ATL: MILTON - Post-Tropical - Discussion

[lovingseason2013]

I hope someone is on the ground ready to buy these people who are on these recon flights a beverage of their choice. They certainly deserve it.

My friend is a pilot on the Air Force HH aircraft. Can’t wait to sit down with him over a beer and chat.

[SVT1118]

My girlfriend’s parents live in a condo on St Pete Beach. Originally they weren’t going to evacuate, just like they didn’t for Helene. Today, thankfully they decided they are going to evacuate.

[aspen]

The insane volumes of website traffic have begun. Tropical Tidbits just gave me a 502 error.

[USTropics]

At which point will Milton hit the MPI? And do we know what it even is?

This map suggests the minimum potential pressure is in the 890s (higher towards Mexico coast, a bit lower further north). However, Beryl did outperform the wind MPI, though I'm not sure if there are any instances of storms outperforming pressure MPI.

[url]https://i.postimg.cc/KcTDb1jj/atlpot.png [/url]

MPI is only winds (intensity is winds). A storm can't exceed the MPI (it is a maximum), in fact very few ever reach MPI.

Determining the maximum wind speed a tropical cyclone can reach involves applying some thermodynamics, namely we model the mechanisms of a tropical cyclone as a Carnot heat engine (not too dissimilar from a motor/car engine). This allows us to determine the MPI (maximum potential intensity) as others have mentioned by using the Carnot cycle. But what exactly is a Carnot cycle and how does this physically look?

The Carnot cycle is characterized by four stages of expansion and compression. I created a crude diagram below to better show these stages in a cross-section of a mature hurricane:
The first stage (A→B) is isothermal expansion. In this stage, air flows inward towards the low pressure center for the storm.
The second stage (B→C) is adiabatic expansion. Air begins to rise adiabatically up the eyewall to the top of the atmosphere (TOA).
The third stage (C→D) is isothermal compression. Air now flows outward at this point and radiative cooling begins.
The fourth stage (D→A) is adiabatic compression, as air now sinks and begins to warm. Pressure increases, and the cycle begins again.



Now that we can identify the inner mechanisms of a hurricane, what are we really trying to show here? First, we now know the ocean-hurricane interaction provides the fuel pump, and as a hurricane intensifies, a feedback loop begins. As wind speeds begin to increase, this also increases the evaporation rate, which in turn increases the latent heat supply that drives our Carnot engine.

Secondly, we can now apply some math equations to quantify what this value is. From our previous statement, we know our main source of latent heat/warm reservoir is our sea surface temperatures (i.e., through the evaporation process, latent heat is released). If we also treat our TOA as the outflow (think cool reservoir), we can now mathematically model a hurricane using the Carnot efficiency ratio. Skipping some of the setup using the First Law of Thermodynamics and determining work done for each leg of the cycle, we arrive at our most simplified equation:



Where Ts is our inflow surface temperature of the ocean (hot reservoir), To is our TOA outflow temperature (cold reservoir), and E is a ratio of enthalpy and surface drag (i.e., heat exchange coefficients). In this sense, we can state the mechanical energy produced by our heat engine (V, or work done) is the energy of the winds (hurricane intensity)!

If we consider E to be constant (not the safest assumption, but will do for now), our maximum potential intensity, as stated by thermodynamics, is simply governed by the outflow temperature and the inflow temperature. In other words, this means changes in our cloud top convection or sea surface temperature strictly dictates the maximum wind speeds a tropical cyclone can reach.

With all that said, it’s important to note that we’re discussing the theoretical maximum potential intensity. Cyclones rarely reach this intensity because this requires ideal atmosphere and oceanic conditions—in other words, environmental factors rarely allow a system to reach MPI. This includes
Land interaction: this obviously removes our fuel source (latent heat release from the ocean surface)
Vertical wind shear: This causes the cyclones core to become asymmetrical, weakening the convective pattern or even creating an absence of convection on the upshear side of the cyclone (this raises our To)
Ocean interaction: As stated previously, increased wind speed can increase evaporation, but too much wind speed over a very specific area of the ocean can also cause upwelling. This localized cooling of the ocean layer decreases our Ts variable.
Dry air entrainment: If our adiabatic cooling/expansion leg of the cycle becomes disrupted by dry air, this decreases the convective potential of our cyclone and To.

[FireRat]

MILTON 10/7/2024



Image from John Morales.
Historic day we'll never forget. Wow.

[FLLurker32]

My brother and sister-in-law are in Odessa. Newer block home not in a flood zone so he’s shuttering it up and refusing to leave despite having family to stay with more inland.

I hope they don’t end up regretting that decision.

[cycloneye]

Yucatán radar where the eye looks very impressive.

[jdjaguar]

My brother and sister-in-law are in Odessa. Newer block home not in a flood zone so he’s shuttering it up and refusing to leave despite having family to stay with more inland.

I hope they don’t end up regretting that decision.

My son and sister-in-law live in Seminole right across from Indian Rocks and they have prepped but have not left!

[norva13x]

Im in Lake Wales, I have an old cinder block house from the 50s but I just got a new roof and am worried about roof damage or window damage. I honestly feel sick to my stomach not just in fear for my property but my friends and family in Tampa where I grew up. I worry it may not be recognizable in a few days

[BIFF_THE_UNRULY]

My brother and sister-in-law are in Odessa. Newer block home not in a flood zone so he’s shuttering it up and refusing to leave despite having family to stay with more inland.

I hope they don’t end up regretting that decision.

I am in the same boat. Agonizing wether to stay or go.

[eastcoastFL]

There is. Gas stations empty. Roads bumper to bumper going north or east....

WAWA always has gas fyi

Do they have magical unlimited storage tanks?

I don't think so. Gas will be hard to come by in the next 24 hours. Get it today or plan to sit in long lines risking not getting any.

[NDG]

[InfernoFlameCat]

Yucatán radar where the eye looks very impressive.

https://i.imgur.com/2hcJyy6.jpeg

I am seeing signs of an onset of an EWRC there with a small moat. But we might get an eyewall meld instead.

[Michele B]

Assuming Milton gets C5... which I think is all but inevitable now. Are there any Category 5s on record which have been recorded moving west to east or will Milton be the first?

Nope, this would be a first. At least specifically in the Gulf. Lenny got close at 155 mph, but that was in the Caribbean Sea

The prognosticators sure missed what this season was going to be remembered for!

Remember everyone saying "Multiple storms!! More than ever!!!" Boy did they miss it!

[BIFF_THE_UNRULY]

Im in Lake Wales, I have an old cinder block house from the 50s but I just got a new roof and am worried about roof damage or window damage. I honestly feel sick to my stomach not just in fear for my property but my friends and family in Tampa where I grew up. I worry it may not be recognizable in a few days

Yeah come monday the city wont be the same


The city has poured billions of tons of concrete and added a half million people since the last irrigation project, which was Sweetwater creek canal systems in the 1950's.

Tampa is in big big trouble and to speak frankly, this event may cause a sort of real estate crisis across the economy at large with Tampa being one of the hottest markets in the country.

[chaser1]

There is. Gas stations empty. Roads bumper to bumper going north or east....

Miami is not a bad alternative. Should be TS gusts correct?

There's arguably a heightened flash flood risk for SE Florida.

I see no significant risk of flooding in Miami-Dade or Broward if away from the coast. 6-8" for inland areas may pose a temporary nuisance but not particularly threatening, as long as you're not driving around in it

[mpic]

Just my opinion regarding the decision to leave...After seeing the damage that Helene caused and the possible damage Milton will cause, would you rather be gone and not need to be or stay and be sorry? It's a question that only you can answer.

[kevin]

This is a once-in-a-generation storm. 2005 had Wilma. 2024 has Milton.

[FireRat]

What yall thinking next advisory? I'm thinking 180 something with pressure in the 900s

Sounds plausible!

[Cat5Danny]

My brother and sister-in-law are in Odessa. Newer block home not in a flood zone so he’s shuttering it up and refusing to leave despite having family to stay with more inland.

I hope they don’t end up regretting that decision.

My
Mother and my brother live in Springhill and Riverview. Both are staying. Not sure they made the right decision.