S/Y Belisama
Wednesday, 6 August 2025
Cold fronts
Warm fronts
Mesoscale drivers, understanding regional weather drivers in the Northern Adriatic
When the synoptic map shows nothing special, the real action often comes from local and regional weather drivers.
Understanding these mesoscale effects is essential for safe and comfortable sailing in this highly variable and geographically complex region.
40 knots bora katabatic wind in Senj, while only 10 knots in Mali-Lošinj, from Northeast over the Triest and Senj area on 9 June 2025.
1. Sea breeze and land breeze cycles
Sea breeze (daytime)
- Driven by temperature contrast between land (which heats faster) and sea.
- Warm air over land rises; cooler, denser air from the sea rushes in to replace it.
- Typically builds late morning, peaks in the afternoon (10-20 knots), and fades around sunset.
- Most reliable in spring and summer, during clear-sky high-pressure conditions.
- Driven by temperature contrast between land (which heats faster) and sea.
- Warm air over land rises; cooler, denser air from the sea rushes in to replace it.
- Typically builds late morning, peaks in the afternoon (10-20 knots), and fades around sunset.
- Most reliable in spring and summer, during clear-sky high-pressure conditions.
Land breeze (nighttime)
- Land cools faster than sea after sunset.
- Cold air over land flows out to sea, usually as a light offshore wind (less than 10 knots).
- Can oppose or reinforce synoptic winds depending on alignment.
- Watch out: the transition period around sunset and sunrise can be tricky, especially when sea breeze fights against a light synoptic wind.
2. Mountain and valley winds
The Dinaric Alps and surrounding terrain create downslope (katabatic) and upslope (anabatic) flows:
Katabatic winds
- Cold, dense air descends rapidly down mountain slopes.
- Strengthens at night, especially during Bora events.
- Can cause sudden gusts even when synoptic maps show calm conditions.
Anabatic winds
- Sun heats mountain slopes during the day.
- Warm air rises, sometimes enhancing cloud formation over inland hills.
- Can trigger localised convection, cumulus development, or instability.
Example: inland hills east of Trieste can enhance the afternoon sea breeze or destabilize conditions.
3. Thunderstorms and squall lines ("nevera")
- Triggered by hot, moist surface air meeting a cold air mass aloft or by convergence zones.
- Typically form in late afternoon or evening and may come from the northwest, crossing from Italy or forming over Istria.
- Nevera: sudden violent squall line, short-lived but dangerous. Winds can spike to 30+ knots with thunder, lightning, and downbursts (see "Never ever again unprepared for Nevera, 16 June, Šibenik").
Saturday, 2 August 2025
Synoptic scale: understanding global weather drivers
Understanding weather begins at the global level, what meteorologists call the synoptic scale. The word "synoptic" comes from Greek and means "seen together" or "comprehensive." In meteorology, it refers to large-scale atmospheric patterns and interactions that influence the weather over wide areas.
Monday, 28 July 2025
Setting the global picture: how air moves around the earth
“To understand what’s going to happen next in your sailing spot, you need to know what’s happening around the world.”
When planning a sailing trip, particularly in the relatively enclosed Adriatic, knowing where the wind comes from, where it might go next and what will be the drivers is vital. Most of the winds we experience aren't just random gusts. They are part of a much larger earth’s atmospheric circulation.
Figure 1. Idealised depiction (at equinox) of large-scale atmospheric circulation on Earth, Wikipedia
This post explores how the global engine of wind and weather works, and why it matters every time you raise your sails...
Sunday, 27 July 2025
Adriatic weather forecast sites

Wednesday, 23 July 2025
Belisama in Limfjord, 20-21 July 2025
As part of or summer explorations, we decided to explore the Limfjord with a couple of South-African friends on a weekend where all conditions could be met: none of us four having to work and weather permitting. The ride from Marina Polesana is 27 nautical miles, heading north through Fažana and Rovinj, before heading up the Limfjord.
Our Australian friends were there for a couple of days last year after we met in Umag and they were advising us to visit this place. And we did and understood why...