GaWx

As someone else who also hates the spread of misinfo, especially when it is done purposefully to overhype/get more attention and sell more of a product, I fully endorse his post about this error about the AMO. Spreading misinfo on the internet is a pet peeve of mine. We’re in the Age of Misinfo, sadly. It’s the least we can do to try to reduce the spread of it. Even unintentional errors should be corrected. Keep in mind that there are numerous less informed guests that read these threads. So, we’re not just targeting members in our attempt to make corrections.

Yeah, I realize that. I’m just looking ahead.

BULLETIN Tropical Storm Melissa Advisory Number 13 NWS National Hurricane Center Miami FL AL132025 1100 AM EDT Fri Oct 24 2025 ...AIRCRAFT DATA SUGGEST THAT MELISSA COULD BE REFORMING TO THE EAST... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF SOUTHERN HISPANIOLA AND JAMAICA THROUGH THE WEEKEND... SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...15.7N 74.6W ABOUT 215 MI...345 KM SE OF KINGSTON JAMAICA ABOUT 250 MI...405 KM SW OF PORT AU PRINCE HAITI MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...ESE OR 105 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Watch is in effect for... * Southwestern peninsula of Haiti from the border with the Dominican Republic to Port-Au-Prince * Jamaica A Tropical Storm Warning in effect for... * Southwestern peninsula of Haiti from the border with the Dominican Republic to Port-Au-Prince * Jamaica Tropical Storm Melissa Discussion Number 13 NWS National Hurricane Center Miami FL AL132025 1100 AM EDT Fri Oct 24 2025 The Air Force Reserve reconnaissance that has been flying through Melissa this morning found the center significantly further to the east-southeast than what was observed last night. How much of this position is related to a real motion, or a center reformation is unclear at this time. The storm remains about the same on satellite imagery this morning, with a large burst of deep convection, primarily along its southeastern flank, with evidence of northwesterly shear still undercutting the outflow. A WSFM microwave pass shows very deep hot towers, but not with that much structure beyond that. In addition, there hasn't been a significant change to Melissa's intensity, with peak 850 mb flight level winds of 49 kt, and these winds support maintaining 40 kt intensity this advisory. As has been stated for the last few days, the lack of persistent steering currents, due to competing mid-level ridges to the southeast and northwest of Melissa, is responsible for the storm's very slow motion. This is likely to continue for the next day or so, and much of the system's motion could be just as influenced by center reformations during this time period. After 24 hours, the mid-level ridge located to the northwest is expected to strengthen to the north of Melissa, and the guidance is coming into better agreement on a very slow westward motion through 72 hours. Beyond that time frame, a strengthening mid-latitude trough expected to move into the Southeastern U.S., should provide an avenue for Melissa to escape the Caribbean Sea to the northeast by the end of the forecast period. The track guidance overall has shifted south over the first few days, but there is still substantial spread in solutions at the end of the forecast period, related to when and how fast Melissa turns to the northeast. The latest NHC track forecast is a little south of the prior one early on, but is shifted a little eastward in 4-5 days, roughly a blend of the latest HCCA and GDMI model aid solutions. On the forecast track, Melissa could potentially be near western Jamaica by day 4 and near or over southeastern Cuba by day 5, though timing still remains more uncertain than usual. The GFS and ECMWF-based SHIPS shear guidance indicates the deep-layer shear is lower than yesterday, between 14-17 kt, but there still appears to be mid-level shear undercutting the outflow layer. Until Melissa also become better aligned vertically, any intensification is likely to be slow to occur over the next 12 h or so. After that, once Melissa's structure improves, environmental conditions still appear favorable for a period of rapid intensification (RI). Every single Google DeepMind member shows the system become a Category 4 hurricane or higher, and the uncertainty is more related on the timing of when RI occurs. After 96 hours, Melissa could weaken some due to the combined effects of land interaction, and an increase in southwesterly vertical wind shear by the end of the forecast period. The latest NHC intensity forecast is on the higher end of the model solutions, but more or less in line with the latest GDMI guidance. Key Messages: 1. Jamaica: Due to Melissa’s slow motion, the risk of a prolonged multi-day period of potentially damaging winds, heavy rainfall resulting in life-threatening flash flooding and numerous landslides, and storm surge continues to increase for Jamaica. Preparations to protect life and property should be rushed to completion, since strong winds and flooding rains could begin in Jamaica on Saturday or Sunday. 2. Haiti: Heavy rainfall will result in catastrophic flash flooding and landslides across southwestern Haiti into early next week. Extensive damage to roads and buildings is expected, potentially isolating communities for an extended period of time. This is a life-threatening situation and immediate preparations to protect life and property should be taken. Strong winds could also potentially last for a day or more over the Tiburon peninsula of Haiti. 3. Remainder of Hispaniola and Eastern Cuba: Heavy rainfall could also produce significant, life-threatening flash flooding and numerous landslides in southern Dominican Republic. Interests in Cuba should monitor the progress of Melissa since the risk of heavy rainfall, damaging winds, and storm surge appears to be increasing. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 15.7N 74.6W 40 KT 45 MPH 12H 25/0000Z 15.9N 74.5W 45 KT 50 MPH 24H 25/1200Z 16.3N 74.6W 60 KT 70 MPH 36H 26/0000Z 16.5N 75.3W 70 KT 80 MPH 48H 26/1200Z 16.6N 76.0W 85 KT 100 MPH 60H 27/0000Z 16.6N 76.8W 105 KT 120 MPH 72H 27/1200Z 16.6N 77.5W 125 KT 145 MPH 96H 28/1200Z 17.5N 78.3W 130 KT 150 MPH 120H 29/1200Z 20.4N 76.7W 105 KT 120 MPH...INLAND $$ Forecaster Papin

Hey Anthony, I had just added this at the end right before you posted: The caveat is that this recent decades pattern of -NAOs during only weak sunspot periods has been due to randomness. I’m only looking at the period since 1980, when -NAO winters started becoming rare. There have only been 6 (13%) of them with a -NAO. All were within 2 years of a sunspot minimum with sunspots averaging <35 during DJF. I can’t prove it hasn’t been coincidental though. That’s why I said, Therefore, based on the last 45 winters and assuming that pattern continues, ~2028-9 should be the next winter with a good shot at a sub -0.25 NAO averaged out.

There have been only 6 (13%) sub -0.25 NAOs averaged over DJF since 1980 and they were all within ~2 years of a sunspot cycle minimum: 1984-5, 1986-7, 1995-6, 2009-10, 2010-1, and 2020-1. Being that this autumn has been in a persistent very active sunspot period after the peak only about a year ago, 2025-6 will still be during a mainly active sunspot period. As we get out to 2028-9 and going into the early 2030s, we should then be within ~2 years of the next cycle min. Therefore, based on the last 45 winters and assuming that pattern continues, ~2028-9 should be the next winter with a good shot at a sub -0.25 NAO averaged out. Hopefully like was the case in the mid-1980s and 2009-1, we’ll get two -NAO winters between 2028-9 and ~2031-2. The caveat is that this recent decades pattern of -NAOs during only weak sunspot periods has been due to randomness.

IF the NHC forecast were to play out, Melissa could end up having the 3rd highest ACE on record for so late in the season of the last 100 years behind only Mitch of 1998 and the Nov Cuba H of 1932! Wilma wouldn’t qualify because it dissipated too early (10/25). Going back further to 1851 on the record, only storm #6 of 1896 would appear to quite possibly have higher ACE later than Melissa again assuming NHC forecasts verify. So, Melissa could very well end up in rare company regarding the lateness of a very large ACE for a single storm on record. ———— Edit: This from yesterday’s Euro Weeklies illustrates well how high the ACE potential is: this shows 4.1 the normal ACE or ~15, which is near the normal for the peak week climo centered around Sept. 11th! That is almost entirely from Melissa. But that is only for Mon (10/27) through Sun (11/2). So, that doesn’t even include today through Sun.

This last post I made about him is to make sure I’m not losing my mind. Also, communicating to him and actually getting a response is very difficult. So, I’d rather just talk to my ENSO thread buddies here and see what y’all think.

What in tarnation is Bastardi talking about….why is he saying 2010-1 is a 30 mb QBO analog to 2025-6? They’re opposites! Can someone here make sense of this? Metric 2010/11 (Actual) 2025/26 (Forecast) Similarity / Difference QBO Phase at 30 hPa – Oct +8 m/s (weak westerly) +10 to +12 m/s (moderate westerly) High similarity – both start in waning westerly phase QBO Phase at 30 hPa – Dec –5 m/s (early easterly onset) –8 to –12 m/s (early easterly) Very close – both transition in December QBO Phase at 30 hPa – Jan–Feb –25 to –30 m/s (strong easterly peak) –22 to –28 m/s (strong easterly) Excellent analog – both reach deep easterly regime QBO Descent Rate ~1 km/month (normal) ~1 km/month (normal) Identical Vertical Structure (50–10 hPa) Easterlies descending from 20 hPa → 50 hPa by Feb Easterlies descending from 15 hPa → 50 hPa by Feb Near-identical shear zone timing ENSO State Moderate La Niña (ONI: –1.4°C) Weak La Niña (ONI: –0.6 to –0.9°C) Moderate difference – 2010/11 colder; 2025/26 milder baseline Polar Vortex Response Major SSW on Jan 20 → vortex split Elevated SSW risk (30–40% probability) Similar setup, but 2010/11 had confirmed SSW Northern Hemisphere Winter Outcome • Coldest U.S. East winter in 30 yrs • Record snow: NYC 61", Chicago 57" • Blocked pattern (–NAO/–AO) • Above-average cold/snow risk: East Coast, Midwest, N. Europe • Potential blocking, but less extreme than 2010/11 Strong analog for pattern, but amplitude likely lower due to weaker La Niña

AAM, which as expected has risen to near neutral after a long period of solid -AAM, is progged to return to La Niña supporting solid -AAM in early Nov: @snowman19

-Atlantic 2025 ACE finally just reached 100. -Though Melissa has yet to produce much ACE (2.2), there’s a whole lot of potential based on the NHC forecast of a combo of very slow movement for many days and reaching cat 4 status in a few days. IF this all materializes, we’d realistically be looking at the possibility of 30+ more ACE though forecasting the ultimate intensity is at a well above average difficulty for this storm. This is still struggling with shear and thus has been holding pretty steady. On the low end, this could never get much above cat 1 and end up with <15 total ACE. Of course, Melissa may not be the last storm. My pre-season prediction was 139 by the way.

Chris, Thanks. I still don’t see why the reduction of sulfates would cause such a sudden warming in the Pacific over a short period in early 2023. That still seems odd and thus it’s pretty fascinating!

I wouldn’t at all be surprised if IOD were to go positive as early as January based on past seasonal patterns and the recent positive favored IOD era we’re now in. If El Niño is going to occur next year, I’d think that would probably also help it rise.

Hey Brian, I checked the coordinates as Gilbert passed over Jamaica: It went from 17.6N, 75.3W to 18.3N, 78.5W over a 12 hour period. Per a lat/long mileage calculator, that’s 216 statute miles, which means a brisk 18 mph. That’s a whopping 6 times faster than the very slow average of 3 mph that Melissa is forecasted to move while adjacent to Jamaica! So, Gilbert held onto its strength while moving right over it at 18 mph. How would Melissa do moving a mere 3 mph but just south of the island? I don’t see how it wouldn’t weaken some, possibly significantly, at some point during that 48 hour period if it is initially at MH strength, even if not immediately due to drier inflow from Jamaica.

Hey Chris, If the sudden early 2023 spike was due to sharp mid-latitude Pacific warming, then what caused that sharp early 2023 Pacific warming?

Thanks Charlie, This tells me that they still don’t know why there was a sudden spike in the first half of 2023. Just a lot of speculation.

I also wonder about that as the highest mountain on Jamaica is over 7,000 feet up! So, hopefully it won’t although it is likely that the enormous rainfall potential is the biggest threat, regardless. 12Z Icon: weaker with strongest being 992 mb near Haiti per WxBell.

Based on the last 11 years or so (back to when the SAI was first tracked in Jerry’s autumn Siberian snowcover threads), the SAI connection to a winter -AO hasn’t worked well at all. I remember that first Oct (maybe Oct of 2014) having a large SAI and getting many of us excited only to end up with a strong +AO winter. So, I don’t think that the SAI matters one way or the other these days. It used to correlate well, but not since it became famous. Maybe it was shy and couldn’t take the popularity.

It’s highly likely that the IOD is now near its lowest of this cycle per climo. Met. autumn is by far the season when they dip the furthest in a cycle. This is the link to NOAA monthly IODs back to 1870 (I think I got this from snowman): https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data Looking back to 1950, these were when the lowest cyclical monthly lows (<-0.7) were hit: 7/2016, 10/1998, 10/1996, 6/1992, 6/1989, 9/1981, 8/1980, 10/1975, 10/1974, 9/1973, 9/1971, 9/1968, 10/1964, 10/1960, 8/1959, 9/1958, 7/1956, 9/1955, 7/1954 Analysis: -# months since 1950 with these minimums: Sept and Oct each had 6 followed by July with 3, and June and August each with 2. So, all were June-Oct. So, IOD tends to dip to lows ~3 months earlier than ENSO dips. -With no sub -0.7 cyclical low since 1950 in Nov, it would be very surprising if the IOD didn’t rise substantially next month. -Sub -0.7 months have been much less common since 1998 as overall average IODs have risen substantially -Positive IOD months used to be pretty rare but since 2006, 60% have been positive. Since 2017, 70% have been positive! -1870-1899 had 6% positive, 1900-1924 had 4%, 1925-49 had 8%. There were positives in 12% of months during the 1950s. 28% during the 1960s, and 33% during the 1970s. There was a temporary drop back to 23% during the 1980s. Then positives rose to 37% during the 1990s, 43% during the 2000s, 59% during the 2010s, and 60% during 2020-4. Does anyone know why the average IOD has risen so much since the early 1900s and continues to rise?

The hurricane models often overdo intensity by a lot, regardless.

Didn’t the 2023 warming come in way too early to be attributed to the 2023-4 El Niño? I distinctly recall the discussions here and elsewhere about that because it started in spring (as early as March) and also the possibility that Hunga Tonga was the main factor due to the enormous amount of water vapor sent up into the stratosphere. All of this remains mysterious to me.

18Z Euro gives much of Jamaica near or just over 20” qpf with heavy rain still likely continuing for a few more hours with the storm still centered over SW Jamaica and SLP way down at 943 mb, which would apparently be the record low per what I read. Lowest on record 958 (Charlie of 1951) followed by 960 (Gilbert of 1988). It’s then moving slowly NNE while SSE of a strong upper trough that’s then over the E US.

I love this look for Halloween with quite a chilly one in much of the E US! Nice +PNA:

Natgas was relatively little changed today, which is indicative of little change in the GEFS/EPS week 2 forecasts for the E US. So, the cooler model runs released Mon and even moreso on Tue for next week, held up well today. The mainly mild levels of modeled E US HDDs have not returned. True autumn seems to be here.

1988-9: 0.9” (Feb) 1989-90: 8.0” (Dec) (record) Same consecutive years for SAV

BULLETIN Tropical Storm Melissa Advisory Number 2 NWS National Hurricane Center Miami FL AL132025 500 PM EDT Tue Oct 21 2025 ...HEAVY RAINS EXPECTED TO SPREAD OVER HISPANIOLA DURING THE NEXT COUPLE OF DAYS... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...14.2N 73.0W ABOUT 305 MI...495 KM S OF PORT AU PRINCE HAITI MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...W OR 275 DEGREES AT 15 MPH...24 KM/H MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES Tropical Storm Melissa Discussion Number 2 NWS National Hurricane Center Miami FL AL132025 500 PM EDT Tue Oct 21 2025 Satellite data indicate that Melissa is struggling in strong shear, which has been the theme for many systems over the deep tropics this year. The low-level center of the storm is exposed to the west of the main area of thunderstorms. Air Force Hurricane Hunters have been investigating the system this afternoon and found that the minimum pressure is around 1003 mb. Based on their observations, ASCAT passes, and Dvorak estimates, the initial intensity is held at 45 kt. Melissa's wind field is also quite asymmetric, with most of the tropical-storm-force winds occurring on the system's east side. Some of the outermost northern bands are approaching Hispaniola, and these heavy rains are expected to spread across that island during the next couple of days. Melissa is a little south of the previous track and it continues to move westward at about 13 kt. There has been no change to the track forecast scenario, which remains complicated. Over the next couple of days, there is fair confidence that Melissa should slow down and gradually turn to the northwest or north and approach Haiti and Jamaica late this week. The motion after that appears to be linked to how strong and vertically aligned the system gets, and that is when the models diverge. If Melissa organizes like the GFS predicts, it could turn northeastward into the weakness in the ridge and move over Hispaniola. Conversely, if Melissa remains sheared and lopsided, it will likely stall and eventually drift westward as a ridge builds north of it. Given the expected continued shear, the NHC track forecast leans toward the latter scenario. This prediction is a little left of the previous forecast and remains a blend of the latest Google DeepMind ensemble mean, the corrected consensus aid HCCA, and simple consensus TVCA. Although the ocean is very warm, the models suggest that the vertical wind shear could persist over Melissa during the next few days. In addition, there is also some dry air in the storm's vicinity. Based on these mixed signals, the strengthening trend is expected to be slow. In fact, the new guidance supports nudging the short term intensity down a bit. If Melissa remains over the Caribbean late this week and over the weekend, the upper-level winds could become more conducive for more significant strengthening. The NHC intensity forecast is in best agreement with the HCCA model. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 14.2N 73.0W 45 KT 50 MPH 12H 22/0600Z 14.5N 73.7W 45 KT 50 MPH 24H 22/1800Z 15.0N 74.4W 50 KT 60 MPH 36H 23/0600Z 15.5N 75.0W 55 KT 65 MPH 48H 23/1800Z 16.1N 75.1W 60 KT 70 MPH 60H 24/0600Z 16.5N 75.0W 60 KT 70 MPH 72H 24/1800Z 16.9N 75.0W 60 KT 70 MPH 96H 25/1800Z 17.3N 75.0W 65 KT 75 MPH 120H 26/1800Z 17.5N 75.2W 75 KT 85 MPH $$ Forecaster Cangialosi