Amateur forecast for Irene - 5:00 PM Aug 10

[wxmann_91]

EDITED for this, very important:

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

Tropical Depression Irene Advisory 25
2:00 PM PDT Aug 10 2005 (5:00 PM EDT or 21Z Aug 10 2005)

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For official forecasts...please refer to the NHC. This is an independent product.

Please remember...tropical cyclones can be very unpredictable and can make sudden changes and/or shifts in both track and intensity.
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Irene's organization has improved today...and some banding is visible. An anticyclone is forecast to build over a cyclone and the shear is relaxing. Will go out on a limb here and have Irene near hurricane strength in three days. The confidence in the bullish forecast...though...is low. For one...an upper level low off the coast of Florida could hinder this system...or help it. The position of it is critical. If it remains stationary...it will shear Irene. If it moves out...it will moisten the atmosphere up for Irene. If it moves into the right position...then it could help channel the outflow from Irene...and Irene could intensify even faster than what is indicated here. The dry air surrounding Irene is a factor right now as well...and that could limit the intensification somewhat for the next 24 hours. And...with the absence of a strong LLC right now...the small nature of this system...and the extremely dry air surrounding it...this system could still open up to a wave and dissipate within the next 12 hours...though the window for this to happen is closing quickly. Of course...the intensity forecast assumes this doesn't happen.

The threat for the east coast is increasing by the minute. The models continue to trend west...and the ridge continues to be strong. However...it is still too early to tell where and when Irene makes landfall...if it does at all...but everyone living on the east coast should watch Irene very closely. My forecast track is on the left edge of the model guidance envelope...and is similar to the shallow BAM.

Forecaster Tang


Hour Position Intensity
--------------------------------
Initial 22.8N 58.8W 30 kt
12 hr 23.2N 60.3W 35 kt
24 hr 23.7N 61.9W 40 kt
36 hr 24.4N 63.9W 45 kt
48 hr 25.3N 66.2W 50 kt
72 hr 27.0N 70.0W 65 kt
96 hr 29.0N 73.9W 75 kt
120 hr 31.2N 78.3W 80 kt


Track:




Comments and suggestions welcomed as always.

[gatorcane]

how does the intensity forecast affect the position forecast. The weaker the system would follow the left edge of your guidance envelope and a stronger system would follow the right edge?

[sweetpea]

Great post. Even though I don't like your cone in FL. Still to close for me.

Debbie

[jimpsummers]

Your forecast at 120H brings it right over some 87 degree SSTs off of Savannah... yikes! The BAM has been the closest to being correct with Irene so far, so I think you've got a good forecast (or bad for SC!?). You are correct on another thing -- the threat for the east coast, Carolina coast to be more specific, seems to be growing by the minute.

[gatorcane]

but remember the track keeps shifting left by the minute so in a few days FL would be under the gun big time at the rate we are going.

[jimpsummers]

OK by me... y'all can have her down there! Seriously though, Florida is by no means out of the woods, in fact maybe more in the woods than the Carolinas and Georgia... I like watching these things when they are out at sea, but I'm getting a sick feeling watching this situation develop...

[wxmann_91]

how does the intensity forecast affect the position forecast. The weaker the system would follow the left edge of your guidance envelope and a stronger system would follow the right edge?

Well, it depends on the strength of the ridge. Yes, the strength of the system is important, but the strength of the ridge is more important, and where Irene goes I think is now based on the ridge.

but remember the track keeps shifting left by the minute so in a few days FL would be under the gun big time at the rate we are going.

Actually I've shifted a bit right today from yesterday night. Right now it is still too early to see where Irene will make landfall. Anywhere from Miami, FL to Norfolk, VA should watch this guy closely.

[shaggy]

sound forecast except in the past storms that are more developed tend to TRY and turn more poleward thats my only concern with the track.Have seen so many storms forecast to hit SC then bump NNW or NWWD towards NC.Just going to watch as it seems to be 5-7 days out for now

[WindRunner]

sound forecast except in the past storms that are more developed tend to TRY and turn more poleward thats my only concern with the track.Have seen so many storms forecast to hit SC then bump NNW or NWWD towards NC.Just going to watch as it seems to be 5-7 days out for now

I agree. The 25N line isn't that far away, and the recurvature will start to have a pull, maybe even enough to make it drag the coast before landfall. I'm not saying that the typical recurvature is going to play a major role here, but it is something to keep in mind. Good intensity forecast, however.

[Swimdude]

Your wind speed forecast is also that of the NHC's. Unfortunately, it seems that the NHC always seems to predict a weaker storm than it ends up being.

[wxmann_91]

Thanks for all the comments!

BTW Swimdude, my forecast is more aggressive than the NHC's by 10 kt at the end of the period.

[ConvergenceZone]

OK by me... y'all can have her down there! Seriously though, Florida is by no means out of the woods, in fact maybe more in the woods than the Carolinas and Georgia... I like watching these things when they are out at sea, but I'm getting a sick feeling watching this situation develop...

Even if this does hit Florida, don't let it give you a sick feeling. They aren't predicting this to be a strong hurricane, in fact, it will more than likely be a fairly weak hurricane. Personally, I don't think this will get above a cat 1...no worries.

[Hybridstorm_November2001]

Here is the storm that I feel might most closely mirror Irene's eventual tack (maybe a bit further north and west near the end though, or when she get North of 40 N):





Hybridstorm_November2001