Milton is currently a category 5 hurricane over the warm and deep waters of the Gulf of Mexico. It is predicted to hit the west coast of Florida as a category 3 which implies wind speeds between 111 - 129 miles/hour. Does the fact that Milton is now a 5 mean that will have different characteristics when it makes landfall than if it had “only” been a category 3 over the gulf?
AIUI, once a hurricane hits land it decreases in intensity fairly quickly. So while it may be a cat 3 over water, as soon as it hits shore the winds will start to decrease, and within hours may become a tropical storm. There can still be a lot of rain, but with much lower wind speeds. Land masses slow down hurricanes fairly quickly, while over warm water they will usually increase wind speeds. Helene didn’t slow down much after hitting land and I think that’s why the damage caused was so widespread compared to other comparable hurricanes.
No, and yes. Hurricanes are susceptible to upper level winds, veering winds, temperature differentials. I think what will cause Milton to lose strength and change direction more east than northeast is a weak cold front/stationary front currently over north Florida.
I think the greatest threat to a hurricane is a cold front (as well as major geographic elevation/hills/mountains). You can have a cat 5 170mph hurricane encounter a run-of-the-mill mid-latitude cold front and it will be a smear on a weather map in a day.
According to the weather guy on CNN the storm surge has already been created. So the amount of water hitting barrier islands will probably completely overwash them.
So yeah that effect doesn’t decrease.
The wobble north or south cannot be predicted with much accuracy.
I’m not sure how true that is but that’s what the man said.
Yes, passing over land eliminates the warm waters that fuel storms. Helene had momentum when it continued over land. However, land can also lift the warm moist air in the storms causing torrential rains and flooding a la Helene.
They can with some accuracy.
You can see in the link below how the “cone” of the hurricane’s future track widens over time. That is the error but, mostly, weather forecasters know it will be in that cone and not just randomly meander around. The forecasters are pretty good at this stuff when looking ahead only a few days.
You only need a sharpie to predict what’s going to happen.
I thought the same thing.
As mentioned above, yes but not as directly as you might think.
The hurricane categories are purely about maximum sustained wind speed. So even with the same category any other characteristic can be totally different - amount of rainfall, the amount of storm surge, the size of the wind field (how big an area hurricane force winds are present), etc. Two different Cat 1 storms will have similar max wind speeds but can be totally different in every other aspect.
Of course, more wind tends to mean more destructive because more energy will do that. But it’s not a very tight correlation. But any storm that has gotten up to cat 5 (maximum sustained winds of at least 156 mph) is going to be powerful and destructive.
For what it’s worth, there’s been talk for a long time about coming up with a hurricane categorization scale that is tied more directly to destructive potential. The Saffir-Simpson scale measures sustained wind speed, so it can be misleading in some cases. For example, a storm that does not have so much wind but could bring tremendous rains and floods. Or the size of a storm - Helene was “only” a Cat 4 but its wind field was significantly larger than Cat 5 Milton’s wind field will ever get.
Unfortunately, it’s not easy developing such a scale that is straightforward and simple enough for the general public to understand without requiring a lot of additional knowledge or context.
Depending on conditions, it’s a great deal of accuracy. Unfortunately, it’s also the case that a shift of just a few miles to landfall can make a huge difference in how much destruction there will be.
If Milton shifts just a few miles further south than the current track, Tampa Bay may only have very bad storm surge rather than catastrophic. That’s a lot of accuracy to ask for a storm that’s still hundreds of miles out.
I understand there was a lot of warm moist air over the land in the Southeast before Helene made landfall that helped fuel it much further than it normally would have gone.
I wonder if the answer is that a Cat5 will pick up more water over the Gulf than a Cat4 or 3? And so the rainfall potential will be much higher? Would a Cat5 have created a bigger storm surge before it weakens that carries on to some extent, compared to a continuously Cat3?
To what extent does the moisture content affect the force of the same speed wind? That water weight (and raindrop impact) has to count for something, even if a few percent.
Probably, but I think it went about as far as many other major storms, the hills and winds (shear)/temps being a limiting factor. These storms carry so much water, if they get stuck somewhere it ends up in catastrophe. Usually they move along or dissipate.
A cat 5 or cat 4 storm will not maintain that strength more than a few hundred miles inland at most, but can still affect a very large land area even as tropical depression.
Each storm is different! The categories are a wind “scale” only, not rainfall or area or pressure, etc. It’s complicated --everything can affect everything. I don’t think “moisture content” is something quantified in hurricanes.
I think @Great_Antibob does a much more thorough job explaining than I can so maybe he’ll weigh in.
It’s all inter-related.
The sheer volume of all that hot water and hot, moist air helps drive hurricane intensification, so there is definitely a positive correlation between the max wind speed and rainfall potential, i.e. Cat 5 storms will tend to involve more water than Cat 4 or Cat 3 or lower storms but it’s not an absolute tendency.
As suspected, there is how much time the storm has to build up over that water. Naturally, the longer the storm builds up over warm water, the bigger the affected area and the bigger the potential storm surge.
Both Harvey and Helene were tremendous rain makers, picking up (and then dropping) ridiculous amounts of water over a large area but both were “only” Cat 4 storms.
The surge from Harvey peaked at about 12 feet and Helene had an absolutely monstrous 15 feet of surge, while it looks like we’ve gotten relatively lucky (for a given definition of ‘luck’) with Milton, which is currently estimated to have brought roughly 10 feet of surge to the region around Sarasota. If it had hit even 20 miles further north, Tampa Bay would have gotten 10-12 feet of surge.
Likewise, both those storms dropped a lot more rain over land than Milton will, which will still drop upwards of a foot of rain over parts of Florida. Tropical Storm Allison didn’t even get to hurricane strength but still dropped over a foot of rain in places. So, the Category is definitely correlated but not absolutely with surge and rainfall.
As explained in an earlier post, the Saffir-Simpson hurricane categories are solely about maximum wind speed. There have been pushes to come up with categories that track with surge and rain and potential for damage, but it may be impossible to develop one that actually does that while still being simple enough to explain to the general public. We have enough trouble with Saffir-Simpson, and that’s solely wind speed.
I don’t think that’s such a big obstacle. The simple explanation to the public can be just “It goes from 1 to 5, and higher numbers are worse” (which is the level at which most folks understand the current system). The next-most-complicated explanation can be “The rating depends on a number of factors, including wind speed, area, water content, and pressure differential”. Those two explanations will be enough for most people. There will still be some people who want more details, of course, but those are, by and large, mostly going to be the people who can handle that greater level of detail.
Years ago, I rode out an earthquake in Japan with an American seismologist. He remarked that they’d shifted to the moment magnitude scale years before, but that whenever they tried to explain that to the press, they ended up just saying “yeah, Richter scale” out of frustration.