GaWx

I have a family member planning to visit NYC Thu-Sun. Is it going to be bad enough for him to consider canceling? What are the chances of major coastal flooding causing a big mess through much of NYC? TIA

From the 11AM EDT advisory for TD 15E: ...INTERESTS IN THE HAWAIIAN ISLANDS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM... SUMMARY OF 500 AM HST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...14.5N 154.4W ABOUT 320 MI...520 KM SSE OF SOUTH POINT HAWAII ABOUT 525 MI...840 KM SSE OF HONOLULU HAWAII MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 290 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- Interests in the Hawaiian Islands should closely monitor the progress of this system. A Hurricane or Tropical Storm Watch will likely be required for a portion of the state later today. —————————— The depression has slowed since the last advisory and seems to be moving west-northwestward at about 5 kt. A ridge to the northeast of Hawaii is forecast to weaken and slide eastward as a mid- latitude trough drops over the northwestern Hawaiian islands. This evolution is likely to the cause the cyclone to slow down later today or tonight and then turn northward or north- northeastward by tomorrow with some increase in forward speed. The trough is forecast to move westward this weekend as the ridge rebuilds north of Hawaii, which should force a sharp westward turn while the cyclone is close to the Big Island. At this time frame, it is impossible to know exactly when that turn will happen and, unsurprisingly, there is a large north-south spread in the guidance. Our best guidance is on the northern side of the track envelope, and new NHC forecast remains essentially the same as the last advisory. Interests in the Hawaiian Islands, especially on the Big Island, should closely monitor the system, with life-threatening catastrophic flooding possible over the steep terrain on this track. The depression should intensify slowly at first, given the current structure of the low-level center not co-located with the mid-level circulation as seen on satellite. However, after the system develops an inner core, the environment seems conducive for significant strengthening, with low shear, high mid-level moisture and SSTs from 28-29C. The rapid intensification probabilities are increasing, and the best model guidance is showing this as a major hurricane in a few days. Given the environment and the best-performing aids (Google DeepMind and HCCA) again showing major-hurricane strength, the NHC forecast is raised from the previous one and shows the cyclone as a major hurricane when it approaches the Big Island of Hawaii by the weekend. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 14.5N 154.4W 30 KT 35 MPH 12H 24/0000Z 14.7N 155.2W 40 KT 45 MPH 24H 24/1200Z 15.0N 155.5W 50 KT 60 MPH 36H 25/0000Z 15.7N 155.2W 65 KT 75 MPH 48H 25/1200Z 16.7N 154.8W 80 KT 90 MPH 60H 26/0000Z 17.6N 154.5W 90 KT 105 MPH 72H 26/1200Z 18.2N 154.7W 100 KT 115 MPH 96H 27/1200Z 18.1N 157.0W 100 KT 115 MPH 120H 28/1200Z 18.7N 160.2W 95 KT 110 MPH $$ Forecaster Blake

The very rough 2026 for Hawaii looks to get even rougher later this week! TD 15E had formed in the E PAC back on Sep 13th from an AEW that had moved off of Africa way back on Aug 27th. This was actually the very next wave after the one that produced Dolly in the Atlantic! This then degenerated in the E PAC into an open wave late on Sep 15th. But one week later (late last night), this reorganized back to TD 15E 405 miles SSE of Hilo, Hawaii, moving WNW. It’s forecasted to become a TS later today and then turn sharply N tonight. It is then forecasted to become a H tomorrow night and reach high end cat 2 H status Fri night while not too far S of the big island of Hawaii meaning a potential serious threat there then: From the NHC discussion: The depression is moving west-northwestward at about 10 kt on the southwest side of a low- to mid-level ridge. This ridge is expected to shift eastward and weaken while a mid- to upper-level low dives southwestward near the northwestern Hawaiian Islands. This pattern change should cause the cyclone to slow down and then turn northward or north-northeastward later this week. That motion should take the cyclone near the Big Island of Hawaii late Friday or on Saturday. Around that time, the upper low is expected to weaken and move westward, allowing mid-level ridging to become re-established to the north of the system. In response, the cyclone should turn and then accelerate westward. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 14.0N 153.7W 30 KT 35 MPH 12H 23/1800Z 14.4N 154.7W 35 KT 40 MPH 24H 24/0600Z 14.6N 155.5W 45 KT 50 MPH 36H 24/1800Z 15.0N 155.6W 55 KT 65 MPH 48H 25/0600Z 15.9N 155.2W 70 KT 80 MPH 60H 25/1800Z 17.0N 154.9W 85 KT 100 MPH 72H 26/0600Z 17.9N 154.7W 95 KT 110 MPH 96H 27/0600Z 18.3N 156.0W 95 KT 110 MPH 120H 28/0600Z 18.2N 159.0W 95 KT 110 MPH

I just noticed that CHS this afternoon lowered my temps for late week into the weekend to the solidly BN range, thanks at least in part to the big nor’easter off the NE US: FRIDAY SUNNY. HIGHS IN THE UPPER 70S. FRIDAY NIGHT MOSTLY CLEAR. LOWS IN THE UPPER 50S. SATURDAY SUNNY. HIGHS AROUND 80. SATURDAY NIGHT MOSTLY CLEAR. LOWS IN THE UPPER 50S. SUNDAY MOSTLY SUNNY. HIGHS IN THE MID 80S. The treadmill may get a break during this period! Hello park! It’s a wonderful time of the year!

Joe Bastardi makes a good point about this likely being warm core at least in the early stages since it would be forming over 82-83F water. He said it weakens as it moves toward the coast because that’s what a warm core storm would do as it gets into cooler SSTs.

Also, regardless of upwelling, this like all TCs of course removes heat from the upper layers of the ocean (potential energy) since that heat is converted to kinetic energy (conservation of energy). So that, alone, should always induce its own cooling even without upwelling per se. And a very strong one like Polo should be taking heat from the ocean at a more rapid rate than a weaker one. That, alone, often brings the SSTs in and near the center down 1-2C based on my following SSTs in the past with deep warmth.

A batch of heavy showers has popped up, which lead to mainly heavy rain starting at 12:50PM. It is continuing to rain at a moderate rate and this is adding up nicely. 1/2”++ has already fallen. The showers are moving SSW. Before today, I had received 2” MTD. So, these are beneficial rains.

This is tricky. Whereas cyclonicwx’s OISST graph has indeed had it at +2.5 for the past 10 days including last week, keep in mind that NOAA had it at only +2.1 for last week. Thus, NOAA had it 0.4 cooler than cyclonicwx’s OISST graph. Actually, NOAA has been cooler than cyclonicwx by 0.4 for 9 straight weeks! NOAA labels their weeklies as OISSTv2.1. Thus, I wonder if cyclonicwx uses an older version of OISST. If so, that could possibly explain the 0.4 difference for the last 9 weeks. Note that cyclonicwx in late June/early July was warmer by only 0.1. I wonder if the latest version of OISST started being used just after that. So, per NOAA, last week’s equivalent RONI (based on OISSTv2.1) was still only +2.1. So, with that being the case, there’s quite a ways to go to see if it actually does reach a +3.0 trimonthly peak per NOAA. NOAA Weeklies: https://www.cpc.ncep.noaa.gov/data/indices/rel_wksst9120.txt *Edit: I just found out that OISSTv2.1 was first implemented way back on 4/26/2020: https://www.ncei.noaa.gov/products/optimum-interpolation-sst So, it remains a mystery why cyclonicwx’s OISST graph has been 0.4 warmer than NOAA’s OISSTv2.1 based weeklies for 9 weeks! So, until NOAA’s weeklies get close to cyclonicwx (if they do), I’ll continue to treat cyclonicwx’s OISST graphs as too warm vs NOAA. The NOAA August’s +1.67, which is ERSSTv6 based, was even a little cooler than NOAA’s OISSTv2.1 based weeklies would have suggested! So, NOAA and cyclonicwx are world’s apart.

The latest CFSv2 RONI peak prog unlike for recent days doesn’t have most of the blue lines underneath most of the red lines. When it did, that predicted well the subsequent reductions in the progged peak, which came all the way down to +2.8 from +3.5 in late July. The current configuration is much more balanced and even has the average blue a little warmer than the avg. red. Thus, I don’t expect more drops in the progged peak over the next few days and there’s even a small chance for a slight bounce upward:

Whereas historical stats certainly agree that La Niña is quite possible in ‘27-‘28, that same history says that there’s actually a decent chance for either neutral or, believe it or not, even El Niño in ‘27-‘28. Here’s why: El Niños peaking at +1.4+ occurred in the following 19 fall/winters and were followed by these: +1.4+ Nino: subsequent fall/winter ENSO 1877-8: cold neutral 1888-9: strong Nina 1896-7: cold neutral 1899-1900: warm neutral 1902-3: moderate Nina 1905-6: weak Nina 1918-9: weak Nino 1930-1: cold neutral 1940-1: moderate Nino 1957-8: weak Nino 1965-6: cold neutral 1972-3: strong Nina 1982-3: moderate Nina 1986-7: moderate Nino 1991-2: weak Nino 1997-8: strong Nina 2009-10: strong Nina 2015-6: moderate Nina 2023-4: moderate Nina ————————— So, these 19 +1.4+ El Niños were followed by these: Strong Niña: 4 (21%) Moderate Nina: 4 (21%) Weak Nina: 1 (5%) Cold neutral: 4 (21%) Warm neutral: 1 (5%) Weak Nino: 3 (16%) Moderate Nino: 2 (11%) ————————— Tally: 47% Nina 26% neutral 26% El Nino ——————— Conclusion: La Nina is the best single possibility for ‘27-‘28 due to its large plurality (being at 47%), but neutral or even El Niño are obviously each quite possible as the two of them, combined, actually occurred about as often as La Nina after these strongest 19 El Niños on record. https://www.webberweather.com/ensemble-oceanic-nino-index.html https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/

Excellent post as a whopping ~90% of the daily graphs since July 1st have averaged a -AAM in the 30N to 40N corridor! The 40N to 50N corridor also has a very high % that are -AAM although not quite as high as the 90% especially due to the last few weeks.

Thanks, Ray. Indeed, that 9/21/26 graph has the only significant pocket of -AAM centered at our latitudes as you noted. However, I assume you realize that these lat. based graphs are quite fluid, and thus it could look quite different at our latitudes within just a few days for all anyone knows. Also, the extremely + tropical latitudes overall have little choice but to drop back at least some soon. I’ll try to follow these daily from this point on. Here’s the brand new update for 0Z on 9/22/26: note that the -AAM pocket at our latitudes is still there and still the most significant -AAM area but isn’t as negative. Also, although 52N-61N has dropped, 63N to 90N is significantly more positive vs yesterday with a peak of +2 SDs at 78N vs +1.3 yesterday: Compare to yesterday’s: The corresponding global mean for 9/22/26 is as expected per prior days’ CFSv2 progs on its last legs of the extreme level of +4+ although it fwiw keeps a very strong +3+ mean on all but a few days in early Oct:

Thanks for posting this. For the first time I examined past versions of this because I just realized that the excellent website has these graphs going back to 4/11/2022. So, there’s ~1,000 of these to compare to. Now I know why the relative global AAM standardized anomaly graphs have been at extreme levels (>+4). This latitudinal based graph for 9/21/26 is an absolute beast overall and thus exhibits the strength of this Nino very well! Why? 1. Back to 4/11/22, I couldn’t find even one other day’s graph with a more positive avg std. AAM anomaly for the area from -40 to +30! The straight avg std. dev above the mean for that huge area on 9/21/26 is clearly >2. Keep in mind that 2 std dev above the mean at any one latitude is way up at the 98th percentile and thus nearly 1/3 of the globe (20N to 17S) is >>+2 std dev/>>98th percentile! 2. The # of degrees of latitude with a negative AAM anomaly of the 180 total degrees on this 9/21/26 graph adds to only 29 degrees of the 180 total (16%). I couldn’t find even one other with that small a % of latitudes <0! 3. As one can see, most of the latitudes with a -AAM anomaly on 9/21/26 are only down to the 0 to -0.3 std dev range. The lowest is only down to -1.1, which is quite high for the lowest vs the other ~1,000 graphs. The highest lowest I could find is only barely higher (~-0.9) and it overall still had a much larger area below the 0 line than 9/21/26: So, it appears that 9/21/26 has the smallest area <0 of any back to 2022! Here again is this 9/21/26 beast of a +AAM anom by latitude. Keep in mind that just 1 std dev above the mean is up at the 84th percentile: Below is the corresponding relative global AAM, which since 0Z of 9/19/26 has been at an extreme level of >+4 std dev! This is probably the peak day as it should get back to <+4 by 9/23/26. How rare is 4 std dev above the mean? Per stat. formulas, only 1 in 31,574 days (that’s once per 87 years) gets to that level! (For 3 std dev, it’s ~once/year):

WB CFSv2 temp maps: 1. Have algo issues that lead to bad artifacts. I’ve posted on this here in the past. Here are some examples -note the cold spot over S Lake Michigan and warm spot only 250 miles to the north over N Lake Michigan that are almost always on these WB maps; the real CFSv2 output essentially never has these -note the E coast down to FL usually looks like a thin sharp warm barrier to any colder anomalies to the west; again, this essentially never is on the real output 2. WB CFSv2 maps are strongly cold biased for much of the E US. And this is the case even with WB using the colder 1981-2010 climo instead of 1991-2010, which the CFSv2 site uses! All one has to do to know this is to compare to the maps at the CFSv2 site. All 4 (DJFM) are notably too cold in almost all of the area away from the E coast. But I’ll focus on the Dec map to illustrate the strong cold bias: -Chicago’s +0.5C/1F vs 1981-2010 on WB but the CFS site’s relevant 10 day mean maps (see below) are all significantly warmer and they average +2.25C/4F vs the warmer 1991-2020 meaning WB is ~4F too cold. -SL’s 0.0 C/F vs 1981-2010 on WB but CFS actual maps are all significantly warmer and average +1.5C/3F vs 1991-2020 meaning WB is ~4F too cold -Knoxville’s -1C/-2F vs 1981-2010 on WB but CFS actual maps have it at +0.6C/+1F vs 1991-2020 meaning WB’s ~4F too cold -Despite the CFS site’s maps averaging AN from TN-NC north, WB in inland areas doesn’t have AN start til 500 miles to the N in N IL to N OH to NW PA and that’s even vs a colder climo base! That’s ignoring the immediate E coast, which has its own problems as already noted and is actually a bit too warm overall despite it being 4F too cold for much of the inland areas! Relevant 10 day mean Dec maps at CFSv2 site: 9/10-19: 8/31-9/9: 8/21-30: 8/12-21: @Stormchaserchuck1@donsutherland1

I’ve already compared the current Nino to the prior one for both GLAAM and for OHC (like night and day). 1. Here’s a similar comparison of PDO: Current: -0.71 Sept of 2023: ~-2.4 on Sept 19th though these are admittedly volatile as one can see it rose steeply Oct 1-20th: 2. SOI: 90 day mean is now way down at ~-22. The mean was down to only -8 for the same 90 day period in 2023. It was -18 in 2015 and -14 in 1997. A rough estimate using monthlies (due to no dailies that far back) for 1982 is -19 to -20. The only other 90 day mean as of Sept 20th back to 1876 that realistically could be about as low as 2026’s -22 based on monthlies is 1896 (incoming strong Nino) though that chance is <50% as it is more likely in the -20 to -21 range. So in summary: 2026: -22 2023: -8 2015: -18 1997: -14 1982: -19 to -20 1896: -20 to -21 The other super-Ninos’ rough estimates: none even close to 2026, 1896, 1982, 2015: 1972: -13 1965: -14 1957: -5 1888: -11 1877: -10

OHC of 180-100W appears to currently be at its highest yet (~+3.3): To compare, look how low was the same point in Sept of 2023 (only ~+1): Highest 2023-4 ever got was only just over +1.5:

Further to my global relative AAM post above showing it >+4 since yesterday and to show the huge contrast to the prior El Nino, here are some of the graphs I saved from 2023-4, which all show a much lower amplitude (keep in mind that CFSv2 progs looking out especially past 2 weeks have been biased positive as comparing these graphs to each other clearly show): 11/6/23: +0.15 12/16/23: +0.7: 12/30/23: +1.15 (highest of any I saved from 2023-4) 1/8/24: +0.15 2/3/24: +0.5 2/21/24: +0.2 3/1/24: -0.35

The global relative AAM remains in historic territory of +4+, which should last into tomorrow. This is probably its highest since Feb of 1998. For comparison, 2023-4 was no more than in the low +1 region on any of the graphs I saved with most of them <+0.5:

The AAM went over +4 as expected yesterday (9/19) per the image below, an extremely rare/historic event. The last time it was this high may very well have been in early Feb of 1998. It appears that it will likely stay >+4 into Sept 21st:

https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml

The main CFS site actually has 40 run averages (10 days x 4 runs/day).

Also, the TT maps use colder 1984-2009 climo instead of the CFS site’s 1991-2020. The TT 3 day (12 run) avg does jump around more than the CFS site 10 day (40 run) avg. Regardless, I haven’t seen any 3 day avg Feb recently nearly as cold as those record cold Febs that were on some Aug 3 day means in the SE to S Plains. Then again, that degree of cold was hardly believable especially that far out. They were dreamable for me but not believable. I’ll keep following the trends of both the TT 3 day means and the CFS site 10 day means.

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Sat Sep 19 2026 For the North Atlantic...Caribbean Sea and the Gulf of America: 1. Eastern Subtropical Atlantic (AL99): Showers and thunderstorms have become more concentrated near the center of a low pressure system located several hundred miles southwest of the western Azores since yesterday. A short-lived tropical depression or tropical storm is expected to form later today or tonight while moving north-northeastward at about 5 mph, but remaining well to the southwest of the Azores. Upper-level winds are forecast to become less conducive for development beginning late Sunday. * Formation chance through 48 hours...high...90 percent. * Formation chance through 7 days...high...90 percent. Forecaster Berg

Recent 3 day mean CFS’ have cut way back on the degree of cold in Feb: 9/16-18 Compare that to this from 8/7-9:

There indeed have been UK runs with false TCs though not false canes. But in this case, all models have a low off the NE coast as opposed to it being just on the UK. But would it be T, ST, or ET and would it stay offshore?