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Cat 4 Idalia | peak 130mph 940mb | post-tropical (but wait)


StretchCT

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  • The title was changed to Cat 4 Idalia | peak 130mph 940mb | current 90 mph 972 mb inland
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3 hours ago, StretchCT said:

It might be tough finding data on the ground to support the winds that NHC assigned.  No doubt there are gusts over 100mph, but I have a feeling  I'm going to struggle to find sustained winds of over that.  

So far I'm correct.  They can't find any gusts over 85mph.

 

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  • The title was changed to Cat 4 Idalia | peak 130mph 940mb | current 65 mph 985 mb inland
  • The title was changed to Cat 4 Idalia | peak 130mph 940mb | current 60 mph 990 mb offshore
  • Moderators

NHC disco explains what is going to happen with the classification of Idalia. In short, it will go extra/post tropical due to it's involvement with the front and lack of convection.  Then it will release from the front and reform.  So don't be surprised when this is classified as post/extra and then tropical.  Same name. Same storm.  I'm imagining that the front/trough is sucking some of the energy out of it as well.  You can see this on the 500/700/850mb maps as the more intense vorticities escape into the trough and come back later around Bermuda.

Global model fields show winds increasing on the northwestern side
of the frontal boundary during the day as Idalia is pulling away
from the coast of North Carolina, and as a result, the NHC intensity
forecast shows some strengthening in the short term.  Idalia is
expected to become fully extratropical by this evening, which is
now shown in the official forecast.  Winds should begin decreasing
tonight, and simulated satellite imagery from the GFS and ECMWF
models suggests that the circulation will continue to be devoid of
deep convection, and attached to a front, through at least 36
hours.  By 48 hours, the low will reach warmer waters, the
front is likely to weaken, and the ECMWF shows deep convection
redeveloping.  As a result, the official forecast shows Idalia
becoming a tropical storm again on Saturday.  Intensity-wise, the
guidance indicates that the peak winds are likely to fluctuate
between 40-45 kt from days 2 through 5.
INIT  31/1500Z 33.6N  75.8W   50 KT  60 MPH
 12H  01/0000Z 33.6N  73.2W   55 KT  65 MPH...POST-TROP/EXTRATROP
 24H  01/1200Z 32.8N  70.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  02/0000Z 31.7N  68.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  02/1200Z 31.1N  67.3W   40 KT  45 MPH...TROPICAL CYCLONE
 60H  03/0000Z 31.1N  66.6W   40 KT  45 MPH
 72H  03/1200Z 31.8N  65.3W   45 KT  50 MPH
 96H  04/1200Z 34.3N  62.0W   45 KT  50 MPH
120H  05/1200Z 37.0N  61.0W   45 KT  50 MPH
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4 hours ago, StretchCT said:

Yes, this is Idalia, as a TS, sitting and spinning off the New England Coast for four days, finally dying. 

image.thumb.png.40127537724beba5a09f6d3730f3abc0.png

image.thumb.png.441d59dd25ce4d0ad952063afd45a0b8.png

First it was a loop to the south. Now it's a hook northwest. At what point do the models decide a fourth wall break is in-play, lol. In all seriousness, if Idalia retrogrades towards the NE next week, it's probably worth watching as Tuesday is the first day of school for many.

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  • The title was changed to Cat 4 Idalia | peak 130mph 940mb | post-tropical (but wait)
  • Moderators
Even though Idalia is no longer explicitly forecast to transition 
to a tropical or subtropical cyclone, NHC advisories will continue 
until tropical storm conditions diminish on Bermuda and the 
Tropical Storm Warning is discontinued (most likely some time 
Sunday morning). 

INIT  02/1500Z 31.6N  63.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 12H  03/0000Z 31.7N  62.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  03/1200Z 32.9N  60.6W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  04/0000Z 34.7N  58.8W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  04/1200Z 36.8N  57.4W   45 KT  50 MPH...POST-TROP/EXTRATROP
 60H  05/0000Z 39.0N  56.9W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  05/1200Z 40.8N  57.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  06/1200Z 42.3N  58.7W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  07/1200Z 44.3N  58.6W   30 KT  35 MPH...POST-TROP/EXTRATROP

20232450950-20232451510-GOES16-ABI-AL102023-GEOCOLOR-1000x1000.thumb.gif.236cb5c1ae76be0a9cdac8ae018b52cb.gif

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