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PTC Matthew

PaEasternWX

By PaEasternWX,
in Tropical Headquarters

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Roger Smith

Roger Smith

Posted
Posted

Interesting to compare 96h forecast position for 12z today (18.0 N 75.2 W) with actual (18.2 N 74.5 W), an error of about 50 nm. The intensity error was much more significant (the forecast was 80 kts).

As to a landfall, probably best to deal in probability rather than yes-no, at this point from the entire guidance available, would be prudent to say a one in three or perhaps one in four chance of a landfall in SC/NC and somewhat lower in northeast FL, perhaps one in five. Looking fairly unlikely now in the northeast US except possibly eastern Maine, chances increase to 40% for NS and 50-50 for Newfoundland however storm might only be a strong tropical storm or minimal cat-1 by then. 

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Roger Smith

Roger Smith

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Posted
12 minutes ago, Raine1212 said:

Newbie and lurker here, i may have missed it what is the square miles of coverage is this storm covering? I live about 140 miles from the coast. Sorry if i have postd in the wrong thread.

Your question probably indicates an interest in how far from the center hurricane conditions might extend ... as it moves up the southeast coast this extent would probably be 25-75 miles depending on intensity (25 for a cat 2 and 50 for a cat 3, 75 for a cat 4) as a rough guide, you would be on the "weak" side of a storm that grazed the coast and did not come inland. For clarity, I should add that those distances refer to minimal hurricane winds, not for example that cat 4 winds would be felt 75 miles inland from a shoreline cat-4, but cat-1 winds there. Cat-2 or 3 winds sometimes come inland up to 50 or even 100 miles but rarely, and with a storm moving along a coastline, it would be mostly cat-1 winds over land away from any eyewall rotating over shore, that eyewall would contain near-maximum winds for the storm (the max would be on the forward side of the eyewall).

Out in the ocean, those distances would be greater, such as 60 miles for a cat 2, 100 for a cat 3 and 150 for a cat 4 (once again, approximate). Tropical storm winds might extend inland as far as 150 miles from the center and on the seaward side 250-300 miles would be possible. 

These stats are available for the specific forecast points if you look at the NHC advisories, they are expressed as radii of hurricane and tropical storm winds and use four quadrants as these will not always be equal (right now Matthew is a rather symmetrical storm but as they move faster and along coastlines they become more asymmetric). 

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Raine1212

Raine1212

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1 minute ago, Roger Smith said:

Your question probably indicates an interest in how far from the center hurricane conditions might extend ... as it moves up the southeast coast this extent would probably be 25-75 miles depending on intensity (25 for a cat 2 and 50 for a cat 3, 75 for a cat 4) as a rough guide, you would be on the "weak" side of a storm that grazed the coast and did not come inland. Out in the ocean, those distances would be greater, such as 60 miles for a cat 2, 100 for a cat 3 and 150 for a cat 4 (once again, approximate). Tropical storm winds might extend inland as far as 150 miles from the center and on the seaward side 250-300 miles would be possible. 

These stats are available for the specific forecast points if you look at the NHC advisories, they are expressed as radii of hurricane and tropical storm winds and use four quadrants as these will not always be equal (right now Matthew is a rather symmetrical storm but as they move faster and along coastlines they become more asymmetric). 

Ty Sir for the information, exactly what I was trying ask

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Roger Smith

Roger Smith

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8 minutes ago, Raine1212 said:

Ty Sir for the information, exactly what I was trying ask

thanks and you might want to read my post again because I edited it after you quoted it, don't want to give you any wrong concepts, the land coverage of hurricane winds quickly falls off to minimal hurricane strength, it's not a situation where a cat-4 just off the coast would spread cat-4 winds inland. 

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Raine1212

Raine1212

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3 minutes ago, Roger Smith said:

thanks and you might want to read my post again because I edited it after you quoted it, don't want to give you any wrong concepts, the land coverage of hurricane winds quickly falls off to minimal hurricane strength, it's not a situation where a cat-4 just off the coast would spread cat-4 winds inland. 

Thank you

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Roger Smith

Roger Smith

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There were no models in 1954 so we don't know how well a model might handle the Hazel scenario. All it would take here is an error trend on the approaching capture trough combined with a maxed out hurricane not making quite as leisurely a tour of the southeast coast and you could have a poleward-westward shift on this. I saw where someone was wondering if this could go sub-900 (in the Bahamas, presumably) -- would not be surprised by 910 and therefore I think any "carved in stone" thinking about what will actually happen past Friday is way, way premature. This can easily become a high impact storm for the eastern U.S. and there won't be clarity on this until late tomorrow at the earliest. 

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klw

klw

Posted
Posted
3 minutes ago, PackGrad05 said:

What does this mean?  What core?

It means that the Hurricane Hunter Josh who someone posted a few pages back is in the Bahamas would miss the center of the storm.

 

Meanwhile here is another good satellite page in case people need one:

http://weather.cod.edu/satrad/

 

I recommend the 2KM regional product and choose the furthest SE option.

 

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