The seasonal models are dumpster fires for winter forecasts at this range. I haven't even really tested the 2013-14, 2021-22 blend yet. It just looks like the SST pattern and seems to have some matching tendencies to recent US conditions. But I haven't subjected the various blends I'm looking at to rigorous testing yet.

It's always amusing how no matter what I say on here the most extreme warm/cold case is what people latch onto. When I talk about 2013-14, it's only as a blend with 2021-22 that I'm interested in it. I don't expect the winter to be very much like 2013-14 by itself. The bulge in warmth isn't quite south of Alaska, it's to the West by the dateline which probably favors more cold Plains than Midwest. Look at the blend. That's fairly close to what I expect at 500 mb, although I reserve the right to change my mind by the time I put out my forecast.

Least active September hurricane seasons are an interesting group if we hold on. Especially in direct opposition to years like 2017 which saw extraordinary activity in September. Arizona should see quite a bit of rain with Ilena once it dies. Don't think we'll get much at all here.

I don't like 2007-08 much as an analog but this is what snow looks like.

Still waiting on how hurricane season plays out in the Atlantic. But the SST configuration from the Canadian looks a lot like a simple blend of 2013-14 and 2021-22 to me. That gets you to ~90 ACE for the season which looks like a decent guess at the moment. August was almost identical. Kind of toying with 2013-14, 2021-22 and then some maybe minor input from 1966, 1970, 2001, 2008, 2020, 2022. I'm tempted to do something like this but I still need to play with the weighting. I am planning to have my outlook by 10/10. 2013-14 x4 2021-22 x3 2022-23 x2 1966-67 x2 1970-71 2001-02 2008-09 2020-21

If we end up with very low ACE for this hurricane season, I'm probably going to blend in the -AMO/-PDO La Ninas with the modern La Ninas. There is just no way in hell this La Nina is going to be super similar to the hyper active / high ACE / +AMO years. A lot of the cold neutrals actually have pretty high solar too. Those years should be incorporated too - 1959-60, 1966-67, 1967-68, 1980-81, 1989-90, 2001-2, 2013-14. The modern El Nino years with high Atlantic hurricane activity flipped are a good sanity test too, 2004, 2018, 2023. We also tend to see exceptionally dry winters out here following heavy rain in September. No indication of any type of major rain event this month for us locally so far. Here is Mexico City in January 1967. -AMO / -PDO, fairly high solar, near La Nina / cold neutral. Nino 3.4 was actually colder in August 1966 than August 2024. Cold penetrates much further south in the cold AMO.

We'll see what CPC says, but supposedly record +NAO in August. That's actually a fairly widespread, though not particularly strong, cold signal for the US in Nov-Jan. https://x.com/WorldClimateSvc/status/1831059382450499794 A lot of deeper blues over the West in December. I'd have to look, but maybe that's how the hurricane and cold air wave thing works in the West. Maybe the +NAO Augusts kill the hurricane season? I've never looked really. -NAO August is probably more common in La Nina if I had to guess.

MJO phase five won't do what it has done in recent winters if the WPO is in the opposite phase.

These cold shots in the East are actually consistent with the pseudo Modoki El Nino look we have at the moment. Nino 3/3.4 aren't really below 1961-2020 averages meaningfully, but Nino 4 is well above 1961-2020 averages. Looks like we'll make it to 9/5 without a tropical storm. Phil K was saying first time since 1968 we've gone without a storm from Aug 13-Sept 3. https://x.com/philklotzbach/status/1830918338458923381 We'll see what happens, but La Nina with Atlantic August-September ACE under ~40 or so (<50% of average) has to be a major hint for the winter. It looks like 1931, 1934, 1946, 1956, 1959, 1962, 1970, 1973, 1983, 1984, 2013 are low ACE Aug/Sept, cold ENSO since 1931. 1934/1959 are true blue neutral. But the cold-neutral / La Nina years are similar to my thinking - as are the most recent five years. We'd have to stay under 76 ACE through 9/30 for this to work. The middle picture is pretty close to what I'd expect for cold severity if everything clicked correctly. But I'd dim it down to both modern averages and to constrain the extent.

At this point I'd say it's 50/50 we reach 125 ACE for the year in the Atlantic. Over 150, I'd go 1/4 odds. Same for under 100. My gut is 80-140 for the season. I don't think we're going to see much at all from African waves. Gulf & Caribbean should continue to produce into October or even November. A lot of the very active Atlantic seasons get pretty cool in August in the middle of the country. We saw that briefly this year but it didn't last. No one really finished more than a degree (F) below average in August. You had pretty widespread chilly Augusts in 2004, 2005, 2008, 2016, 2017 Subsurface remained at -0.65 for August.

The Canadian has a -WPO look for Oct-Feb looks like. La Nina is dead in February. The look isn't really a technical La Nina. It's cold from 100-150W, but barely below average for 120-180W. It's close enough, but may not ever get designated officially as a La Nina. To me the Canadian is on the right track - it has the North Central US cold with cold air in Western Canada feeding the US cold. Doesn't look crazy if Canada isn't flooded with warm air from the +WPO. If cold dumps into the US from Western Canada to the North-Central Plains I'd expect the warmest areas of the US to be areas of the SE/SW most separated by mountain ranges from the cold waves in the Plains. So Southeast US east of the Appalachians and Southwest US west of the Continental Divide. We'd be in this weird transition zone here where one or two of the Blue Northers would be tall enough to move directly north to south, and then the Arctic air in the Plains would probably ooze over the shorter mountain passes here a few times. As we have literally no hurricane activity in the Atlantic, I've just about given up on going super hot here. Atlantic is rapidly correcting toward 'average' not hyperactivity at the moment. The lower activity hurricane seasons tend to see arctic air dumps into the West. I will say, the pattern v. 2020 is semi-opposite. Fall 2020 had basically all-time record -WPO cold dumps into the Rockies/Plains/Mexico in Sept/Oct that then flipped back to very +WPO conditions for a while. We're looking at +/neutral WPO conditions in September and then only 'normal' -WPO conditions in October.

My forecast calls for -3 to -5 for the Northeast this winter, with the first ever 0" snowfall season for the Boston area. Nothing but 37-42 degree rain, with storm after storm moving in during the 'just warm enough' afternoons but never at night. After each storm, a powerful cold front will drive through pushing temps well below average overnight. These cold fronts will also clear the moisture out of the air. So lows will be cold with highs near average. But timing will prevent measurable snow. You saw it here first. Meanwhile due to slightly better timing, with storms arriving in the morning, Philadelphia and DC will be just cold enough for each system, and see 50-60 inches of snow. The South will be graced with ice and sleet, floods, tornado outbreaks, with the Plains and West alternating between brief record cold snaps and +10 readings for the rest of the winter.

That composite should hold if we see 'average' hurricane activity the rest of the way. With very little activity, I think 2022 takes over. With much stronger activity, you have to start to look at the warmer high solar active years and blend them with the stormier years for the east, so 1995, 1998, 1999, 2000, 2010, 2016, 2017 as a blend. I don't think you'd go cold/stormy with the way the background signals are, but stormy + mostly warm / some cold would be possible with much higher ACE activity (say 180+ by 11/1).

August looks like the blend of the five years for most of the US, minus the unusual shot of cold air into the mountains of CA recently. This is fairly similar to what I get whenever I test features that are consistently showing up. Cold Plains, average / warm elsewhere. Actually a pretty cold December nationally.

ACE so far has been (rounded) 7 / 29 / 18 for June / July / Aug in the Atlantic. 2008: 0 / 38 / 26 2008: 0 / 38 / 26 1966: 14 / 19 / 21 1966: 14 / 19 / 21 2022: 2 / 0 / 0 ----------------- Blend: 6 / 23 / 19 2024: 7 / 29 / 18 1966: 145.2 (x2) 2008: 145.7 (x2) 2022: 95.1 ----------------- Blend: 135.4 Sept in blend: 1966: 39 (x2) 2008: 61 (x2) 2022: 76 --------------- Blend: 55 If we're below this, I can't see the rest of the season perking up too much. Oct in blend: 1966: 30 (x2) 2008: 11 (x2) 2022: 5 --------------- Blend: 17 Pretty quick slowdown from a pretty active September. Nov in blend: 1966: 15 (x2) 2008: 9 (x2) 2022: 10 -------------- Blend: 12 Data implies a fairly average September - we'll see.

The subsurface data for 100-180W at 0-300m below the surface looks like it will be about the same or a touch warmer than July. A lot of the late developing La Ninas are still pretty weak in that zone but they are typically trending steadily down by now. The -0.80 reading for Apr/May doesn't seem like it is coming back anytime soon. We're likely around -0.5 again for the subsurface. April-May were consistently below -0.75. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

Also, as a reminder from my 2022-23 winter outlook, La Ninas without high ACE values tend to see major cold waves in the Southwest.2022 Atlantic ACE = 95.1. X is ACE in the Atlantic, Y is cold days in Nov-Feb (at least 5F below daily averages) Y = -0.1177x + 42.063 Y = (-0.1177 * 95.1) + 42.063 Y = 30.863 days that are 'cold' (5F or more below daily averages from Nov-Feb) Nov: 14 cold days 2022-11-18 40 28 34.0 -10.6 31 0 0.00 0.0 0 2022-11-11 48 26 37.0 -10.5 28 0 0.00 0.0 0 2022-11-04 48 32 40.0 -10.4 25 0 0.03 T 0 2022-11-16 44 26 35.0 -10.4 30 0 0.00 0.0 0 2022-11-17 47 23 35.0 -10.0 30 0 0.00 0.0 0 2022-11-19 46 24 35.0 -9.2 30 0 0.00 0.0 0 2022-11-15 49 26 37.5 -8.3 27 0 0.00 0.0 0 2022-11-12 54 24 39.0 -8.1 26 0 0.00 0.0 0 2022-11-20 50 23 36.5 -7.3 28 0 0.00 0.0 0 2022-11-05 58 29 43.5 -6.5 21 0 0.00 0.0 0 2022-11-24 47 25 36.0 -6.2 29 0 0.00 0.0 0 2022-11-22 49 25 37.0 -6.0 28 0 0.00 0.0 0 2022-11-14 49 32 40.5 -5.7 24 0 0.01 0.0 0 2022-11-23 55 20 37.5 -5.1 27 0 0.00 0.0 0 December: 5 cold days 2022-12-17 37 16 26.5 -9.8 38 0 0.00 0.0 0 2022-12-18 36 21 28.5 -7.7 36 0 0.00 0.0 0 2022-12-16 37 22 29.5 -6.9 35 0 0.00 0.0 0 2022-12-23 41 19 30.0 -5.9 35 0 0.00 0.0 0 2022-12-13 39 24 31.5 -5.4 33 0 0.00 0.0 0 January: 5 cold days 2023-01-26 40 19 29.5 -9.0 35 0 0.00 0.0 0 2023-01-27 43 17 30.0 -8.7 35 0 0.00 0.0 0 2023-01-19 41 21 31.0 -6.7 34 0 0.00 0.0 0 2023-01-25 41 25 33.0 -5.4 32 0 0.00 0.0 0 2023-01-22 44 22 33.0 -5.0 32 0 0.00 0.0 0 February: 7 cold days 2023-02-16 34 19 26.5 -15.6 38 0 T 0.1 T 2023-02-17 44 17 30.5 -11.8 34 0 0.00 0.0 0 2023-02-10 43 21 32.0 -8.9 33 0 0.00 0.0 0 2023-02-15 41 25 33.0 -8.9 32 0 0.14 1.0 1 2023-02-09 40 27 33.5 -7.2 31 0 T T 0 2023-02-27 55 21 38.0 -6.8 27 0 0.00 0.0 0 2023-02-11 49 21 35.0 -6.1 30 0 T 0.0 0 That's 31 cold days. Formula implies 30.8. Yay math. For a 'warm' favored pattern that's not bad, especially since 31 cold days represent 1/4 of the period (120 days). We're certainly well ahead of 2022 so far, but that year had 76 ACE in September and then not much else in the other months. Wouldn't shock me if we saw something similar.

I've found that hyperactive Atlantic hurricane seasons tend to occur in seasons with a big year/year warming in the tropical Atlantic. Do we have that this year? Not at all. Could it still change? Yes, but it is becoming less likely. The cold AMO has the blue backward c around the Greenland-Iceland-Azores zones with the warm tongue in between, like you see below on the y/y change map. You can see the 1994-1995 flip from cold AMO to warm AMO has the exact opposite signature flip by intensity and spatial composition. Since 1950, the La Ninas following an El Nino with a colder tropical Atlantic are pretty rare. Your La Nina after El Nino years are 1954, 1964, 1966 (close enough to a Nina), 1970, 1973, 1980 (close enough), 1983, 1988, 1995, 1998, 2005, 2007, 2010, 2016 (close enough), 2020. Of those years, 1954, 1964, 1970, 2007 are really the only ones in which the tropical Atlantic (blue stripe west of West Africa) is colder than the prior El Nino year in July. Atlantic ACE in those years is 104/153/40/74 or about 93. 2007 had two cat 5 hurricanes, despite the low ACE. 1964/1970 are both cold AMO years in a colder global period, so I'd expect ACE to be somewhat higher than the 93, but maybe pretty average in the modern context (105-145). A 125 ACE year is well below the recent La Nina mean of 155 or so.

I think we're moving into the cold AMO transition. If you subtract out the cold AMO years from the warm AMO years in La Nina, the three areas of biggest change are very warm/very cold east of Japan, very warm/very cool by West Africa, very warm/very cold by NE North America. The cold AMO La Ninas tend to be snowier with severe (albeit brief) cold dumps into the SW US and Southern Plains. -PDO was roughly 1947-1976 -AMO was roughly 1964-1994 Some pretty severe and unusual cold-ENSO winters in the brief -PDO/-AMO period - ala 1964-65, 1966-67, 1967-68, 1970-71, 1971-72, 1973-74, 1974-75, 1975-76. La Nina has a reputation for dryness out here. That's largely true, but if the tropical Atlantic and tropical Pacific remain cold, I'd imagine the air over the deserts would get exceptionally dry to the point that someone out here would see a winter with sporadic near to record cold lows. January 1971 got to -17F ln Albuquerque in a January that isn't even that cold if you look at the records - that month was nuts.

One thing I've never seen on here is what is the response if the subsurface is completely neutral? Does everything just go more chaotic? Or maybe the PDO takes over? Or momentum from the prior pattern continues? I think the subsurface could be pretty dead-on neutral by mid-winter.