August Hurricane Climatology for South Florida

[jinftl]

NWS Miami published a review of ts/hurricane climatology for the month of August (link to full report below).

Some highlights:

• August ranks 3rd in the number of hurricanes affecting Mainland South Florida, behind September and October.

• Since 1851, a total of 20 named storms have affected Mainland South Florida during the month of August

• Of the 20 storms, 10 were hurricanes, 5 of which were major hurricanes (Category 3 or greater).

• The southeast Florida coast has been most prone to ts & hurricanes in August (being affected by 17 systems), while the southwest Florida coast has been affected much less, a total of 10 times.

http://www.srh.noaa.gov/images/mfl/news/August_SoFLTC.pdf

[gatorcane]

Indeed, August is 3rd which would likely surprise most people. September and October are the big months, but things can happen in August also (ala Andrew 1992, Charley, 2004). September features hits from the east from more Cape Verde-like systems, while October is typically more from the South/Caribbean, although South Florida has been impacted from the east in October also.

Today marks the day of what I call the "real" hurricane season for Southern Florida from August. 1st to Oct. 31st.

[King-6]

Seems like The African Wave Train might start to show signs even though the SAL is very active this summer. Waves might be tracking out from Africa too fast forward to stack up because windshear and dust.

[jinftl]

Yep, with one recent noteable exception, I believe something like 90% of the hurricanes that impact south florida occur between August 15 and October 15. I was very surprised to learn that no hurricanes have ever made landfall in south florida in the month of July....i would have figured there were a few over the decades. In other words, the lack of threats this season to date essentially means little in the way of an early 'sigh of relief'.

Down here we are always at the mercy of ridges and troughs...and a trough that could be our friend and turn the cape verde storms out to sea could be the worst enemy in october if it drags a storm to our south over us (wilma).

:uarrow:

Indeed, August is 3rd which would likely surprise most people. September and October are the big months, but things can happen in August also (ala Andrew 1992, Charley, 2004). September features hits from the east from more Cape Verde-like systems, while October is typically more from the South/Caribbean, although South Florida has been impacted from the east in October also.

Today marks the day of what I call the "real" hurricane season for Southern Florida from August. 1st to Oct. 31st.

[gatorcane]

jinftl. I posted this in another thread but check out what happened on these "slow starting" years for South FL (in that Aug.15 to Oct. 15 window you mention). It's interesting to note alot of hurricane statistics don't include these years from way in the past.

Below, I included the year and when the first name storm formed. Click the link below to see what kind of activity South FL had as a result later in that season.

I'm not saying it will happen this year like those years, but one cannot rule out the fact that alot of season is left to go. I just hope the "el nino" hype by the media does not cause any undue complacency here.

1925: Hurricane #1 22 JUL- 2 AUG
1928: Hurricane #1 3-12 AUG
1935: 1 Hurricane #1 18-26 AUG
1941: Tropical Storm #1 11-16 SEP
1947: 1 Tropical Storm #1 31 JUL- 2 AUG
1949: 1 Hurricane #1 21-28 AUG
1992: Hurricane ANDREW 16-28 AUG
2004: Hurricane ALEX 31 JUL- 6 AUG

http://weather.unisys.com/hurricane/atlantic/

[jinftl]

wow.......so in other words, late-starting seasons from the past produced this infamous list: 1935 had a landfalling Cat 5 in Monroe, 1947 had a landfalling Cat 4 in Broward, 1949 had a landfalling Cat 4 in Palm Beach, and 1992 had a landfalling Cat 5 in Miami-Dade. Not to say that 2009 will follow suit....but, let's just say, i am almost wishing we were into the E storm by now given that track record!!!

That is quite amazing....thanks for the info...i am surprised local tv mets and media don't use this info as a 'cautionary tale' to not let your guard down if a season starts slow....because in reality, some of the strongest and most legendary south florida storms came from seasons that were duds to date like this one (including 2 of the 3 landfalling Cat 5s in U.S. history)...

:uarrow: jinftl. I posted this in another thread but check out what happened on these "slow starting" years for South FL. It's interesting to note alot of hurricane statistics don't include these years from way in the past.

Below, I included the year and when the first name storm formed. Click the link below to see what kind of activity South FL had as a result.

I'm not saying it will happen this year like those years, but one cannot rule out the fact that alot of season is left to go. I just hope the "el nino" hype by the media does not cause any undue complacency here.

1925: Hurricane #1 22 JUL- 2 AUG
1928: Hurricane #1 3-12 AUG
1935: 1 Hurricane #1 18-26 AUG
1941: Tropical Storm #1 11-16 SEP
1947: 1 Tropical Storm #1 31 JUL- 2 AUG
1949: 1 Hurricane #1 21-28 AUG
1992: Hurricane ANDREW 16-28 AUG
2004: Hurricane ALEX 31 JUL- 6 AUG

http://weather.unisys.com/hurricane/atlantic/

[CourierPR]

South Florida also had damaging Cleo in late August of 1964.

[CourierPR]

Yes, I know that Cleo wasn't the first storm in '64, but I made the notation because the season did get off to a rather slow start.

[jinftl]

On a side note, i hope we never see another stretch like we saw in the 1940's....a direct major strike every other year....

Studies have been done on what the damage would be with storms from that era if they hit the same areas today. In the mid to late 1940's, the population of Broward County (Fort Lauderdale and suburbs) was between 60,000 and 80,000. The 2005 census figures reached 1.6 million for just that one county. The 1947 hurricane was a direct landfall in Broward.

In 2005 dollars, it is estimated that same storm would have caused $48.0 billion in damage...making it #3 costliest storm behind Katrina and Andrew in the U.S.

Similarly, the 1949 Palm Beach hurricane would do an estimated $13.5 billion in 2005 $.

The big 'winner' by far in terms of potential damage in $ if the same storm hit today is the 1926 Miami Hurricane. If it hit today, it would do an estimated $160 billion in damage....twice that of Katrina. Inconceivable....and that was a cat 3/4. What would a do cat 4/5 of that size hitting where it did do? Scary.

http://sciencepolicy.colorado.edu/admin ... 008.02.pdf

:uarrow: jinftl. I posted this in another thread but check out what happened on these "slow starting" years for South FL (in that Aug.15 to Oct. 15 window you mention). It's interesting to note alot of hurricane statistics don't include these years from way in the past.

Below, I included the year and when the first name storm formed. Click the link below to see what kind of activity South FL had as a result later in that season.

I'm not saying it will happen this year like those years, but one cannot rule out the fact that alot of season is left to go. I just hope the "el nino" hype by the media does not cause any undue complacency here.

1925: Hurricane #1 22 JUL- 2 AUG
1928: Hurricane #1 3-12 AUG
1935: 1 Hurricane #1 18-26 AUG
1941: Tropical Storm #1 11-16 SEP
1947: 1 Tropical Storm #1 31 JUL- 2 AUG
1949: 1 Hurricane #1 21-28 AUG
1992: Hurricane ANDREW 16-28 AUG
2004: Hurricane ALEX 31 JUL- 6 AUG

http://weather.unisys.com/hurricane/atlantic/

[Blown Away]

:uarrow: jinftl. I posted this in another thread but check out what happened on these "slow starting" years for South FL (in that Aug.15 to Oct. 15 window you mention). It's interesting to note alot of hurricane statistics don't include these years from way in the past.

Below, I included the year and when the first name storm formed. Click the link below to see what kind of activity South FL had as a result later in that season.

I'm not saying it will happen this year like those years, but one cannot rule out the fact that alot of season is left to go. I just hope the "el nino" hype by the media does not cause any undue complacency here.

1925: Hurricane #1 22 JUL- 2 AUG
1928: Hurricane #1 3-12 AUG
1935: 1 Hurricane #1 18-26 AUG
1941: Tropical Storm #1 11-16 SEP
1947: 1 Tropical Storm #1 31 JUL- 2 AUG
1949: 1 Hurricane #1 21-28 AUG
1992: Hurricane ANDREW 16-28 AUG
2004: Hurricane ALEX 31 JUL- 6 AUG

http://weather.unisys.com/hurricane/atlantic/

How many of those years were El Nino years? 1992 and 2004 were El Nino I believe.

[jinftl]

Looks like 1925 & 1941 were el nino years, along with 1992 and 2004.

On the list below, only 1949 was a 'la nina' year...the rest were either el ninos (4) or neutral (3).

http://www.ems.psu.edu/~nese/elninyr2.htm

:uarrow: jinftl. I posted this in another thread but check out what happened on these "slow starting" years for South FL (in that Aug.15 to Oct. 15 window you mention). It's interesting to note alot of hurricane statistics don't include these years from way in the past.

Below, I included the year and when the first name storm formed. Click the link below to see what kind of activity South FL had as a result later in that season.

I'm not saying it will happen this year like those years, but one cannot rule out the fact that alot of season is left to go. I just hope the "el nino" hype by the media does not cause any undue complacency here.

1925: Hurricane #1 22 JUL- 2 AUG
1928: Hurricane #1 3-12 AUG
1935: 1 Hurricane #1 18-26 AUG
1941: Tropical Storm #1 11-16 SEP
1947: 1 Tropical Storm #1 31 JUL- 2 AUG
1949: 1 Hurricane #1 21-28 AUG
1992: Hurricane ANDREW 16-28 AUG
2004: Hurricane ALEX 31 JUL- 6 AUG

http://weather.unisys.com/hurricane/atlantic/

How many of those years were El Nino years? 1992 and 2004 were El Nino I believe.

[HurricaneJoe22]

http://blogs.palmbeachpost.com/eyeonthe ... ne-season/

[wxman57]

A couple of things. The 1935 hurricane struck in September, not August. It wasn't the 1st hurricane of 1935, it was the 2nd. The 1st hurricane of 1935 was a fish storm.

Hurricane #2 29 AUG-10 SEP 140kts 892mb Cat 5

http://weather.unisys.com/hurricane/atl ... index.html

I like to use the Coastal Services Center past track plotter for studies like this. You can search by "Climatology" and select all La Nina or El Nino years, if you like:

http://csc-s-maps-q.csc.noaa.gov/hurricanes/viewer.html

But I do agree that the pattern we're seeing out there is one that could pose a hurricane threat to Florida to the Carolinas this year.

[MiamiensisWx]

I must state that you can't cherry-pick several random seasons that featured late starts and ensuing South FL hurricane landfalls in order to support a greater risk for this region (or others) in 2009. There must be a sound meteorological justification for the selection of these specific years as analogs or analogous examples of similar pattern evolutions, based on numerous intraseasonal/long term factors. Climatological factors must be included. Firstly, atmosphere/ocean dynamics are extremely fluid. Thus, you can't analyze a few factors and similarities between those "privileged" years and 2009 and formulate a conclusion that 2009's pattern will be similar to the aforementioned years (i.e. favor S FL strikes). In meteorology, the analysis of a few factors in order to prove that A and B = C (i.e. 2009 will also feature South FL strikes, based on ---) does not hold water. It is inherently flawed. All factors must be analyzed in order to assess the favored pattern across the Atlantic basin, including ENSO, equatorial subsurface anomalies (T depth), long term outgoing longwave radiation, mid/upper tropospheric wind anomalies in the Pacific, stratospheric warming/cooling events, the Indian Ocean Dipole, global ocean/atmosphere teleconnections between various regions, etc. I can name numerous additional considerations, as well. Furthermore, comparisons between previous pattern evolutions must be utilized as a rough guide; one should not assume that all factors will be similar among different years. Every year is ultimately unique in one or more ways. Thus, each year will ultimately produce a unique outcome to varying degrees.

Nevertheless, if we're going to examine climatology, it should be noted that we will be entering an El Nino event in 2009. Let's examine the starting date of the current El Nino event and compare this event's period of origination to other past El Nino events. These past El Nino events will not include years that featured a weakening El Nino during the Atlantic hurricane season. They must be years that featured a developing El Nino during the season. They must also include El Nino events that 1) formed during similar periods as the '09 El Nino and 2) featured a relatively similar SST evolution/distribution. According to the CPC, this El Nino event developed during the May-June-July (MJJ) period. The exact month of origination was July. An El Nino event must feature a three-month SST average of at least +0.5 C in order to attain El Nino classification. Until recent weeks, the T depth anomalies in the equatorial Pacific were more typical of a moderate or strong El Nino, although these subsurface anomalies have recently diminished. Latest SST data indicate that the 2009 event is likely evolving into an east based El Nino with the warmest SSTA in NINO 1 and 2 zones. Let's check previous similar ENSO cases.

The following ENSO events developed during AMJ (April-May-June) or MJJ (May-June-July). SSTA value is average of two periods’ SSTA. The data are extracted from CPC’s database.

YEAR...SSTA...TIME...LOCATION
1965…..0.8……MJJ….West based
1972…..0.7……AMJ....East based
1982…..0.7……AMJ….East based
1991…..0.7……AMJ….East based
1994…..0.5……AMJ….West based
1997…..1.5……AMJ….East based
2004…..0.5……MJJ….West based
2009.....~0.5….MJJ….???

The other El Nino events that developed before or during the Atlantic TC season include 1951, 1963, 1969, 1976, 1986, and 2006. Of these years, 1951, 1976, 1986, and 2006 were east based; 1963 and 1969 developed farther west (as west based events). In all, we have 14 events in our data samples. Of these events, only 14 percent (two seasons) featured hurricane strikes in the South Florida region. The years were 1965 (Betsy) and 2004 (Frances/Jeanne). Both years featured west based El Nino events. A strike is defined as a landfall that produced hurricane force winds over a portion of South Florida. Thus, although Frances and Jeanne struck Central Florida, they are counted as South Florida hits. South Florida, represented by the NWS Miami office’s County Warning Area, is defined as Palm Beach, Broward, Miami-Dade, mainland Monroe, Collier, Glades, and Hendry counties.

Based solely on ENSO climatology, the probabilities of a hurricane impact in South Florida are extremely low during early developing El Nino situations. In any given year, the odds of a South FL hurricane landfall are still quite low. Major hurricanes strikes are extremely scarce in S FL, and their rare occurrence decreases markedly during years with early developing El Nino events. However, some east based El Nino events may be more unfavorable for South FL hurricane strikes than west based events. Specifically, the location of the SSTA can partially contribute to differing locations of the convection-induced tropical forcing and zonal wind anomalies in the Pacific basin. These effects can influence the downstream pattern, including the depth, amplitude, and location of the longwave trough over the East Coast.

Of course, other factors must be taken into considerations, but it is noted that the east based events often show a tendency for a deeper longwave trough along/off the East Coast during August and September; thus, the pattern would favor more recurves with systems developing in the deep Atlantic or MDR.

500 mb pattern for east based events:



500 mb pattern for west based events:



By the way, many posters will mention Andrew as an exception to ENSO climatology. However, check the CPC data. Andrew occurred after a weakening El Nino event ended in July. Thus, Andrew is NOT an example of a major hurricane impact in South FL during El Nino.