Hurricane Dean Recon Discussion

[DESTRUCTION5]

Wow..I had a dream last night I was dropping dropsonds outside of the plane door... This storm is taking up my life! lol

Spit all over the Friggin place...LOL

[sevenleft]

964MB...Closed, but ragged eyewall.

[Swimdude]

I think Dean is stronger than most of us anticipated this morning. Winds are still around 100-105 mph. That's impressive, considering the dry air that Dean had to inevitably slam through on this part of his journey.

[cycloneye]

000
NOUS42 KNHC 171530
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT FRI 17 AUGUST 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 18/1100Z TO 19/1100Z AUGUST 2007
TCPOD NUMBER.....07-085

I. ATLANTIC REQUIREMENTS
1. HURRICANE DEAN
FLIGHT ONE FLIGHT TWO
A. 18/1200,1800Z A. 19/0000, 0600Z
B. AFXXX 0604A DEAN B. AFXXX 0704A DEAN
C. 17/100Z C. 18/2200Z
D. 15.8N 69.0W D. 16.7N 72.3W
E. 18/1100Z TO 18/1800Z E. 18/2300Z TO 19/0600Z
F. SFC TO 10,000 FT F. SFC TO 10,000FT

FLIGHT THREE
A. 19/1200Z
B. AFXXX 0804A DEAN
C. 17/0930Z
D. BOUY DROP MISSION--12 BOUYS CNTR NEAR 20N 84W
E. 19/1200Z TO 19/1800Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES. BEGIN 2 A
DAY GIV MISSIONS AT 20/0000Z.



Here is the plan of the day product about the next missions.

[Extremecane]

so whens the next mission?

[cycloneye]

so whens the next mission?

A. 18/0000,0600Z
B. AFXXX 0404A DEAN
C. 17/2200Z
D. 15.1N 64.9W
E. 17/2300Z TO 18/0600Z
F. SFC TO 10,000 FT


This evening into the overnight hours.Plane departs around 6:00 PM EDT.

[Chris_in_Tampa]

Time (Z) / Coordinates / Acft. Static Air Press. / Acft. Geo. Hgt. / Extrap. Sfc. Press. / Flt. Lvl. Wind (30s) / Peak (10s) Flt. Lvl. Wind / SFMR Peak (10s) Sfc. Wind / SFMR Rain Rate
16:01:30 14.75N 62.83W 694.6 mb 2,849 m 959.6 mb From 143° (SE) at 38 kts (43.7 mph) 45 kts (~ 51.7 mph) 51 kts 5 mm/hr
16:02:00 14.77N 62.82W 695.7 mb 2,855 m 963.2 mb From 144° (SE) at 63 kts (72.4 mph) 75 kts (~ 86.2 mph) 86 kts 5 mm/hr
16:02:30 14.78N 62.78W 697.0 mb 2,865 m 969.1 mb From 151° (SSE) at 93 kts (106.9 mph) 100 kts (~ 115.0 mph) 96 kts 9 mm/hr
16:03:00 14.80N 62.77W 693.5 mb 2,951 m 975.7 mb From 151° (SSE) at 113 kts (129.9 mph) 115 kts (~ 132.2 mph) 96 kts* 10 mm/hr*

Vortex message coming in soon.

[Brent]

Major Hurricane???

URNT12 KNHC 171614
VORTEX DATA MESSAGE AL042007
A. 17/15:59:50Z
B. 14 deg 40 min N
062 deg 54 min W
C. NA mb 2787 m
D. 69 kt
E. 215 deg 006 nm
F. 307 deg 065 kt
G. 215 deg 005 nm
H. 963 mb
I. NA C/ 3040 m
J. 18 C/ 3027 m
K. 11 C/ NA
L. CLOSED WALL
M. CO17-32
N. 12345/7
O. 0.02 / 2 nm
P. AF304 0404A DEAN OB 22
MAX FL WIND 115 KT NE QUAD 16:03:00 Z
INNER EYE OPEN SW-S

[JTD]

Major Hurricane???

URNT12 KNHC 171614
VORTEX DATA MESSAGE AL042007
A. 17/15:59:50Z
B. 14 deg 40 min N
062 deg 54 min W
C. NA mb 2787 m
D. 69 kt
E. 215 deg 006 nm
F. 307 deg 065 kt
G. 215 deg 005 nm
H. 963 mb
I. NA C/ 3040 m
J. 18 C/ 3027 m
K. 11 C/ NA
L. CLOSED WALL
M. CO17-32
N. 12345/7
O. 0.02 / 2 nm
P. AF304 0404A DEAN OB 22
MAX FL WIND 115 KT NE QUAD 16:03:00 Z
INNER EYE OPEN SW-S

I would think so. Cat 4 winds at flight level would translate to at least cat 3 at the surface.

Maybe 120 mph? Not sure if that's the exact conversion.

[CrazyC83]

We have a major hurricane now! I would go 100 kt/963mb at this point...

[SouthFloridawx]

Yeah isn't the conversion @ .75 of the flight level?

[Chris_in_Tampa]

SFMR said 110 mph surface wind. The 11AM advisory used a 90% reduction it seemed for flight level, so 115 knot flight level might be 119 mph, so about 120 mph. They might split the difference and say 115 mph at 2PM EDT though. Would seem to be a cat 3, even though the pressure is a little high. (would expect about 960mb or lower)

Although the HDOB extrap estimate was about 959 mb. But that it not always valid and the NHC officially went with 963 mb for the vortex.

[JonathanBelles]

I'm going 105kt 963mb, we have the first Major Hurricane of the Atlantic Hurricane Season.

[RL3AO]

Yeah isn't the conversion @ .75 of the flight level?

.9

[SouthFloridawx]

Yeah isn't the conversion @ .75 of the flight level?

.9

Thanks...

[Aric Dunn]

key thing is the concentric eyewalls!!... ERC is most likely starting and when it complete we may see some much much further strengthening

[mf_dolphin]

We also have 2 eyewall according to the vortex message. One at 17 and one at 32.

[Aric Dunn]

We also have 2 eyewall according to the vortex message. One at 17 and one at 32.

yeah exactly.. !! that would be concentric eyewalls.. which indicates a possible ERC

[WxGuy1]

Yeah isn't the conversion @ .75 of the flight level?

.9

I think the reduction is typically 10% if flight-level is 700mb (so sfc ~ 0.9 x FL-wind), and 15-20% of flight-level if it's 850mb. In this case, it appears that flight level is approx 700mb (~3000m ASL), so the 10% reduction can be used.

That said, this reduction factor is NOT valid for every storm! Studies have shown that, for some tropical cyclones, the reduction is closer to 30-40% (meaning that sfc winds are only 60-70% of the measured 700mb winds). In addition, the reduction varies across the storms -- for example, the reduction may well be quite different in different parts of the storms! Looking at some studies, the FLx0.9 sfc equivalent is on the higher-end of measurements, with many measurements showing that it's more on the high said than on the low side.

The ratio of the surface to 700 mb wind (R700) is 0.78 in the outer vortex and 0.91 in the eyewall. Note that the former figure is not far from Powell and Black's (1990) estimate of 0.73.

--> See Eyewall Wind Profiles in Hurricanes Determined By GPS Dropwindsondes (Franklin, Black, and Valde 2000)

I'm sure some folks are more up-to-date when it comes to eyewall wind profile studies. The point of this is that there is no single "best" reduction factor! So, use the "rule-of-thumb" factor with a big grain of salt!

[drezee]

124 kts at flt

171330 1457N 06313W 6963 02889 9752 +089 +089 108116 124 098 036 03