Alfredo Contaldovideo
WEATHER for recreational boating ⛵ how to read SYNOPTIC CHARTS, fronts, pressure, isobars...
30 April 2025 · 58 min · 13K views
What this video covers
A second tutorial in Alfredo Contaldo's recreational boating meteorology series teaches sailors how to read synoptic charts for passage planning.0:03 Contaldo works through a printed Met Office UK analysis chart (carta analisis), explaining that these charts are issued every six hours in UTC and that forecast charts extend to 72 hours, though he considers anything beyond 48 hours unreliable.1:01 He covers isobars — lines of equal pressure in hectopascals — and explains how the Coriolis effect causes wind to flow parallel to isobars rather than directly from high to low pressure, producing clockwise divergent circulation around highs and counterclockwise convergent circulation around lows.4:57 To estimate surface wind speed at any point, he demonstrates measuring isobar spacing with a nautical compass, reading geostrophic wind from the latitude scale, then multiplying by 0.7 to reduce by 30%; direction is adjusted 30 degrees toward low pressure over land, 5 degrees over sea.17:11 He identifies four isobaric configurations — slope, ridge, trough, and saddle — and their associated weather.52:12 Warm fronts show cirrus at 1,000 km, with precipitation beginning at 350 km; cold fronts bring shorter, more intense, localized precipitation.33:00 HF SSB radio reception of meteofax charts is mentioned as an offshore option.3:11 Mediterranean forecasting is flagged as particularly difficult.57:05
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