ATL: Tropical Storm Bertha RECON Discussion

[CrazyC83]

92 kts flight-level. 85% reduction = 78 kts

I thought it is a 90% reduction at 700mb? 92 kt would translate to 83 kt at that level (supports 80 kt intensity).

[KWT]

Yep supports 80kts however surface estimates are only in the 65kts sort of range, depends on what you believe I suppose is more likely!

[Matt-hurricanewatcher]

Looks like it has a central pressure of 975.9mbs according to recon, so about 976mbs then!

Look like my guest what not bad. Lets see if we find some 80-85 knot surface winds.

[CrazyC83]

Yep supports 80kts however surface estimates are only in the 65kts sort of range, depends on what you believe I suppose is more likely!

What is that column between the direction/winds and the SFMR?

[KWT]

Temps and dew points I believe?

Matt, what I've seen supports 80kts, not sure about 85kts mind you just yet we need to see those surface estimates increase but we do still have to sample the strongest quadrant typically, the NE side.

[Thunder44]

Max FL Wind they found so far in SE Eyewall was 99kts. They are flying around 3000 meters. So reduction is 90%. Surface winds would be 89kts. Cat 2.

Although SFMR reports don't support this upgrade yet.

[HURAKAN]

[Chacor]

171700 2820N 06135W 6969 03041 9958 +069 +050 222092 099 066 010 00

222092 and 099, what's the difference? Both are FL winds, right?

[RL3AO]

171700 2820N 06135W 6969 03041 9958 +069 +050 222092 099 066 010 00

222092 and 099, what's the difference? Both are FL winds, right?

92 = 30 sec avg
99 = 10 sec gust

[KWT]

Also that 99kts was only for a 10 second sample, the 30 second smaple was at 92kts which is why we are using that for the reduction rather then the 99kts and as you say surface estimates are only around 65-70kts.

[CrazyC83]

Here is what we have now (surface estimates):

Flight level - 83 kt (SE quad)
SFMR - 72 kt (NW quad)

That likely will mean holding it at 75 kt for now, although 80 kt is possible.

[Matt-hurricanewatcher]

Max FL Wind they found so far in SE Eyewall was 99kts. They are flying around 3000 meters. So reduction is 90%. Surface winds would be 89kts. Cat 2.

Although SFMR reports don't support this upgrade yet.

This suggests that this system has been 5-10 knots stronger then what the nhc has said it was. So it was possible it did reach cat3 during its second peak...

[HURAKAN]

Crazy, they haven't investigated the NE quadrant yet.

[CrazyC83]

Crazy, they haven't investigated the NE quadrant yet.

OK I corrected the estimates.

[Thunder44]

Max FL Wind they found so far in SE Eyewall was 99kts. They are flying around 3000 meters. So reduction is 90%. Surface winds would be 89kts. Cat 2.

Although SFMR reports don't support this upgrade yet.

This suggests that this system has been 5-10 knots stronger then what the nhc has said it was. So it was possible it did reach cat3 during its second peak...

That report is also 10 second gust. So I don't know what they are going to do with it.

[KWT]

They would go for the longer time sample because NHC uses 1 min sustained winds.
Indeed it would probably be a split between surface estimates and upper winds found, probably would be around 80kts, maybe 85kts if anything higher is found in NE quadrants.

[Thunder44]

KWT, the 2pm Advisory says Recon reported back a pressure of 977mb. If that's what in the VDM...

[KWT]

Yep 977mbs, a little bit above the estimate but then are just estimates anyway. I just wonder what we will find once recon goes into the NE quadrant of the hurricane?

[Derek Ortt]

Also that 99kts was only for a 10 second sample, the 30 second smaple was at 92kts which is why we are using that for the reduction rather then the 99kts and as you say surface estimates are only around 65-70kts.

you use the 10-second winds for reduction, not the 30 second

[KWT]

Looks like recon is going to make another run at the NE eyewall fairly shortly, this will give us a good indication of Bertha's strength.