Major Hurricane Melissa - 892mb - 185mph at landfall

[nycwinter]

i am wondering if the slow movement for days gave melissa the opportunity to strengthen as much as she did..

[Nibor]

Daybreak to landfall

[WEATHER53]

20 minutes ago, WolfStock1 said:

 

OK then follow-up - why would non-straight-line winds be more destructive than straight-line?   Same force isn't it?

Perhaps it's that tornadoes' winds tend to swirl upward, and thus tend to lift more debris, than hurricane winds?

It’s a kin to what a blender does versus pushing with straight line equsl force but no torque 

[Interstate]

You can already see the effects that land is having on the structure of the hurricane... The south side is already eroding.  It will be very interesting to see how Melissa holds up across Jamaica. 

[nycwinter]

6 minutes ago, WolfStock1 said:

 

Perhaps, but in both case total destruction generally only happens in a small area; in the case of winds it's around the eye; in the case of rainfall it's low-lying areas - along rivers and such.   River damage is only a couple hundred yards wide typically though; this eye is 20 miles wide.    A house that's not along a creek or river will see no damage from rainfall but tons of damage from wind.

Reality will be both of course.

Bad hurricane flooding typically comes from storm surge.   Helene was an exception last year of course - but that's mostly because the watershed areas are quite large for the rivers that did the big damage.    E.g. the watershed for the French Broad in NC is about 10,000 sq miles.   In Jamaica the watershed for say the Black River is about 100 sq miles, so even twice the rainfall as Helene would result in only 1/50 the flow.   It's one of the advantages of being an island - it'll drain better.    

Not saying there won't be some catastrophic flooding - the will be, but I think wind will probably cause more overall damage.

watching the weather channel as melissa was making landfall a recorded gust less then 900 feet up was over 250 mph jamaica is a  very hilly country..

[ATDoel]

19 minutes ago, Normandy Ho said:

I wouldn’t say it’s all horizontal with canes, but the scale of the circulation is such that any vertical component wouldn’t be strong enough to suck you upwards.  But yea in general you are correct.  I do think hurricanes and tornadoes are more similar than one would think (which is why they look like each other on radar, size of the circulation Being the major difference) 

practically speaking it's all horizontal.  Tornadoes loft debris tens of thousands of feet in the air, a hurricane doesn't loft debris any appreciable amount, event light stuff.  You can step out into 150 mph winds from a hurricane and most likely be fine, you do that during an EF3 and you're dead.

[str8liner]

2 minutes ago, nycwinter said:

i am wondering if the slow movement for days gave melissa the opportunity to strengthen as much as she did..

What is really weird is the fact that she sat in basically the same spot for days and still strengthened. Usually the upwelling of colder water will hinder strengthening to some extent.

Evidently there was so much warmer water in this area it didn't happen?  

[Brian5671]

Just now, str8liner said:

What is really weird is the fact that she sat in basically the same spot for days and still strengthened. Usually the upwelling of colder water will hinder strengthening to some extent.

Evidently there was so much warmer water in this area it didn't happen?  

yeah the warm water was alot deeper in this region something like 600 feet down

[nycwinter]

1 minute ago, str8liner said:

What is really weird is the fact that she sat in basically the same spot for days and still strengthened. Usually the upwelling of colder water will hinder strengthening to some extent.

Evidently there was so much warmer water in this area it didn't happen?  

not only was the water temps 30c but the water is warm and deep in the part of the caribbean..

[Amped]

It slowed down quite a bit at landfall.

[Eskimo Joe]

 

 

[nycwinter]

so after melissa is the season done?

[NJwx85]

3 minutes ago, Interstate said:

You can already see the effects that land is having on the structure of the hurricane... The south side is already eroding.  It will be very interesting to see how Melissa holds up across Jamaica. 

This is what happens, especially when you consider the high terrain. But, the Northeastern portion of the eye wall is already more than halfway across.

[WolfStock1]

Just now, gallopinggertie said:

Not sure about this. In the geology video I linked to, the geologist actually compares Jamaica during Melissa to the Blue Ridge Mountains in Helene…and he says that this situation is actually worse. Jamaica’s river valleys are smaller but more prone to landslides because the rock is actively being uplifted by a fault, making the rocky slopes steeper and more fragile/prone to crumbling. The rock itself collapses - versus in the Blue Ridge, the slides are soil and debris. Also he says that the rivers in Jamaica are really large in terms of flow, despite not being very long. 

 

True enough - I wasn't really addressing landslides, just flooding water volume.   In that respect yeah - the landslides will certainly be worse.

River flow is a direct function of land area X rainfall rate/level right?   While the normal flow might be higher on a per-land-area-served basis; presumably that's due to Jamaica getting more rain during normal periods than NC; given an equal amount of heavy rainfall though they both would flow the same of course.   

That said - one key difference here may simply be the very *fast* dumping of rain in certain areas; moreso than Helene where the rate of rainfall wasn't as fast as Melissa.    So tributaries will probably be worse-off for short periods than Helene.

FWIW - I've driven through a lot of the Helene areas.    While the damage was really bad; it wasn't "wipe large areas off the map" bad.   The bad thing about Helene was that the damage was spread over a *huge* area - like several dozen Jamaicas.

 

[40/70 Benchmark]

4 minutes ago, str8liner said:

What is really weird is the fact that she sat in basically the same spot for days and still strengthened. Usually the upwelling of colder water will hinder strengthening to some extent.

Evidently there was so much warmer water in this area it didn't happen?  

It seems like intensification was reinvigorated when it began moving a bit more readily, so upwelling may have slowed the rate a bit for a spell.

[40/70 Benchmark]

5 minutes ago, Brian5671 said:

yeah the warm water was alot deeper in this region something like 600 feet down

Right, but probably a bit cooler.

[wthrmn654]

Satellite estimates say 160,161 knot winds when it made landfall

[gallopinggertie]

3 minutes ago, WolfStock1 said:

 

True enough - I wasn't really addressing landslides, just flooding water volume.   In that respect yeah - the landslides will certainly be worse.

River flow is a direct function of land area X rainfall rate/level right?   While the normal flow might be higher on a per-land-area-served basis; presumably that's due to Jamaica getting more rain during normal periods than NC; given an equal amount of heavy rainfall though they both would flow the same of course.   

That said - one key difference here may simply be the very *fast* dumping of rain in certain areas; moreso than Helene where the rate of rainfall wasn't as fast as Melissa.    So tributaries will probably be worse-off for short periods than Helene.

FWIW - I've driven through a lot of the Helene areas.    While the damage was really bad; it wasn't "wipe large areas off the map" bad.   The bad thing about Helene was that the damage was spread over a *huge* area - like several dozen Jamaicas.

 

That’s the thing, in the video he said that in fact homes in jamaica are often built a good bit above the river anyway. The threat (according to him) is moreso landslides/rockslides caused by huge amounts of rain falling on crumbling and steep terrain, rather than houses getting swept away by the water itself. 

[Interstate]

6 minutes ago, NJwx85 said:

This is what happens, especially when you consider the high terrain. But, the Northeastern portion of the eye wall is already more than halfway across.

Yeah I wonder if Melissa will be able to regroup once it gets back over water. I know that wind shear is going to become a factor too.

[olafminesaw]

3 minutes ago, wthrmn654 said:

Satellite estimates say 160,161 knot winds when it made landfall

Like an angry hornet and Jamaica just stepped on it's nest

[str8liner]

6 minutes ago, Interstate said:

Yeah I wonder if Melissa will be able to regroup once it gets back over water. I know that wind shear is going to become a factor too.

What are the water temps between Jamaica and Cuba? That will play a factor. If they are just as warm I would think it would have to strengthen some.

[ATDoel]

11 minutes ago, WolfStock1 said:

 

True enough - I wasn't really addressing landslides, just flooding water volume.   In that respect yeah - the landslides will certainly be worse.

River flow is a direct function of land area X rainfall rate/level right?   While the normal flow might be higher on a per-land-area-served basis; presumably that's due to Jamaica getting more rain during normal periods than NC; given an equal amount of heavy rainfall though they both would flow the same of course.   

That said - one key difference here may simply be the very *fast* dumping of rain in certain areas; moreso than Helene where the rate of rainfall wasn't as fast as Melissa.    So tributaries will probably be worse-off for short periods than Helene.

FWIW - I've driven through a lot of the Helene areas.    While the damage was really bad; it wasn't "wipe large areas off the map" bad.   The bad thing about Helene was that the damage was spread over a *huge* area - like several dozen Jamaicas.

 

The only reason the damage was bad for Helene was because so many communities built in the floodplain of the creeks and rivers.

[NJwx85]

5 minutes ago, Interstate said:

Yeah I wonder if Melissa will be able to regroup once it gets back over water. I know that wind shear is going to become a factor too.

It’s moving almost due North, right along 78W. It should be back over water in 2-3 hours. It’s a much shorter trip than if it was moving more Northeasterly. It also will keep it over water longer before reaching Cuba.

[GaWx]

6 minutes ago, str8liner said:

What are the water temps between Jamaica and Cuba? That will play a factor. 

 Note that the 30C+ area around Jamaica did shrink a lot due to some cooling although unfortunately not nearly enough cooling to help. As Melissa was coming in, it was going over mainly 30+.

[NJwx85]

1 minute ago, str8liner said:

What are the water temps between Jamaica and Cuba? That will play a factor. If they are just as warm I would think it would have to strengthen some.

The water is about the same but shear will be gradually increasing.

[wncsnow]

Just now, ATDoel said:

The only reason the damage was bad for Helene was because so many communities built in the floodplain of the creeks and rivers.

Yeah, sure that's the only reason. Not the fact it rained 30 inches over 5-6k ft peaks with gusts of over 80 mph leading to hundreds of landslides, some of them miles long. Helene flooded plenty of areas outside of flood plains. 

[WxWatcher007]

As we are all rightfully concerned with the impact on Jamaica right now, I also want to take a moment to discuss the environment after Melissa leaves Jamaica. 

What happens next is highly dependent on structure--how much the mountainous terrain disrupt Melissa's inner core. Melissa has an very small core. On one hand, that increases the odds that over the coming hours the center is significantly disrupted, reducing the risk of reintensification over water. On the other, such an intense inner core is inertially stable, making it possible that if a strong enough core emerges from the coast, it is able to take advantage of the environment, if favorable enough. 

The key is shear, and Melissa is straddling the line (and has been lately) between favorable and more modest deep layer shear. 

 

Looking at the environment however, shear may not be as much of an issue until Melissa crosses Cuba. In fact, the shear has been subtly declining ahead of its path. 

 

The extraordinarily favorable thermal environment that helped Melissa become an upper echelon C5 isn't quite as favorable after Jamaica, but it seems to be plenty if Melissa has the time and space to reorganize. 

Finally, the diurnal cycle that has helped Melissa may prove favorable once again as the storm approaches Cuba later tonight. 

Just something to keep in mind. All dependent on how much the core is disrupted today. (Edit: and what the actual shear profile is later)

[eyewall]

[NJwx85]

It probably peaked about 3 hours ago, but my guess is second LF into Cuba as a high end major. Probably 125kts if I had to guess.

[NorthHillsWx]

1 minute ago, NJwx85 said:

It’s moving almost due North, right along 78W. It should be back over water in 2-3 hours. It’s a much shorter trip than if it was moving more Northeasterly. It also will keep it over water longer before reaching Cuba.

I was thinking this too as a result of the continued westward drift. It also avoids the highest terrain if it stays west. As for intensity, the NE eyewall most definitely came ashore at peak intensity. Perhaps it filled a few mb before the center crossed but being the strongest winds were already onshore it does not matter