Gustav Recon Discussion

[CrazyC83]

Dropsonde in the supposed "eyewall" seems to have gotten spun around a bit...surface reported 935mb/16kts, and looking at the wind profile it probably got spun out of the eyewall somewhere between 700 and 850mb...

That happened with Felix when he was bombing (in fact, it spun a whole loop around before landing in the eye).

[physicx07]

Dropsonde in the supposed "eyewall" seems to have gotten spun around a bit...surface reported 935mb/16kts, and looking at the wind profile it probably got spun out of the eyewall somewhere between 700 and 850mb...

Wow! We can only hope it's not really that low.

[CrazyC83]

Dropsonde in the supposed "eyewall" seems to have gotten spun around a bit...surface reported 935mb/16kts, and looking at the wind profile it probably got spun out of the eyewall somewhere between 700 and 850mb...

Wow! We can only hope it's not really that low.

That would be well below the original dropsonde and extrapolations. I wouldn't be surprised though.

[CrazyC83]

Dropsonde reading confirmed at 116 kt, so it is definitely a Cat 4 now.

[WindRunner]

Dropsonde in the supposed "eyewall" seems to have gotten spun around a bit...surface reported 935mb/16kts, and looking at the wind profile it probably got spun out of the eyewall somewhere between 700 and 850mb...

That happened with Felix when he was bombing (in fact, it spun a whole loop around before landing in the eye).

Haha I think I remember that.

And yes, looking at the extra wind data it seems that the wind profile is as follows:
700mb - 315/78kts
723mb - 325/88kts
736mb - 325/75kts
757mb - 330/98kts
788mb - 305/120kts
850mb - 295/114kts
862mb - 290/115kts
872mb - 290/121kts
889mb - 285/121kts hold on....

Actually, I'm now realizing that this drop reads 935mb/116kts!!!

EDIT: to finish the wind profile...
899mb - 280/125kts
909mb - 275/118kts
922mb - 275/121kts
935mb - 265/116kts

Somehow MBL wind of only 112kts, which makes me doubt these specific readings.

[physicx07]

Dropsonde reading confirmed at 116 kt, so it is definitely a Cat 4 now.

Yes, and that was in the weaker SW portion of the storm.

[WindRunner]

Man, I actually was planning on going out and doing some shopping this afternoon...looks like that's getting blown out of the water!

[cycloneye]

Here is a detailed version of the VDM that just came out.

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 17:24Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)
Storm Number & Year: 07L in 2008
Storm Name: Gustav (in the North Atlantic basin)
Mission Number: 15
Observation Number: 03
A. Time of Center Fix: 30th day of the month at 16:54:50Z
B. Center Fix Coordinates: 21°27'N 82°21'W (21.45N 82.35W) (View map)
B. Center Fix Location: 109 miles (176 km) to the SE (128°) from Pinar del Río, Cuba.
C. Minimum Height at Standard Level: 2,638m (8,655ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 105kts (~ 120.8mph)
E. Location of the Estimated Maximum Surface Wind: 12 nautical miles (14 statute miles) to the NE (50°) of center fix
F. Maximum Flight Level Wind Inbound: From 140° at 141kts (From the SE at ~ 162.3mph)
G. Location of Maximum Flight Level Wind Inbound: 18 nautical miles (21 statute miles) to the NE (51°) of center fix
H. Minimum Sea Level Pressure: 945mb (27.91 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,048m (10,000ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 3,042m (9,980ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 5°C (41°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Closed Wall
M. Eye Shape & Diameter: Circular with a diameter of 30 nautical miles (35 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 140kts (~ 161.1mph) in the northeast quadrant at 16:49:30Z
Maximum Surface (likely estimated by SFMR) Wind Outbound: 108kts (~ 124.3mph) in the southwest quadrant at 16:58Z

[Chris_in_Tampa]

Here is why the dropsonde that measured 935mb seems to be wrong.



See those coords well away from the flight path? That is where the sonde landed, in the eyewall, with 133 mph winds. That makes no sense to have a pressure like that where it landed. Something must have been damaged on the way down so that it reported that very wrong pressure. The 945mb sonde dropped in the eye. Where that sonde dropped is noted where the wind shift occurred.

Although, this is my opinion that the 935mb is invalid.

[WindRunner]

Here is why the dropsonde that measured 935mb seems to be wrong.



See those coords well away from the flight path? That is where the sonde landed, in the eyewall, with 133 mph winds. That makes no sense to have a pressure like that where it landed. Something must have been damaged on the way down so that it reported that very wrong pressure. The 945mb sonde dropped in the eye. Where that sonde dropped is noted where the wind shift occurred.

Although, this is my opinion that the 935mb is invalid.

I agree...although in terms of its location relative to the flight path, I see no problem with that...the strong winds should blow it around about that much, and the slow backing of the wind as it dropped supports about that much rotation around the eyewall as well. I think the winds are fine, I'm just not sure why the pressure would read funny. The pressure IS fine when the sonde leaves the plane (first wind report was at 698mb, the flight level at that time), but I don't see any horrible discontinuities elsewhere. Personally, I'll wait the ~40 minutes to the next fix before making any wholehearted suggestions otherwise.

[gotoman38]

Interesting that they're flying over Cuba's landmass - they usually avoid flying over ANY land, especially Cuba (except in transit) - any ideas on this?

[CrazyC83]

Last data supports 130 kt intensity.

[WindRunner]

Last data supports 130 kt intensity.

Yeah, but with the landfall and frictional effects I wouldn't be surprised if they left it as-is at 125kts.

Also interesting to note that FL winds supported hurricane-strength winds for about half the width of the Cuban island on the most recent outbound leg, using the traditional reductions. In reality, near-hurricane force winds are probably being felt along a line starting at Havana and running appx. SErd.

[CrazyC83]

137 kt at 13,000 feet (620mb) is what at the surface?

[gotoman38]

Cuban landfall area

[CrazyC83]

Looks like the VDM missed the eye since the 941 is not lined up with the clearing.

[cycloneye]

Here is the detailed recent VDM:

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 22:30Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)
Storm Number & Year: 07L in 2008
Storm Name: Gustav (in the North Atlantic basin)
Mission Number: 15
Observation Number: 17
A. Time of Center Fix: 30th day of the month at 21:54:10Z
B. Center Fix Coordinates: 22°21'N 83°05'W (22.35N 83.0833W) (View map)
B. Center Fix Location: 39 miles (63 km) to the E (98°) from Pinar del Río, Cuba.
C. Minimum Height at Standard Level: 2,604m (8,543ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 53kts (~ 61.0mph)
E. Location of the Estimated Maximum Surface Wind: 41 nautical miles (47 statute miles) to the NW (315°) of center fix
F. Maximum Flight Level Wind Inbound: From 66° at 123kts (From the ENE at ~ 141.5mph)
G. Location of Maximum Flight Level Wind Inbound: 14 nautical miles (16 statute miles) to the NW (320°) of center fix
H. Minimum Sea Level Pressure: 941mb (27.79 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 10°C (50°F) at a pressure alt. of 3,052m (10,013ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 3,048m (10,000ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 6°C (43°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Closed Wall
M. Eye Shape & Diameter: Circular with a diameter of 24 nautical miles (28 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind Outbound: 123kts (~ 141.5mph) in the southeast quadrant at 21:57Z
Remarks Section - Additional Remarks...
MAX FL WIND 143 NE QUAD 2014Z
CENTER EYE MOVING ONSHORE

[Nexus]

Interesting that they're flying over Cuba's landmass - they usually avoid flying over ANY land, especially Cuba (except in transit) - any ideas on this?

They are allowed to fly over land during the day. I do wonder what the cutoff for "daytime" is though, being the center is onshore now, and it's getting dark soon.

[WindRunner]

Interesting that they're flying over Cuba's landmass - they usually avoid flying over ANY land, especially Cuba (except in transit) - any ideas on this?

They are allowed to fly over land during the day. I do wonder what the cutoff for "daytime" is though, being the center is onshore now, and it's getting dark soon.

It really doesn't matter, as it'll still technically be dusk/pre-sunset around when they make their last fix of the flight, at 00z. After that, they'll leave the storm and not come back until much later (next fix scheduled for 06z) and the center should be out over water by that point anyway.

[CrazyC83]

NOAA plane just reported 127 kt at about 650mb - in the SE quad.