Hurricane Helene

[Gray-Wolf]

For crying out loud, Dawlish. Don't come on here and muck this thread up as well now with your "dose of realism" nonsense.

However much I love the majority of your threads Paul I must concur with Mondy's well measured synopsis. There is a 'time and a place' for reality and here and now is, apparently, not it!!!

We would all be as stunned and appalled as the next person if a hybrid Storm/Hurricane survived its re-curve journey across the Atlantic and presented itself in the Bristol Channel to then plough it's way along the M4 and later enhanced and re-animated by a Jet 'Sting' as it closed on London..... in reality we are all just enjoying the 'possibilities' before they become enshrined in the 'reality' that awaits all things (far too much of that in life already) and as we all know it's all about the journey, not the arriving!

*****All of the above is laid down with a tongue firmly placed in ones cheek ****

EDIT: And now I'll have a look at where she's at!! Probably a tropical storm by now (seemed to be floundering this a.m.)

Edited September 23, 2006 by Gray-Wolf

[Rustynailer]

http://www.nrlmry.navy.mil/tc-bin/tc_home2...f&SIZE=full

This one can't help but bring a grin from me

I know the chances are low at the mo' but its nice to just even think about it

(edit)The wind is a bit low when it gets to Ireland, but it can always change.

Edited September 23, 2006 by Rustynailer

[Gray-Wolf]

She's still holding onto her central core and has some convection to her North and East which seems to be wrapping around her barren southern side. Could she stabilise over the current SST's and last a day or so longer (as Gordon did) I wonder? Each time she procrastinates tracks are modified (even if it's just the intensity and not the direction) so maybe my earlier post will itself hold some reality within it!!

[Rustynailer]

Maybe this is one hurricane too many for the low to absorb,a sort of hurricane indigestion. Your theory sounds like fun GW I can't wait to see the result if your right

Edited September 23, 2006 by Rustynailer

[Dawlish]

However much I love the majority of your threads Paul I must concur with Mondy's well measured synopsis. There is a 'time and a place' for reality and here and now is, apparently, not it!!!

We would all be as stunned and appalled as the next person if a hybrid Storm/Hurricane survived its re-curve journey across the Atlantic and presented itself in the Bristol Channel to then plough it's way along the M4 and later enhanced and re-animated by a Jet 'Sting' as it closed on London..... in reality we are all just enjoying the 'possibilities' before they become enshrined in the 'reality' that awaits all things (far too much of that in life already) and as we all know it's all about the journey, not the arriving!

*****All of the above is laid down with a tongue firmly placed in ones cheek ****

I know Gray Wolf!

If ever Mondy thinks he can erase an opposing point of view, because it doesn't agree with his own - he's wrong. I base my observations on an analysis of LRF on gfs, which, so far, is proving quite successful. It is completely open, I've explained my theory of appearance, sticking, disappearance, reappearance and sticking for at least 4 runs and I'm prepared to test it in the full light of our Mondys who can criticise it to death and criticise me to death when I'm wrong. I don't mind.

The technique also identifies non-spots and I'm presently applying that to Helene. I've honestly lost count of the exact number of gfs runs that keep Helene away from our shores. I think it is at least 12 - at least 3 full days, with not a single run showing Helene will be a problem for us. She won't happen now and she wasn't going to happen a couple of days ago - in my opinion. I would put her chances of significantly affecting the UK, on the scale of even Gordon, at 33/1 against, after the 12z today.

I would think that those observations are as relevant as anyone's. By looking at weather forecasting, in terms of probabilities and odds, there is always space for being wrong. Odds are always quoted to something - usually 1, eg 33/1. that means that, in my opinion, the event would occur only 1 in 33 times, given the run of gfs charts I've watched and the present situation, on the 06z. In other words, it is very unlikely, but there are never certainties. I simply don't deal with them. I also only look at the gfs, because trying to fathom all the models is beyond me! I'd rather get to know one well enough to trust, or not to trust, than not know any well.

If someone wishes for an event, that's fine. If I think the odds are stacked against it, I'll say so; no matter what anyone wishes I would do(!). I won't be rude and I would never be abusive, but when I disagree with someone, and they get upset about being challenged; that won't change what I think about the chances of the event occuring, nor what I say about those chances.

A dose of reality goes a long way and I know I'm an argumentative git for defending that view - but I reserve the right to do that!

Paul

Edited September 23, 2006 by Dawlish

[Thundersquall]

The National Hurricane Center currently has Helene's track coming straight for the British Isles.

She will be an extre-tropical storm by the time she reaches us, but I think the forecast models

are down-playing the strength of Helene.

She's practically gone on GFS when she crosses our shores.

Still predicted to be in the "S" category approaching SW Ireland (Sustained winds 39-73 mph).

Edited September 23, 2006 by Thundersquall

[Mondy]

I think it's worth putting the latest NHC disco up.

500 PM EDT SAT SEP 23 2006

HELENE CURRENTLY DISPLAYS BOTH TROPICAL AND EXTRATROPICAL

CHARACTERISTICS. THE CYCLONE HAS A FRONTAL-LIKE AND ASYMMETRIC

APPEARANCE IN SATELLITE IMAGERY WITH LIMITED DEEP CONVECTION.

HOWEVER...FSU CYCLONE PHASE SPACE DIAGRAMS DIAGNOSE HELENE TO STILL

HAVE A DEEP WARM CORE WHICH IS CONSISTENT WITH ITS ABILITY TO

STILL PRODUCE CONVECTION...ALBEIT LIMITED...NEAR THE CENTER. HELENE

IS SOMEWHERE IN PROCESS OF EXTRATROPICAL TRANSITION AND IT IS NOT

CLEAR AT WHAT POINT THE TRANSFORMATION WILL BE COMPLETE. SINCE THE

OVERALL STRUCTURE APPEARS UNCHANGED SINCE THE EARLIER 0915 UTC

QUIKSCAT DATA...WHICH SHOWED 80 KT MAXIMUM WINDS...THE INITIAL

INTENSITY WILL REMAIN AT 80 KT FOR THIS ADVISORY. WATER VAPOR

IMAGERY SHOWS A MIDDLE TO UPPER-LEVEL SHORTWAVE TROUGH QUICKLY

APPROACHING HELENE FROM THE WEST RESULTING IN THE UPPER-LEVEL

OUTFLOW BECOMING INCREASINGLY RESTRICTED. IF THIS TREND

CONTINUES...AN INCREASINGLY SHEARED HELENE COULD LOSE WHAT REMAINS

OF ITS INNER CORE CONVECTION AND THEREFORE LOSE WHAT TROPICAL

CHARACTERISTICS IT HAS LEFT. ASSUMING EXTRATROPICAL TRANSITION

COMPLETES IN ABOUT 12 HOURS...AS CURRENTLY FORECAST...THE CYCLONE

SHOULD GRADUALLY WEAKEN OVER THE NEXT DAY OR SO. MORE RAPID

WEAKENING IS FORECAST THEREAFTER AS THE CYCLONE LOSES SOME OF ITS

BAROCLINIC SUPPORT.

HELENE HAS BEEN MOVING A LITTLE SOUTH OF THE PREVIOUS FORECAST TRACK

WITH AN INITIAL MOTION ESTIMATE OF 070/19. THERE HAS OTHERWISE

BEEN LITTLE CHANGE IN THE TRACK FORECAST PHILOSOPHY IN THE

SHORT-TERM...AND GUIDANCE REMAINS TIGHTLY CLUSTERED THROUGH 48

HOURS. THEREAFTER...THE TRACK GUIDANCE BEGINS TO DIVERGE BUT NOT

NEARLY AS MUCH AS BEFORE. THE NOGAPS MODEL...WHICH WAS PREVIOUSLY

THE NORTHERN OUTLIER...HAS SHIFTED SIGNIFICANTLY SOUTH AND IS NOW

ALONG THE SOUTHERN SIDE OF THE GUIDANCE SUITE. THE UKMET

MODEL...WHICH PREVIOUSLY SHOWED A TURN DUE SOUTH WITH THE

ECMWF...HAS SHIFTED NORTH AND IS NOW IN GOOD AGREEMENT WITH THE

OFFICIAL FORECAST. THE ECMWF CONTINUES TO SHOW THE SOUTHWARD

TURN...BUT THIS IS CONSIDERED A LESS LIKELY SCENARIO GIVEN THE NOW

BETTER AGREEMENT AMONG THE OTHER DYNAMICAL MODELS. THE OFFICIAL

FORECAST IS SHIFTED JUST A LITTLE SOUTH OF THE PREVIOUS ONE.

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/2100Z 38.0N 44.4W 80 KT

12HR VT 24/0600Z 39.1N 40.9W 75 KT...EXTRATROPICAL

24HR VT 24/1800Z 41.3N 36.4W 70 KT...EXTRATROPICAL

36HR VT 25/0600Z 43.2N 32.4W 65 KT...EXTRATROPICAL

48HR VT 25/1800Z 44.6N 28.8W 55 KT...EXTRATROPICAL

72HR VT 26/1800Z 47.0N 21.0W 45 KT...EXTRATROPICAL

96HR VT 27/1800Z 49.0N 15.0W 35 KT...EXTRATROPICAL

120HR VT 28/1800Z 51.0N 11.0W 30 KT...EXTRATROPICAL

From yesterday to now the +120HR has shifted from 58N 15W to 51N 11W.Big dip southwards.

Bearing in mind the NHC will soon "ignore" Helene as she makes her way further east(ish)..

Who knows yet..??

Edited September 23, 2006 by Mondy the clumsy

[flagpole]

From yesterday to now the +120HR has shifted from 58N 15W to 51N 11W.Big dip southwards.

Bearing in mind the NHC will soon "ignore" Helene as she makes her way further east(ish)..

Who knows yet..??

Thanks for the update Mondy. Who knows indeed!

[Gray-Wolf]

All in all she (remnants by then) may just be part of the 'ingredients' of some notably 'blustery,wet weather' later on next week ('bout time for the equinocturnal gales I'd say ) and as for a little retrogression later on to re-build that large L.P. SW of Iceland and start throwing up more clement conditions our way , well wouldn't that be nice?

Another week of dry, warm sunny weather (with radiation fog mornings) followed by Kirk full on as the mother of all re-curves...........

Edited September 23, 2006 by Gray-Wolf

[crimsone]

My my that track looks pretty

http://en.wikipedia.org/wiki/Image:TD82006atlantic.gif

Incidentally, this GFDL run looks interesting. It seems that at the moment, the models are divergingmore on the subject of intensity rather than the track...

http://moe.met.fsu.edu/cgi-bin/gfdltc2.cgi...;hour=Animation

Incidenentally though, it also appears to recurve Isaac into the mid atlantic, but it does seem to be sending a possible Joyce into the Carribean.

....Then again, it's the GFDL I'm takling about here. lol

Edited September 23, 2006 by crimsone

[Matty M]

The soon ex Hurricane will/very very likey will become nothing but a slack low pressure before

it comes within 400 miles of B&I.

[Sugar79]

I am trying to learn all about hurricanes and when they turn in to tropical storms etc, iam finding it quite hard to understand at the mo..

I was having a look at the info on Helene on..

http://en.wikipedia.org/wiki/2006_Atlantic...orm_information

it says: September 23 8 a.m. AST (1200 UTC) - Tropical Storm Helene restrengthens into a hurricane

so does this mean Helene weakened then gained strenth again yesterday to be hurricane again??

and what does this mean for us in the UK??

Helene

Edited September 23, 2006 by Sugar79

[crimsone]

In reply to your first question, yes, it does

As for the second question - that's something that none of us can answer with any certainty. The track forecast is just like any other forecast in that the further away you try to forecast, the harder it is and the greater the margin of error. This is what is shown by the "cone of probability". While the line represents the best idea of where the cyclone will go, the shaded cone around it indicates a margin for error.

The trouble is, while intensity forecasts for the cyclones themselves can (in theory) be predicted with far more certainty than we could the weather in the UK (baroclynic synoptics) at a longer period, The uncertainty of the forecast for environmental conditions (fronts, highs, lows, etc) means that the further away we forecast, the harder it is to predict what effect theywill have on a tropical system, and thus what effect they will have on it's track and intensity.

At 5 days out, there is a significant margin for error.

As it stands, the current NHC track brings helene just short of Ireland in a weakened state. (depression rather than storm). It's worth mentioning though that while extra-tropical systems generally bring somewhat less rain than their tropical counterparts (or pervious incarnations), the effects of the winds can be considered to be no different from tropical systems - if a cat 3 hurricane goes through extratropical transition, and the resultant "extratropical storm" re-strengthens and deepens with windspeeds as deep as a cat 2 hurricane, the winds will do just the same damage.

As a general rule though, extra-tropical storms arising from hurricanes are far broader than their tropical cousins, and so effect a wider area.

Overall, it could turn out to be a damp squib for the UK, or it could turn out to be quite strong. We just can't tell yet.

If I've said anything out of place, no doubt one of the others will pick me up

[Sugar79]

Thank you Crimsone, that was very informative

[crimsone]

No problem Happy to help.

[Mondy]

Looks like we'll be saying cheerio to Helene soon:

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/0900Z 39.9N 39.9W 75 KT

12HR VT 24/1800Z 41.6N 36.6W 70 KT...EXTRATROPICAL

24HR VT 25/0600Z 43.2N 33.1W 65 KT...EXTRATROPICAL

36HR VT 25/1800Z 44.5N 30.0W 60 KT...EXTRATROPICAL

48HR VT 26/0600Z 45.0N 26.0W 50 KT...EXTRATROPICAL

72HR VT 27/0600Z 47.0N 18.0W 45 KT...EXTRATROPICAL

96HR VT 28/0600Z...ABSORBED

[Dawlish]

Looks like we'll be saying cheerio to Helene soon:

True Mondy. In her extra-trpoical clothes, she won't cause the UK any major problems and she will be a much less significant system than Gordon ever was.

Paul

[Gray-Wolf]

Well she's already dropped to a tropical storm once and recovered so 'never say never' eh? Let's see if her core is finally overwhelmed today (she'd dropped a cold front south yesterday but then divorced herself from it as she re-intensified) I don't know where abouts the NAD current is but maybe she'd found some anomalous splodge of warmer waters.

I still think that with the weak El-nino keeping storms from the Gulf and re-curving things mid-atlantic it is only a matter of time before a 'beefy' system hits NW Europe this year...........my monies on Kirk (it's life Jim.......)

[Somerset Squall]

Well she's already dropped to a tropical storm once and recovered so 'never say never' eh? Let's see if her core is finally overwhelmed today (she'd dropped a cold front south yesterday but then divorced herself from it as she re-intensified) I don't know where abouts the NAD current is but maybe she'd found some anomalous splodge of warmer waters.

I still think that with the weak El-nino keeping storms from the Gulf and re-curving things mid-atlantic it is only a matter of time before a 'beefy' system hits NW Europe this year...........my monies on Kirk (it's life Jim.......)

If the extra-tropical storm stops being fed with baroclinic energy (as it is forecast to do), then it looks like Helene will be a weak affair when it hits Britain.

Edited September 24, 2006 by AtmosFear

[BrickFielder]

WXTLIST WMO=WTNT43 MATCH=KNHC

WTNT43 KNHC 240835 2006267 0835

TCDAT3

HURRICANE HELENE DISCUSSION NUMBER 49

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082006

500 AM EDT SUN SEP 24 2006

HELENE CONTINUES TO MAINTAIN DEEP CONVECTION NEAR THE

CENTER...ALTHOUGH THERE IS LESS OF IT NOW THAN 6 HOURS

AGO. THE INITIAL INTENSITY WILL REMAIN 75 KT BASED ON THE EARIER

QUIKSCAT DATA. OVER THE NEXT 24 HOURS...HELENE WILL BE MOVING OVER

COOLER WATERS AND THE VERTICAL SHEAR IS EXPECTED TO INCREASE.

HOWEVER...INTERACTION WITH A SHORT-WAVE TROUGH IN THE WESTERLIES

APPROACHING HELENE COULD KEEP THE WINDS UP...SO LITTLE CHANGE IN

INTENSITY IS SHOWN UNTIL AFTER 24 HOURS...WHEN THE BAROCLINIC

FORCING IS EXPECTED TO DIMINISH. HELENE IS EXPECTED TO LOSE

TROPICAL CHARACTERISTICS AS IT IS OVERTAKEN BY THE SHORT-WAVE

TROUGH IN ANOTHER 12 TO 24 HOURS...IF IT HASN'T ALREADY LOST IT'S

DEEP CONVECTION BY THEN.

MODEL GUIDANCE IS IN VERY GOOD AGREEMENT NOW ON A CONTINUED

EAST-NORTHEASTWARD MOTION...WITH ONLY THE ECMWF DROPPING HELENE

SOUTHWARD NEAR THE AZORES. MUCH OF THE GUIDANCE SUGGESTS A SLOWING

OF THE TRACK IN ABOUT 24 HOURS AS MID-LATITUDE SHORT WAVE ENERGY

DROPS SOUTH OF HELENE...WEAKENING THE STEERING CURRENT. THE

OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY AND TO A

TIGHTLY-CLUSTERED GFS/GFDL/UKMET/NOGAPS CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/0900Z 39.9N 39.9W 75 KT

12HR VT 24/1800Z 41.6N 36.6W 70 KT...EXTRATROPICAL

24HR VT 25/0600Z 43.2N 33.1W 65 KT...EXTRATROPICAL

36HR VT 25/1800Z 44.5N 30.0W 60 KT...EXTRATROPICAL

48HR VT 26/0600Z 45.0N 26.0W 50 KT...EXTRATROPICAL

72HR VT 27/0600Z 47.0N 18.0W 45 KT...EXTRATROPICAL

96HR VT 28/0600Z...ABSORBED

$$

FORECASTER FRANKLIN

WXTLIST: done

Some interesting differences in the models ECMWF still takes the hurricane south as the trough extends south.

Nogaps brings the reminants of Helene through much faster.

Jetstream long wave is forecast by most models to firstly pick up Helene and then dip south of it allowing Helene to diminish. This relies on the forecast over the eastern US being correct with the trough lifting out. There are problems with the forecasting of this and in particular the way the GFS and CMC models are handling things. The lifting looks a little too aggressive timing wise and high pressure build over southern sattes looks a little too far north.

Most models agree that Helene's core is still fairly warm and will take time to cool which seems to be in direct contrast to how the models fade Helene away. I would expect Helene's core to keep going even though Helene as a whole is turning extra tropical, this I expect will introduce an element of vorticity which should speed the long wave trough east a little quicker than forecast.

I am not expecting Helene to arrive on our shores as a significant storm at the moment, but nor do I think the models are handling it very well.

[Gray-Wolf]

By the looks of things Helene's core has now had its last burst and I would now expect the transition to ex-tropical to speed up (seeing as a lot of the transition had begun, apart from the stubborn core!!!). As for the what next..........well.

[Mondy]

1100 AM EDT SUN SEP 24 2006

CONVECTION CONTINUES TO SLOWLY WEAKEN NEAR THE CENTER OF HELENE.

LATEST SATELLITE IMAGERY INDICATES THAT THE SYSTEM HAS ACQUIRED

DEFINITIVE FRONTAL FEATURES WITH EXTENSIVE COLD AIR ADVECTION OVER

THE SOUTHWESTERN SEMICIRCLE...AS EVIDENCED BY THE LARGE

STRATOCUMULUS FIELD. MOREOVER...A QUIKSCAT PASS FROM AROUND 0900

UTC SUGGESTED THE STRONGEST WINDS WERE BECOMING REMOVED FROM THE

CENTER...AND THE WIND FIELD IS EXPANDING AS IS TYPICAL OF AN

EXTRATROPICAL CYCLONE. ALTHOUGH MICROWAVE DATA AND MODEL ANALYSES

BASED ON THESE DATA IS SHOWING A WARM CORE...WE BELIEVE THIS IS DUE

TO A WARM SECLUSION THAT IS COMMON IN STRONG EXTRATROPICAL

CYCLONES. BASED ON THE ABOVE ANALYSES...THE EXTRATROPICAL

TRANSITION IS CONSIDERED COMPLETE... AND THIS WILL BE THE LAST

ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON HELENE.

THE INITIAL MOTION IS 055/18...A LITTLE SLOWER THAN BEFORE.

DYNAMICAL MODELS SHOW ADDITIONAL SLOWING OF THE FORWARD SPEED AS THE

SYSTEM INTERACTS WITH AN UPSTREAM SHORTWAVE TROUGH. GUIDANCE

REMAINS IN FAIRLY GOOD AGREEMENT THROUGH 48 HOURS AND THEN BEGINS

TO DIVERGE AT THE EXTENDED RANGES. IN LIGHT OF THE MODEL

SPREAD...THE OFFICIAL FORECAST IS CLOSE TO THE MODEL CONSENSUS.

THE AFOREMENTIONED QUIKSCAT PASS SHOWED ONLY A COUPLE 65 KT VECTORS

AND...ASSUMING GRADUAL WEAKENING SINCE THE TIME OF THOSE

OBSERVATIONS...THE INITIAL INTENSITY IS LOWERED TO 60 KT. A

CONTINUED SOURCE OF BAROCLINIC ENERGY SHOULD MAINTAIN THE CYCLONE

WITH ONLY SLOW WEAKENING OVER THE NEXT DAY OR SO UNTIL IT COMBINES

WITH ANOTHER EXTRATROPICAL CYCLONE OVER THE EASTERN NORTH ATLANTIC.

ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS

FORECASTS ISSUED BY THE OCEAN PREDICTION CENTER UNDER AWIPS/WMO

HEADERS NFDHSFAT1/FZNT01 KWBC AND BY METEOFRANCE UNDER WMO HEADER

FQNT50 LFPW.

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/1500Z 40.9N 37.5W 60 KT...EXTRATROPICAL

12HR VT 25/0000Z 42.5N 34.6W 60 KT...EXTRATROPICAL

24HR VT 25/1200Z 43.6N 31.8W 55 KT...EXTRATROPICAL

36HR VT 26/0000Z 44.2N 28.0W 50 KT...EXTRATROPICAL

48HR VT 26/1200Z 45.1N 23.7W 45 KT...EXTRATROPICAL

72HR VT 27/1200Z 48.5N 14.0W 40 KT...EXTRATROPICAL

96HR VT 28/1200Z...MERGED WITH EXTRATROPICAL SYSTEM

[crimsone]

NHC seems to have issued its final advisory on Helene, concluding as they do that extratropical transition is now complete.

[BrickFielder]

GFS brings it through Wednesday night into Thursday Morning.

Could be a bit windy and wet over in Ireland.

With A strong jetstreak comming of the US a low pressure system is likely to develop at the jet streak left exit to the north west of Helene. The trough Helene is in is being squashed and this can be seen in the flattening of Helene. High pressure looks fairly fixed over spain which leaves very little place for Helene to go.

Squeezed north and absorbed looks like a good bet although with center pressure down at 964 this is still a substantial system.

[Dawlish]

GFS brings it through Wednesday night into Thursday Morning.

Could be a bit windy and wet over in Ireland.

With A strong jetstreak comming of the US a low pressure system is likely to develop at the jet streak left exit to the north west of Helene. The trough Helene is in is being squashed and this can be seen in the flattening of Helene. High pressure looks fairly fixed over spain which leaves very little place for Helene to go.

Squeezed north and absorbed looks like a good bet although with center pressure down at 964 this is still a substantial system.

That looks about right BF. Windy and wet over Ireland, with the system being forced Northwards would by my view, at this stage, as well.

Paul

Edited September 25, 2006 by Dawlish