Hurricane Katia

[OHweather]

What would happen if the trough over the east took on more of a negative tilt than currently progged and became less progressive?

It would potetntially draw the storm farther west, but I highly doubt that happens. There is no blocking over the Davis Striat or Greenland to help a shortwave slow down/amplify over the eastern US, it will likely stay positive tilt which will help in weakening the ridging over the western Atlantic/maintaining a weakness for Katia to recurve through.

[atownwxwatcher]

Think the 18 Z GFS is getting kind of close?

[stormspotterlive]

GFS has yet again gone more west not far from a outer banks hit if this continues 00z could get very interesting. All things considered still favoring out to sea unless everything continues west and we see some hits.

[BethesdaWX]

It would potetntially draw the storm farther west, but I highly doubt that happens. There is no blocking over the Davis Striat or Greenland to help a shortwave slow down/amplify over the eastern US, it will likely stay positive tilt which will help in weakening the ridging over the western Atlantic/maintaining a weakness for Katia to recurve through.

What is with all the comments implying any sort of certainty in models 8-10 days out? Not that I don't agree but the reasoning for the re-curve solution is climo, not the GFS prognostics 2 weekends from now.

[am19psu]

What is with all the comments implying any sort of certainty in models 8-10 days out? Not that I don't agree but the reasoning for the re-curve solution is climo, not the GFS prognostics 2 weekends from now.

Some of us can make synoptic forecasts across North America 10 days out.

[LakeEffectKing]

What is with all the comments implying any sort of certainty in models 8-10 days out? Not that I don't agree but the reasoning for the re-curve solution is climo, not the GFS prognostics 2 weekends from now.

Many have put too much value in a model progged "pattern" as if somehow it can't morph into something quite different in 7 days.....especially with the added feature (and uncertainty) in the GOM....and with Katia remaining fairly weak, other models and a significant number of ensemble members still implying a very large threat, this is not yet even close to being called....

[LakeEffectKing]

Some of us can make synoptic forecasts across North America 10 days out.

Consistantly?? I hope you are making a TON of money.....

[BethesdaWX]

Some of us can make synoptic forecasts across North America 10 days out.

Well of course but that is not the same thing as a TC track 8-10 days out, where the slightest synoptical change can have huge implications.

How can you possibly compare synoptical "forecasts" with "model certainty"/ability to predict the track of a TC 8-10 days out?

[am19psu]

Consistantly?? I hope you are making a TON of money.....

LOL... it's pretty standard in the private sector. I'm certainly not the best on this board at it, but it's patently obvious there won't be a blocking high in place across the Davis Straits. Could it miss the trough and head into FL/SE? Sure. I've been briefing clients of that possibility, but this is not going to come up the coast like Irene did.

[BethesdaWX]

Many have put too much value in a model progged "pattern" as if somehow it can't morph into something quite different in 7 days.....especially with the added feature (and uncertainty) in the GOM....and with Katia remaining fairly weak, other models and a significant number of ensemble members still implying a very large threat, this is not yet even close to being called....

This If 5 days out Irene went froma Gulf/FL threat to a Fish threat, what can happen 8-10 days out? Model resolution and ability in general decline compoundly the farther out you go.

[stormspotterlive]

Lol easy.. Mets said there would be porn solutions and this one is still a fish

GFS solution can happen it is pointing out a few things we have not seen yet that seam rather reasonable since the pattern is still the same as it was with Irene. Its less impressive with the east coast trough and it is a bit slower with it. This is something we have seen time after time again the last month. Now I am not saying jump all over this solution this is whats going to happen but one would wounder if this continues on future runs. Remember now the Euro ensembles were west of Euro op that was simply cause it shows what the GFS upper level pattern is showing here. very interested to see 18z GFS ensemble even though I don't like to use it too much for tropics it may shed some light here. Should all make for a rather interesting evening. as it has opened a few more pathways for Katia to follow.

[am19psu]

Well of course but that is not the same thing as a TC track 8-10 days out, where the slightest synoptical change can have huge implications.

How can you possibly compare synoptical "forecasts" with "model certainty"/ability to predict the track of a TC 8-10 days out?

Because if there is no ridge over the Davis Straits/NW Atlantic, you can't get a system to come up the coast. This COULD be a FL/SE threat, though still not likely, but this has no chance of hitting the NE like Irene did.

[BethesdaWX]

Because if there is no ridge over the Davis Straits/NW Atlantic, you can't get a system to come up the coast. This COULD be a FL/SE threat, though still not likely, but this has no chance of hitting the NE like Irene did.

Of course thats true, but that is not what I was alluding to in my original response to "OHWeather", and the reasoning implied.

[NaoPos]

Many have put too much value in a model progged "pattern" as if somehow it can't morph into something quite different in 7 days.....especially with the added feature (and uncertainty) in the GOM....and with Katia remaining fairly weak, other models and a significant number of ensemble members still implying a very large threat, this is not yet even close to being called....

Whats with the westward shift? Is it just the fact that katia is staying a bit weaker, and hence, not attacking the weakness in the ridge? Or is the ridge becoming slightly stronger each run? I'd say a combo of the 2? So my real question is : has the overall synoptic H5 pattern changed, minus the cause and effect that katia has, or is it simply because she's not as strong as progged?

This question isn't strictly directed towards you, but maybe you can help here?

[OSUmetstud]

Because if there is no ridge over the Davis Straits/NW Atlantic, you can't get a system to come up the coast. This COULD be a FL/SE threat, though still not likely, but this has no chance of hitting the NE like Irene did.

Adam, what are you looking at to determine how much ridging or how little ridging is going to be in the NW Atlantic? Ensembles? Indices?

[am19psu]

Adam, what are you looking at to determine how much ridging or how little ridging is going to be in the NW Atlantic? Ensembles? Indices?

Both. It's inexact, of course, but this isn't really a marginal case. There isn't any evidence at all that a N Atlantic ridge will pop up.

[OSUmetstud]

Both. It's inexact, of course, but this isn't really a marginal case. There isn't any evidence at all that a N Atlantic ridge will pop up.

there's some positive height anomalies on the ECMWF ensemble mean at 168 hours in the Nova Scotia/Labrador area...but obviously not sufficient to cause a tangible threat.

[OSUmetstud]

Both. It's inexact, of course, but this isn't really a marginal case. There isn't any evidence at all that a N Atlantic ridge will pop up.

I didn't see this until now...don't you want a positive NAO for more western North Atlantic ridging? What did that product look like for irene?

[BethesdaWX]

Both. It's inexact, of course, but this isn't really a marginal case. There isn't any evidence at all that a N Atlantic ridge will pop up.

Have there been any trends in the models you posted? I know the CPC ensembles tend to change quote a bit on occasion in relatively short timeframes. Likely there will be no heights rises, agree there, but have always thought of that within another realm compared to "certainty" in any given synoptical scenario, and what we can expect over a week out.

[am19psu]

I didn't see this until now...don't you want a positive NAO for more western North Atlantic ridging? What did that product look like for irene?

Positive west NAO gives zonal flow across n atlantic

[am19psu]

Have there been any trends in the models you posted? I know the CPC ensembles tend to change quote a bit on occasion in relatively short timeframes. Likely there will be no heights rises, agree there, but have always thought of that within another realm compared to "certainty" in any given synoptical scenario, and what we can expect over a week out.

No not really. Other things like mountain torque and soi don't support blocking either.

[am19psu]

sorry that my opinion isn't what you wanted to hear! You're going to ban me for saying what I think? Cool, bro. Saying you're sure of anything meteorologically more than a few days out is just silly, and you know that having a degree in meteorology.

No, because you never post anything of value and only troll me in the main thread... do you think I miss your posts in the SNE threads? Keep it there if you want bash me.

To your second point... I get paid to be right about ten day forecasts. Its not terribly hard to do once you get the hang of it.

[free_man]

Positive west NAO gives zonal flow across n atlantic

Many of the big NE hits tended to be more +NAO prior to landfall, at least in an overall composite.

[am19psu]

Many of the big NE hits tended to be more +NAO prior to landfall, at least in an overall composite.

That's not the composite im familiar with... you need ridging over nw atl/davis straits to get storms to come up the coast

[Clinch Leatherwood]

there's some positive height anomalies on the ECMWF ensemble mean at 168 hours in the Nova Scotia/Labrador area...but obviously not sufficient to cause a tangible threat.

True but I like what you were saying earlier in terms of the time range.

Model verifications don't really support definitive statements at days 8 and 9, JMHO. Every single major respected TV met here in Boston has stressed the same thing...about the only thing they know for sure is that in several days it'll be somewhere south or south southwest of Bermuda. From there...check back later.

Recent model verifications http://www.hpc.ncep.noaa.gov/html/model2.shtml

[TalcottWx]

No, because you never post anything of value and only troll me in the main thread... do you think I miss your posts in the SNE threads? Keep it there if you want bash me.

To your second point... I get paid to be right about ten day forecasts. Its not terribly hard to do once you get the hang of it.

You both are good dudes... lets all call it a truce and be happy

Snownh... on the otherhand...

[OSUmetstud]

That's not the composite im familiar with... you need ridging over nw atl/davis straits to get storms to come up the coast

I was taking a look at the daily composites of Edna, Carol, Gloria and Bob, and Irene...I think the correlation with Nova Scotia/Labrador height anomaly is stronger. Both Bob and Carol did not feature ridging in the Davis Strait area, Bob especially.

[NaoPos]

Just gonna point out the shift west on the gfs and why the 18z was closer to the coast:

12zGFS:

18zGFS:

the base of the trough becomes a bit more neg tilt than the 12z due to the interaction of the trough and the GOM disturbance. Seems as if this will play a role in how far west Katia gets before the modeled recurve? Not forecasting here, just breaking down what i see.

ANyone care to take a stab at the height differences up by the davis straights?

[Amped]

Just gonna point out the shift west on the gfs and why the 18z was closer to the coast:

12zGFS:

18zGFS:

the base of the trough becomes a bit more neg tilt than the 12z due to the interaction of the trough and the GOM disturbance. Seems as if this will play a role in how far west Katia gets before the modeled recurve? Not forecasting here, just breaking down what i see.

ANyone care to take a stab at the height differences up by the davis straights?

Looks transient in Davis Straight The west ridge just plows east too fast on most runs t which is the second problem with the setup for the EC.

[am19psu]

I was taking a look at the daily composites of Edna, Carol, Gloria and Bob, and Irene...I think the correlation with Nova Scotia/Labrador height anomaly is stronger. Both Bob and Carol did not feature ridging in the Davis Strait area, Bob especially.

Agreed... its either/or