Bryan Norcross: Potential for tropical impacts in Hawaii and the Caribbean this weekend
A broad tropical disturbance officially tagged Invest 93C by the National Hurricane Center is just over 1,000 miles southeast of the Big Island of Hawaii. It has a well-defined circulation, but thunderstorms are not yet wrapping around the center. The odds are it will organize sufficiently to be designated a tropical depression or storm today or tonight.
A broad tropical disturbance officially tagged Invest 93C by the National Hurricane Center is just over 1,000 miles southeast of the Big Island of Hawaii. It has a well-defined circulation, but thunderstorms are not yet wrapping around the center. The odds are it will organize sufficiently to be designated a tropical depression or storm today or tonight.
There is a strong consensus in the computer model forecast that the system will intensify into a tropical storm or hurricane over the next few days as it heads in the direction of the Hawaiian Islands.
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The forecast is not set in stone. The system hasn't even developed yet. But the threat is sufficient that everyone in Hawaii should: 1) Plan where they could go to be safe if they live in housing vulnerable to strong winds, heavy rain, and/or elevated tides, and 2) Stay up to date on the latest information from local officials.
Since the exact track of the storm is not knowable very far in advance, everybody has to be ready for a variety of eventualities. For example, if the center of circulation of a tropical storm or hurricane interacts with or tries to pass over 13,679-foot Mauna Loa on Hawaii Island, the storm will be disrupted and could reform to the north or south of the islands.
The exact track will also dictate which parts of the islands will receive strong onshore winds and which won't. The windward slopes normally get the heaviest rain. There's no way to know the details right now, and there likely won't be until late in the week.
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Tides are already elevated due to strong trade winds, the moon’s distance from the earth, and thermal expansion of the ocean due the water being unusually warm. Waves will be extremely large, even if the storm misses, and it could be dangerous to remain near some of the beaches. The National Weather Service in Honolulu and the Hawaii Emergency Management Agency will be analyzing the threat to keep everybody safe.
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On the current schedule, weather conditions on the Big Island will start to deteriorate late Friday, Hawaii time, with the storm passing near or over the islands over the weekend.
The system threatening Hawaii will be given the Hawaiian name Lala if it intensifies as forecast by the computer models.
The only thing to do now is to make a good plan and stay informed.
Another disturbance just east of the one that's threatening Hawaii is designated Invest 99E by the National Hurricane Center. This one has an E on it because it's technically in the Eastern Pacific. The potential Hawaii storm is in the Central Pacific and therefore has a C on its invest number.
In any case, this system might organize into a tropical depression or storm briefly, but the broad circulation around likely-Lala will disrupt it and that should be that. It's no threat to land except that it will add extra energy to the ocean and produce big waves.
Since this system is in the Eastern Pacific – east of 140° west longitude – it will get the name Hernan if it reaches tropical storm strength.
There are two systems of note. The first one is the disturbance we've been following that the NHC has designated Invest 92L. It's midway between Africa and the Caribbean islands. The second one is still near Africa, but behind it on a similar track.
The National Hurricane Center gives Invest 92L a high chance of developing into at least a tropical depression before it gets to the islands about Saturday. It will be fighting off Saharan dust and plowing into strong upper-level winds as it approaches the Caribbean. That will likely keep it from intensifying very much, if at all.
The current consensus is that it will move into the northeast Caribbean as something of a moisture surge, but the Saharan dust will limit how much of a moisture envelope it has. At least that seems to be the most likely outcome right now.
As always, all forecasts for disorganized or just developing systems are subject to significant change, but the hostile environment near and over the Caribbean gives us some confidence that a strong storm is very unlikely.
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