May 10, 2025 Saturday Weather Update

Southeast drenched over next few days with slow moving cut-off low

Good morning!

Only 3 weeks away from the beginning of Atlantic Hurricane Season. We typically look “close to home” for development as the tropical wave season in the “Main Development Region” or MDR doesn’t get going until July. Couple reasons: (1) the tropical waves aren’t strong due to heavy Saharan air and dust, and (2) ocean temperatures are too cool (< 26°C) for sustained tropical convection.

Across the Tropical Atlantic today, a plume of dust is cross into the Caribbean with fairly thick haze along 15°N. It shows up well in the true color satellite imagery.

From a model perspective, the NASA GEOS-5 (a cousin of the NOAA GFS) includes aerosols or dust particles in the forecasting model. A lot more dust or sand positioned to come off the African continent in the coming days.

Sea Surface Temperatures May 9, 2025

The 26°C isotherm or contour of constant temperature dips into the 10°N latitude in the central and eastern Atlantic as of May 9th. However, that was significantly further north last year as the Atlantic was much warmer.

Compare to May 9, 2024

2025 minus 2024

On its own, this cooler central and eastern Atlantic is a signal for less activity in the upcoming hurricane season assuming the cooler SSTs remain. A change in the trade winds could easily allow the MDR SSTs to jump upward along with the march of the seasons into summer.

The warmer water where the Bermuda high is centered provides a good memory of the overlying weather systems that mix (or don’t mix) the ocean surface below.

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