After its most sluggish start to a hurricane season since 2014, the Atlantic is threatening to break its silence with a short-lived system over the open waters of the subtropical Atlantic.
The window for development is exceptionally narrow, and regardless, the system is no threat to land. It could, however, briefly steal the “A” name (Andrea) before rip-roaring upper-level winds quickly slam the door shut on further development tomorrow.
Close but no cigar (yet)
On Sunday, the low-pressure system designated Invest 90L by the National Hurricane Center had several of the characteristics we look for in a tropical depression such as a well-defined circulation, air at the center warmer than its surroundings, and no frontal features. What was noticeably missing from the checklist, however, was persistent deep thunderstorm activity. The cloudtops were largely shallow – meaning only light to moderate rain accompanied the system – and while 90L sparked sporadic bursts of deeper storminess, they were mostly fleeting.
This continued to be the case Monday morning, with satellite pictures showing thunderstorms struggling to coalesce around the low-pressure circulation.
While we haven’t had any new satellite-derived wind estimates since late Sunday, the last estimates indicated surface winds in the 30 to 35 mph range, or just under the threshold for tropical storm strength.
So for now, if something formed it would likely be a tropical depression or borderline tropical storm at best.
For now, the National Hurricane Center is indicating 70% odds of a short-lived tropical depression or storm on Monday before the curtain falls on Tuesday.
Mum’s the word across the tropical Atlantic
While unforeseen systems like 90L can happen at any time from initially non-tropical systems in the subtropics (the higher-latitude band of waters just outside the main tropical belt from 10 to 20 degrees north), they usually have less time to cook and strengthen than the classic ones coming from the deep Main Development Region of the Atlantic.
Unlike the precursor to Category 5 Hurricane Beryl – the earliest Category 5 Atlantic hurricane on record – which formed this week last year in the deep tropics, the tropical Atlantic looks to stay dormant through the last week of June, with a generally inhospitable environment sticking around into the early days of July.
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