Imelda Organizing, Likely to Strengthen Further

By: MAweatherboy1 , 10:50 PM GMT on April 08, 2013

Share this Blog
2
+

After a lengthy stretch of quite in the global tropics, there has been one tropical cyclone active for the past few days, Cyclone 21S in the Southern Indian Ocean, which has been officially named as Imelda. As of the 5PM EDT advisory from the Joint Typhoon Warning Center, Imelda is currently located about 755 nautical miles NE of La Reunion island, and is moving west at 9kts. The system's maximum 1 minute sustained winds are estimated to be 45kts by JTWC, or about 50mph. Persistent vertical wind shear over the past few days did not let up as quickly as anticipated over the system, keeping the center frequently exposed or just on the eastern edge of the convection. Now, however, shear is relaxing over the cyclone, and the center is moving directly under the central dense overcast (CDO) that the system has developed.


Figure 1: Cyclone Imelda, showing the system's CDO with deep convection.

Forecast for Imelda
Cyclone Imelda has been, and continues to be, steered W and WSW by a subtropical ridge, and this will remain the dominant steering force for the next 36 hours or so. After that time, the steering ridge will be weakened by an approaching mid-latitude trough, causing a southerly turn of the cyclone, and eventually a more SSE/SE motion. Regarding intensity, steady strengthening is likely for the next 24-36 hours as wind shear continues to abate and the system develops a better defined inner core. After this time, between about 36 and 60 hours out, there will be an opportunity for the cyclone to rapidly intensify as environmental conditions become more conducive for a stronger cyclone. The Joint Typhoon Warning Center forecasts a peak intensity of 95kts, or about 110mph, making Imelda a high end Category 2 hurricane equivalent on the Saffir Simpson Scale. They forecast the system to turn south before it can impact the Reunion Islands.


Figure 2: Official JTWC forecast of Imelda.

My forecast (not official of course) is shown in Figure 3. I forecast a slightly more westward path than JTWC as I think the steering ridge will be a little slower to break down than they do. My intensity forecast is a bit higher than JTWC's as I forecast somewhat more rapid intensification than they do in the 36-60 hour range. It should also be noted that Dvorak ADT numbers are approaching 4.0, which would indicate Imelda is considerably stronger than the 45kts JTWC has stated. While these are likely overdone, it is possible Imelda's current intensity is closer to 50kts, which may make the final peak intensity a little higher than what JTWC has listed.



This graphic does not show my forecast peak intensity as I believe it will occur between the second and third lines, with the storm topping out at around 115mph. Regarding land impacts, the only area that may be at risk are the Reunion Islands. Right now, it appears Imelda will pass far enough east of there to prevent significant impacts, but this could change if the track shifts west. Residents there should stay alert of the situation since Imelda will likely be a powerful cyclone when it is at that latitude. I will provide updates in the comment section as necessary.

Thank you for reading, and I hope you have a great week!

MAweatherboy1

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 6 - 1

Page: 1 — Blog Index

6. WunderAlertBot (Admin)
12:36 PM GMT on May 04, 2013
MAweatherboy1 has created a new entry.
5. MAweatherboy1
3:10 PM GMT on April 14, 2013
This is the initial position on Imelda from the 6z GFS this morning:



Pretty close to where I had it on my track at that latitude. Also close to where I was expecting peak intensity. And somehow or another, after almost randomly dissipating the other day (which I clearly didn't forecast) it actually is near peak intensity this morning, with T numbers suggesting it's at around 105mph, though the last JTWC advisory put it at only 70mph. I forecast 115mph, so if it is around 105mph than that isn't too bad. It should start weakening soon though, if it hasn't already. There's evidence of weakening in the NW eyewall:



Certainly an unusual storm. That rapid weakening of a couple days ago was completely unexpected.
Member Since: February 11, 2012 Posts: 83 Comments: 7779
4. MAweatherboy1
10:10 PM GMT on April 09, 2013
Not making changes to my forecast graphic tonight, intensity forecast still looks good (it's up to 70mph now) and track forecast philosophy remains similar, though Imelda will likely be more along the eastern edge of the cone than in the center in the latter stages of the forecast. Major impacts to the islands still look unlikely.

Quoting efkednn:
I find your article quite insightful, but i guess you forgot that 200kms closer to the cyclone and east of Reunion island; there is Mauritius Is.
plus i find that you're one of the rare persons to think differently from jwtc forecast after tau 48 and the intensity.
Hopefully will read more updates from you on this storm.

I'm not exactly a geography expert, I kind of just lumped all those islands together into "Reunion Islands". My intensity forecast is in pretty good agreement with JTWC, though my track is still a bit further west in later stages.
Member Since: February 11, 2012 Posts: 83 Comments: 7779
3. efkednn
10:54 AM GMT on April 09, 2013
I find your article quite insightful, but i guess you forgot that 200kms closer to the cyclone and east of Reunion island; there is Mauritius Is.
plus i find that you're one of the rare persons to think differently from jwtc forecast after tau 48 and the intensity.
Hopefully will read more updates from you on this storm.
Member Since: April 9, 2013 Posts: 0 Comments: 0
2. MAweatherboy1
10:55 PM GMT on April 08, 2013
Thanks for stopping by Max!
Member Since: February 11, 2012 Posts: 83 Comments: 7779
1. trHUrrIXC5MMX
10:52 PM GMT on April 08, 2013
I agree with your intensity. Thanks for the info
I'll bbl to read your post.
Member Since: April 23, 2011 Posts: 104 Comments: 14873

Viewing: 6 - 1

Page: 1 — Blog Index

Top of Page

About MAweatherboy1

Average 18 year old weather nerd. Freshman at Plymouth State University, majoring in meteorology, with the goal of becoming a professional forecaster.