May 21, 2026 Thursday Tropical Update
Atlantic hurricane season starts June 1st and may be front loaded
May 2026 was the 29th-warmest May in the 132-year national record (1895–2026), at 61.7°F against a 1991–2020 normal of 61.0°F (+0.6°F).
May 2026 was the 63rd-driest May in the 132-year national record (1895–2026), at 2.9in against a 1991–2020 normal of 3.1in (-0.2in).
NOAA/NCEI Climate at a Glance, contiguous United States. This is the observed record for the month, not a score of anything said in this piece — the forecast ledger begins 2026-08-17 and cannot reach earlier posts.
My Atlantic Hurricane Season Forecast (2026)
From April 7, 2026: Atlantic Seasonal Hurricane Forecast: (11/5/2)
9-13 Named Storms (11 most likely)
4-7 Hurricanes (5 or 6 most likely)
1-3 Major Hurricanes (2 most likely)
Accumulated Cyclone Energy: 75-85 (well below normal)
NOAA 2026 Atlantic Hurricane Season Forecast
Link: Media Release from NOAA
Not much unexpected here from NOAA in their morning press release. The upcoming season has a 90% chance of being below normal to near normal … and only 10% chance of being above normal primarily due to El Niño in the equatorial Eastern Pacific.
The range of named storms is 8-14 and hurricanes 3-6 and major hurricanes 1-3, but you can point to combinations over the past several decades, and come up with 14/6/1 or 8/3/3 … largely dependent upon sub-seasonal features like the MJO, dust outbreaks, and what’s happening in the Western Pacific typhoon alley with the monsoon. I’d go down the middle with 11/6/2 and ACE of 80.
Climate Prediction Center (CPC) details about 2026 Hurricane Season
El Niño conditions are likely through the hurricane season. During the peak months (ASO)
High-activity era for Atlantic hurricanes which began in 1995 — likely to continue in 2026 but favorable conditions are not likely to be as strong as during many years in the last decade. These conditions include (1) warmer sea-surface temperatures (SSTs) and (2) weaker trade winds in the Atlantic hurricane Main Development Region (MDR), along with (3) weaker vertical wind shear, and a (4) conducive West African Monsoon.
Multivariate ENSO Index (version 2) —> Link: NOAA page
The El Niño/Southern Oscillation (ENSO) - a naturally occurring anomalous state of tropical Pacific coupled ocean-atmosphere conditions - is the primary predictor for global climate disruptions. These can persist over several seasons and thereby produce severe regional effects.
The MEI, which combines both oceanic and atmospheric variables, facilitates in a single index an assessment of ENSO. It especially gives real-time indications of ENSO intensity, and through historical analysis - provides a context for meaningful comparative study of evolving conditions.
Current Value is -0.6
I have always favored the MEIv2 to assess the intensity and evolution of ENSO since the climate system is much more complicated than the SST anomaly in arbitrary rectangles in the equatorial Pacific.
The El Niño of 2023-24 was not that long-lasting or intense, and really didn’t negatively impact the 2023 Atlantic hurricane season because other factors overwhelmed the otherwise weak teleconnections.
The climate system has been in La Niña since summer 2024, and continues at weak Niña intensity through March/April (-0.6).
Wild cards:
Will we see strong atmosphere ocean coupling and teleconnection between the anomalous warmth in the central and eastern Pacific with the Northern Hemisphere into Summer/Fall? Yes, I think so, more along lines of 1997-98 (but less Super)
Late onset of El Niño in the MEIv2 could mean front-loaded hurricane activity
Eastern Pacific + Central Pacific Infrared Satellite
Some convection along the monsoon trough / ITCZ but nothing spinning or expected to develop further
Atlantic Basin Satellite Channels — major dust cloud coming off Africa
GeoColor show the visible “true color” just as you’d see from space — in geostationary orbit (locked in place to look down) … aside from the puffy clouds and some storms, you can see the milky brown haze = African dust or Saharan Air Layers (SAL) that come off Western Africa into the Atlantic Ocean. SAL is bad for the hurricane business = stable/warm layer that limits instability and convection (storms)
Infrared (Channel 13) colorized —> showers and thunderstorms
Water Vapor (Mid-Level Ch. 9) - troughs + areas of descending/dry air
ECMWF 12z | Precipitation Type + MSLP | Next 8-days
The Intertropical Convergence Zone (ITCZ) in the tropics along 5°N to 10°N is where moist air can ascend and form thunderstorms or like a convective pot boiling over = convection. In the coming weeks, especially into late June, we’ll look for areas of disturbed weather — which means persistent convection — and potential formation of low pressure swirls along the ITCZ with tropical waves, in the Caribbean and Gulf of Mexico (America) with decaying frontal boundaries, and other pathways like tropical transition or subtropical cut-off lows. Lots of options/ways to form a tropical storm in the Atlantic in any given season.
The Bermuda High —> Azores High in the subtropics usually keeps things quiet in the latitude around 30°N and suppresses the ITCZ to the south in late May into June. On the periphery of the Bermuda High, moisture plumes out of the Caribbean into the Gulf and then Texas + Southeast.
NASA GEOS5 —> African dust plume forecast next 10-days
NASA runs a version of GFS internally that is configured to ingest / test various satellite based instruments. Their dust algorithm with GEOS-5 is very good, and I really like to show the evolution of African dust (Saharan Air Layers) over the Atlantic.
Right on schedule into late May, we have a major plume coming off the continent that should enter the Caribbean in next 5-days, with persistent SAL flow into June.
North Atlantic Tropics | Quiet Next 7-days
2 Tropical Waves — but neither will develop in the Atlantic or Caribbean … but will be watched as they enter the Eastern Pacific
Global Ocean Temperatures —> Sea Surface Temperature (SST)
Tropical storms need at least 26°C SST to form and intensify … and hurricanes most often become major with 28°C SST (at least) … the Atlantic has plenty of real estate that could support a TS or H, but nothing percolating as the basin is very hostile or unfavorable to formation. Note, it is the “actual” ocean temperatures that fuel hurricanes, not anomalies or deviations from climatology.
There are still rather cool (relative) areas in the Western Pacific and North Atlantic compared to the excessive warmth along the Equator and off the western coast of Mexico. The recent 20-year climatology highlights much better than an older 1991-2020 baseline.
However, we do look at SST anomaly to see where excessive warmth may be located e.g. "marine heat waves” that could fuel stronger hurricanes than otherwise expected.
The Atlantic is actually cooler than past 2-decades across the Main Development Region from the Lesser Antilles (Caribbean) to the Azores and coast of Africa. This is NOT a positive signal you’d expect for an active season.
My favorite parameter —> Precipitable Water (PWAT) next 8-days
Tropical storms and hurricanes are bundles of high moisture air > 2” in the column (or more) so we look for areas of concentrated high PWAT air in the tropics —> and we also can view frontal boundaries or dry air input from the middle-latitudes into the subtropics or tropics + Saharan Air Layers (dry)
Integrated Vapor Transport —> IVT next 10-days
The transport of rivers of moist air —> IVT is great metric to show tropical storm development. Here, we see the Bermuda High / subtropical ridge in charge — extending to the Azores across the Atlantic.
Western Pacific Basin — Typhoon Season is Underway
Watching area of possible development in 5-7 days near Mariana Islands, but nothing suspect in the next 48-hours from JTWC. Next name is Jangmi.
Ocean Temperatures (SST) very warm > 28°F over the “warm pool” plenty sufficient for any category of Super Typhoon, assuming one can form, but actually slightly cooler than normal along the northern side of the warm pool.
ECMWF Full Physics Ensemble Tracks — 50 members next 12-days
Tropical Storm formation possible in 5-days, and then development into a strong Typhoon — but the full-physics system actually has 3 potential TS formation chances along the zonal monsoon trough
IVT shows the circulation and intensification into Days 8-10 (May 29-31)
Pretty maps! IVT is under-utilized for tropical storm formation forecasting
WPAC Precipitable Water (PWAT) next 8-days
Plenty of convection / instability across the MDR of the WPAC mainly east of the Philippines — Next 12-days ECMWF 12z (MSLP+Precip)
ECMWF AIFS-Single v2 (Data Driven Forecast System)
ECMWF flagship A.I. weather modeling system Days 5-12 — develops a 950s mb typhoon (Cat 3)
And, the ensembles from AIFS-ENS v2 (different than AIFS-Single) — quite ambitious with the storm formation and intensification!
Eastern Pacific Tropics | Quiet next 7-days
Ocean temperatures are very warm across the basin with the cooler water roughly WNW of 15°N and 110°W
Thank you for reaching the end of this post! Hopefully you enjoyed the tour of the global tropics and what’s coming in the weeks/months ahead in the tropics here on Weather Trader on Substack.
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For 2026 Hurricane Season: Every 6 or 12 hours, we get an update including these model output:
ECMWF EPS full-physics ensembles … 50 perturbed members + control/HRES
ECMWF AIFS-Ensemble (data driven) … another 50 members + control
ECMWF AIFS-Single … a special deterministic system that has exceptional skill
NOAA GEFSv12 Ensembles … 30 perturbed members + control
NOAA GFSv16 … 13-km high resolution global deterministic
UK Met Office MOGREPS lagged ensembles … global 14-km 72-members per day
Environment Canada ensembles + Germany ICON + Australia BOM Unified Model
New Google WeatherNext 1000-member ensemble system (!) more on that in future post
- Milepost
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