End of Hurricane Season Definition

[DanKellFla]

I know the end of the season is Nov. 30th. But is there a definition that Meteorologists use to define the end of a season? Some dominant feature the shows up?

In South Florida, the dry season begins when there are 3 days in a row with the dew point being at 72 degrees or less. There really is no 'fixed' date. To me, it seems logical that hurricanes don't look at a calender and say, 'nope, too late for than, I think I'll just be a nor'easter."

[sargeabernathy]

I remember in 2005, when the year was almost up and Zeta came out of no where there were questions about what would happen if the storm (or another one) formed in January. NHC replied that it would get the first A name of the 2006 list. That's pretty much your separation as far as naming goes. But meterologically? I don't know.

[Frank2]

Good question - hopefully some of the professional folks will post an answer...

From what others have said, the end of the active season is seasonally connected with lower sea surface temps (due to cooler air temps, which are due to shorter daylight hours) and strong upper level winds...

Since the Caribbean has both warm sea surface temps and fairly low wind shear even during the winter months, it's the one area that has seen tropical cyclone formation in the months between December and May (if I'm not mistaken, there's been at least one tropical cyclone in 4 of the 6 months during that time of year), so, it could be said to some degree that the Caribbean does have a "year round" hurricane season...

[JonathanBelles]

The season is over when the last storm dies

[MBryant]

While I don't have a meteorological basis for this idea, here it goes. Rather than simply using the Calendar year as the cutoff for the naming of off season hurricanes, why not use the midpoint between the peak of the season?

Using March 1 or March 10, depending on whether you consider September 1 or September 10 as the peak of the hurricane season would make sense to me.

Fortunately, this wouldn't have too much of an effect on the placement of storms since there are so few which have occurred between January 1 and March 10th.

[RL3AO]

When January gets here and there are no active storms. That is the definition in my book.

[CrazyC83]

I agree that the end of hurricane season is the day the last system (which including Invests) dies for good...

[Recurve]

Let's not forget there is a definition, and since it's the one the NHC uses, it's the only valid one. Hurricane Season is over after the last second of Nov. 30. That's it.

Of course it's tied to climatology, but there's no single weather feature -- the first time dewpoints are lower than 70 degrees F at surface south of 25 N or something. Of course there's no set of weather events that would mean "no more hurricanes possible."

It's just arbitrary. It's for the public to have a sense of the threat from the tropics. It's better that it be a calendar event than some obscure meterological criterion.
As for naming, let's not get into something other than calendar-year sets of names. It's too friggin confusing.

[DanKellFla]

Let's not forget there is a definition, and since it's the one the NHC uses, it's the only valid one. Hurricane Season is over after the last second of Nov. 30. That's it.

Of course it's tied to climatology, but there's no single weather feature -- the first time dewpoints are lower than 70 degrees F at surface south of 25 N or something. Of course there's no set of weather events that would mean "no more hurricanes possible."

It's just arbitrary. It's for the public to have a sense of the threat from the tropics. It's better that it be a calendar event than some obscure meterological criterion.
As for naming, let's not get into something other than calendar-year sets of names. It's too friggin confusing.

Thanks, that was the information I was looking for.

[Category 5]

The "Official" end of hurricane season is obviously november 30th.

The people I disagree with may say otherwise of course.

[CrazyC83]

The "Official" end of hurricane season is obviously november 30th.

The people I disagree with may say otherwise of course.

The official and actual start and end are completely different. We won't know the actual end of the season until we get into 2008. Likewise, the season this year in reality started in early May, regardless of official definitions.

[americanrebel]

We could have a season that ends in mid December for 2007 and 2008 start in the mid of Jan. Is that what you are saying? For actual season and not official season.

[CrazyC83]

We could have a season that ends in mid December for 2007 and 2008 start in the mid of Jan. Is that what you are saying? For actual season and not official season.

Yes if storms form during those times. On the other hand, a season could start much later (i.e. 2004 if based on actual tropical cyclones) or end much earlier (i.e. 2006).

[mightyerick]

I think that every between-season system must be placed in the season which is closest is the storm. Example:

Example: If a TS formed in feb 2006, and last 2005 storm ended in january, the new storm was by far closest to the ending of the 2005 season than it is from the beginning of the next one in June 2006. It must be assigned to the 2005 Season, because it is possible that conditions that let the development of this system are representative of 2005, not 2006. It is just my opinion.

[Category 5]

IMO, Hurricane Season ends December 15th.

[Ed Mahmoud]

Official hurricane season fits exactly what I would consider 'real' Summer and 'real' Autumn. Ignoring the astrological definitions, the warmest weather is right about the middle of Summer, and hurricane season peaks just after the turn from 'real' Summer to 'real' Autumn.



That being said, and Hurricane Kate into Florida is a notable exception, if you had to lose a month, June is usually a more interesting month than November.

[Ed Mahmoud]

JJA being what I call summer, and SON being what I call real Autumn.

[jlauderdal]

I know the end of the season is Nov. 30th. But is there a definition that Meteorologists use to define the end of a season? Some dominant feature the shows up?

In South Florida, the dry season begins when there are 3 days in a row with the dew point being at 72 degrees or less. There really is no 'fixed' date. To me, it seems logical that hurricanes don't look at a calender and say, 'nope, too late for than, I think I'll just be a nor'easter."

i believe the atlantic basin has seen a hurricane in every monthof the year so if true it never ends, swirl watchers unite you have a full time job

[Frank2]

There used to be a believe that the first strong cold front through South Florida meant the end of the season (at least for Florida), but, I've found that is not always a very reliable indicator...

In 1985, we had one or two cold fronts pass through this area - followed by Hurricane Kate, just a few days before Thanksgiving (however, '85 did see favorable conditions in the tropics well into Fall (there was a large summer-type Bermuda high in place), so, that's something to consider)...

Still, once the rainy season is determined to be over, and, the temps and dew points in Florida lower into the 50s and 60s, then, it's pretty safe to say that that's about it for hurricane season in this part of the world...

[Recurve]

There used to be a believe that the first strong cold front through South Florida meant the end of the season (at least for Florida), but, I've found that is not always a very reliable indicator...

In 1985, we had one or two cold fronts pass through this area - followed by Hurricane Kate, just a few days before Thanksgiving (however, '85 did see favorable conditions in the tropics well into Fall (there was a large summer-type Bermuda high in place), so, that's something to consider)...

Still, once the rainy season is determined to be over, and, the temps and dew points in Florida lower into the 50s and 60s, then, it's pretty safe to say that that's about it for hurricane season in this part of the world...

Charley, driven into Florida by a strong cold front. In august.
Wilma. Driven into florida by a front in October.
Floyd, Cat 1, Florida Keys, 1987. November.

I definitely see your point. We used to relax more after cold fronts. But really, the climatology here is that a cold front can steer hurricanes into Florida. And the weather often goes back to summer after the first cold front. The storms that hit us late-season form in the Caribbean, where the cold fronts don't matter much.

At the risk of getting repetitive, if we are discussing hurricane climatology, that's one thing. But "hurricane season" is a simple, calendar-based, arbitrary, official designation. June 1 to Nov. 30. That's it. Trying to match the name "hurricane season" to some never-fail scientific method for when hurricanes will form is futile, and beside the point.

I believe the basin has seen hurricanes, or maybe some kind of TC, in all but two or three months (April and May? sorry I haven't checked lately). BTW, for Florida, June seems less dangerous than November IMO.