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Azores #96L fails to complete transition into a Sub-Tropical Storm. Elsewhere, weak low pressure in Caribbean may linger into next week.
Days since last H. Landfall - US: Any 44 (Nate) , Major: 62 (Maria) Florida - Any: 72 (Irma) Major: 72 (Irma)
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Ed DunhamAdministrator
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)


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Posts: 2565
Loc: Melbourne, FL
Does A Preseason Storm Suggest A Busy Season?
      #96382 - Mon Jul 04 2016 01:26 PM

The short answer is 'not necessarily'. By established definition, the Atlantic Hurricane season (which is more properly the Atlantic Tropical Cyclone season) begins on June 1st and ends on November 30th. The total number of Tropical Storms (including Subtropical Storms) and Hurricanes are recorded for the calendar year. Preseason Tropical Storms and Hurricanes - activity prior to June 1st - and post season events during December are included in the annual totals, but using a Calendar Year to determine seasonal activity does have some flaws from a meteorological perspective. The rare Tropical Storms and Hurricanes that occur in January and February are recorded as preseason early activity for the current year but these events are really post-season events, i.e., they represent an extension of the meteorological conditions that prevailed during the previous calendar year.

If you examine all of the years that recorded a preseason event, some of them must be discarded. The February storm in 1952 and the January storm in 1978 were post-season events of the prior year. (Note that in 2016, Hurricane Alex (January) was a 2015 post-season storm, but TS Bonnie (May) qualifies 2016 as a preseason year.) In 1916 and 1934, the storms in May were later reclassified as extratropical systems. In 1997 the system defined on May 31st did not become a tropical cyclone (actually a TS) until June 1st so it really wasn't a preseason event. Finally in 2007 the first storm in May was reclassified as extratropical and the second system on May 31st did not become a TS until June 1st.

1887 and 2012 had two storms in May and 1908 had one storm in March (probably the 1908 season rather than the previous year) and one storm in May. 1992 and 2003 each had a storm in April and 16 other seasons had a preseason storm in May (1865, 1889, 1890, 1932, 1933, 1940, 1948, 1951, 1953, 1959, 1970, 1972, 1976, 1981, 2008 and 2015). Therefore in the 165 seasons from 1851 through 2015 there were 21 of them that had preseason activity - which is 12.7 percent of all seasons. The average storm totals for those 21 seasons: 11.2 named storms, 6 hurricanes - 2 of which became major hurricanes (Cat III or greater). Six of those seasons ended up with 10-12 named storms (an average season); 8 of those seasons had 9 named storms or less (a quieter season); 7 of those seasons had 13 named storms or more (an active season). From a climatological standpoint, a preseason storm has no impact on what the final seasonal numbers will be. Even in the 51 years of the satellite era, the 9 preseasons averaged 11.6 named storms with 3 seasons of normal activity, 3 seasons of below normal activity and 3 seasons of above normal activity.
ED


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Ed DunhamAdministrator
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)


Reged: Sun
Posts: 2565
Loc: Melbourne, FL
Re: Does A Preseason Storm Suggest A Busy Season? [Re: Ed Dunham]
      #96477 - Tue Aug 09 2016 12:04 PM

I decided to take another climatological look at the season since July had no storms to add to this years list. It turns out that zero storms in July is a common event with no July storms in 47 of the last 100 seasons. Current long range projections for the tropical Atlantic suggest that Earl might end up being the only August storm in the basin - however extended forecasts that far in advance still must be taken with a grain of salt.

But if that projection verified, what might the rest of this season look like for overall seasonal activity? The past century has only had 5 seasons with at least one storm in May and/or June, no named storms in July and one storm in August.

Here are those seasons along with 2016 and the ENSO anomaly for May/June/July and the total storm tally for the year:

1957 +0.9 developing El Nino, 7/3/2
1968 +0.2 ENSO neutral from La Nina, 8/4/0
1982 +0.7 developing strong El Nino, 6/2/1
1986 0.0 developing El Nino, 6/4/0
1992 +0.8 ENSO neutral from strong El Nino, 7/4/1
2016 +0.2 ENSO neutral from strong El Nino, 5/2/0 (so far)

All of these seasons had below normal seasonal activity and 1992 is the only one with similar ENSO SST conditions to 2016. However, 2016 has returned to an ENSO Neutral state a lot faster than it did in 1992. Unless the tropical Atlantic gets busy in late August, climatology suggests that 2016 could end up being a 'below normal activity' season.
ED


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