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Hurricane Irene Model and Forecast Discussion


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Definitely concerning that there has been an east trend for days. Early on, this looked like a Florida threat. Then Georgia. Then Carolinas. If the models are now showing this as a Long Island threat, I would bet on it going well east of LI. Hard to fight the trend here. I'd love to experience a hurricane, but it doesn't look like a good chance to me.

ditto

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I wouldnt really worry about this storm right now. Seriously, it was forecast by NHC to be going over the DR a few day ago and it went right. At the same time, the extended forecast had it over FL in the long range. Look at how far it is to the right of FL now? This thing is trending right and I see no reason why that trend wont cont as it moves N twds our area (NYC). The right front quad is where the action is, I see MAYBE only E LI getting into that action, otherwise, just some heavy rain for a 6 hr period, then poof it's gone. Typical trend to the E. I recall when I was forecasting Charlie when I worked at NBC4 back in the day as a wx producer and all the models had it hitting the area. We had a tropical storm warning for the city and we ran crawls on the TV all for nothing. If the models have any kind of E trend...it is death. U want a due N trend, and that is not the deal here. I know the standard error in the NHC track at 5 days is some 250 miles, and that will be in play here. I see this sucker trending E with time so it's a glancing blow to the area, heavy rain yea, but not much else. Just my 2 cents.

Its very rare to see a left trend once inside 72 and especially 48 hours for EC hurricanes. That is why this storm needs to trend west again in the next 2-4 model cycles to make it a much higher probability. Isabel is the only storm I can recall that trended left in the final 3 days for an EC landfall. An eastern New England landfall is probably the most realistic landfall this storm will make on the U.S. if it does at all at this point.

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While I understand your thinking, and you are entitled to your opinion and you could ultimately end up being correct, I think your statement is a bit premature for a storm that is still 4 days away, just my opinion.

I wouldnt really worry about this storm right now. Seriously, it was forecast by NHC to be going over the DR a few day ago and it went right. At the same time, the extended forecast had it over FL in the long range. Look at how far it is to the right of FL now? This thing is trending right and I see no reason why that trend wont cont as it moves N twds our area (NYC). The right front quad is where the action is, I see MAYBE only E LI getting into that action, otherwise, just some heavy rain for a 6 hr period, then poof it's gone. Typical trend to the E. I recall when I was forecasting Charlie when I worked at NBC4 back in the day as a wx producer and all the models had it hitting the area. We had a tropical storm warning for the city and we ran crawls on the TV all for nothing. If the models have any kind of E trend...it is death. U want a due N trend, and that is not the deal here. I know the standard error in the NHC track at 5 days is some 250 miles, and that will be in play here. I see this sucker trending E with time so it's a glancing blow to the area, heavy rain yea, but not much else. Just my 2 cents.

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Its very rare to see a left trend once inside 72 and especially 48 hours for EC hurricanes. That is why this storm needs to trend west again in the next 2-4 model cycles to make it a much higher probability. Isabel is the only storm I can recall that trended left in the final 3 days for an EC landfall. An eastern New England landfall is probably the most realistic landfall this storm will make on the U.S. if it does at all at this point.

I wonder why even if there is no front or trough in place that is always takes that turn out to sea. Well there will be front on Thursday night into Friday which is suppose weaken and High pressure is suppose take over. No matter what the set up is it always takes the out to sea solution.

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The synoptic setup is different in a lot of ways from past close recurving busts...this one will have a much more gradual eastward turn as opposed to a quick one, so I'm not sure you can simply equate what happened in the past with what's going on now.

He's using Edouard as an example though, and that wasn't a quick recurve either-- but an excruciatingly slow one. I do agree that it's premature to commit to any track 4 days out.

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I wonder why even if there is no front or trough in place that is always takes that turn out to sea. Well there will be front on Thursday night into Friday which is suppose weaken and High pressure is suppose take over. No matter what the set up is it always takes the out to sea solution.

Because there are westerlies in the upper levels that will want to push it east...we actually want a deep trough to help suck it N or NNW...but we don't have that...we are relying on a W ATL ridge to bulk up to offset the weak westerlies that this storm will encounter...the steering currents are weak in this, but they are still there and matter when we are talking about 50-75 miles on a 4-5 day prog.

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The synoptic setup is different in a lot of ways from past close recurving busts...this one will have a much more gradual eastward turn as opposed to a quick one, so I'm not sure you can simply equate what happened in the past with what's going on now.

Still think it will miss the entire east coast based on the trends right now. If it does take turn a bit later than anticipated and makes landfall at the outbanks of NC than it could brushed the Cape and LI and Coastal CT could still get some rain out of this but I start to think this will be a fish storm.

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Because there are westerlies in the upper levels that will want to push it east...we actually want a deep trough to help suck it N or NNW...but we don't have that...we are relying on a W ATL ridge to bulk up to offset the weak westerlies that this storm will encounter...the steering currents are weak in this, but they are still there and matter when we are talking about 50-75 miles on a 4-5 day prog.

Any chance that W ATL ridge can build in more than modeled? It's late August, for chrissakes.

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Because there are westerlies in the upper levels that will want to push it east...we actually want a deep trough to help suck it N or NNW...but we don't have that...we are relying on a W ATL ridge to bulk up to offset the weak westerlies that this storm will encounter...the steering currents are weak in this, but they are still there and matter when we are talking about 50-75 miles on a 4-5 day prog.

Yep... and we thought the westerlies were supposed to be at an anomalously high latitude and not be a problem :(

Will, do you think there was some kind of different cyclical climate pattern back in the 1800s and again between the 1930s and 1960 that made NE hurricane strikes much more likely and, if so, what do you think was the cause of it? It's obviously not just the AMO but a bunch of factors in unison that made periods like that possible. This AMO "warm" period has mostly been characterized by gulf hits and atlantic recurvers since it started in 1995.

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Here is a comparison of the 12z with the most recent 00z run of the ECWMF. The thing that is most obvious with the new run is that its WAYYYY faster and also pretty significant shift to the east. It definitely looks like it wants to join the GFS camp unfortunately for all those landfall lovers out there.

5d48wz.gif

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Because there are westerlies in the upper levels that will want to push it east...we actually want a deep trough to help suck it N or NNW...but we don't have that...we are relying on a W ATL ridge to bulk up to offset the weak westerlies that this storm will encounter...the steering currents are weak in this, but they are still there and matter when we are talking about 50-75 miles on a 4-5 day prog.

How would a deep trough help to suck in the system, unless it was negatively tilted or a phase occurred? I'd think a deep trough would provide stronger westerlies, and have them at a further south latitude. Or do you mean that you want a deep trough vs a flatter/more broad one, since a more broad trough as opposed to a deep trough has westerlies that cover more "area"?

Perhaps now that we are about to be "in between" troughs for a couple of days, some of the models might actually be underplaying the effects of the W ATL ridge. It's kind of odd that we are "in between" troughs right now, so the weakness between the two troughs combined with the W ATL ridge might be two things that the models could be underplaying.

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Sure there is def a chance. You got me as to how good that chance is though (which I know you don't want to hear). :P

Very subtle differences in strength and position of that ridge, Will. I guess that can have a big impact when we're talking about such a small distance of where we're "hoping" it makes landfall. The 12z run of the GFS had it as a 1024 mb ridge and the 00z had it slightly farther east at 1020 mb.

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How would a deep trough help to suck in the system, unless it was negatively tilted or a phase occurred? I'd think a deep trough would provide stronger westerlies, and have them at a further south latitude. Or do you mean that you want a deep trough vs a flatter/more broad one, since a more broad trough as opposed to a deep trough has westerlies that cover more "area"?

Because most deep troughs become negatively tilted before they reach the EC. Also, you have a level of mid-latitude cyclone phasing when you have a deep trough...so that also sucks it NW even if the trough is not severely tilted negative.

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