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Hurricane Florence Catch all Thread


Brian5671

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2 hours ago, LongBeachSurfFreak said:

Surfers do not like onshore gale force winds, the ocean right now is a washing machine. Offshore winds are ideal with calm or very light onshores second. The further north Florence eventually makes it the more influence it will have on turning our winds onshore.

Based on a high end cat 4 heading generally in our direction there will be huge surf here later in the week. Swells of that magnitude lead to washovers that flood beaches and anything near the beach front. They also cause a good amount of erosion. So this storm will definitely be a high impact event for local beaches.  

These storms throw up huge swells even when they are well offshore; even tropical storms can do this. It's the one thing I get seasick in. This storm is gonna hurt, not like it will to our south, but there will be impacts. For reasons that I never understood, the fish turn off in these swells. Don't if the bottom becomes unsettled or what, but they just shut off. It's actually been bad enough the last couple days and today's storm is no slouch.

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3 hours ago, LongBeachSurfFreak said:

Surfers do not like onshore gale force winds, the ocean right now is a washing machine. Offshore winds are ideal with calm or very light onshores second. The further north Florence eventually makes it the more influence it will have on turning our winds onshore.

Based on a high end cat 4 heading generally in our direction there will be huge surf here later in the week. Swells of that magnitude lead to washovers that flood beaches and anything near the beach front. They also cause a good amount of erosion. So this storm will definitely be a high impact event for local beaches.  

You knew that someone would venture into the early Sandy washing machine before the main event in the evening. 

 

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You can see the much larger area of wind maximum after the EWRC. This acts to increase the swell generation potential. Winds above a certain speed aren’t very efficient in transferring energy into the ocean. So a small pin hole eye with say 160mph winds creates smaller seas then a large eye with winds of 130mph. 

So what that means for us is that a larger more powerful swell is on tap. With this large swell event comes more of a threat for beach washovers and erosion. Historically we have never had a storm this strong on this trajectory. I fully expect major coastal effects including some damage at our area beaches late this week.

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On 9/9/2018 at 5:23 PM, Cfa said:

I remember reading an article/study which mentioned that the theoretical max for the NYC metro is a Cat 4. That or a high end Cat 3 would be our worst case scenario.

Sandy wasn’t a joke, far from it, but it was a storm surge storm more than anything else. Sandy’s winds, while severe, were manageable. Rainfall wasn’t anything special with it either.

You're right and so is LBSF about the track, it was calculated that our worst case scenario would be a hurricane tracking into Monmouth County, and the maximum possible wind speed that those waters can support was calculated to be 145 mph.  A cat 4 may have reached our latitude and hit eastern New England when the Colonial Hurricane happened back in the 1600s, that one was said to be stronger than the 1938 hurricane.  NYC may also have been hit by a Cat 4 back in pre Columbian times.

That 1821 Hurricane really intrigues me and how was it able to maintain its strength with a track so close to the coast.

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2 minutes ago, LibertyBell said:

You're right and so is LBSF about the track, it was calculated that our worst case scenario would be a hurricane tracking into Monmouth County, and the maximum possible wind speed that those waters can support was calculated to be 145 mph.  A cat 4 may have reached our latitude and hit eastern New England when the Colonial Hurricane happened back in the 1600s, that one was said to be stronger than the 1938 hurricane.  NYC may also have been hit by a Cat 4 back in pre Columbian times.

That 1821 Hurricane really intrigues me and how was it able to maintain its strength with a track so close to the coast.

Great post!

The great colonial hurricane is the gold standard for what’s possible at our latitude that we have direct evidence of. I say at our latitude because it most likely took a track over eastern LI and up into New England. That storm likely was a high end 3, so stronger the both 38 and carol which were low end 3’s. 

The pre Columbian sediment evidence is especially intriguing. Was it a hurricane? Nor’ Easter? Or possibly even a tsunami? We will never know, but the deposits point to something off the scale.    

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4 hours ago, LongBeachSurfFreak said:

You can see the much larger area of wind maximum after the EWRC. This acts to increase the swell generation potential. Winds above a certain speed aren’t very efficient in transferring energy into the ocean. So a small pin hole eye with say 160mph winds creates smaller seas then a large eye with winds of 130mph. 

So what that means for us is that a larger more powerful swell is on tap. With this large swell event comes more of a threat for beach washovers and erosion. Historically we have never had a storm this strong on this trajectory. I fully expect major coastal effects including some damage at our area beaches late this week.

Is this why the surge with Katrina was much higher than its category?  Also hurricanes that were Cat 5 once still maintain that surge for awhile even when they start to weaken

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10 minutes ago, LongBeachSurfFreak said:

Great post!

The great colonial hurricane is the gold standard for what’s possible at our latitude that we have direct evidence of. I say at our latitude because it most likely took a track over eastern LI and up into New England. That storm likely was a high end 3, so stronger the both 38 and carol which were low end 3’s. 

The pre Columbian sediment evidence is especially intriguing. Was it a hurricane? Nor’ Easter? Or possibly even a tsunami? We will never know, but the deposits point to something off the scale.    

Thanks and I was wondering about that too if it was a megatsunami that could even be from a meteorite hitting our coastal waters.

We need a really fast moving storm to curve into the coast around the Atlantic Highlands in late August or September timed with the highest tides of the month (maybe around the equinox when the highest tides of the year are supposed to be- thats around when 1938 came in) in a really hot/humid summer with above normal rainfall prior to the storm to get the kind of high end storm worst case scenario we're talking about, not that we ever want to see something like that in our lifetimes.  A trillion dollar disaster with probably even more lives lost than 911 :(  A truly sobering thought on this day.

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On 9/9/2018 at 7:44 PM, qg_omega said:

Getting a cat 4 coming in from the SE is almost impossible, pressure wise sandy was the strongest storm ever to hit our area.  The size of the surge was also historic in terms of coastline impacted.  Winds also remained on shore after landfall given it's landfall location and direction. All very unusual and historic

Wow thanks for this- what track did you model for this- into Sandy Hook?  And was the max wind speed modeled 145?

 

It would be interesting to model the same track four different times, one with each category.

 

edit- this was for Hailstorm sorry

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2 hours ago, LibertyBell said:

That 1821 Hurricane really intrigues me and how was it able to maintain its strength with a track so close to the coast.

I just found a great presentation on the 1821 hurricane.

https://ams.confex.com/ams/95Annual/webprogram/Paper257982.html

Tuesday, 6 January 2015: 2:30 PM
128AB (Phoenix Convention Center - West and North Buildings)
Megan E. Linkin, Swiss Re America Holding Corporation, Armonk, NY
 
Hurricane Sandy, with its unique track, 1,000 mile wide wind field and low central pressure, pushed record breaking storm surge into the New York and New Jersey coasts, destroying businesses, homes and lives in a short 24 hour period. But for all the devastation and damage that Hurricane Sandy brought, its intensity at landfall, measured by 1-minute maximum sustained winds, was equivalent to a minimal Category 1 hurricane. Other events in recent years (Irene, Isabel, Gloria, Bob), while significant, weakened prior to landfall, coming onshore as either Category 1 or Category 2 hurricanes, and not the major hurricanes originally anticipated and feared. 

History, however, shows us that we may not always be as fortunate. The 1821 hurricane, commonly referred to as the Norfolk � Long Island hurricane, roared through the Mid-Atlantic and Northeastern United States in early September, passing over or near major cities and tourism regions such as the Outer Banks, Norfolk, Cape May and New York City. Coastal communities in North Carolina were washed away, ships in Norfolk, VA were pushed ashore and the Delaware Bay flooded Cape May, NJ. On eastern Long Island, the aftermath was described as, "the most awful and desolating ever experienced." The hurricane was a devastating event for the expanse of Northeast United States, with communities, farms and churches laid in ruins from North Carolina to New Hampshire. The hurricane is notable not only for its strength, but its contribution to science; it is the storm that led to the discovery that in the Northern Hemisphere, these weather systems rotate in a counterclockwise direction. 

With all existing documentation around the 1821 hurricane referring to a catastrophic, devastating event, and with today's models we can reconstruct a track for this hurricane to understand how it moved up coast, along with its wind field and storm surge field to determine what the loss potential is if the 1821 hurricane recurred today. 

Using Swiss Re's proprietary tropical cyclone model, a deterministic wind field and storm surge analogs are developed for the 1821 hurricane. The wind footprint calculated for the 1821 hurricane results in a large area of the Eastern Seaboard being affected by powerful winds and wind gusts; in parts of coastal North Carolina, the wind gusts are in excess of 150 mph, with wind gusts up to 130 mph reaching as far north as Connecticut. Storm surge values for the analog hurricanes range from 11 � 13 feet at The Battery, and up to 25 feet in Atlantic City, NJ. 

With trillions of dollars of residential, commercial and automotive exposure currently in the path of such a storm, the loss potential of the 1821 Norfolk-Long Island hurricane exceeds economic losses from other notable East Coast storms, including the 1938 Long Island Express and Hurricane Sandy. Physical economic losses are calculated to be in the range of USD 100 billion; actual economic losses, which include the intangibles, such as lost tax revenue and changes in asset values, are closer to USD 150 billion. 

It is imperative that we, as a nation and a society, look into the past to plan for the future, especially peering through the veil of climate change. Hurricanes Irene and Sandy served as harsh reminders that the Eastern Seaboard, particularly the Northeast US, is not immune to hurricane strikes. A recurrence of the 1821 Norfolk Long Island hurricane would be a paradigm shifter, severely and negatively impacting the economy and altering the culture of the oldest part of the United States going forward. Comprehending the potential consequences of historical storms today will help both improve our understanding of the "worst case event," and motivate those in coastal areas to take the necessary steps to prepare for all storms which are possible, even those beyond our current generations' memories.

 

 

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12 minutes ago, Rtd208 said:

Still a decent chance we will see some rain early next week with the remnants of Florence. It is going to be amazing to watch this storm unfold over the Carolina's and even portions of Virginia the next 4-5 days. Hopefully everyone in that area stays safe.

South Carolina now in the game with some models showing a SW drift right at or just prior to landfall.

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