Wednesday, August 30, 2017

Tropical Depression Horrible Harvey, Tropical Storm Irma, and Tropical Storm Lidia: August 30, Update A

I am writing to you from another planet today, so this will have to be a short note - but after the very long ones over the last few days, I’m sure you are all relieved! ;-)

Tropical Depression Horrible Harvey
Thank goodness he has made landfall for the final time – and I mean final. There is no doubt in my mind that they will retire the name after this season and replace it with another ‘H’ name. ‘Humperdink’ perhaps (or Hodor - thanks Chris H. for the GoT names suggestions!)? Any storm that causes excessive loss of life and damage gets retired.

I know you have read (or watched) the stories and stats, but (from the BBC who got it from the NWS I think), an interesting graphic to depict what the record 52 inches of rainfall(!!) looks like:

That’s just rainfall, not flooding from a river! The flooding was extensive, covering an area about 15 times the size of Manhattan and unfortunately, it looks like at least 25 people lost their lives.

He is currently at 31.2N, 92.6 W, heading NNE at 8mph. Central pressure is 998mb, winds are 35mph.  He still has some circulation but not a lot of convection (thank goodness), which we can see in the satellite imagery:

He will be moving across a number of states:
but shouldn't be too much of an issue (I hope). I may be back for one more update on Harvey. 

Tropical Storm Irma
This is the next one to watch – she was the Atlantic Blobette out in the eastern Atlantic yesterday. Although her convection is not quite cohesive, you can certainly see the structure in the infrared satellite imagery and almost don’t need to look at the vorticity (circulation) maps to see what a beauty she is going to be!
 She is 16.4N, 31.2W, heading W at 15mph. Her central pressure is estimated to be 1001mb, and winds are estimated to be 60mph. I think she may be a bit stronger because there is already a signal in the upper troposphere (see graphs below), which suggest to me that she is closer to hurricane strength – so maybe 70-75mph. I agree with the NHC that she will be a hurricane very soon.

The forecasted track will take her generally westward towards the Caribbean:
I think that shift to the south is reasonable, but it is too soon to say how far south she will go as she approaches the Caribbean – I think there’s a possibility that she will remain in the southern half actually.

Tropical Storm Lidia (E. Pacific)
This is the Pacific Blobette from yesterday and also got named today, although she is not as well developed as Irma by a long shot. She is at 20.7N, 109.2W, heading NNW at 7mph. Min pressure is 1001mb, winds are 40mph – so she is barely a Tropical Storm at the moment. You can see the difference in the structures of Lidia, Harvey, and Irma in the vorticity maps… the lowest level of the troposphere (850mb):
 The middle of the troposphere (500mb):
 And the upper troposphere (200mb):
From these you can see a couple of things - first, in the upper level map, you can clearly see Irma's circulation. Second, you can see that Lidia is not very well developed (with that elongated blob in the middle level of the troposphere) as even Harvey at this point, but she does have some jolly decent convection, which means rain and possibly thundery weather:
The forecast is for her to head towards the Baja area on Friday:
So take your rain ponchos and wellie boots!

Now I must go and observe the wildlife on this planet.
Until tomorrow!

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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. 

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