ATL: ARTHUR - Post-Tropical - Discussion

[RL3AO]

Quite a dropsonde.

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 115° (from the ESE)
- Wind Speed: 90 knots (104 mph)

[CrazyC83]

Based on that dropsonde, the SFMR and other data, I would put the intensity at 85 kt right now.

[brunota2003]

Bold!!! lol

Well, thanks, I guess? Hah. In all seriousness though, that "moat" people were saying was because of dry air I've seen in EPac systems right before they RI...I'm pretty confident it's going to at least attempt RI, but land may (thankfully) keep it in check. Check out my post a couple posts ago, I showed one of the systems that ran from 65 knots to a Cat 4 in less than 24 hours after that gap appeared. NOT saying that'll be the case here, but definitely worth keeping an eye on.

[Aric Dunn]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

that appears match up with doppler estimates..

[cycloneye]

URNT12 KNHC 031908
VORTEX DATA MESSAGE AL012014
A. 03/18:41:40Z
B. 33 deg 02 min N
078 deg 12 min W
C. 700 mb 2902 m
D. 82 kt
E. 071 deg 14 nm
F. 141 deg 82 kt
G. 066 deg 19 nm
H. EXTRAP 977 mb
I. 10 C / 3049 m
J. 13 C / 3052 m
K. NA / NA
L. CLOSED
M. C30
N. 12345 / 07
O. 0.02 / 1 nm
P. AF301 1101A ARTHUR OB 19
MAX FL WIND 84 KT 174 / 34 NM 17:06:00Z
SLP EXTRAP FROM 700 MB

[Hurricaneman]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

If true this will probably be upgraded to a cat 2 hurricane and with possible further strengthening cat 3 can't be ruled out

and also those residents of SE New England should continue to monitor the progress of this as the NHC has said

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

[ravyrn]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

Where do you find this data at? Also, was that a gust or sustained?

[CrazyC83]

Should a Tropical Storm Watch (at least, if not a Hurricane Watch) be posted for the Cape and Islands?

[Fego]

Kind of more to the west than the official path.

[SunnyThoughts]

So the vortex message says 84kt flight level...but the dropsonde says 89knt at the surface?

[TheAustinMan]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

Where do you find this data at? Also, was that a gust or sustained?

I used the live TropicalAtlantic recon program (with the Google Earth plugin) which automatically decodes the recon data. Not sure if gusts or sustained, depends on what dropsondes typically measure.

[RL3AO]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

Also, was that a gust or sustained?

Remember these things are falling after being dropped from an airplane. They don't get a chance to measure sustained winds only near-instantaneous gusts. Derek Ortt used to talk about taking 90%(?) of the mean boundary layer winds from dropsondes. In this case that would be 90% of 90kt or 81kt sustained wind.

[Kingarabian]

Kind of more to the west than the official path.

Looks like it hasn't executed the turn to the NE yet. Should be soon though.

[Aric Dunn]

Kind of more to the west than the official path.

Looks like it hasn't executed the turn to the NE yet. Should be soon though.

its wobbling....

[ravyrn]

TropicalAtlantic recon program (with the Google Earth plugin) which automatically decodes the recon data. Not sure if gusts or sustained, depends on what dropsondes typically measure.

Where can I find the raw dropsonde data? Is it reported on the NHC site? And thank you for the explanation RL3AO.

[Aric Dunn]

south port in the next hour going to get hit by that strong bad from the outter part of the eyewall.. no warnings out yet...

[Kingarabian]

Bold!!! lol

Well, thanks, I guess? Hah. In all seriousness though, that "moat" people were saying was because of dry air I've seen in EPac systems right before they RI...I'm pretty confident it's going to at least attempt RI, but land may (thankfully) keep it in check. Check out my post a couple posts ago, I showed one of the systems that ran from 65 knots to a Cat 4 in less than 24 hours after that gap appeared. NOT saying that'll be the case here, but definitely worth keeping an eye on.

Yes I saw your post. Makes a lot of sense. Would be devastating if it pulled a Kenneth.

I sometimes wonder if the dry air in the EPac is different from the one in the Atlantic. I see EPac systems working quite well with a lot of dry air around, and I see Atlantic storms cough and choke on the slightest bit of dry air.

[artist]

Dropsonde has recorded 89 knots (102 mph) at the surface. (1859 UTC)
987mb (29.15 inHg) Sea Level (Surface) 24.6°C (76.3°F) 24.5°C (76.1°F) 95° (from the E) 89 knots (102 mph)

Also, was that a gust or sustained?

Remember these things are falling after being dropped from an airplane. They don't get a chance to measure sustained winds only near-instantaneous gusts. Derek Ortt used to talk about taking 90%(?) of the mean boundary layer winds from dropsondes. In this case that would be 90% of 90kt or 81kt sustained wind.

speaking of Derek, from his twitter -

Derek Ortt @DerekOrtt · 3m latest ECMWF has a repeat of Isabel for Hatteras #Arthur Reply Replied to 0 times RetweetRetweetedRetweeted 0 times FavoriteFavoritedFavorited 0 times More
Embed Tweet
Derek Ortt @DerekOrtt · 5h if the current intensification continues, cat 2 almost certain. Cannot rule out cat 3 #Arthur

[windnrain]

So am I correct in assuming the NHC completely blew it by not issuing warnings by now? It's pretty clear that the eyewall of a borderline category 1-2 storm is getting mighty close to an unwarned area.

[RL3AO]

TropicalAtlantic recon program (with the Google Earth plugin) which automatically decodes the recon data. Not sure if gusts or sustained, depends on what dropsondes typically measure.

Where can I find the raw dropsonde data? Is it reported on the NHC site? And thank you for the explanation RL3AO.

Yes it is on NHC's site. However this will show the latest from the NOAA flight and the AF flight. If you just want the latest from the AF flight into the eye, use this.

ftp://tgftp.nws.noaa.gov/data/raw/uz/uznt13.knhc..txt