Saturday, October 03, 2015

Hurricane Joaquin: October 3, Update A

The news today isn't so good, alas. The cargo ship is still missing, and as the Bahamas emerges into the 'sunlight', there are reports of loss of life and, as we expected, severe damage on a number of islands. And on top of that, tenacious Hurricane Joaquin decided to strengthen, which I have a lot to say about! 
He is currently at 27.3N, 69.6W, heading NE at a really rapid 17mph. The track has been shifted slightly to the east and at this rate, he is expected to pass close to/over Bermuda late tomorrow:
I would go with the NHC track from here on out, because as I said yesterday, I don't have the  best information on this. 
His winds are officially 145mph, central pressure is 937mb. This makes him a strong cat 4 storm (cat 4 range: 130-156mph). I would agree that he did reach cat 4 strength today because he has had a good looking and persistent eye. Here is what he looks like now:

I know the winds that the planes reported were around 150-155mph, but the convection is not been as strong or well formed (circular) as you would normally see in such a strong cat 4/borderline cat 5 storm. Also, the eye is not as clear as it was, indicating that he is probably around a cat 3 now, possibly a cat 2. So I don't agree with the official word as far as the intensity. However, as he is heading towards Bermuda, I would prepare according to the official intensity!
Regarding intensity... <Soapbox Alert!> Joaquin has been a classic example of how poor our collective knowledge of hurricanes and their intensity really is.
The NHC statement at 11am today was: "...SEVERE HURRICANE JOAQUIN WITH 130 MPH WINDS MOVES AWAY FROM THE BAHAMAS..."
Just one hour later, they issued a special statement: "...RECONNAISSANCE PLANE FINDS SEVERE HURRICANE JOAQUIN WITH 155 MPH WINDS..."
First, I also thought that Joaquin would gradually weaken, so I'm not surprised that they were on the same page. The wind shear is actually quite strong (around 30-40 knots - in fact, I think it is that wind shear that is probably stopping him from becoming a cat 5 right now!) and he is heading into a region of even stronger wind shear. His vorticity (circulation) has remained strong throughout the troposphere, and I think that turned out to be more important than wind shear in this case. Also, he is interacting with the front that brought rain to the east coast this week, which is complicating things. Luckily he had moved away from the islands before intensifying (the islands, although small, may have been enough to stop him from intensifying at that time). 
Second, the reason the NHC increased his wind speed so drastically after an hour is because they got data back from a hurricane hunter plane. In this day, why are they still depending on sending people in planes into a storm to gather the data they need to work out the intensity? Surely we can do better than this? This has been our method of gathering data from these storms for ~70 years -  since the 2nd World War! Surely it's time to rethink this and get continuous, good data? (by the way, if you have a few $100k lying around and are interested in figuring this out send me a note, I know exactly how I would go about sorting this out!)
Third, there is now of course the inevitable debate over computer models, tracks, and our ability to forecast weather. Three/four days ago, the NHC track had Joaquin clipping/hitting the US east coast, the best US model (that NOAA uses) - the GFS), was showing a track to the east of that, and the Europeans model (ECMWF) was showing a track that took him close to/over Bermuda. Here's a pretty good article from the New York Times on this: http://www.nytimes.com/2015/10/03/upshot/hurricane-joaquin-forecast-european-model-leads-pack-again.html. I agree with this, it isn't ultimately about 'how big is my computer', but rather 'how good is the observational data' and 'how good is the model'. The observations are used to set the stage for models, and then the models calculate what will happen in the future, based on what we know about the physics of the storms. Bad data in = bad data out. And incorrect physics (i.e. not understanding the system) = Incorrect forecast. In this case, both the US and European models are very good, so it therefore boils down to the good data in piece. 
<End Soapbox Alert!>
I'm a bit parched after all that... time for a cuppa tea and a jaffa cake or two. 
Stay safe Bermuda!!
Until tomorrow,
J.
Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
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DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know.

2 comments:

Steven Bell said...

we have a tad of precipitation and a few gusts.

Steven Bell said...

did you see the rugger?