Post by Dr. Ryan N. Maue
Update: August 29 — Tropical Depression 12 has formed out of the strong African easterly wave near 30W. It will generally move Westward over the next 5-days gaining strength steadily, likely becoming a major hurricane by the end of the week. Colorado State satellite imagery — here.
Update: the wave that had 0-10% chance of developing near Bermuda was given the name Jose. Actually, the Canadian Met Model predicted this genesis a week ago, kudos to them. It is a “baby-whirl” and will last 12-24 hours and be one of the shortest-lived and weakest storms in history.
As hurricane season ramps up, eyes turn towards the African coast as “easterly waves” emerge over the warm waters of the North Atlantic. Invests or areas of concern are “named” by simply numbering them starting with 90 and lettered according to basin: Atlantic = L, Eastern Pacific = E, and Western North Pacific = W. So, 92L has just come off the African coast and already has a 30% chance of developing into a tropical cyclone during the next 48-hours according to the latest National Hurricane Center Tropical Weather Outlook. The next named storm will be Katia.
Current forecast model animation links follow:
The king of global weather forecast models ECMWF sees a very strong Category 4+ hurricane NE of the Lesser Antilles in 6 to 7 days, with the GFS showing proto-Jose Katia recurving North much sooner. At this point, we can sit and watch things develop, but keep an eye to the “tropical update” — too bad John Hope isn’t around to make us love meteorology again.
ECMWF 10-day Forecast (click to animate) — updated twice-daily …
NCEP GFS 16-day forecast — updated 4-times daily
A quick way to visualize the “tracks” of the storms is to look at a “wind swath” map:
What does Piers Corbin of WeatherAction say about Katia?
After all, he predicted Irene 85 days ago.
REPLY: We don’t know that he in fact successfully predicted Irene 85 days ago. I’ve asked him to provide his original proof of forecast, so far no response. I find it pretty hard to read Piers’s claims, they are too full of self aggrandizing for my tastes. If he really has a valid method, he’d do a lot better if started presenting them in a verifiable way. Right now I don’t see his claims as verifiable. – Anthony
Dr. Maue
Maybe you can answer this here or write up a separate post.
While trying to wrap my mind around the confusion engendered by Irene, I tried to work through the issue of sustained winds. It was then that I discovered that while the WMO standard is the average speed for 10 minutes at a height of 10 m, the Saffir-Simpson scale only uses a 1 minute average. I also found that there are different standards employed in India & Australia.
My question is, how do you reconcile the different standards when working up your numbers for ACE? Or do you take the values from each method at face value as long as they remain consistent over time, and treat them as being the same?
[RyanM: ACE is one-minute sustained winds, the maximum intensity estimate from each 6-hour synoptic advisory. You can use the WMO standard which is 10-minute and apply a 1.14 multiplication factor to normalize. JMA uses 10-min vs. JWTC which is 1-minute … this has caused confusion for sure]
http://www.ghcc.msfc.nasa.gov/GOES/
http://vortex.plymouth.edu/mollsat_ir_an.gif
Ryan’s current ECMWF track at http://coaps.fsu.edu/%7Emaue/tropical/plots/ec850uva.html
says it’s one for the fish.
Ryan,
Do you think this has a chance to be on the same track as 1938 or 1893? Looks like if a high builds over Bermuda that it could be on one of those tracks?
Jim Arndt
So far, 12L or proto-Katia recurves…
Hi Ryan,
Starting indeed to look like Katia will only be a threat to Bermuda. However, that system in the Gulf is looking interesting. ECMWF has it bringing some much-needed rain to Texas, but GFS shows it looping away from the Texico coast and making a bolt for New Orleans with near-100kt winds.
Have you any view yet on which of these scenarios, if either, is more likely? Seems a larger-than-usual discrepancy between models, and one with greater-than-usual potential impacts.
I looked at the 38 and although they are somewhat similar the 96 120 start to seperate them pretty far and the 38 dug into a southerly route before recurving to an almost straight N on the 73. With this storm being almost ten degrees farther east when it passes the 24 I dont see it having a chance of following a similar path. It seems to me its only chance of landfall would be between NC and Delaware, if the westerlies drift far North. More likely it will be ripped back out to sea by the gulf stream due to its more NE placement and also slow forward speed later in the forecast.