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Old 09-09-2017, 01:40 AM
 
Location: Lewes, Delaware
3,490 posts, read 3,770,184 times
Reputation: 1953

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Quote:
Originally Posted by pbmaise View Post
Someone asked about interactions between Irma and Jose.

Let's look.

Firstly Irma at 77 Degrees and Jose at 59 degrees are 18 degrees apart. Times 60 gives us Nautical Miles of 1080. Or miles of 1200 miles. Actually a bit farther because I ignored latitude difference. Jose is more South.

Under guidelines established by Meterological​ wonder of cyclones Mr. Fujiwhara, if the two interact, Irma will be slowed down and pushed South. Jose will speed up and move North.

"The effect becomes noticeable when they approach within 1,400 kilometres (870 mi) of each other."

We are over 1200 miles apart so no Fujiwhara effect.

However, don't go away yet.

Winds going past Jose continue on to Irma.

Think of it as if Jose ate the black bean dip. Jose is doing something to the winds that Irma is seeing.

Hint. Right now, because of Jose, it is raining about three inches an hour in a big area of the ocean. If you guessed Jose is producing wet air that feeds Irma you are almost correct.

Instead the important thing is Jose is producing warm air. And lots of it. It is this heat that helps feed Irma just as the heat in the warm Bermuda water feeds her.

Even more importantly, Jose is one of the reasons the pressure below Cuba is so low. Warm air rises, and this is partly the reason Irma is defying the model makers and continues moving West.

Oops another hour past time for me to check where the eye is.

How odd. The eye is now over the town of Playa Cunagua on Cuba's mainland.

Let's keep this discussion secret since I am patiently waiting for this incredible turn to the North.

Oh check pressures.

Sorry guys my model indicates directly between Irma and Florida a low pressure of 972.

Even though South Florida is still 1006 I am expecting Irma to end her visit above the mainland of Cuba and pay Florida a visit.

I am predicting when I next check the eye in 40 minutes that it will no longer be over Cuba and will have moved back over the sea.
In terms of pressure wouldn't Irma coming into the area drop the pressure as it heads north to Florida? Actually my question is why is this storm heading north? Or how did the European model or any model for that matter know it was going to head north?
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Old 09-09-2017, 01:50 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
Quote:
Originally Posted by James420 View Post
In terms of pressure wouldn't Irma coming into the area drop the pressure as it heads north to Florida? Actually my question is why is this storm heading north? Or how did the European model or any model for that matter know it was going to head north?
Yes it will. It is one of the signs that bad weather is on the way. Most vessels like mine carry a very expensive barometer just for this reason.

Understanding that it is the latent heat of water that causes the air to rise and fall in pressure is key.

Up till now Irma's rainfall has been mostly circular around the eye.

After landfall on the edge of Cuba there was a dramatic change in the rainfall around the eye.

Rains are now mostly North of the eye.

It is this greater rainfall North of the eye that caused the low pressure that will coax Irma to stop visiting Cuba.

BTW god help the residents of Playa Cunagua they are directly under the eye now.
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Old 09-09-2017, 01:57 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
I again apologize that I don't tell you where my data comes from. The resources I use tend to get overloaded right when it is most important to use them. The wave model is currently acting up and I suspect 100,000 boat owners are frantically trying to use the same model to see if their boat is in trouble. Pictures were released from BVI showing Irma flipped dozens of catamarans completely upside down. Many many sailboats lost their mast and there are all the boats on the bottom that we can't see in the photos.

5 minutes till my model updates.
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Old 09-09-2017, 02:04 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
Irma moved NE off Cuba.

This was largely in the direction of heaviest rainfall. I.E. lowest pressure.

Rains NE of the eye are still highest by far. There currently is, according to my model, very little rain West of the eye.

Hence for this next hour I anticipate movement either due North or again NE.

When rains fill back around the West side of the eye wall it will change course to NW.

Pressure in the heaviest rain area, which is to the NE, is 967, and pressure to the NW is 973.

Cuba is quite a big island and Irma might very well do another bump and rebound with it before the day is over.

I apologise in previous post when I said it would depart Cuba to the NW. I failed to notice the pressure was actually lower to the NE.

Last edited by pbmaise; 09-09-2017 at 02:16 AM..
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Old 09-09-2017, 02:30 AM
 
Location: SW Florida
5,586 posts, read 8,348,131 times
Reputation: 11210
Quote:
Originally Posted by pbmaise View Post
I am troubled by the thought of a whole bunch of people on Florida's East coast now doing the happy dance and thinking they are in the pink.

Well that is my whole point. You are still in the pink of the wave model.

You may not be seeing the surge and giant wind. However, the wave model is predicting large waves in the 20 ft range all the way up the East Coast as far as West Palm Beach. Just high enough to drop a little sand into the pools of the billionaires and other high mucky mucks.

Again.

There is still a chance the worst of the winds will still go up that Eastern seaboard too.

No one let your guards down.
Right, the original projection of the spaghetti plots all showed it making a sharp 90-degree turn that took it over the East side of FL or even out over the ocean. And they said "we know it's going to make a right turn, we just don't know exactly when." So millions of SW FL residents based their decision on the prediction it would hit on the East Coast. And then suddenly today, when it's too late to join the millions of cars clogging up the roads and running out of gas, the European model turns the path west and not really a 90-degree turn anymore. Sooo, now it's heading straight up past me in Bradenton to Tampa. And hopefully it will change again tomorrow, because it never hits exactly where you think it's going to.
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Old 09-09-2017, 02:32 AM
 
Location: Lewes, Delaware
3,490 posts, read 3,770,184 times
Reputation: 1953
Quote:
Originally Posted by pbmaise View Post
Irma moved NE off Cuba.

This was largely in the direction of heaviest rainfall. I.E. lowest pressure.

Rains NE of the eye are still highest by far. There currently is, according to my model, very little rain West of the eye.

Hence for this next hour I anticipate movement either due North or again NE.

When rains fill back around the West side of the eye wall it will change course to NW.

Pressure in the heaviest rain area, which is to the NE, is 967, and pressure to the NW is 973.

Cuba is quite a big island and Irma might very well do another bump and rebound with it before the day is over.

I apologise in previous post when I said it would depart Cuba to the NW. I failed to notice the pressure was actually lower to the NE.
Does say kinetic energy generated by a huge storm like this make a difference as well? IIRC, Sandy a tropical storm wrapped in cold air had huge amount of kinetic energy party due to its size (huge). Something like 2 Hiroshima bombs, and even though it was just a T storm at landfall the Kinetic energy produced made it even more powerful than Katrina.

I get storm surge though would have a lot of factors like coastline geometry and the continental shelf drop off.

Do you consider kinetic energy a good way to predict damage?
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Old 09-09-2017, 03:05 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
Irma has during this past hour marched West and right back above Cuba again. My program puts the eye just SE of Maximo Gomez.

Wasn't that a character in a movie?

So much for my forecasting.

Again most rain is all West of the eye. Lowest pressure is again West of the eye which lends me again to expect a bounce to NE.

Most of South Florida now reading 1007 hPa. Same same unit called MB.
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Old 09-09-2017, 03:44 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
Quote:
Originally Posted by James420 View Post
Does say kinetic energy generated by a huge storm like this make a difference as well? IIRC, Sandy a tropical storm wrapped in cold air had huge amount of kinetic energy party due to its size (huge). Something like 2 Hiroshima bombs, and even though it was just a T storm at landfall the Kinetic energy produced made it even more powerful than Katrina.

I get storm surge though would have a lot of factors like coastline geometry and the continental shelf drop off.

Do you consider kinetic energy a good way to predict damage?
James an object in motion tends to remain in motion.

Momentum versus Kinetic Energy.

Momentum indicates the hitting force where as KE reflects how long that force will be applied in a non-elastic collision.

The force we are talking about is air molecules impacting water molecules to create waves. This is a nonelastic interaction hence KE is proper to examine.

Yes, the greater the KE, the greater the waves the greater the damage.

Further air itself can strike objects and cause damage and the KE of the air represents that force since it is again a nonelastic interaction.

I don't consider this however a proper way to predict damage.

Instead I use toolbox at this website.


Wind Velocity and Wind Load

I also found a great resource at the
North American Wood Pole Council.

Once I determined load caused by the wind, I consulted tables published by NAWPC to determine how many wires were needed to support the load.

Of course the third element I look at is wind load in a sail.

All of these are concerned with wind speed, and size of the object standing up to the wind.

One factor that became clear from Irma regarding sailboats, is the wind might do no damage to the boat at all. Instead gravity and waves do the damage after small and light catamarans flip upside down. They may be perfectly in tact before and while being flipped upside down, however, after they are upside down problems begin.

Prediction of damage is a very difficult subject as it requires knowing maximum forces average structures in the area can with stand.

Further you need to know costs.

Perhaps 100% of the homes may be destroyed, however if these are all bamboo huts, the replacement cost is low.

To locals the impact of losing their home that costs just $500 to replace in full may be more of a social hardship than a $20,000,000 home of a billionaire with insurance and a tax write-off.

The same can be true for a fishing boat versus a yacht. One is a man's living and the other is a mere pleasure. Which has a bigger social cost.
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Old 09-09-2017, 04:11 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
The placement of the eye in NHC reports is within 10 Nautical Miles. .

I wish to acknowledge this since to a degree what I am doing is zooming in on a model which places the eye with a degree of error too.

Hence when I see the eye wall has moved from a to b, or in the direction X this may be entirely in correct.

What I do see however are trends.

These seem overall pretty accurate.

Time to check again.

West now over Mayajigua.

South Florida down to 1006 hPa

Heaviest rains again to West of eye and perhaps more in SE.
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Old 09-09-2017, 04:14 AM
 
Location: Big Island of Hawaii & HOT BuOYS Sailing Vessel
5,277 posts, read 2,775,369 times
Reputation: 1932
Forecast 41

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 10 KT


ESTIMATED MINIMUM CENTRAL PRESSURE 930 MB EYE DIAMETER 30 NM MAX SUSTAINED WINDS 135 KT WITH GUSTS TO 165 KT.

64 KT....... 60NE 60SE 30SW 60NW.
50 KT.......100NE 90SE 50SW 80NW.
34 KT.......160NE 160SE 120SW 170NW.

12 FT SEAS..480NE 30SE 30SW 90NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 22.5N 78.8W AT 09/0900Z AT 09/0600Z CENTER WAS LOCATED NEAR 22.3N 78.3W

FORECAST VALID 09/1800Z 22.9N 80.0W MAX WIND 130 KT...GUSTS 160 KT. 64 KT... 60NE 60SE 30SW 60NW. 50 KT...100NE 90SE 50SW 80NW. 34 KT...160NE 160SE 120SW 170NW.

FORECAST VALID 10/0600Z 23.8N 81.1W MAX WIND 130 KT...GUSTS 160 KT. 64 KT... 60NE 60SE 30SW 60NW. 50 KT...110NE 100SE 60SW 90NW. 34 KT...170NE 160SE 120SW 170NW.

FORECAST VALID 10/1800Z 25.4N 81.8W MAX WIND 130 KT...GUSTS 160 KT. 64 KT... 70NE 70SE 40SW 60NW. 50 KT...120NE 120SE 70SW 100NW. 34 KT...220NE 180SE 140SW 200NW.

FORECAST VALID 11/0600Z 27.7N 82.4W...INLAND MAX WIND 105 KT...GUSTS 130 KT. 50 KT...130NE 120SE 90SW 110NW. 34 KT...250NE 220SE 150SW 240NW.

FORECAST VALID 12/0600Z 32.5N 84.5W...INLAND MAX WIND 45 KT...GUSTS 55 KT. 34 KT...120NE 180SE 60SW 60NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 13/0600Z 35.5N 88.0W...INLAND MAX WIND 25 KT...GUSTS 35 KT.

OUTLOOK VALID 14/0600Z 36.0N 87.5W...POST-TROP/INLAND MAX WIND 20 KT...GUSTS 30 KT.
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