Jeanne Shows Flat Edge On West Side

[Sanibel]

There's a flat edge on one of Jeanne's outermost bands to her west near Florida. Floyd did this too. Sure sign of trough edge contact and precursor of a turn!


Canaveral...

[Jevo]

Quote from Stacy Stewart "There is nothing in the next 12-24 hours that can turn this storm north" Not sure youre seeing the steering currents correctly

[PurdueWx80]

The flat edge you see is bit of a stretch, but the trough edge thing is not correct whatsoever. I'm assuming you mean ridge, or perhaps something else. There is no trough flattening the western side of Jeanne, not one forecast, not one there per any observation. Ridges flatten outflow, not troughs. Troughs simply suck on the outflow.

[Sanibel]

Watch the flat edge and watch the turn...

[PurdueWx80]

Still watching...still waiting..still no trough there...still deep easterly to northeasterly flow......

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

[Sanibel]

Then what is causing the flat edge?

[PurdueWx80]

It's moderately flat...but still arced. The far outer reaches of the northern outflow are flat...because a ridge is there. Like I said previously, when the outflow bumps into a ridge, it will flatten. Troughs act to enhance and pull on outflow, rather than flattening it. I'm not trying to be rude or anything - the only trough remotely close to Jeanne is the rapidly weakening trough in the Midwest/Plains, and the upper low over the Gulf. Neither of these have begun to affect the flow immediately surrounding Jeanne yet.

[paul e]

RE this flattening, are you talking about the Central Dense Overcast area? I DO see a flattening or a squaring off of the left hand side on the 3:15 frame.. But I see NO such flattening of the outflow anywhere, so I do not believe this to be evidence of the ridge getting ready to turn the storm.

[Sanibel]

I'm not trying to be rude either Pudue - Are you saying it is encountering the second High over Florida and reacting? If you follow your contention through you then have the cyclone bumping against a secondary ridge. OK - but this action would entail a turn SW. Perhaps NHC completely missed a clearly oppositional synoptic on their path chart?

I frequent hurricane boards and have all too often seen persons use stuck logic off their own personal prediction bias as a means of ignoring common weather logic.

So what then is causing the flat edge?

[caneman]

I'm not trying to be rude either Pudue - Are you saying it is encountering the second High over Florida and reacting? If you follow your contention through you then have the cyclone bumping against a secondary ridge. OK - but this action would entail a turn SW. Perhaps NHC completely missed a clearly oppositional synoptic on their path chart?

I frequent hurricane boards and have all too often seen persons use stuck logic off their own personal prediction bias as a means of ignoring common weather logic.

So what then is causing the flat edge?

Sanibel for what it is worth, I think he is right. Look at the floater WV loop and look closely North of the syystem and you will see Easterlies streaming North of the system. In fact, where it stops being flat on the NW edge you could argue that is when the WNW or NW turn will take place. SOmewhere around 77.5 or 78.

[PurdueWx80]

I'm not trying to be rude either Pudue - Are you saying it is encountering the second High over Florida and reacting? If you follow your contention through you then have the cyclone bumping against a secondary ridge. OK - but this action would entail a turn SW. Perhaps NHC completely missed a clearly oppositional synoptic on their path chart?

I frequent hurricane boards and have all too often seen persons use stuck logic off their own personal prediction bias as a means of ignoring common weather logic.

So what then is causing the flat edge?

I've made absolutely no forecasts, or even a hint of a forecast here, so you certainly must not be talking to me. I do agree with the stuck logic option, as people here do that all the time, but there is nothing for me to stick to, other than pure meteorology and observations. Apparently we see things differently on the satellite images.

Regarding the CDO, there is very little cloud mass on the western side because up until recently, there hasn't been much convection there with all the dry air that had been entrained earlier.

Following my logic, yes, that might indicate a turn to the WSW or SW...the outflow certainly indicates something like that, but the center of the storm is basically heading due west w/ little wobbles either side of this.

Check out this big WV image, it shows the edge enveloping the entire western and northern portions of the storm (basically the red/dry parts).
http://www.rap.ucar.edu/weather/satelli ... _US_wv.jpg

The RUC analysis at 500 mb shows this nicely...the ridge is in various other locales at different pressure levels, but the dry air shown is allowing us to see down near 500-600 mb, which is why the analysis agrees with this satellite. I've also shown the forecast of the ridge up through 12 hours...most of the fcst is still from 00Z and will update within half an hour.

http://www.rap.ucar.edu/weather/model/d ... 06hr09hr12

[Sanibel]

The easterlies are at a lower level. The reason you can see them is because they are surface clouds.


You need to review Floyd and where his flat edge appeared in relation to his turn...


(Granted, Frances had a square box to her outflow. But that was an entirely different synoptic)

[NorthGaWeather]

There is no trough to turn this in the next 24 hrs in the area. The high has been building South all day.

[caneman]

The easterlies are at a lower level. The reason you can see them is because they are surface clouds.


You need to review Floyd and where his flat edge appeared in relation to his turn...


(Granted, Frances had a square box to her outflow. But that was an entirely different synoptic)

I know you want know part of this but now with the GFS coming in. It sure looks like it will be alot closer to you and I. Frances re-born. Why not? Ivan was re-born.

[PurdueWx80]

You can't see surface clouds on a WV image...and it is difficult to see them with an IR, although stratus and stratocu are visible there. The RUC analyses/forecasts show easterly flow at 500 mb...and even up to ~ 300 mb. Above this is the outflow region, and the motion there is clearly anticyclonic with the outflow moving clockwise and outward....except near the flat edges.

Sanibel - Have any links for arhcived Floyd data???

[Sanibel]

Bingo. Your 3:15U WV image confirms a pancaked WNW periphery. The western band cuts up into a conforming edge in relation to this flat edge.

Watch this start turning gentlemen...

[NorthGaWeather]

What's turning the hurricane?

[Sanibel]

This is very interesting because if you go back and get Floyd images you'll see he had a similar clear-air synoptic in front of him. If you used WV imagery for Floyd you would have practically mirrored the comments you are seeing here...

It has to be a reflection of the trough, since we've established that it can't be the High...

[NorthGaWeather]

hmmm, I seem to recall a completely different situation with Floyd but whatever.

[Foladar]

Thank god Sanibel isn't a met :| .. no offense of course, but it ain't turnin bud.