North Atlantic SSTA Pattern Cools Slightly Ahead of TC Season

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Highlight: North Atlantic SSTA analysis and trend.

Fig. 1-3: The Gulf of Mexico SSTA analysis and 2-week change (top) plus SSTA across the tropical North Atlantic (index) region.

Fig. 4: The daily North Atlantic SSTA observations.

Fig. 5: The daily North Atlantic SSTA 2-week change observations.

Discussion: The North Atlantic SSTA analysis reveals a developing cooler trend. The cool changes are in the Gulf of Mexico and the Bahamas. In the Gulf of Mexico, the unusually warm SSTA of earlier this spring causing increased low-level atmospheric moisture was used by passing low-pressure areas to unload historic rains on Louisiana into Texas the past 3-6 weeks. The energy provided by the anomalous warm SSTA is easing as the two-week SSTA trend is much cooler (Fig. 1-2). Implied is ability to generate excessive rainfall in the Gulf (or farther north) region is now greatly diminished.

In-between the Caribbean Sea and northwest coast of Africa the tropical North Atlantic index is slightly warm (Fig. 3) and the change has been minimal the past 30 days. This zone is also the main development region (MDR) for hurricanes.

The North Atlantic basin remains marginally warm with regions of both cool and warm SSTA and a two-week cooler trend (Fig. 4). The current analysis is by far the least warm of 2021 so far. However, forecast models indicate a warm-up over the summer.