Saturday, August 20, 2011

TS Harvey, TS Irene, and the Atlantic Blob: August 20, Update A

My, my, we are on a role today, aren’t we? Two Tropical Storms in one sitting! So much activity… it must be a weekend. ;-)

TS Harvey:
He made landfall in Belize at around 1pm EST this afternoon, as a mid-to-strong Tropical Storm with winds of 60mph (TS range: 39-73mph) and central pressure of 998mb. Over the last 7 hours or so he has lost some of that intensity and is now a mid-level Tropical Storm with winds of 50mph (central pressure still estimated to be around 998mb). Although he is over land, his circulation is still very good in the lower half of the troposphere and he is dumping bucket-loads of rain over Belize, Guatemala, and the Yucatan Peninsula.  He is not very well organized so I can’t really see where his center is at the moment. The NHC have it at around 17.2N, 88.8W with him moving WNW at 13mph. It almost looks like he’s a bit south of that, but I’ll go with the NHC center.

TS Irene:
This one is going to be interesting to watch. She’s currently still on the Atlantic side of the Leeward Islands. According to the NHC, her winds are around 50mph, central pressure is estimated to be 1006mb. There is a bit of wind shear, but she is also still in that Saharan Air Layer, which is keeping her a little off-kilter. Water temperatures are 28-29 deg C, with the upper ~100m warmer than 26 deg C.

At the moment both her circulation and her convection is a bit messy (she really should clean her house and she can even listen to Rick Springsteen as she’s doing it if she likes. It’s ok, we won’t judge ;-)).  Because she’s so messy, I can’t quite make out the center of circulation in her either (the theme for this evening!). It kinda looks like it is a bit south of where the NHC center of cone is, but it is night now so the satellite imagery is not very clear. I am not convinced of her forecast track yet, which takes her to the Dominican Republic by Monday evening:

If her center is south of her current official location, then I think she might continue moving a little farther west than the track shows – that’s hopefully something we’ll find out tomorrow.

The track takes this to the Dominican Republic, potentially as a hurricane. Until she crosses the leeward islands and gets out of that Saharan Air Layer, I am not certain of this intensity forecast either.

I’ve heard from Tom in St. Thomas (US Virgin Islands) who is as ready as they can be for whatever Irene brings them.  The outer bands have just about reached the US VI according to the satellite images, but it seems that the folks there did not get much warning. From Tom about 40 minutes ago: “we expect rain soon...we did not see anyone getting prepared for this storm and there was a brief mention of some wind and rain for late tonight and sunday on a news website”.

I think everyone should keep an eye on this one – of course those in the Caribbean, but also in Florida (both sides of the state) and along the US eastern seaboard. The long-range computer models have her going from a panhandle/west Florida landfall, all the way to heading east of Miami and along the east coast. If she heads along the current forecast track, she is unlikely to be a major hurricane because of the northern Caribbean Islands. At the moment there is a lot of uncertainty about Irene. I’ll run out tomorrow when the shops open and get some window cleaner so hopefully things will be a bit clearer tomorrow and we can see the center.

Atlantic Blob:
The blob that came off Africa still has stronger circulation than Irene, but the convection is a bit of a mess now. They have downgraded this to a 20% chance of forming. With Irene (and Harvey) out there, I’ll refrain from writing about this one unless something happens. My brain is already full! ;-)

That’s it for now. I’ll keep you updated with any in the field reports 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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