Tropical Storm Helene,Analysis,Sat Pics,Models Thread #3

[Sanibel]

No naked spiral there. Now that's a category 3!

Warm tops probably signify that will be it for intensity. Top out at category 3.

Cloudy eye at category 3.

[Brent]

http://icons.wunderground.com/data/images/at200608_5day.gif

Mike look at the 5 PM trrack.You are correct.

Here fishy fish.

[brunota2003]

If your bored go watch Gordon threaten the Azores...already a TS Watch up there just encase...

[fci]

[

Here fishy fish.

Well, for my money; the Tropics can just continue to bore you and I all the way for the balance of the season.

And how about adding next year to that too!!

[Lowpressure]

WXMAN57, thanks for the rationale in helping me to understand the model differences this year. Great response, very informative.

[superfly]

Microwave also shows what recon found, open eye to the SW.

[HURAKAN]

Does anyone think the 125 mph estimate this morning was exaggerated?

I know the RECON found a weaker system, but I think there was something wrong when only 79 knots were found when the system doesn't look like a 90-mph hurricane. Could they have missed the strongest side of the storm, or was there a malfunction of the equipment? I don't know but that measurement sounds and looks wrong.

[MGC]

Strong Cat-2 IMO. I am a bit troubled by the SFMR data that only observed 79KTS. I never have trusted the SFMR data and I don't believe it now. Helene is likely a 95KTS hurricane by my estimation. Helene should miss Bermuda.....MGC

[curtadams]

A dramatic shift north and east is assured...in fact the new 120H verify point could be as much as 600NM from the 12Z 120H verify position.MW

Mike, why are the models doing so porely this year. They all had this right the first time, then some wanted to bend west (split camps). They seem to really be having a hard time with synoptic patterns. I am not suggesting they are all wrong, just that it seems they are really struggling this year moreso than usual. Is this year really that awkward?

I think they're doing just fine. From very early on, we had some models predicting more or less the current consensus - the first two fronts miss and the 3rd gets her. Short-term the model have been close and accurate throughout. The disagreement has been over the intensity and location of fronts generally 5 or more days out - and that's just not something models are very exact on, nor have they been in the past. The difference is a) the fronts have started a bit early, b) we're looking at front-subject storms in the mid Atlantic that would normally get ignored and c) models aren't as good over ocean because there's little data. Until recently, there just wouldn't be much discussion of the exact track of a very-likely-fish at least a week from the EC in the unlikely event she came there. Even with Ernesto the differences arose mostly from that front digging in - it's just unusual to have a strong front in FL then.

[MiamiensisWx]

Does anyone think the 125 mph estimate this morning was exaggerated?

I know the RECON found a weaker system, but I think there was something wrong when only 79 knots were found when the system doesn't look like a 90-mph hurricane. Could they have missed the strongest side of the storm, or was there a malfunction of the equipment? I don't know but that measurement sounds and looks wrong.

I tend to agree that the area and pockets of highest flight-level winds may well have been missed, based on the structure of Helene.

[trugunz]

You think it weakened because of Eye wall replacement cycle?

[storms in NC]

Where do you see a Eye wall replacement takeing place at? The eye looks fine to me. I don't think there is any eye wall replacement going on.

[MWatkins]

A dramatic shift north and east is assured...in fact the new 120H verify point could be as much as 600NM from the 12Z 120H verify position.

MW

Mike, why are the models doing so porely this year. They all had this right the first time, then some wanted to bend west (split camps). They seem to really be having a hard time with synoptic patterns. I am not suggesting they are all wrong, just that it seems they are really struggling this year moreso than usual. Is this year really that awkward?

I dont know what the error rates are on a storm by storm basis this season (although I will be calculating that out sometime soon)...but they did not handle Ernesto well...and they are going to have a large west of track bias (except...perhaps...the GFDL) with Helene.

I think the biggest difference has been the overall complicated steering pattern with these systems north of 20N. Typically...the models do very well with westward moving systems in the deep tropics...but once they get out of the deep tropics and begin interacting with other weather systems...or the westerlies...the error rates go up.

Ernesto had all sorts of complications...a rouge upper low...unpredictable land interaction...dry air...etc which affected intensity and track. The upper pattern for Helene has also been complicated...with Gordon to the north and the upper system to the west...all happening as this is moving north of 20.

When you have such a complicated upper pattern...individual model biases in the handling of these paticluar features begin to show up...hence...the varied solutions we have been seeing with Helene up until now.

Also...Helene is in a data-poor environment...which means the models have to fill in big gaps of information on their own...again harder to do with such a complicated pattern...which again will produce varied solutions over time.

So the model performance...especially with Helene and Ernesto...suffered more because of the overall complexity of the synoptic environments they were forecasting...rather than any specific limitations of the models themselves.

Forecasting track with systems like these two is just much more difficult...and prone to more error...IMHO.

MW

[wxwatcher91]

Trugunz may have been looking at the microwave image posted above which does show a bit of a dry moat, however no, there is no ERC going on.

In fact it is likely that Helene has not weakened at all but just is being read incorrectly either in the latest advisory or in the past advisories.

[Stratosphere747]

Where do you see a Eye wall replacement takeing place at? The eye looks fine to me. I don't think there is any eye wall replacement going on.

He was asking if the storm weakened because of an ERC. Most likely the wind speed was estimated too high earlier, hence the reason why it appears to have weakened.

Note, the term ERC is overused, much like "annular."

[wxman57]

You think it weakened because of Eye wall replacement cycle?

Why assume it has weakened? Observations today, limited as they were, measured a lower central pressure. The recon in Helene has been quite limited. Earlier intensity estimates were based mostly upon satellite data, not direct observations. So we cannot be sure that Helene was as strong as the NHC was estimating before. Therefore, perhaps it has not weakened, we just learned it wasn't as strong as we thought.

[P.K.]

I dont know what the error rates are on a storm by storm basis this season (although I will be calculating that out sometime soon)...but they did not handle Ernesto well...and they are going to have a large west of track bias (except...perhaps...the GFDL) with Helene.

Mike have a look at

Edit - Just let me sort the links out........

http://hurricane.methaz.org/tracking/ops/AL052006/AL052006_perf.html
http://hurricane.methaz.org/tracking/ops/AL062006/AL062006_perf.html
http://hurricane.methaz.org/tracking/ops/AL072006/AL072006_perf.html
http://hurricane.methaz.org/tracking/ops/AL082006/AL082006_perf.html

No performance pages for the storms before those.

[Jim Hughes]

There was also a considerable solar wind increase today above the 500 km/sec level. The solar wind speed is currently in the 630 km/sec range. Must I redundantly point out to everybody that ATL tropical systems become somewhat disorganized during these times. A pressure rise makes sense and this is not post analysis since I have written about this endless times.

[wxman57]

There was also a considerable solar wind increase today above the 500 km/sec level. The solar wind speed is currently in the 630 km/sec range. Must I redundantly point out to everybody that ATL tropical systems become somewhat disorganized during these times. A pressure rise makes sense and this is not post analysis since I have written about this endless times.

Didn't the pressure fall since yesterday? I seem to remember a 970mb pressure on the 17th, and 964mb today. Helene looked stronger today than yesterday, and recon measured a lower pressure. Keep in mind we're comparing partial recon with satellite estimates to create a trend. Bad satellite wind estimates previously may have to be discarded. Helene could heave strengthened in the past 24 hours, meaning it was weaker than estimated earlier.

[sma10]

hmmm, even the most ardent EC hit people must have given up...cat 3 storm and we only have 3 posts in the last hour in this thread and heck we are discussing drawing eyelashes on a sat photo

Oh I suspect a few "un-named" members who consistently predict an EC or Fl landfall for most every storm; will pop up with their usual "it's going more west than expected" or " The 17 troughs may STILL miss her" or something like that!

These things you can always depend on!!!!

One cannot call them "dream"casters but I do perfer 'location biased forecasters' because I can demonstrate that undeniably with statistics to those who post lat/long. I always find it amusing that people will cling to the slightest hope that it will hit their area. One has to wonder if they ever give up hope, even when the storm is by Newfoundland.

You can also tell by the historic storm tracks that are mentioned, e.g. "Didn't Andrew/Katrina/Hugo etc......do this, too?"