May 25, 2026 Monday Tropical Update
Powerful Typhoon Jangmi ready to come online this week in Western Pacific
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
More details in Thursday, May 21, 2026 Tropical Update
Atlantic Basin Satellite Channels — major dust cloud in Eastern Atlantic
Earlier this evening, the GeoColor satellite shows 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
Very limited convection over the tropical basin … but some storms with a tropical wave moving through Colombia
Water Vapor (Mid-Level Ch. 9) - troughs + areas of descending/dry air
Huge trough from Florida extending through Bahamas along 25°N latitude to eastern Atlantic = hostile environment in late May.
ECMWF 18z | Precipitation Type + MSLP | Next 6-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 multiple plumes coming off the continent that will sweep into the Caribbean this week.
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.
The Atlantic remains cooler than past 2-decades across the Main Development Region [MDR] 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, but Atlantic SST varies on short-time scales (1-2 weeks) and a change in position of the Bermuda/Azores subtropical ridges can adjust trade winds to quickly warm up the Atlantic MDR.
My favorite parameter —> Precipitable Water (PWAT) next 6-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)
Boatloads of tropical moisture from the Caribbean and Gulf of Mexico surging into the Southeast U.S.
Integrated Vapor Transport —> IVT next 12-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 | Invest 99W
Medium change of development of Invest 99W —> into a powerful Typhoon during next several days
ECMWF 18z Next 6-days Precipitation and MSLP
Next name is Jangmi —> should become a major Typhoon by this weekend
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, with a sharp gradient north of the Kuroshio Current wall.
ECMWF Full Physics Ensemble Tracks — 50 members next 10-days
Majority of ensemble tracks recurve east of Taiwan and then near Japan
IVT shows the circulation and intensification of Invest 99W —> Jangmi
IVT is under-utilized for tropical storm formation and intensity forecasting
WPAC Precipitable Water (PWAT) next 6-days
ECMWF AIFS-Single v2 (Data Driven Forecast System)
ECMWF flagship A.I. weather modeling system through Day 10 — develops a 950s mb typhoon (Cat 3)
And, the ensembles from AIFS-ENS v2 (different than AIFS-Single) — also quite ambitious with the storm formation and intensification!
Eastern Pacific Tropics | Quiet next 7-days
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
- 942 · laid 2026-05-26T02:21:50.123000Z
- Source
- https://weather.substack.com/p/may-25-2026-monday-tropical-update
- Digest
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- Machine
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