14 September 2021

Hurricane Nicholas hits Texas, and keeping a close eye on Africa

Since my previous update two days ago, Tropical Storm Nicholas formed on September 12th in the Bay of Campeche, then rapidly intensified to a hurricane just as it made landfall near Galveston in the early morning hours of the 14th. Nicholas is the season's 14th named storm and 6th hurricane... the average dates for those to occur: November 18th and October 15th.  This is quite an exceptional level of activity so early in the season.

[By the way, Category 2 Hurricane Ike made landfall in Galveston too, on September 13th, 2008... Nicholas missed that anniversary by a few hours.]

Throughout the day on Monday, Nicholas had some really favorable conditions to work with, and some not-so-favorable. The center reformed in different locations, shear made the storm lopsided, dry air eroded large portions of it away, but at the end of the day (literally), the super-warm Gulf of Mexico provided it with enough fuel to just barely cross the Category 1 hurricane threshold.


By far, the greatest threat from Nicholas has been and continues to be the heavy rain.  As you can see in that radar loop above, most sectors of the storm are devoid of rainfall, but where it does exist, it's persistent and slow-moving.  The areas at highest risk for flash flooding are highlighted below:

We've been watching pre-Nicholas for the past 5-6 days, since it was near Nicaragua. Although some of these storms aren't named systems for very long, or it seems like they pop up out of nowhere, they most definitely do not. Some just take a long time to fester and once they finally get their act together they're already near landfall.

As my friend and colleague Bob Henson pointed out in a blog post, Nicholas is now the 19th named storm to make landfall in the U.S. since May 2020... the average is about three per year.

Now shifting our attention to Africa, recall that easterly wave I mention in Sunday's update.  It has wasted no time getting better organized once it left the coast.  Currently tagged as Invest 95L, it is quite close to becoming Tropical Depression 15, and then Tropical Storm Odette would be the next name.

The GFS and ECMWF global model ensembles both favor this for development, but neither are alarmingly bullish on intensifying it too soon.  It's in no rush to head westward, so even if it were to develop and reach the Lesser Antilles, it wouldn't reach the islands until the Sunday-Tuesday timeframe.  There's plenty of time to wait and let this do its thing.

One thing the ensembles have indicated in the past several runs is that a stronger version of the storm is more likely to turn northward well before the Lesser Antilles, while a weaker version could cruise much closer to the Caribbean.  We would be wise to watch the progress of a strong wave in the deep tropics in mid-September very closely.

And finally, that area north of the Bahamas that I mentioned on Sunday now has a more focused low pressure center, and we could see some development of that in the coming days as it drifts north.  As of now, it's nothing to be concerned about, just worth keeping an eye on it.  The National Hurricane Center is giving it a 60% probability of becoming a tropical cyclone in the next five days somewhere in the shaded area on the map.

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