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Atmospheric pressure measurements collected by M3E buoys helped improve forecasts during Storm Harry. The study provides initial evidence of the value of a denser observing network in the Ionian Sea and central Mediterranean, where direct measurements at sea remain scarce.
A storm can be detected days in advance while its local impacts remain difficult to predict. That was the case with Harry in January 2026, a challenge that matters when planning fishing trips, returns to port and work at aquaculture facilities.
A study published on 12 October 2026 in the Quarterly Journal of the Royal Meteorological Society shows how drifting buoys can contribute to better forecasts. Led by David Lavers of the European Centre for Medium-Range Weather Forecasts (ECMWF), the research examines Storm Harry and the contribution of observations collected through the Mediterranean Extreme Events Experiment (M3E). The international initiative is jointly coordinated by OGS and CMCC.
Why more observations at sea are needed
The Ionian Sea and central Mediterranean can experience intense storms, yet atmospheric measurements collected directly at sea have historically been sparse. Expanding this coverage provides forecasting systems with additional information from the areas through which storms develop and move.
M3E uses drifting buoys equipped with barometers and sea surface temperature sensors. The instruments transmit observations by satellite every hour, making them available to forecasting centres in near real time. Deployments began in September 2025, and the campaign described in the study involved 20 buoys.
The role of atmospheric pressure
Atmospheric pressure helps describe the position and intensity of low-pressure systems. Measuring it in an area with limited observations gives models a reference for reconstructing current conditions and calculating how they may evolve.
This process is known as data assimilation: observations are combined with existing information to update the model’s initial state. The buoys therefore add local measurements to the observing network used by weather forecasting systems.
What the Harry case study shows
The authors of the study on M3E and Storm Harry assessed the contribution of these observations using two methods.
An initial analysis, which estimates how individual observations influence forecast quality, indicated a reduction in 24-hour atmospheric forecast error. A beneficial impact was identified for a buoy in the Ionian Sea during the storm’s passage.
A second experiment compared simulations using observations from drifting buoys in the Mediterranean with simulations in which those data were excluded. The clearest differences in forecast pressure emerged near the Balearic Islands, close to small low-pressure systems associated with the storm.
The comparison indicates that forecasts of these systems are sensitive to measurements collected at sea. The benefits for local wind and rainfall forecasts remain to be quantified, along with the effects on marine forecasts. The authors describe the findings as a preliminary assessment.
Harry had already highlighted how predictability can vary between regions. Heavy rainfall in southern Italy was forecast around a week in advance. Forecasting precipitation in North Africa proved more difficult, partly because of smaller, rapidly evolving low-pressure systems. These systems are among the priorities for future observing campaigns.
Potential benefits for fishing and aquaculture
Marine forecasts also depend on how atmospheric conditions are represented, starting with wind. ECMWF atmospheric forecasts provide essential inputs to the Mediterranean Forecasting System, the CMCC ocean forecasting system operating within the Copernicus Marine Service.
“A better atmospheric forecast also means a better forecast of the sea,” explains Emanuela Clementi, a CMCC researcher and co-author of the study.
The damage Harry caused to fisheries in southern Italy demonstrated how weather and sea conditions can affect fishing fleets and port operations. More reliable information could help fleets assess operating windows and plan returns to port. For offshore farms, it could support decisions about staff access to facilities and maintenance work.
These are potential applications of improved forecasting. Their operational benefits for businesses still require dedicated assessment.
The next step is to expand the network. CMCC’s announced plans for autumn 2026 include seven new buoys for the Tyrrhenian Sea, alongside further deployments in the Ionian Sea. The aim is to strengthen data collection in areas where better coverage could help track the development of Mediterranean storms.
Image credit: OGS – M3E project.
L’articolo Storm Harry shows how drifting buoys can improve forecasts proviene da Pesceinrete.
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