ATL: DANNY - Remnants - Discussion

[Gustywind]

From Accuweather Experts

Tropical Storm Danny Churns West

Aug 19, 2015; 12:00 AM ET Tropical storm Danny will continue to strengthen as it spins west over the Central Atlantic.

http://videowall.accuweather.com/detail ... Start=true

[Slughitter3]

DATE/TIME LAT LON CLASSIFICATION STORM
19/0545 UTC 11.3N 39.2W T2.5/2.5 DANNY
18/2345 UTC 11.0N 38.3W T2.5/2.5 DANNY
18/1745 UTC 11.1N 37.0W T2.0/2.0 04L
18/1145 UTC 10.2N 35.9W T2.0/2.0 96L
18/0545 UTC 9.5N 34.4W T1.5/1.5 96L
18/0000 UTC 9.3N 33.2W T1.0/1.0 96L
17/1745 UTC 9.8N 32.8W T1.0/1.0 96L
17/1145 UTC 9.6N 31.0W T1.0/1.0 96L
17/0545 UTC 9.8N 29.9W T1.0/1.0 96L

Could someone point me in the direction of explaining what all this actually means? I know that it is important but I have no understanding of it whatsoever. Thank you!

-Shawn
Huntingtown, MD

[Evil Jeremy]

DATE/TIME LAT LON CLASSIFICATION STORM
19/0545 UTC 11.3N 39.2W T2.5/2.5 DANNY
18/2345 UTC 11.0N 38.3W T2.5/2.5 DANNY
18/1745 UTC 11.1N 37.0W T2.0/2.0 04L
18/1145 UTC 10.2N 35.9W T2.0/2.0 96L
18/0545 UTC 9.5N 34.4W T1.5/1.5 96L
18/0000 UTC 9.3N 33.2W T1.0/1.0 96L
17/1745 UTC 9.8N 32.8W T1.0/1.0 96L
17/1145 UTC 9.6N 31.0W T1.0/1.0 96L
17/0545 UTC 9.8N 29.9W T1.0/1.0 96L

Could someone point me in the direction of explaining what all this actually means? I know that it is important but I have no understanding of it whatsoever. Thank you!

-Shawn
Huntingtown, MD

This is the Dvorak Classification Technique, a way of quantifying a storm's intensity based off of satellite images. The technique is based on the overall appearance of the storm, tightness of circulation, and shape/size of it's Central Dense Overcast (convection). Higher the number, more intense the storm.

Happy Hurricane season everyone! We're well underway now!

[SouthDadeFish]

Looks like dry air got ingested into the core of Danny overnight. The low level center is now exposed on visible satellite imagery. It remains to be seen how long it takes for this dry air to mix out and further intensification won't happen until it does so.

[Gustywind]

DATE/TIME LAT LON CLASSIFICATION STORM
19/0545 UTC 11.3N 39.2W T2.5/2.5 DANNY
18/2345 UTC 11.0N 38.3W T2.5/2.5 DANNY
18/1745 UTC 11.1N 37.0W T2.0/2.0 04L
18/1145 UTC 10.2N 35.9W T2.0/2.0 96L
18/0545 UTC 9.5N 34.4W T1.5/1.5 96L
18/0000 UTC 9.3N 33.2W T1.0/1.0 96L
17/1745 UTC 9.8N 32.8W T1.0/1.0 96L
17/1145 UTC 9.6N 31.0W T1.0/1.0 96L
17/0545 UTC 9.8N 29.9W T1.0/1.0 96L

Could someone point me in the direction of explaining what all this actually means? I know that it is important but I have no understanding of it whatsoever. Thank you!

-Shawn
Huntingtown, MD

This is the Dvorak Classification Technique, a way of quantifying a storm's intensity based off of satellite images. The technique is based on the overall appearance of the storm, tightness of circulation, and shape/size of it's Central Dense Overcast (convection). Higher the number, more intense the storm.

Happy Hurricane season everyone! We're well underway now!

Thanks for this explanation Here is a complete document http://www.nhc.noaa.gov/pdf/06velden.pdf


The Dvorak Technique Explained http://www.ssd.noaa.gov/PS/TROP/dvorak.html



The Dvorak technique is a method using enhanced Infrared and/or visible satellite imagery to quantitatively estimate the intensity of a tropical system. Cloud patterns in satellite imagery normally show an indication of cyclogenesis before the storm reaches tropical storm intensity. Indications of continued development and/or weakening can also be found in the cloud features. Using these features, the pattern formed by the clouds of a tropical cyclone, expected systematic development, and a series of rules, an intensity analysis and forecast can be made. This information is then standardized into an intensity code.
Full Satellite Intensity Estimate Code:

EXAMPLE: Ttt/cc/Lvv/xxhrs
Where:
T - Tropical (ST is used for Sub-Tropical systems)
tt - Satellite Derived T-Number
cc - System Current Intensity T-Number
L - Past Change
D - Developing
W - Weakening
S - Little or No change (Same)
vv - Amount of Past change in T-Number
xx - Hours over which the change was observed


EXAMPLE: T3.5/3.5/D1.0/24hrs


Translation: The system appears on satellite imagery to be T-Number 3.5 storm. This value matches the Current intensity generating about 55 knots of sustained winds. The storm has developed a full T-Number in the past 24 hours increasing the wind speeds from 35 to 55 knots. The atmospheric pressure in the center of the storm has also lowered.
EXAMPLE: T4.5/5.5/W1.0/24hrs


Translation: The system appears on satellite imagery to be T-Number 4.5 storm. The Current intensity is still 5.5 and the system is still generating sustained winds of about 100 knots. As a forecast tool, the Dvorak technique is showing a weakening trend and the likelihood of a lowering CI within the next 24hours.

Our coordination call information only contains the satellite Derived T-Number and the Current intensity (Ttt/cc).


Additional Information:
•Dvorak Current Intensity Chart
•Dvorak Tropical Cyclone Intensity Estimation Technique PDF
•Tropical Cyclone Intensity Analysis Using Satellite Data (Original Dvorak Paper from 1984)



Dvorak Current Intensity Chart http://www.ssd.noaa.gov/PS/TROP/CI-chart.html




CI MWS MWS MSLP MSLP Saffir-Simpson
Number (Knots) (MPH) (Atlantic) (NW Pacific) Category
1 25 KTS 29 MPH (Approximate)
1.5 25 KTS 29 MPH
2 30 KTS 35 MPH 1009 mb 1000 mb
2.5 35 KTS 40 MPH 1005 mb 997 mb
3 45 KTS 52 MPH 1000 mb 991 mb
3.5 55 KTS 63 MPH 994 mb 984 mb
4 65 KTS 75 MPH 987 mb 976 mb 1 (64-83 KTS)
4.5 77 KTS 89 MPH 979 mb 966 mb 1 (64-83 KTS); 2 (84-96 KTS)
5 90 KTS 104 MPH 970 mb 954 mb 2 (84-96 KTS); 3 (97-113 KTS)
5.5 102 KTS 117 MPH 960 mb 941 mb 3 (97-113 KTS)
6 115 KTS 132 MPH 948 mb 927 mb 4 (114-135 KTS)
6.5 127 KTS 146 MPH 935 mb 914 mb 4 (114-135 KTS)
7 140 KTS 161 MPH 921 mb 898 mb 5 (136+ KTS)
7.5 155 KTS 178 MPH 906 mb 879 mb 5 (136+ KTS)
8 170 KTS 196 MPH 890 mb 858 mb 5 (136+ KTS)


CI -- Current Intensity
MWS -- Mean Wind Speed
MSLP -- Mean Sea Level Atmospheric Pressure in Millibars


More Information about the Saffir-Simpson Hurricane Categories

[msbee]

You really can't make such big forecast changes over a 1 or 2 hour time period because of the way the satellite image changed. In most cases you just have to let this play out for at least 12 hours at a time before you can make meaningful forecast changes. Nothing of importance can usually be discerned over a shorter time period.

Thank you

[Steve H.]

Thunderstorms and convection have decreased this morning. Also, the ridge is pushing down on him. Doesn't look as good as it did last night IMO.

[Slughitter3]

Thank you Evil Jeremy and Gustywind, I really appreciate the information.

[Gustywind]

Thank you Evil Jeremy and Gustywind, I really appreciate the information.

You are welcomed

[tolakram]

Live visible loop: http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=tropical/tropical_ge_4km_visir2_floater_1&width=640&height=480&number_of_images_to_display=12

IMO Danny looks worse this morning and I see some high clouds streaming north and northeast. Shear is analyzed at 5kts right over Danny but 10 and 15 just to the north and west.

[Alyono]

may be seeing why global models are superior to old statistical models

[tropicwatch]

Not scheduled yet.

[OURAGAN]

Danny is more South 11,1N/ 40,7W

[hurricaneCW]

The dry air is sucking the life out of Danny. There may not be any convection around the circulation at this rate.

[tailgater]

Just starting to show his face on the GHCC site.

[Ntxw]

It needs to build thunderstorms. Otherwise it will get exposed to the elements and we get the naked swirl, I was wondering yesterday when it was moving west and rising air (KW) was moving east if he would start to struggle. Albeit wasn't expected for another 1-2 days.

Still though short term changes, let see if he can fire them off later today and wrap them back in.

[alienstorm]

It looks like the dry air is starting to do a number on Danny, we will see what the next 12 hrs has but if this trends continue then I dont think it will survive the intrusion.

[Frank2]

Doesn't looks as impressive this morning - still part of the ITCZ:

http://www.ssd.noaa.gov/goes/east/tatl/vis-animated.gif

[NCSTORMMAN]

http://earth.nullschool.net/#current/wind/isobaric/850hPa/orthographic=-44.36,11.96,2048 realtime. and my bedtime.

If that estimate is true then this is a borderline hurricane?

[SFLcane]

Danny might be on life support circulation appears to be decoupling. Nothing amazes me though from this basin anymore. Can't even get a moderate cane. Rough battle ahead.