Florence

[sidmon]

So happens we were on vacation in Lancaster PA  in 1972 when  Hurricane Agnes threatened my Hobie down on the Gulf. It then came north flooding out the mid Atlantic...

Bastardi is making the very viable warning that as wet as the region is this year, Florence is a serious threat to not only bring stronger hurricane conditions along the coastline and bays, but also rival the catastrophic flooding that Agnes produced:

https://www.pbs.org/video/wskg-public-telecommunications-agnes-flood-72/

 

[sidmon]

Must watch vid from Tropical Tidbits. Last half focuses on Florence:

 

[Foreverslow]

NC govenor already told folks to prepare tonight.

Earlier today, I had to traverse about 40 miles of coastal SE Virginia just north of Yorktown.    Every farm was harvesting like they were on speed.

Tractors, harvesters and tractor trailers everywhere.

Going rac'n tomorrow, but will prep Sunday.

Could be a long 2 weeks what with Florence and the next two depressions.

 

[Soley]

Thanks to that ridge Passage Weather shows it stalling off Chesapeake bay entrance. Interesting situation.

 

[kent_island_sailor]

It can really shove a metric shit-ton of water up our way

 

[sidmon]

Thanks to that ridge Passage Weather shows it stalling off Chesapeake bay entrance. Interesting situation.

Passage Weather is showing the GFS solution. 

If anyone ever invents some code that will perfectly predict the future, then screw messing around with the weather!!!! Time to go on the World's Finest Casino Tour!!

Read-n-Heed Dr. Ryan Maue's analysis of that particular model solution:

https://twitter.com/RyanMaue

 

[Sean]

Not good. 








 
https://mobile.twitter.com/splillo/status/1038492065242464260



 








 


































 















Finally got around to checking this out. The NHC 5-day forecast for


#Florence
is indeed the strongest they have ever projected an Atlantic tropical storm in the last two decades.

 

[sidmon]

Not good. 








 
https://mobile.twitter.com/splillo/status/1038492065242464260



 








 


































 















Finally got around to checking this out. The NHC 5-day forecast for


#Florence
is indeed the strongest they have ever projected an Atlantic tropical storm in the last two decades.

It is important to keep this particular statistic in perspective. 

This paper was published by Chris Landsea and Phillip Klotzback

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0188.1

 Extremely Intense Hurricanes: Revisiting Webster et al. (2005) after 10 Years


Philip J. Klotzbach Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado
 
http://tropical.atmos.colostate.edu/Includes/Documents/Bios/Klotzbach_Bio.pdf
 
Christopher W. Landsea NOAA/NWS/National Hurricane Center, Miami, Florida
 
https://www.nhc.noaa.gov/staff/Landsea_bio_2018.pdf
 


Abstract


Ten years ago, Webster et al. documented a large and significant increase in both the number as well as the percentage of category 4 and 5 hurricanes for all global basins from 1970 to 2004, and this manuscript examines whether those trends have continued when including 10 additional years of data. In contrast to that study, as shown here, the global frequency of category 4 and 5 hurricanes has shown a small, insignificant downward trend while the percentage of category 4 and 5 hurricanes has shown a small, insignificant upward trend between 1990 and 2014. Accumulated cyclone energy globally has experienced a large and significant downward trend during the same period. The primary reason for the increase in category 4 and 5 hurricanes noted in observational datasets from 1970 to 2004 by Webster et al. is concluded to be due to observational improvements at the various global tropical cyclone warning centers, primarily in the first two decades of that study.
(Highly recommend reading the whole paper)


4. Conclusions


It was suggested by Klotzbach (2006) and Landsea et al. (2006) that technological improvements during the 1970s and 1980s were primarily responsible for the dramatic increases in the frequency and percentage occurrences of category 4–5 hurricanes worldwide reported in Webster et al. (2005). With 10 additional hurricane seasons now available to analyze, the long-term (1970–2014) trends showed reduced trends in category 4–5 frequency and percentage globally. When restricted to the most recent 25 years (1990–2014) with the most reliable and homogeneous records, the following conclusions are reached from this analysis:

• Small, insignificant decreasing trends are present in category 4–5 hurricane frequency in the Northern Hemisphere and globally, while there is no virtually no trend in Southern Hemisphere frequency.
  
• Small, insignificant upward trends are present in category 4–5 hurricane percentage in the Northern Hemisphere, the Southern Hemisphere, and globally.
  
• Large, significant downward trends are present in accumulated cyclone energy in the Northern Hemisphere, the Southern Hemisphere, and globally.
  

(emphasis mine)

These results provide more evidence that the changes reported by Webster et al. (2005) that occurred in number and percentages of category 4–5 hurricanes globally during the 1970s and 1980s were likely primarily due to improved observational capabilities. These results are more in line with expectations from climate models (Knutson et al. 2010, 2013; Camargo 2013; Christensen et al. 2013; Bender et al. 2010), which suggest that no appreciable change in category 4–5 hurricane numbers or percentages would be detectable at this time due to anthropogenic climate change.

Because of the additional evidence provided here about the artificial impacts of technology on the best-track databases, it is recommended that global studies addressing trends in extreme hurricanes (as well as combined metrics like ACE) begin around 1990. Before this time, the records are currently incomplete and lead to a distorted view of the actual activity that occurred before that time. We would also encourage the further development and extension backward in time of satellite-only homogeneous databases (Kossin et al. 2013) suitable for trend analysis.

Trends in category 4–5 hurricane numbers and percentages and ACE should be revisited whenever historical TC databases are reanalyzed (Hagen et al. 2012) and when another decade or so of additional seasons are recorded. However, given the large natural variability driven by ENSO and other natural phenomena, it is likely to be challenging to confidently ascribe an anthropogenic signal to changes in the most intense tropical cyclones for the next several decades.



 
 

 

[Sean]

It is important to keep this particular statistic in perspective. 

This paper was published by Chris Landsea and Phillip Klotzback

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0188.1

 Extremely Intense Hurricanes: Revisiting Webster et al. (2005) after 10 Years


Philip J. Klotzbach Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado
 
http://tropical.atmos.colostate.edu/Includes/Documents/Bios/Klotzbach_Bio.pdf
 
Christopher W. Landsea NOAA/NWS/National Hurricane Center, Miami, Florida
 
https://www.nhc.noaa.gov/staff/Landsea_bio_2018.pdf
 


Abstract


Ten years ago, Webster et al. documented a large and significant increase in both the number as well as the percentage of category 4 and 5 hurricanes for all global basins from 1970 to 2004, and this manuscript examines whether those trends have continued when including 10 additional years of data. In contrast to that study, as shown here, the global frequency of category 4 and 5 hurricanes has shown a small, insignificant downward trend while the percentage of category 4 and 5 hurricanes has shown a small, insignificant upward trend between 1990 and 2014. Accumulated cyclone energy globally has experienced a large and significant downward trend during the same period. The primary reason for the increase in category 4 and 5 hurricanes noted in observational datasets from 1970 to 2004 by Webster et al. is concluded to be due to observational improvements at the various global tropical cyclone warning centers, primarily in the first two decades of that study.
(Highly recommend reading the whole paper)


4. Conclusions


It was suggested by Klotzbach (2006) and Landsea et al. (2006) that technological improvements during the 1970s and 1980s were primarily responsible for the dramatic increases in the frequency and percentage occurrences of category 4–5 hurricanes worldwide reported in Webster et al. (2005). With 10 additional hurricane seasons now available to analyze, the long-term (1970–2014) trends showed reduced trends in category 4–5 frequency and percentage globally. When restricted to the most recent 25 years (1990–2014) with the most reliable and homogeneous records, the following conclusions are reached from this analysis:

• Small, insignificant decreasing trends are present in category 4–5 hurricane frequency in the Northern Hemisphere and globally, while there is no virtually no trend in Southern Hemisphere frequency.
  
• Small, insignificant upward trends are present in category 4–5 hurricane percentage in the Northern Hemisphere, the Southern Hemisphere, and globally.
  
• Large, significant downward trends are present in accumulated cyclone energy in the Northern Hemisphere, the Southern Hemisphere, and globally.
  

These results provide more evidence that the changes reported by Webster et al. (2005) that occurred in number and percentages of category 4–5 hurricanes globally during the 1970s and 1980s were likely primarily due to improved observational capabilities. These results are more in line with expectations from climate models (Knutson et al. 2010, 2013; Camargo 2013; Christensen et al. 2013; Bender et al. 2010), which suggest that no appreciable change in category 4–5 hurricane numbers or percentages would be detectable at this time due to anthropogenic climate change.

Because of the additional evidence provided here about the artificial impacts of technology on the best-track databases, it is recommended that global studies addressing trends in extreme hurricanes (as well as combined metrics like ACE) begin around 1990. Before this time, the records are currently incomplete and lead to a distorted view of the actual activity that occurred before that time. We would also encourage the further development and extension backward in time of satellite-only homogeneous databases (Kossin et al. 2013) suitable for trend analysis.

Trends in category 4–5 hurricane numbers and percentages and ACE should be revisited whenever historical TC databases are reanalyzed (Hagen et al. 2012) and when another decade or so of additional seasons are recorded. However, given the large natural variability driven by ENSO and other natural phenomena, it is likely to be challenging to confidently ascribe an anthropogenic signal to changes in the most intense tropical cyclones for the next several decades.



 
 

I appreciate the info, but I’m not sure what it has to do with the graphic I posted. 

 

[sidmon]

I appreciate the info, but I’m not sure what it has to do with the graphic I posted. 

That improved detection is a primary driver of the number of stronger storms recorded. 

Florence is not an unprecedented storm.

 

[Sean]

That improved detection is a primary driver of the number of stronger storms recorded.

The graphic is limited to forecasts between 1998 - 2017. It has no reference to trends over time, but simply that the current Florence forecast predicts a higher intensity than any previous forecast within the last 20 years. Your point is well taken, but I’m not convinced it’s relevant in this instance.

 

[sidmon]

The graphic is limited to forecasts between 1998 - 2017. It has no reference to trends over time, but simply that the current Florence forecast predicts a higher intensity than any previous forecast within the last 20 years. Your point is well taken, but I’m not convinced it’s relevant in this instance.

We are about to hear "strongest" attached to Florence with little regard to context as it amps up and closes the coast, so its important to keep it in perspective.

Intensity forecasts are still problematic in comparison to those that predict track, and there is much effort to improve them.

As there hqve been nearly 40 Cat 4 storms in the period specified, the question begs: Are we seeing the result of a higher skill forecast?

Would also be interesting to see a graph with a start at 60 hours. Bet the same claim cant be made.,

 

[timber]

the data does not give us any knowledge of funding source for the studies. biased reports can be dressed up like putting gloss on a t**d. Has the data been peer reviewed or maybe it has and only the cherry picked stuff is presented here.

 

[sidmon]

the data does not give us any knowledge of funding source for the studies. biased reports can be dressed up like putting gloss on a t**d. Has the data been peer reviewed or maybe it has and only the cherry picked stuff is presented here.

If you are talking about the Klotzbach Landsea paper. It was published in the AMS. Pretty much a gold standard there.

Also, check out their bios in the links above. Phil Klotzbach took over from Dr. Bill Gray who pioneered the hurricane seasonal forecasts, as heqd of the world's leading hurricane research institution.

Chris Landsea is Branch Chief of the Tropical Analysis and Forecast Branch at NHC.

 

[Illegal Smile]

This is the forecast from Windy for next Friday evening. 50+ kt northwesterly winds at the mouth of the Bay, plus lots of extra rain seems like it would mean significant flooding?

What’s most concerning for the Mid-Atlantic is that all the models show an immediate hook to the northeast after landfall, taking this beast right over the region regardless of what part of the coast takes the first hit. 

 

[DryArmour]

This is the forecast from Windy for next Friday evening. 50+ kt northwesterly winds at the mouth of the Bay, plus lots of extra rain seems like it would mean significant flooding?

What’s most concerning for the Mid-Atlantic is that all the models show an immediate hook to the northeast after landfall, taking this beast right over the region regardless of what part of the coast takes the first hit. 

View attachment 281890

That is the ECMWF.  The GFS is significantly different than the EURO.

 

[weightless]

The GFS is significantly different than the EURO.

The GFS is a bit odd around landfall these last couple runs. But maybe more to the point there's still quite a lot of uncertainty in all the forecasts. I wouldn't put much faith in the details yet. Even the EC is all over the place:

 

[weightless]

 

[kent_island_sailor]

Florence is going to dump rain on saturated ground - we are getting minor flooding now from the other one

 

[d'ranger]

Florence is going to dump rain on saturated ground - we are getting minor flooding now from the other one

bad news for falling trees - storm surge and falling trees, those are the 2 big ones.  be safe.