Rising GF99 after surfacing???

[rsingler]

Why does my Shearwater cloud show GF99 continuing to rise for two minutes after I surface?
The log apparently clocks the "end dive GF99" the moment my depth hits zero. But the graph shows it continuing to rise before offgassing makes it fall.
Which is correct? The logged end dive GF99 is not just a few percent lower than the max GF99 graphed; it's significantly different. Where was my actual risk?

When I surfaced after a 100' dive, SW logs 34%

But one minute later...

One minute later, the graph shows GF99 at 47%.
That jump is NOT small potatoes.
At higher N2 saturations, that difference could be between what I think is safe and what to me is risky.
Which is correct?
Why would GF99 rise after surfacing?
Is this a bug?
Is this a graphing lag?
@Shearwater

BTW, Shearwater, that blue "Full Screen Display" button is always in the worst place for looking at GF99. Might it be moved, please?

 

[Alekseolsen]

I can't explain why, but I do find the same in several of my dives, all I could find (from a brief check) involve some sort of Nitrox.

 

[Fastmarc]

I found a few under V81 that rose a litlle after end surface was 'captured?', but just at most a couple of %. None under the current version. I'm on AIR.

 

[inquis]

Initially, I thought it might be that a change in weather dropped ambient from what it was pre-dive, but a normal thunderstorm would only increase the GF by about 0.1%. Bug perhaps?

 

[rsingler]

I suspect it's a tabulation lag that is reflected in the graph. What I haven't been able to document is whether the displayed SurGF that guides my recreational diving correlates with the GF99 on surfacing, or with the max GF99 graphed a minute or two later.

With this surprising jump after surfacing from this average deep dive, it's no longer a minor dive log anomaly, but a question of actual calculated gas loading.

Gas permitting, on repetitive rec dives I linger U/W at the ten foot level until my SurGF is well below the 70 that is my GFHi. And on finishing deco, I'd hate to be surfacing at 70, only to find my GF99 indicating 13% higher after a minute or two as in the example above.
I don't dive GF50/83. I dive GF50/70.
After 40 years of diving, I've never been bent.
I don't want to start now.

I'm really hoping Shearwater weighs in on this...

 

[L13]

If it works like it "should", GF99 on surfacing <= SurfGF immediately prior to final ascent and should start dropping (slowly) immediately after surfacing.

 

[rjack321]

Maximum bubbles scores are 30mins to 2hrs after surfacing depending on the dive and which tissues are loaded. So the drop is actually rather fast/abrupt.

 

[L13]

Maximum bubbles scores are 30mins to 2hrs after surfacing depending on the dive and which tissues are loaded. So the drop is actually rather fast/abrupt.

The drop in GF? Or the drop in bubbles? Or the drop in risk?

 

[rsingler]

I started looking at other dives...
This was a CCR dive to 130' for 90 min with modest deco.
GF99 on surfacing: 42%

GF99 two minutes later: 56%

But logged end dive GF? 28% Huh?

I'm an old fashioned guy that keeps a paper log, with pertinent data that I pull from the computer and from Shearwater Cloud.
Do I have to start inspecting every GF99 graph now to know what my real surfacing GF was? It's what I use (together with how I feel) to gauge what my personal GF should be. I need to be able to trust the numbers.

 

[Fastmarc]

Is this present in all firmware versions?
I see this is V84. The first one you mentioned was the current frimware?