jconsor

Satellite loops this Sunday morning show 99L has a small circulation. This is confirmed by two satellite wind estimates (ASCAT and microwave-based MIRS). Model guidance is playing catchup big-time with #99L, with deep convection and strong vorticity persisting for several days despite model forecasts that 99L would remain an open wave with little convection. 99L's small size is likely a big factor in this (we something similar before Oscar formed last year). Read my in-depth analysis of 99L and its potential to organize further late this week into this weekend in the western Caribbean and eventually BOC/GOM: https://hurricanehacker.substack.com/p/caribbean-cruisin

Hurricane Erin, despite weakening significantly in the past 24 hours, may have one more round of strengthening in its arsenal. With a fetch of tropical storm force winds extending out hundreds of miles into the ocean piling up water over three days of high tide cycles, water levels from NC to SE Virginia could rival levels during Dorian and Irene. The Delmarva Peninsula to southern NJ could see a top 5 water level on record as well. https://hurricanehacker.substack.com/p/too-close-for-comfort

Erin continues to remain on the southern side of forecast spread today, but that may not matter much for possible impacts from NC to SE New England. Will Erin re-intensify now that her eyewall replacement cycle is done? Starting to make about half of my posts paid this week, so I encourage all of you tropical freaks to subscribe and support my work so you can see all of my hurricane-related posts. https://hurricanehacker.substack.com/p/systematic-bias

@bugalou These graphics of NHC cone/track overlaid with Erin satellite loop are very helpful. Did you create this via an app or website? I am familiar with WeatherNerds satellite loops that allow overlay of EPS/GEFS members. The CIMSS storm-specific page allows overlay of the *current* NHC track, but doesn't dynamically update it every 6 hours as your loop did: https://tropic.ssec.wisc.edu/real-time/storm.php?&basin=atlantic&sname=05L&invest=NO&zoom=4&img=1&vars=111110000000000000000000&loop=0&llval=OFF

Thanks man! Appreciate the encouragement and positive feedback. I expect to post an update today.

Powerful Hurricane Erin continues to track on the southern edge of the model spread on Sat, as shown in the attached image. Erin's actual track in six hour increments is shown in the black X's, with NHC's main consensus forecast model TVCN shown in blue, with darker shades indicating more recent forecast model runs. You can see Erin made a notable bend to the left (turning from west-northwest to due west) in the past 12-18 hours and is currently about 50-75 miles south of consensus model forecasts from 24 hours ago. Here's an in-depth post I wrote on Fri describing my concerns that ensemble forecasts are underdoing W. Atl ridging, and explaining why US impacts can't be ruled out yet. It wasn't posted until now due to coming down with a stomach virus and some technical issues. My thoughts on Erin's track and potential US impacts haven't changed much since Fri. Would appreciate if you can take a look at the post and send me feedback (you can PM me here or write to [email protected]), as well as spread the word about my Substack. Thank you guys! https://hurricanehacker.substack.com/p/arrested-development

Tropical Storm #Erin continues trucking west and is showing signs of life after nearly two days of struggling. While a weakness in the western Atlantic ridge is a given, how quickly the ridge rebounds and what role an eastern US trough play could lead to some longer-term track intrigue. In-depth analysis and a parody of a 1970s R&B classic here: https://hurricanehacker.substack.com/p/losin-latitude

Please post the link for the vertical instability graphic. Thanks

ECMWF and Australian BOM models (amongst other seasonal models) suggesting a Central Atlantic NIno developing. This, along with portion of the very warm anomalies west of Europe gradually bleeding SW the Canary Islands and eastern tropical Atlantic, could help ramp up activity in the deep tropics, particularly west of 40W. https://x.com/yconsor/status/1930624747382964591

Hi Chuck, Interesting comparisons! I personally think using named storms to characterize active vs. inactive years is not particularly meaningful, given the human subjectivity and changes in NHC criteria over the years in terms of what is named. If we take the years with the most and least ACE since 1995, removing years that were El Ninos in the Apr-May timeframe (since they tend to be strongly correlated with -NAO), here are the most active years: 2020, 2005, 2004, 2003, 1999, 1996, 1995 The least active years: 2014, 2013, 2009, 2007, 2006 This year has some characteristics in common with the least active years (-MSLP anomaly from NW Territories of Canada to Greenland and +MSLP anomaly from the NW US to Hudson Bay and off the coast of the NE US). However, what is different from the inactive year composite, and closer to the active year composite, is the -MSLP from near Newfoundland to the central Atlantic near the Azores and then southward into the far east Atlantic and w. Africa. Additionally, the strong +NSLP from near the UK to Iceland is more similar to the active year composite. In short, a mixed bag, probably closer to inactive years but not a clear signal!

I was referring to highly unlikely possibility that so many of the hurricanes in both basins will become majors.

7 hurricanes and 5 majors in the Atlantic (and 6 and 5 in the East Pacific) is a rather comical outlook

In my view, it's mportant not to lump all La Ninas together. Modoki (central Pacific-based) La Ninas are notably different from traditional (East Pacific-based) Ninas. This has big implications for the level of Atlantic TC activity and where in the basin it tends to be focused. This year is more likely to end up a Modoki La Nina, with cooler water relative to normal focused in the central Pacific: https://x.com/yconsor/status/1927306239920283821

Thread explaining why I think chances for tropical development in the NW Caribbean and Gulf of Mexico ramp up significantly around Jun 4-10. https://x.com/yconsor/status/1926690131181731976

After not being much of a factor from 2019-24, looks like the N. Atlantic warm hole, a pool of relatively cooler water south of Greenland, is returning and should remain through peak hurricane season. This tends to ramp up the risk for E. Coast hurricanes, particularly slow-moving ones: https://x.com/yconsor/status/1925494559032668254

268Weather, an eastern Caribbean-based forecast service, has updated its hurricane season outlook: They are going for 21 TS, 9 hurricanes and 5 MH, with ACE expectation of 185. They indicate a 48% chance of ACE above 223 and a 52% chance of at least 11 hurricanes, each of which would place 2025 amongst the most active hurricane seasons on record. Seems odd that their baseline forecast for H is 9 and ACE is 185, yet there is around a 50% chance of ACE and hurricanes well above these numbers. If you look back at their track record, their May forecasts were considerably too high (bullish) in 2021 (ACE forecast 179), 2022 (175) and 2024 (218). On the other hand, their May 2017 forecast (ACE of 110) strongly underestimated activity. They were on the few seasonal forecasting agencies to catch onto slightly above normal activity (based on 1950-2020 normals) in 2018 and 2019. https://268weather.wordpress.com/2025/05/16/268weather-may-2025-update-atlantic-hurricane-season-still-projected-to-be-above-normal/

Levi Cowan (from Tropical Tidbits) raises significant skepticism about this report claiming AccuWeather forecasts were more accurate last year: https://x.com/TropicalTidbits/status/1925320719732547804

16/9/5

Detailed thread about recent trends in the Indian Ocean and ENSO regions, and indicators as to which seasonal models are more likely to have the right idea on ENSO situation during peak hurricane season: https://x.com/yconsor/status/1922643952135557481

Thanks for posting the S&P outlook, Barry. Very interesting! One of the few *data-driven* (not totally qualitative) landfall risk outlooks I have seen. Their maps seem to suggest higher than usual activity in the central Atlantic portion of the MDR (around 40-60W) and the Bahamas area (off FL coast) as well as the Caribbean and GOM.

Early indications from seasonal models favor an active Atlantic hurricane season, perhaps even hyperactive. https://x.com/yconsor/status/1901982720378425715

While I agree that extratropical (non-MJO) forcing played a significant role in the cold Jan 2025 outcome across the eastern/central US, we need to be careful using VP averaged across an entire month. Subseasonal variability clearly played a role here. In addition, the NCEP reanalysis has some notable biases in VP - it tends to show overly positive VP anomalies near C/S. America and Africa. See Stanfield et. al 2024, A Climatological Analysis of Upper-Level Velocity Potential Using Global Weather Reanalysis, 1959–2020: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8659 The vast majority of the cold anomalies in the eastern/central US occurred in the first two-thirds of Jan. From around Jan 23 onward it turned warmer than normal. The Jan 1-10 and Jan 11-20 VP anomalies show -VP anomalies migrating from the central/eastern Pacific and W. Atlantic, to the e. Atlantic and w. Africa. The magnitude is not as high as the negative anomalies that developed from the eastern IO to Maritime Continent in the Jan 21-31 period. However, especially in the Jan 11-20 period I would argue the MJO had a significant role, given the coherent wave of -VP (and corresponding +VP across the c/e. Pacific) that developed.

The Jan 22, 1987 snowstorm you are referring to is one of the main events that got me interested in weather. I grew up on the North Shore of LI (Roslyn) and I recall the forecast being for an inch or two, then quickly changing to rain. Instead snow piled up at 1-2" per hour and there was never a change to plain rain, just a little freezing drizzle at the end. As Ed said, it was traffic chaos. I was in second grade at the time and we were stuck at school for about 6 hours! The plows couldn't keep up with the snow and the hills on the roads in/around Roslyn made things even worse.

Some additional context to the unusual nature of this cold outbreak stratosphere-troposphere wise: https://bsky.app/profile/drahbutler.bsky.social/post/3lekmlyusmc25

Indeed, as we get closer in the guidance is correcting to a stronger high pressure and CAD wedge for the last week of Dec. https://x.com/yconsor/status/1870772344031268877