Wednesday, September 20, 2017

Hurricane Maria, Tropical Storm Jose, and the Blob-formerly-known-as-Lee: September 19, Update A

It’s mostly about Maria today. The news out of the Leeward Island of Dominica (population: 72,000) where, about 24 hours ago, she made a direct hit as a cat 5 (wind speed of 160mph) is that there is no news. Unfortunately all communication with the island went down overnight, after early reports that roofs had been blown off (including from the Prime Ministers’ residence). It sounds like Martinique, just south of Dominica, fared better than Guadeloupe, to the north of Dominica. Guadeloupe also lost contact with two of their smaller islands. Hopefully we will have more tomorrow from these silent islands.

Hurricane Maria
Maria spent the day waltzing across the northeastern Caribbean. She did drop down to a cat 4 after crossing Dominica, but rapidly regained strength and is now a very strong cat 5 with winds of 175mph, central pressure 908mb: 
As a reminder, a category 5 storm (cat 5 range: >156mph) is the highest on the Saffir-Simpson scale because the categories are based on an engineering-wind metric of the level of destruction. So cat 5, by definition, is catastrophic destruction (essentially ‘total annihilation’). This is what we are seeing in places that have been directly hit by a cat 5. For a refresher on the Saffir-Simpson Scale, check out the Science Alert! in this post.

She is now at 17.4N, 64.9W, heading WNW at 10mph, and is 20 miles SSE of St. Croix, US Virgin Islands, and about 105 miles SE of San Juan, Puerto Rico:
Hurricane force winds extend approximately 60 miles from the center, so St. Croix is currently experiencing some level of a hurricane. Tropical Storm force winds extend about 150 miles from the center, which means that parts of Puerto Rico are now under a Tropical Storm. She was making a beeline for St. Croix for most of today, but looks like she has just taken a small jiggle to the left, and her eye may not entirely engulf the island – although one side of the eye may clip it as she moves on towards Puerto Rico. This would be the second cat 5 hit that the US Virgin Islands have had in two weeks – Irma was a direct hit on St. Thomas and St. John! The west side of the storm is the worst, so the USVIs will be in for another rough night tonight. 

< Technical Alert!> If you want to check the satellite imagery for yourselves, a reminder that one of my favourite places is this NOAA site which has imagery for all tropical storms across the world: Click on the storm you are interested in (Maria today!), then go to the Column marked ‘Animated GIF’ and under the ‘With Lat/Lon’ column click on ‘AVN’. This is the infrared imagery (the colorful one) that you see above. Generally (from having been under one of these to experience the weather), blue = light rain; yellow = heavy rain; orange = heavy rain and thunderstorms; dark orange and red = heavy rain, thunderstorms that shake buildings, and tornadoes. To get updated imagery, you will have to go back to the menu and refresh the page otherwise it will play the same loop. If you click on ‘Visible’ you get the visible imagery (also above – just not as good at night because it’s not as visible!). If you click on ‘Water Vapor’ you get the water vapor imagery I’ve shown in the past. Have a play – there’s all sorts of other stuff on this excellent site. < End Technical Alert! >

Forget the wine tonight… I think it’s time for a spot of delicious Puerto Rican rum! We are all watching… stay safe out there my friends!  

Tropical Storm Jose
Jose is now a Tropical Storm with winds of 70mph, central pressure 973mb (TS range: 39-73mph) and is generally hanging out in the Atlantic, bringing rain to the fishies out there…
(and maybe a few parts of the coast). He is currently at 37.9N, 70.8W, heading NE at 9mph, and is projected to be patrolling back and forth off the coast there for the next few days:
Seems about right. Those folks from DC to New England need something to keep an eye on them! 

Tropical Depression ‘I’m not dead yet, I think I’ll go for a walk’ (Monty Python) Lee
There is no circulation in the middle levels of the troposphere so he is not a Tropical Storm, but the lowest level of the troposphere still has a toot. In addition, as he slowly emerges from the Saharan Air Layer, the convection is slowly increasing… so he is back to being a Blob and the NHC have currently given him a 60% chance of reforming. I’ll keep an eye on him for now - but he won't go far if that circulation in the middle of the troposphere doesn't develop.

That's it for now. Definitely more 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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