ATL: DEBBY - Post-Tropical

[cycloneye]

General question from someone who is only an avid weather watcher: Is Debbie an 'average' size tropical storm? The NHC listed size, and the book info I have from books indicates she is not large. Is the fact she is in the gulf what makes her seem large to me?

The overall circulation is not a tight one as normally occurs in most of Tropical Cyclones so on that regard, is not small.

[brunota2003]

The NHC bit on one solution, and the other turned out to be closer to the truth. The cone represents where the center will be 66% of the time. The other 34% of the time the center goes out of the cone. Obviously, though, that 34% is usually further along the track (Day 4 or 5) than this time's.

Actually, the size of the cone is set so that the percentage is the same at all time steps.

Yes, but recent advances in errors typically keep the cyclone within the 3 day cone (they use the last ten years, don't they?)...whereas you'd be more likely to see it go outside of the cone in the 4 to 5 day time frame.

[dixiebreeze]

Looks like Debby is broadening and weakening right now on IR

[Cyclenall]

Keep in mind that the 6 and 18z models are generally continuation models. The GFS 0Z and 12Z ones start from scratch and are more important.

See this thread to disprove this.

[vaffie]

Keep in mind that the 6 and 18z models are generally continuation models. The GFS 0Z and 12Z ones start from scratch and are more important.

See this thread to disprove this.

very interesting, thx

[jlauderdal]

The NHC bit on one solution, and the other turned out to be closer to the truth. The cone represents where the center will be 66% of the time. The other 34% of the time the center goes out of the cone. Obviously, though, that 34% is usually further along the track (Day 4 or 5) than this time's.

so there is absolutely no confusion to all the folks on the board, bottom line is that the NHC CONE its all about statistics...if you see a cone or track or anything else from anywhere other than nhc i recommend you do your homework and determine the derivation of such so that you are keenly aware of exactly what you are looking at so you can be informed properly....that doesn't mean nhc is the only one with a brain or is always correct as we have seen the last few days they bit like most others and were wrong, it just means there are many different flavors out there so know what you are consuming.


http://www.nhc.noaa.gov/aboutcone.shtml

Definition of the NHC Track Forecast Cone

Definition:

The cone represents the probable track of the center of a tropical cyclone, and is formed by enclosing the area swept out by a set of circles (not shown) along the forecast track (at 12, 24, 36 hours, etc). The size of each circle is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle. The circle radii defining the cones in 2011 for the Atlantic and eastern North Pacific basins are given in the table below.

One can also examine historical tracks to determine how often the entire 5-day path of a cyclone remains completely within the area of the cone. This is a different perspective that ignores most timing errors. For example, a storm moving very slowly but in the expected direction would still be within the area of the cone, even though the track forecast error could be very large. Based on forecasts over the previous 5 years, the entire track of the tropical cyclone can be expected to remain within the cone roughly 60-70% of the time.

[Tampa Bay Hurricane]

St. Petersburg airport had a wind gust to 56 mph earlier today. There is widespread surge and rainfall flooding.

[jlauderdal]

debby throwing off some more energy towards the keys heading at sw/se florida..been busy in this part of the world the last few days



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[wkwally]

Well looks like this storm has been named right because my sister Debby acts just like T.S. Debby is keeps everyone guessing. I think The NHC is on track right now and that land fall is going to be at or close to their projection unless this storm does some crazy thing, but that would not surprise me one bit IMO

[johngaltfla]

WOW. Channel 8 is now reporting that the Euro rainfall prediction model is adding an additional 5" of rain by Tuesday from the storm; IN ADDITION TO THE 5" we've already received!

Holy Flirkingschmidt!

EDIT TO ADD: Elena's name keeps coming up. Ugh.

[Flakeys]

Is it better to try to guess, or say I don't know.

[Kingarabian]

Keep in mind that the 6 and 18z models are generally continuation models. The GFS 0Z and 12Z ones start from scratch and are more important.

See this thread to disprove this.

Thanks <3.

Anyway with the GFS 18z, @ 57 hours Debbie's center finally moves off-shore.

That's like 16-18 hours on shore if the 18z were to verify.

[Aric Dunn]

Ive noticed the low clouds deck around the center is beginning to thicken and the convection on the side is slowly getting closer. could see a burst near the center over the next hours.

[Aric Dunn]

Also there is ship not too far to the NW of the center reporting sustained of 52mph.

[brunota2003]

The next mission will be this evening with plane departing at 6:45 PM EDT or 5:45 PM CDT.

FLIGHT ONE -- TEAL 70 --
A. 25/0000Z, 0600Z
B. AFXXX 0304A CYCLONE
C. 24/2245Z
D. 27.5N 88.2W
E. 24/2300Z TO 25/0600Z
F. SFC TO 10,000 FT

Here very shortly! Take off: 6:45 pm EDT Time on station: 7 pm EDT to 2 am EDT. First fix: 8 pm EDT.

That is a very short flight!

[Flakeys]

Not much wind in Citrus County. But a TON of rain.

[brunota2003]

Also there is ship not too far to the NW of the center reporting sustained of 52mph.

They better watch their heads, recon is taking off here soon and they might wind up with a dropsonde landing on them!

[Dean4Storms]

Also there is ship not too far to the NW of the center reporting sustained of 52mph.

The NW Quad is where the highest flight level winds were located by Recon. Wonder if this is due to the strong ridge.

[Aric Dunn]

Also there is ship not too far to the NW of the center reporting sustained of 52mph.

The NW Quad is where the highest flight level winds were located by Recon. Wonder if this is due to the strong ridge.

well its the only place that has convection close to the center although weak. also since it stalled for the most part any quad could produce the strongest winds within convection close to the center that might form.

[thetruesms]

The NHC bit on one solution, and the other turned out to be closer to the truth. The cone represents where the center will be 66% of the time. The other 34% of the time the center goes out of the cone. Obviously, though, that 34% is usually further along the track (Day 4 or 5) than this time's.

Actually, the size of the cone is set so that the percentage is the same at all time steps.

Yes, but recent advances in errors typically keep the cyclone within the 3 day cone (they use the last ten years, don't they?)...whereas you'd be more likely to see it go outside of the cone in the 4 to 5 day time frame.

Okay, I see what you're saying now, misread it. I had previously thought you were saying the percentage split was different for different times.

Yes, since the cone is determined by recent statistics (5 years, actually, not 10), if track forecasting is improving, you would actually expect greater than 2/3 of the points to be within the cone. Although what percentage that actually ends up being depends on the improvement in forecasting at that time step. So, while it might seem intuitive that it would be outside the cone at long ranges more often, it might actually be the opposite if long-range track forecasting is improving at a greater rate than short-term forecasting. To be honest, I really don't know off the top of my head where track forecasting is improving the most, so I can't accurately speak to it.