ATL: IDA - Remnants - Discussion

[johngaltfla]

https://i.imgur.com/5PGW0Fw.gif

Have to admit this morning I did not expect Ida to make it to Cuba with this impressive of a radar presentation.

Wait until this time tomorrow.

[Clearcloudz]

OK GUYS.... Im about to Rant or Cry, Im not sure which one!

The Mayor of New Orleans is on right now saying there is now no time for Mandatory Evacuations for the city!

THIS is why I have been raving for two days about Local Meteorologist being more vocal about the possibility of what this storm could be!

WE ALL WATCHED IT! Saw that tight group of spaghetti models, the gulf temps... And even people like me that have no more experience than living through so many of these dang storms saw what the catastrophic potential was.

WHY Didnt the weather services, and the local meteorologists at least put a little more emphasis on what this storm could be? Its like they are too afraid to be wrong. Why not at least err on the side of caution, and risk being wrong more, but sparing lives when the worst cases happen? Im sorry Im frustrated, Im sleep deprived, and Im worried. I have been screaming FIRE on facebook for two days to every person I know. But with no msgs from our local weather guys to back me up. It just sucks

New Orleans said they are very confident in the 20 million dollar improvement they have made on the levee system. If it holds up then the city ends of saving billions of dollars in damage hopefully.

The corrupt politicians in that city cant even keep the dang prehistoric pumps running, And wouldnt dare spend the money to replace them. And New Orleans HAS NO CLUE what a wind event is like? When was the last time that they got one with significant winds. Because as far as the wind in New orleans for Katrina it was barely a kiss. In sorry I dont have alot of faith in any of it. and sorry Im not fussing at you. Im just frustrated with it all And edited because of all the typos, geez I need sleep

I completely understand your frustration but I think NHC over the years has learned some big lessons when it comes to evacuating big cities unless its absolutely necessary as it could be more dangerous than the actual hurricane itself but just my 2 cents and Hurricane Rita is a bigger example of what could happen to a city like Houston where people died and the hurricane itself was not that bad for Houston itself. For New Orleans the worst case could be the winds as long the levee system holds up then they should be ok but all of that saying the eye doesn't go over them which at the moment is still possible but not 100 percent certain

[tolakram]

Ok, let's get back on topic please. I understand New Orleans is in the path, I understand it's frustrating, but there's nothing we can do about what local officials decide.

[InfernoFlameCat]

Ida has everything going for it. it took 24 hours to go from depression to hurricane. Thats wicked fast.

[tolakram]

saved loop

[PandaCitrus]

The worst case scenario is basically a Katrina type size storm hitting just west of the city at peak Cat 5 intensity. Then the city is flattened by wind and likely flooded with surge as the levees are only rated to Cat 3.

Now, this is not currently forecast. It's forecast to hit at Cat 4 and significantly west of New Orleans but it's also not impossible. Slight adjustment errors in track and intensity and N.O. is in a world of pain.

New Orleans said they are very confident in the 20 million dollar improvement they have made on the levee system. If it holds up then the city ends of saving billions of dollars in damage hopefully.

The corrupt politicians in that city cant even keep the dang prehistoric pumps running, And wouldnt dare spend the money to replace them. And New Orleans HAS NO CLUE what a wind event is like? When was the last time that they got one with significant winds. Because as far as the wind in New orleans for Katrina it was barely a kiss. In sorry I dont have alot of faith in any of it. and sorry Im not fussing at you. Im just frustrated with it all And edited because of all the typos, geez I need sleep

I completely understand your frustration but I think NHC over the years has learned some big lessons when it comes to evacuating big cities unless its absolutely necessary as it could be more dangerous than the actual hurricane itself but just my 2 cents and Hurricane Rita is a bigger example of what could happen to a city like Houston where people died and the hurricane itself was not that bad for Houston itself. For New Orleans the worst case could be the winds as long the levee system holds up then they should be ok but all of that saying the eye doesn't go over them which at the moment is still possible but not 100 percent certain

[cheezyWXguy]

Anyone have any info on when the key west radar will be back up?

[Sciencerocks]

About to make landfall

[jdjaguar]

Ida has everything going for it. it took 24 hours to go from depression to hurricane. Thats wicked fast.

Boston to Buford?

[jdjaguar]

where is wxman?

I value his input.

[tropicwatch]

saved loop
https://i.imgur.com/NX95avh.gif

Could be close to the northern coast of Cuba by the time AF HH gets there.

[AlphaToOmega]

I wonder what recon finds. Will Ida intensify over land, weaken, or remain at 70 knots and 987 millibars?

[Craters]

Hey! College of DuPage has great satellite graphics, but honestly the distinction between low, mid, and high WV has never made much sense to me. For instance, the "low" WV loop shows plenty of cirrus/outflow-related features. Outside of areas of deep convection, the low-level channel always looks super dry like that.

If you want a more reliable sense of moisture in the low levels, check out some of the dropsondes from the NOAA9 environmental missions. Most show relative humidity >80% at the surface in Ida's near environment.

As for your question: Dry air at all levels negatively impacts tropical cyclones, but environmentally, mid-level dry air is more important. Air rising in convection is sourced from near the surface, and if that air is dry then it becomes saturated less quickly when rising --> the air is less buoyant. This is rarely a problem inside a sufficiently strong TC because surface winds drive evaporation that moistens the TC's inflow. If mid-level dry air works into the TC's circulation, though, it can lead to evaporational cooling: falling precipitation will evaporate, taking latent heat out of the air (just as condensation releases latent heat). This cooling also creates negative buoyancy that strengthens downdrafts.

Downdrafts can cut off updrafts, and they also replace warm, moist surface air with cool, dry air. That leads to the original buoyancy problem I pointed out.

Very good points... One additional thing I will add is that the weighting functions for the WV channels from GOES is such that even the "low-lvl" water vapor channel (the red line) weighting function peaks at just below 600 hpa (~4km AMSL, in a standard atmosphere slightly higher in the deep tropics) and actually typically has more contributions from 300hpa (a level you will often find cirrus) than the surface. So yes you are correct that even though the "low-lvl" water vapor channel is weighted lower than the other 2 GOES channels, it is still mostly picking up a contribution of WV in the 700-500hpa lvl, which many in the meteorology community would refer to as the mid-lvls rather than the low-lvls.

Finally it can be difficult when looking at WV in the vicinity of tropical cyclones to not focus on the fact that the airmass outside of the cyclone is dry relative to the cyclone itself... remember TCs are essentially the greatest cauldrons of moisture the Earth can muster so any airmass outside of it will look dry in comparison, instead look for "absolutely low" values of WV (manifested by the WV band sensing warm brightness temperatures and "seeing" further down into the troposphere).

https://www.researchgate.net/profile/Patrick-Skinner/publication/323623133/figure/fig1/AS:811095908425728@1570391742508/Vertical-weighting-function-for-a-GOES-13-and-b-GOES-16-water-vapor-bands-assuming-a.png

Thanks! That's a useful graphic to visualize those WV channels. I didn't know exactly what was being referred to as low/mid/high.

Thank you, ThetaE and Meteorcane! Absolutely great info. A perfect example of why I spend so much time on Storm2K!

In some of the last red-channel frames, it seemd to me that there were some obvious outflow boundaries in the entire southwestern quadrant, just as I think there have been for most of the afternoon:

I'm thinking that the dry air at the "lower" and mid-levels has had at least some effect on holding back Ida's ramping up, not to mention inducing some of its current asymmetry.

[Kohlecane]

nice blow-up at landfall, what the hell is the NOAA plane doing Im watching it on my radaralive app it did 6 circles went N for a bit and now is headed back.

[ConvergenceZone]

[quote="PandaCitrus"]The worst case scenario is basically a Katrina type size storm hitting just west of the city at peak Cat 5 intensity. Then the city is flattened by wind and likely flooded with surge as the levees are only rated to Cat 3.

Now, this is not currently forecast. It's forecast to hit at Cat 4 and significantly west of New Orleans but it's also not impossible. Slight adjustment errors in track and intensity and N.O. is in a world of pain.

[quote="Clearcloudz"][quote="Stormgodess"]

Plus keep in mind as Meteorologist WXMAN said this morning, Katrina had a MUCH MUCH MUCH larger windfield. Even with some expansion, Katrina's windfield will still be much larger, and that equates to much more damage...................

[ThetaE]

saved loop
https://i.imgur.com/NX95avh.gif

Could be close to the northern coast of Cuba by the time AF HH gets there.

My guess is that's their plan. Also-- don't know that the NOAA plane has left yet? Looks like they crossed Cuba, descended, and are maybe going to take measurements along the north coast. They may just stay in the air until Ida emerges into the Gulf.

[jdjaguar]

I wonder what recon finds. Will Ida intensify over land, weaken, or remain at 70 knots and 987 millibars?

that last hot tower mushrooming, spells intensification.

[Iceresistance]

EXTREMELY Powerful burst over Cuba, I did NOT expect that to happen!

[PandaCitrus]

I don't know we can forecast the wind field until we see how it blows up in the gulf. Katrina didn't have that extensive wind field going over South Florida. It blew up in the gulf.

The worst case scenario is basically a Katrina type size storm hitting just west of the city at peak Cat 5 intensity. Then the city is flattened by wind and likely flooded with surge as the levees are only rated to Cat 3.

Now, this is not currently forecast. It's forecast to hit at Cat 4 and significantly west of New Orleans but it's also not impossible. Slight adjustment errors in track and intensity and N.O. is in a world of pain.

[tropicwatch]

nice blow-up at landfall, what the hell is the NOAA plane doing Im watching it on my radaralive app it did 6 circles went N for a bit and now is headed back.

I think they were thinking of heading to base. They climbed to over 20k feet and then went back down to operational altitude. Go figure