Sub-Tropical Storm Vs. Tropical Storm… What’s The Difference?

http://www.weathernationtv.com/ ^ | 5/26/18

[BBell]

Friday morning, the National Hurricane Center in Miami issued a statement announcing the first named storm of the 2018 Atlantic Basin Hurricane Season. Subtropical Storm Alberto had formed in the northeastern Caribbean, just off the coast of Cozumel, Mexico. Most of us are familiar with the term “Tropical” storm. But what exactly is a “Sub”tropical storm?

A subtropical storm is actually a hybrid of an extratropical storm, and a tropical storm. So we’ll identify all three types of storms.

EXTRA-TROPICAL STORM

An extratropical storm has a cold core at its central point. It is often associated with frontal zones, such as warm fronts and cold fronts. These fronts are essentially lines marking areas of different temperatures and dew points. For example, air masses to the east of a cold front are warm and moist compared to cooler and drier air behind the cold front. We see these kind of systems regularly on the U.S. mainland. They drive our daily weather patterns. These are mid-latitude storm systems, usually forming between 30 and 60 degrees latitude. They produce most of the weather we see here in the United States. Everything from light rain, to super cell thunderstorms with damaging winds, hail, and tornadoes. Snowstorms and blizzards also form with these systems.

TROPICAL STORM

A tropical storm is very different. It has a warm core at its central point. It’s very symmetrical in structure, and does not have temperature and moisture differences radiating out from the center of circulation. These storms typically form over large bodies of warm water. The warm water is the energy source for these storms. Ocean water evaporates, and then condenses back into water droplets. This process releases energy back into the storm, allowing it to increase in strength, when favorable environmental conditions exist. This is very different from extratropical storms, which are fueled by differences in temperature and moisture over a given region.

SUB-TROPICAL STORM

A subtropical storm has characteristics of both a tropical storm and an extratropical storm. They form initially from extratropical storms, which have colder temperatures in the upper levels of the atmosphere than are typically found in the tropics. Therefore, they can form in areas where sea surface temperatures are cooler than those needed for tropical systems to initiate. Since warmer ocean water is not as necessary, subtropical storms can also form earlier or later than the normal dates for hurricane season. Typically, what happens is that an extratropical storm will drop southward into the warmer regions of the subtropics. The system then gets blocked by a big ridge of high pressure, and gets cut-off from the cooler and drier air of the higher latitudes. The system them begins to gain more tropical characteristics in its new environment. As the system gains more tropical characteristics, it will eventually transition into a tropical storm.

In short, a subtropical storm forms when it is no longer an extratropical storm, but doesn’t possess all the characteristics of a tropical storm. It is in a sense a hybrid storm system. This is when the storm is designated “subtropical”.

IN SUMMARY: TROPICAL STORM VS. SUBTROPICAL STORM

TROPICAL SYSTEM

Warm core.

Symmetrical on all sides with respect to temperature and dew points

Thunderstorms near center of circulation and wrapped around low pressure.

SUBTROPICAL SYSTEM

Cold core.

Asymmetrical structure with temperature and dew points. The eastern side of the storm will be warmer with higher dew points and more moisture. This is where the showers and thunderstorms will be. The western side of the storm will be cooler, drier, with no clouds and rain.

Thunderstorms will be a far away from the center of the storm.

[fso301]

Sub-tropical storms are for media ratings.

[hattend]

We used to watch relatively deep low pressure centers drive across the north Atlantic toward the Azores. Cold air dropping in behind the low would cause explosive cyclogenesis.

One day, the Atlantic was clear, the next day it was cloudy, the low had acquired an eye and that bastard would head right for Lajes Field in the Azores. Max gust I ever saw was 135 knots before the wind bird blew off the tower.

Hurricane force winds but not considered a hurricane because of it’s origin. Those were the days.

[DoodleBob]

Thank you for the post. I dug and found my source on this Sandy topic. It was a (no pun intended) perfect storm of situations that caused the confusion though it was noted in this article that:

The classification of the storm carries significant implications for home and business owners, as well as insurers, since most hurricane insurance policies have deductibles that would have been triggered only if the storm still had been a named hurricane at the time of landfall, and if hurricane warnings were in effect. In this case, neither one of those conditions were met.

I worked in NYC during Sandy. I remember being surprised at the devastation from a non-hurricane. I was shocked at how relatively unprepared some areas were for the storm, and I don't mean the people who had their homes washed away: the reports of fights at gas stations (mostly in NJ) and people who didn't prepare for a day or two without electricity, were mind-boggling.

Candidly, I believe these problems stem from a combination of citizens who, sadly, have become dependent upon the state's guidance for preparations, but more on Nanny State horrormongering. Every storm is now The End of the World as we Know It, and while I get the predeliction toward safety, there are costs to conservatism: lost incomes, lost wages, uncompensated business interruptions, and so on. In addition, the "sky is falling" weathercasting as well as outright lying...

...and situations like the hyped NYC blizzard in 2017 that fizzled but then the Feds knew the blizzard forecast was exaggerated — but didn’t want to confuse us has left most of us to navigate these situations via social media. I find FR to be an excellent - and accurate- source of storm coverage nowadays.

And yet, people wonder why a straight-talker like Trump is in the White House...

[Rebelbase]

OMG! 100kpm at landfall. They’re all gonna die!

[N. Theknow]

It makes for better TV to the ignorant masses who watch CNN.

If they are watching CNN, the "m" in masses is silent.

[Jim Noble]

My family lives in Nassau County halfway between the ocean and the sound. They had sustained hurricane force winds with gusts to 90. Almost all the old trees in the neighborhood went down.

[xkaydet65]

I would say they are oversensitizing the public. Naming normal weather systems makes people feel something different is going on...Anthropogenic Climate Change. That’s what this stuff is all about. Raise the alarm. We’re all gonna die.

[P.O.E.]

Thanks - I was wondering that. I have relatives in Florida and saw “sub-tropical” in the weather warning.

I was thinking “what is below the tropics?”. Makes more sense now.

[BBell]

Your welcome. I grew tired of people here not knowing.

[SamAdams76]

Extra-Genius

[MUDDOG]

MAGA!