ATL HANNA: Extratropical - Discussion

[Recurve]

Graphic representation of the track based on the mention by the NHC that the straight track line could be misleading.

This is my own, NON-OFFICIAL representation. Thought it was important to show it graphically for those who haven't seen the NRL plot, and may not read the discussion. THIS IS NOT A FORECAST.

[masaji79]

You make an interesting point. I also think that Hanna could bend a little further westward before landfall.

[El Nino]

I agree, this abrupt curvature looks suspicious to me. But I don't see this storm spending much time inland. Expect strong TS winds in NYC !

[tolakram]

If that's true and the NHC does not expect landfall where the line depicts then they're in for a good deal of criticism. Can anyone confirm this? As a software engineer myself I would hope any map generating software they have would be able to change plot positions based on need.

[RL3AO]

If that's true and the NHC does not expect landfall where the line depicts then they're in for a good deal of criticism. Can anyone confirm this? As a software engineer myself I would hope any map generating software they have would be able to change plot positions based on need.

All they do is make the forecast points. The software just connects the dots and adds the cone based on 2/3 of the average forecast error.

[webke]

Graphic representation of the track based on the mention by the NHC that the straight track line could be misleading.

This is my own, NON-OFFICIAL representation. Thought it was important to show it graphically for those who haven't seen the NRL plot, and may not read the discussion. THIS IS NOT A FORECAST.

Needlessto say because I am impacted by this. I know that previously it was asked for a pro-met to give a opinion on the track, I haven't seen a response to that and if there is a Met looking in what do you think the slight bend in the track would affect.

[Recurve]

Just a guess, that's how they do it. They use straight lines and draw the 2/3 average error as a perpendicular centered on the track. That gives the cone. Usually it works, and it's graphically logical and sound. I just used a Bezier curve.

Look at the NRL plot: http://www.nrlmry.navy.mil/TC.html
Select Hanna and click on the map to enlarge it.

[tolakram]

If that's true and the NHC does not expect landfall where the line depicts then they're in for a good deal of criticism. Can anyone confirm this? As a software engineer myself I would hope any map generating software they have would be able to change plot positions based on need.

All they do is make the forecast points. The software just connects the dots and adds the cone based on 2/3 of the average forecast error.

They better change software or draw it by hand because people looking at the charts are going to expect landfall where the line crosses the coast.

[typhoon_tim]

maybe the nhc should look at updating the old tracking maps we've all grown accustomed to in order to account for such situations where the map may be misleading. kudos for the nhc for getting the word out there that you cannot just look at the track line to infer a landfall point. the mets here in myrtle beach have been harping on that all day long...

[Recurve]

NRL has the curve, not sure how they arrive at it because I always assumed they just used NHC forecast points.

[tolakram]

Just a guess, that's how they do it. They use straight lines and draw the 2/3 average error as a perpendicular centered on the track. That gives the cone. Usually it works, and it's graphically logical and sound. I just used a Bezier curve.

Look at the NRL plot: http://www.nrlmry.navy.mil/TC.html
Select Hanna and click on the map to enlarge it.

And all I'm saying is they could / should do the same thing. If you have a line people are going to focus on it. If the line is crossing NC and south carolina gets hit people are going to ask questions and blaming software isn't going to cut it. If nothing else they could increase the number of plotted locations to better represent the actual path.

[Recurve]

At least people on storm2K will know. Does anyone else even look at NHC maps?

Kidding. Kind of.

[Recurve]

Graphic representation of the track based on the mention by the NHC that the straight track line could be misleading.

This is my own, NON-OFFICIAL representation. Thought it was important to show it graphically for those who haven't seen the NRL plot, and may not read the discussion. THIS IS NOT A FORECAST.

Needlessto say because I am impacted by this. I know that previously it was asked for a pro-met to give a opinion on the track, I haven't seen a response to that and if there is a Met looking in what do you think the slight bend in the track would affect.

Webke, please look at the NRL map: .
They are an official source, Navy pro mets, though I also hope Wxman57 or someone smart is around to confirm for you.

You may be asking something beyond what I showed and NRL has, in that case, we do need a pro and you might want to go to the questions forum, though I'm not sure where that is right now.

[webke]

Thanks for the input.

[SkeetoBite]

Recurve is correct to note that the storm will follow a curve rather than go in a stright line point to point. Much discussion has been had about this over the past several years due to this exact example.

Note this <snip> from the forecast advisory:

IT'S WORTH NOTING THAT CONNECTING THE 48 AND 72 HOUR FORECAST POINTS
WITH A STRAIGHT LINE GIVES A MISLEADING UNDERESTIMATE OF THE
THREAT TO THE GEORGIA AND SOUTH CAROLINA COASTS.

It appears that the NRL site is doing a good job of indicating the curved path graphically.

[cycloneye]

AT 800 PM AST...0000Z...THE CENTER OF TROPICAL STORM HANNA WAS
LOCATED NEAR LATITUDE 22.6 NORTH...LONGITUDE 71.8 WEST OR ABOUT 200
MILES...320 KM...EAST-SOUTHEAST OF SAN SALVADOR IN THE BAHAMAS AND
395 MILES...630 KM...EAST-SOUTHEAST OF NASSAU.

FIXES FROM AN AIR FORCE RECONNAISSANCE PLANE INDICATE THAT HANNA HAS
BEEN MOVING TOWARD THE NORTH NEAR 14 MPH...22 KM/HR. HOWEVER...
HANNA SHOULD BEGIN TO MOVE TOWARD THE NORTHWEST TONIGHT OR EARLY
THURSDAY WITH AN INCREASE IN FORWARD SPEED DURING THE NEXT 24
HOURS. ON THE FORECAST TRACK...THE CENTER OF HANNA SHOULD BE MOVING
THROUGH OR JUST EAST OF THE CENTRAL AND NORTHWESTERN BAHAMAS OVER
THE NEXT 24 TO 36 HOURS.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 65 MPH...105
KM/HR...WITH HIGHER GUSTS. GRADUAL STRENGTHENING IS EXPECTED OVER
THE NEXT COUPLE OF DAYS AND HANNA COULD BECOME A HURRICANE
TOMORROW.

[tallywx]

New VORTEX in with 989 mb pressure and almost a full degree jump to the north. 65 kt flight level winds too.

[tolakram]

[artist]

if Hanna does get her act together sooner than later will that make a difference in her projected track?

[Plibster]

Graphic representation of the track based on the mention by the NHC that the straight track line could be misleading.

This is my own, NON-OFFICIAL representation. Thought it was important to show it graphically for those who haven't seen the NRL plot, and may not read the discussion. THIS IS NOT A FORECAST.

Thank you for bringing this up. It just made me rethink my plans for tomorrow! I sure thought it was going to NC until you showed this map.