ATL: SAM - Remnants - Discussion

[aspen]

The NHC has been going 5kt above the BT intensity for several previous advisories, so given the wealth of recon data, they’ll probably go higher at 130 kt — although I’d go for 135 kt.

[Teban54]

And just like that, Sam is back to almost as impressive as earlier (around the 5pm advisory time). Cloud tops might be even colder, though both the CDO and the eye are still a bit ragged.

[GCANE]

Last radar from Kermit before packing it up

[wxman57]

I'm thinking the NHC might go with 125 kts. Max FL winds "only" 140 kts. Sam is a tiny hurricane. Looking more like it will safely miss the NE Caribbean islands and possibly Bermuda, too. Newfoundland might not be so lucky. Looks like Levi is having trouble with his website again.

[Iceresistance]

I'm thinking the NHC might go with 125 kts. Max FL winds "only" 140 kts. Sam is a tiny hurricane. Looking more like it will safely miss the NE Caribbean islands and possibly Bermuda, too. Newfoundland might not be so lucky. Looks like Levi is having trouble with his website again.

At least it was working when Recon was inside the storm . . .

[tolakram]

NHC just want to stick to their forecast, they ignored the recon.

That's absurd. Best Track is not NHC, NHC can and often does modify best track. They are not going to go with a figure just to "stick to their forecast'.

[cheezyWXguy]

Sam is an impressive storm. The flat western edge of the cdo implies it may be dealing with some light shear, but since the coldest convection is upshear, I imagine it will at least maintain intensity. If the light shear breaks for just a couple of hours, it could reach cat 5 tonight

[Sciencerocks]

[EquusStorm]

It would be nice to get a high end hurricane with a normal wind profile again sometime; I have no idea what to make of the weird FL/SFMR disconnect. Stellar looking cane earlier though, glad we got another decent MDR storm after the last few sloppy looking strugglers.

[Yellow Evan]

I'm thinking the NHC might go with 125 kts. Max FL winds "only" 140 kts. Sam is a tiny hurricane. Looking more like it will safely miss the NE Caribbean islands and possibly Bermuda, too. Newfoundland might not be so lucky. Looks like Levi is having trouble with his website again.

The 90% rule doesn't really always apply with intense hurricanes (see Patricia, Dorian, Irma, Maria).

[Hammy]

NHC just want to stick to their forecast, they ignored the recon.

That's absurd. Best Track is not NHC, NHC can and often does modify best track. They are not going to go with a figure just to "stick to their forecast'.

Is it maintained by NRL?

[skyline385]

I'm thinking the NHC might go with 125 kts. Max FL winds "only" 140 kts. Sam is a tiny hurricane. Looking more like it will safely miss the NE Caribbean islands and possibly Bermuda, too. Newfoundland might not be so lucky. Looks like Levi is having trouble with his website again.

The 90% rule doesn't really always apply with intense hurricanes (see Patricia, Dorian, Irma, Maria).

I was reading the Patricia discussions from the NHC archives a few days ago and remembered them talking about this

The plane measured peak 700-mb flight level winds of 179 kt in the northeastern eyewall, and this may be an unprecedented value for a tropical cyclone. Using the 90percent adjustment value to convert this to a surface wind speed yields an intensity estimate of 160 kt

The aircraft measured 192 kt flight-level winds at 700 mb in the southeastern eyewall, with a 166 kt surface wind estimate from the Stepped Frequency Microwave radiometer.

[Yankee Corn Husker]

I bet this is 130 knots or higher

https://i.imgur.com/qdgAVk2.png

HOLY COW! This pic actually sent a chill down my spine!

[hipshot]

I bet this is 130 knots or higher

https://i.imgur.com/qdgAVk2.png

HOLY COW! This pic actually sent a chill down my spine!

Yeah, the eye actually looks like an eyeball!!! Spooky.

[CrazyC83]

I'm thinking the NHC might go with 125 kts. Max FL winds "only" 140 kts. Sam is a tiny hurricane. Looking more like it will safely miss the NE Caribbean islands and possibly Bermuda, too. Newfoundland might not be so lucky. Looks like Levi is having trouble with his website again.

The 90% rule doesn't really always apply with intense hurricanes (see Patricia, Dorian, Irma, Maria).

Those flight level winds translate to 126 kt at the surface. I see no reason to go at least 130 kt given the data.

[tolakram]

NHC just want to stick to their forecast, they ignored the recon.

That's absurd. Best Track is not NHC, NHC can and often does modify best track. They are not going to go with a figure just to "stick to their forecast'.

Is it maintained by NRL?

It's maintained by the NHC but the initial data is somewhat? automated (ATCF). http://hurricanes.ral.ucar.edu/realtime/

It's not the most clear cut process. I gather it's a best estimate prior to review, similar to DVORAK best estimates. Recon data is one of the review items, I don't know if ever makes it into best track real time, but I'm just not sure about it. Regardless, we have seen NHC increase and decrease best track after analysis.

[supercane4867]

It would be nice to get a high end hurricane with a normal wind profile again sometime; I have no idea what to make of the weird FL/SFMR disconnect. Stellar looking cane earlier though, glad we got another decent MDR storm after the last few sloppy looking strugglers.

There is no such thing as a "normal" wind profile. The standard deduction used for the conversion of FL level to surface winds is derived from historical dropsonde data itself and is by no means conclusive. In Sam's case the boundary layer measurements from dropsonde clearly supports an intensity higher than what the standard deduction implies and thus should be given more weight in the assessment

[Ubuntwo]

It would be nice to get a high end hurricane with a normal wind profile again sometime; I have no idea what to make of the weird FL/SFMR disconnect. Stellar looking cane earlier though, glad we got another decent MDR storm after the last few sloppy looking strugglers.

There is no such thing as a "normal" wind profile. The standard deduction used for the conversion of FL level to surface winds is derived from historical dropsonde data itself and is by no means conclusive. In Sam's case the boundary layer measurements from dropsonde clearly supports an intensity higher than what the standard deduction implies and thus should be given more weight in the assessment

Further research needed. Sam's tight melded core is quite rare and the few similar cyclones that have been sampled displayed a downward shift in vertical wind profile. Sam is especially low latitude which only compounds that. Even accounting for the SFMR bias, 125kt seems low.

[hipshot]

It would be nice to get a high end hurricane with a normal wind profile again sometime; I have no idea what to make of the weird FL/SFMR disconnect. Stellar looking cane earlier though, glad we got another decent MDR storm after the last few sloppy looking strugglers.

There is no such thing as a "normal" wind profile. The standard deduction used for the conversion of FL level to surface winds is derived from historical dropsonde data itself and is by no means conclusive. In Sam's case the boundary layer measurements from dropsonde clearly supports an intensity higher than what the standard deduction implies and thus should be given more weight in the assessment

Further research needed. Sam's tight melded core is quite rare and the few similar cyclones that have been sampled displayed a downward shift in vertical wind profile. Sam is especially low latitude which only compounds that. Even accounting for the SFMR bias, 125kt seems low.

Is Sam still supposed to miss the Lesser Antilles. I hear lots of discussion about strength but not so much about its track. It sure seems to be moving more
west or maybe wnw and that could be a problem perhaps.

[abajan]

LOCATION...13.5N 49.0W
ABOUT 990 MI...1595 KM ESE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...943 MB...27.85 INCHES

First!