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Posted (edited)

Morning folks. 

Yesterday we had Tropical Storm Irma declared and over the last 24 hours or so we have seen steady strengthening such that it now has sustained winds of 70mph and should be declared a hurricane later today. The outlook sees low shear and speed persistent however it will travel over the open ocean with cooler waters and drier air for a while before it ends up west/north west of the Lesser Antillees in about a week.

Models are highly aggressive on strength with the Euro bringing it to category 3/4 on several runs while the GFS has had two runs with sub-900mb pressure values.

Eventual track at this stage is unknown (it will barely pass the islands in a week) however the amplitude of a trough over the eastern US at the time appears to be key. If the flow amplifies then Irma gets caught and recurves (threat only to Bermuda and the Outer Banks) however if the flow flattens then ridging is stronger and anything from a Carolina/Florida hit is possible. 

NHC brings it to a category 3 within 5 days.

This mornings Euro at day 6..

ecmwf_mslp_uv850_watl_7.png

*One thing to note is that being a long track system it will probably end up pretty large with a very large hurricane wind radius. If it does make land anywhere, it's something to bear in mind. 

It should be fantastic for our seasonal ACE total though. 

Edited by Nick L
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06z gfs continues to develop Irma, no surprise there and looks to be as certain as you can given these things.

It shifts the system further west than the 00z, still different to the 00z ECM, but could well be a US hit on east coast further in the run.

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gfsna-0-252.png?6

Irma makes landfall along the Carolina coast and moves up the eastern seaboard reaching New York 12 hours later.

ECM sends it into the Gulf of Mexico on the 00Z OP as a severe storm,

Plenty of uncertainty and one to watch.

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Neither scenario's are very good for the US and both look like they make her a CAT 5 at some stage.

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15 minutes ago, stodge said:

gfsna-0-252.png?6

Irma makes landfall along the Carolina coast and moves up the eastern seaboard reaching New York 12 hours later.

ECM sends it into the Gulf of Mexico on the 00Z OP as a severe storm,

Plenty of uncertainty and one to watch.

Fascinating run! Worth noting that is also brings back the tropical low in the GOM which brings drenching rains in the southern states. I wonder if that develops more how would it interact with Irma.

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26 minutes ago, Iceberg said:

Neither scenario's are very good for the US and both look like they make her a CAT 5 at some stage.

Euro0z had category 3. It then gets shredded by Haiti and Cuba but for some reason the resolution at that range does not show it. 

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3 minutes ago, knocker said:

The 00z ecm

59a7f2ea53431_p1.thumb.JPG.92b3872f3f89054620aefc70193d0768.JPG59a7f2f0a6928_p2.thumb.JPG.9f9284a0e089870ead0e3dbb35f56a56.JPG

If this track proves to be correct (that's a big if at this early stage) then the storm will have to weaken as already said. But a slight shift north or south will keep Irma over water and its intensity will be maintained. Besides, even with this track she will quickly intensify once she emerges in the GOM like Harvey did.

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It'll be interesting to see if the difference in track between the GFS and ECM is almost solely due to the different modelled strengths of the ridge or whether partly due to the stronger intensity that the GFS has the storm attaining. ECM 0z initialized Irma about 10mb weaker than it was, and the NHC expect Irma to be stronger by T48 than the ECM does by T120. 12z ECM will be interesting this evening.

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I think you need to keep the ec global predictions for Irmas strength as a guess. Gfs easily and freely plots on the high res pressure etc. Ec doesn't and only folks that pay for the high res Atlantic data will see it. 

 

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Irma looks to be a certain cat 1 going from sat and radar clear eye and comma structure. 

IMG_1086.JPG

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According to cimss this has been upgraded to a hurricane cat 1. 

Nhc will therefore official prog this in about 1.5 hrs time. 

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Just to re affirm nhc have her as a cat 4 at the end of the forecasting period approaching the Caribbean. 

Probably quite conservative considering it should be an expected major so quickly. 

No recon for a few days though 

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Slower and further south too. Being stronger it should also feel the Azores Ridge more (orientated SW-NE) which could push it further south than some are forecasting. 

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Raw Dvorak have jumped probably in response to the clear eye currently. They indicate a major cat 3 hurricane already. 

Ive got a feeling we will be mentioning wobbles Erc's and have some major eye candy before    This becomes a direct threat. Which it certainly will imho. 

Yep sb the southward direction is indicative of the ecm today's 12z gfs will be interesting but the 00z tomorrow should have everything fully factored in giving us a bit more confidence 

IMG_1088.GIF

IMG_1089.GIF

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Within 24 hrs gfs 12z is starting to shift this quite a bit further south. 

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If it does hang further south the the warmer waters will allow it to reach Cat 5 before reaching the Caribbean. I hope it can avoid the poor Caribbean nations though? I get the feeling that it will be physically large as well as being a high Cat Major. That will mean high winds , big surge and flooding bands over a huge area. One consolation is the scar it leaves in SST's might dissuade the other 3 lows behind it from forming into more nastiness?

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Yep gfs 12z has another low behind and to the south that develops into a potential major hurricane. 

These set ups tend to form conveyors.....

IMG_1090.PNG

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The 12z GFS takes IRMA further east than the previous run so it misses the Carolinas and hits the northeastern states instead.

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Gfs is forecasting Irma to be sub 900 with 900 miles of tropical storm wind north to south and 450 miles of hurricane winds   

It would be one of the largest ever recorded and certainly in the top 6 or so ever recorded for pressure  

 

IMG_1091.PNG

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Bring back memories of the 2005 hurricane season but I reckon Harvey will go down as one of the costliest storms ever in the us

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