The best way to know the difference between a hurricane (barotropic low) and a noreaster (baroclinic low)?
Hurricanes die over land.
Simple.
This was Hurricane Ida 24 hours ago:
And as of 4:45 AM CST:
In the second image, the center of Ida is located near 14.4N, 84.1W – south of the Honduras border over Nicaragua. The center of circulation (COC) is completely void of deep convection or high cloud tops. The coldest cloud tops are in the spiral band to the north.
You can also see to the south and east of the COC lower clouds – or lack thereof – off the coast of Nicaragua. This is dryer air from land sweeping around the system into the COC.
Tropical cyclones don’t feed off water. They feed off the boundary layer, or the immediate layer of warm, moist air above the ocean surface. Warm water temperatures keep the boundary layer warm and evaporation adds moisture content.
Obviously, land does not do this (except in swampy regions such as south Florida or eastern North Carolina which have been known to occasionally support hurricanes longer than other flat land masses – see Hurricane Katrina and Hurricane Danny).
Yesterday, on another message board I frequent occasionally, I saw people saying the mountainous regions of Nicaragua and Honduras would have no affect on Ida because Ida would not pass over those mountains; it would pass to the east.
This is true in the sense that the COC would not be disrupted significantly. But, it still disrupts the systems inflow and circulation. Interaction with the mountains creates shear inside of the system as well as additional rainfall because of updrafts that I’ve discussed many times before. That is moisture – energy – that doesn’t get pulled into the COC.
So, even if the COC itself isn’t disrupted, it has a moisture channel cut off because of the mountains. It’s losing energy. This helps suffocate it.
Want proof? Look at the two images above. Think it’s a coincidence the strongest convection is located to the north of the COC? What mountainous regions are to the east of Ida disrupting inflow? None.
Onto other things, you frequent readers know I love to use NRL Monterey images. I use them because they have the lat/lon lines on them so you guys can see where the system is if you want. Plus, they have a huge selection in one place – I don’t have to surf all over the place.
Unfortunately, all but their basic imagery is over twelve hours old.
I don’t have any plans until later this morning so I’m going to wait until either the imagery is restored or I start running out of time. Either way, look for a full post by about 8:30 AM CST.
Just going off what I’ve seen so far (imagery, obs, NHC statement) – it’s not looking good for Ida. Quite frankly, in my opinion, the entire NHC forecast can be thrown out the window.
I’ll tell you why later this morning.
Related posts:
