31 May 2016

Hurricane season ‘begins’ tomorrow — but it’s already off to a head start

The 2016 Atlantic hurricane season begins on June 1... I go over some new and updated products, impressive records, and the list of names we'll be using in this post on the Capital Weather Gang blog:

Hurricane season ‘begins’ tomorrow — but it’s already off to a head start

30 May 2016

Bonnie weakens and stalls over South Carolina

Tropical Depression 2 was upgraded to Tropical Storm Bonnie on Saturday afternoon, and made landfall near Charleston, SC at about 9am EDT on Sunday after weakening back to a tropical depression.  This was the first tropical cyclone to make landfall on the U.S. since Tropical Storm Bill hit Texas on June 16th, 2015.

Satellite and radar images at the time of Bonnie's landfall on Sunday morning.
As expected, it was not a very eventful landfall, just a lot of rain.  The heaviest rain fell to the north of Savannah, and peaked out at about 8-9", resulting in significant flooding.

What's a bit unusual is that Tropical Depression Bonnie is still lingering in basically the same location, but a northeastward motion is expected to begin today, taking the shallow and poorly-organized cyclone over the North Carolina coastline.

It is nothing to be concerned about though, other than the sporadic heavy rain showers associated with it.  I have a regional-scale two-day radar loop of Bonnie at http://andrew.rsmas.miami.edu/bmcnoldy/tropics/bonnie16/Bonnie_28-30May16_southeast.gif

Visible satellite image from Monday morning showing a low-level swirl (Bonnie) over South Carolina.

28 May 2016

TD2 to hit South Carolina on Sunday morning

On Friday afternoon, the area of interest was upgraded to Tropical Depression 2 based on aircraft reconnaissance data.  As of 3pm on Saturday, it is still a depression, but is right on the threshold of becoming Tropical Storm Bonnie (it's a difference of sustained winds increasing from 35mph to 40mph).

The center of the storm is 150 miles southeast of Charleston and heavy rain is already onshore.

It is moving toward the northwest at 13mph, and that motion will bring the center to the coastline on Sunday morning, though it won't be a very dramatic landfall.  The biggest impact will be rain, and that is already occurring; however, a tropical storm warning is in effect for the entire South Carolina coast.

It's passing over the warm waters of the Gulf Stream, but as you can see from the satellite image at the top, it is strongly sheared which is limiting intensification.  That could change somewhat in the 18 hours between this writing and when it reaches the coastline.  The strongest winds in Charleston will be from about midnight through noon on Sunday and could gust to 45-50mph.

I have a long updating radar loop from Charleston available at http://andrew.rsmas.miami.edu/bmcnoldy/tropics/bonnie16/Bonnie_28-30May16_CLX.gif
(it has Bonnie in the filename, but it is not named yet)

20 May 2016

Hurricane Preparedness Week: Local Edition

The week of May 15-21 is Hurricane Preparedness Week, so what better time to send out some relevant information!  I have been a resident of Biscayne Park and Miami-Dade County since February 2012, but have a long history of tropical cyclone work.  I have some background information on my website at

Seasonal climatology

The Atlantic hurricane season spans June 1 through November 30, and by design, the vast majority of activity is typically confined to those dates (not necessarily all of it).  Within the season, about half of the activity (climatologically) falls between August 20 and September 20th.

Although the climatological peak of the season is in early September, the month with the most hurricane impacts in south Florida is October.  June, July, and November have typically been relatively quiet here, while August and September are when the strongest storms have hit.  Also note that about half of our storms come from the east (generally Jun-Sep) and half come from the west (generally Oct-Nov).

A long lucky streak

Florida has not been hit or affected by a hurricane since October 24, 2005 when Wilma passed across the peninsula.  That span, or "hurricane drought", is unprecedented in known history by a huge margin.  The previous record was about six years, and the average return period is roughly 1.4 years.  There is no obvious physical reason for this, as there have been plenty of hurricanes since then, and other states (and countries) have gotten hit by hurricanes multiple times.  One of these years, our luck will run out.

Zooming in to Miami-Dade County, the hurricane "drought" is not a record yet, but it's long.  The county has only been affected 4 times in the past 50 years, including 1 major hurricane (defined to be Category 3+).  Compare that to the previous 50 years, when the county was hit 17 times, 11 of which were major hurricanes!  The chart below shows a timeline of hurricane impacts with major hurricanes marked in red, and overlaid in the orange line is the county's blossoming population.

The influx of new residents together with a lack of hurricanes results in a dangerous combination of inexperience and complacency.

Trees and Debris

While having a long break from hurricanes is nice, it has also allowed a unique situation to arise: we now have over 10 years of untested tree growth.  Trees can get full, top-heavy, rotten, etc, and strong gusty winds are really good at finding those weak points.  Since October 2005, trees around here have not experienced any serious wind-related threat, so we can expect the next hurricane to create an abnormally large mess (downed power lines, roof and house damage).

This is the perfect time to look around your property to see what you can to minimize damage before a storm threatens.  That includes random unused outdoor items, and especially trees.  Having your trees properly pruned, thinned, and/or topped (or removed if they're dead or rotten) now can save you and your neighbors damage and power loss during a storm.  If the tree is growing into or over power lines, it's best to report it to FPL and they'll take care of it (it saves them time to do preventative work rather than repair work).


305-442-8770 (options 1-1-5... request tree trimming service)

Evacuation zone and Plan

In the event of an intense hurricane approaching, storm surge becomes a concern.  Storm surge is the rise of water levels due to strong onshore winds "bulldozing" the ocean onto land, and is the #1 killer during hurricanes in the U.S. by far.  Storm surge also does not correlate perfectly with a storm's category... it also depends on the size of the storm, coastal topography, offshore bathymetry, and more.  A large slow-moving Category 1 hurricane could generate a larger storm surge than a small Category 3 hurricane, for example.  "There's more to the story than the category!"

In Miami-Dade County, our evacuation zones are defined by storm surge risk (not wind risk), and the zones are not limited to the immediate coast.  The surge of water can travel up canals and rivers if the wind is aligned just right.  The zones are crude in shape, and the entire county would never experience the peak surge or evacuation orders.  But knowing your zone letter gives you a general sense of your potential risk from storm surge... here is a map centered on my local area:

and here is the interactive website if you want to peruse more on your own:

If you ever do decide to evacuate, it is a good idea to have a place and plan in mind before the stress of an approaching storm sets in.  And always let friends and neighbors know where you're going and how to contact you.


Review your policies and coverage, and make sure you know a number to call after a storm if you need to file a claim.  Keep important documents (including insurance policies) in a safe and dry place.  A quick call to your agent is easy and can give you peace of mind that you have the coverage you thought you had.

This summary is just intended to provide some background and general information, but in the event of a storm, listen to official forecasts (National Hurricane Center) and local authorities.

I have been writing updates/blogs on Atlantic tropical cyclones since 1996, and if you wish to be added to my email list so you can be notified of new posts, please let me know (brian[dot]mcnoldy[at]gmail[dot]com).  And if you have any questions regarding anything in this post, don't hesitate to contact me.

Hoping for another safe season,

09 May 2016

A couple pre-season updates and posts

2016 marks my 21st year writing these updates and blog posts.  There was no social media back then, just basic email lists (for the people who had email addresses) and very primitive websites.  Thankfully, things have evolved, and there are now countless sources of information that you can access from anywhere.  With that in mind, I appreciate your continued interest in my input on tropical Atlantic activity -- some of the subscribers to my distribution list have been on it since 1996, and others just joined this month.  If you are a new subscriber and would like to learn more about me, I invite you to peruse my website (http://andrew.rsmas.miami.edu/bmcnoldy/).

Atlantic hurricane season does not officially begin until June 1, but I have a couple related posts that I wanted to share.  Both are on the Washington Post's Capital Weather Gang blog:

The first was published a couple weeks ago but is still relevant...
‘Erika’ and ‘Joaquin’ will no longer be used as hurricane names in Atlantic

and the second, a collaboration with Phil Klotzbach, was just published today...
Do warm waters off of the East Coast imply an increased hurricane threat?

A more thorough hurricane season introduction and outlook will follow closer to June 1, so stay tuned.
Thanks for reading and sharing!