Why has the vertical instability in the Caribbean and tropical Atlantic been lower than average for the entire year?
http://www.ssd.noaa.gov/PS/TROP/TCFP/atlantic.html
Also, vertical instability is obviously an atmospheric phenomenon. So wouldn't one expect that it would change very rapidly because the weather changes rapidly? Its not like sea surface temperature anomalies, which one would expect to remain fairly unchanged over the span of weeks or months (the high amount of energy it takes to heat or cool water). But the graph clearly shows that the vertical instability over both the tropical atlantic and Caribbean has been below average for the whole year. Could it be due to positions and intensities of pressure systems such as Bermuda high?
Why has the vertical instability in the Caribbean been low
Moderator: S2k Moderators
Forum rules
The posts in this forum are NOT official forecasts 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. For official information, please refer to products from the National Hurricane Center and National Weather Service.
Why has the vertical instability in the Caribbean been low
0 likes
All posts by Dean_175 are NOT official forecasts 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.
- AJC3
- Admin
- Posts: 3891
- Age: 60
- Joined: Tue Aug 31, 2004 7:04 pm
- Location: West Melbourne, Florida
- Contact:
Re: Why has the vertical instability in the Caribbean been low
Dean_175 wrote:Why has the vertical instability in the Caribbean and tropical Atlantic been lower than average for the entire year?
http://www.ssd.noaa.gov/PS/TROP/TCFP/atlantic.html
Also, vertical instability is obviously an atmospheric phenomenon. So wouldn't one expect that it would change very rapidly because the weather changes rapidly? Its not like sea surface temperature anomalies, which one would expect to remain fairly unchanged over the span of weeks or months (the high amount of energy it takes to heat or cool water). But the graph clearly shows that the vertical instability over both the tropical atlantic and Caribbean has been below average for the whole year. Could it be due to positions and intensities of pressure systems such as Bermuda high?
First, let me point out that vertical instability was well below climatology all season throughout the entire Atlantic basin, including the subtropical Atlantic....
http://www.ssd.noaa.gov/PS/TROP/TCFP/atlantic.html
Next, let's look at how the parameter is calculated...
http://rammb.cira.colostate.edu/project ... enesis.asp
VERTICAL INSTABILITY: The vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment, for each 5 by 5 degree area.
Essentially there are two causes that would reduce the vertically averaged temperature difference in the basin:
1) Warmer than normal mid level temperatures
2) Drier than normal mid level air
Either one would serve to cap instability. My money is one number 1...for the reasons cited in the following post.
viewtopic.php?f=54&t=111917&p=2198256&hilit=WVBT#p2198256
0 likes
Re: Why has the vertical instability in the Caribbean been low
I think it has to do with the air being drier than normal in the upper atmosphere.
viewtopic.php?f=59&t=112106&start=120
viewtopic.php?f=59&t=112106&start=120
0 likes
- brunota2003
- S2K Supporter
- Posts: 9476
- Age: 33
- Joined: Sat Jul 30, 2005 9:56 pm
- Location: Stanton, KY...formerly Havelock, NC
- Contact:
Re:
brunota2003 wrote:Why not a combination of both?
If the air is warmer than normal, it would mean that the air can hold more water vapor than normal...so by raising the temperature, but not the levels of moisture, wouldn't that also create drier than normal air? Thus causing even stronger of a cap.
Good point. I did note that the upper level is warmer even in active seasons, but the air is wetter than right now. A combination of drier and warmer air suppresses thunderstorms, which leads to a cap.
0 likes
- AJC3
- Admin
- Posts: 3891
- Age: 60
- Joined: Tue Aug 31, 2004 7:04 pm
- Location: West Melbourne, Florida
- Contact:
My contention remains that if the primary cause was drier than normal mid level tropospheric air, then the signal would have mainfested itself in the WVBT. Not only did this not occur, but the opposite actually held true for the most part - on average, WVBTs were colder than nomral, an indication of greater than normal mid level tropospheric moisture. This argues for warmer than normal mid tropospheric air being the root cause of vertical instability being below normal this year. It will be interesting to see if any rigorous post-mortem is done toward this end.
0 likes
Re: Why has the vertical instability in the Caribbean been low
So, would that be a symptom of warming of the atmosphere on an increasing basis in line with Global Warming?
0 likes
- brunota2003
- S2K Supporter
- Posts: 9476
- Age: 33
- Joined: Sat Jul 30, 2005 9:56 pm
- Location: Stanton, KY...formerly Havelock, NC
- Contact:
Or it could be the mid-level temps were the same, but surface temps were actually cooler...but I don't think temps were cooler than average over the entire world
Thinking about it, I think our instability "averages" are too high. If data only goes back to 2000, and we've been in the upside cycle of hurricanes, of course the "averages" will be too high, because it does not incorporate the downside cycle. It has been over a decade since we entered the "up" cycle, perhaps we are starting to swing back into the "down" cycle?
If the times from 2000 - 2010, the vertical instability was "100", and that is the only time period we have, then the "average" is "100". So of course getting a reading of "20" is going to look extremely odd. But if the 100 year average is "50", then that "20" doesn't look so odd in the long run.
Thinking about it, I think our instability "averages" are too high. If data only goes back to 2000, and we've been in the upside cycle of hurricanes, of course the "averages" will be too high, because it does not incorporate the downside cycle. It has been over a decade since we entered the "up" cycle, perhaps we are starting to swing back into the "down" cycle?
If the times from 2000 - 2010, the vertical instability was "100", and that is the only time period we have, then the "average" is "100". So of course getting a reading of "20" is going to look extremely odd. But if the 100 year average is "50", then that "20" doesn't look so odd in the long run.
0 likes
- AJC3
- Admin
- Posts: 3891
- Age: 60
- Joined: Tue Aug 31, 2004 7:04 pm
- Location: West Melbourne, Florida
- Contact:
Re:
brunota2003 wrote:Or it could be the mid-level temps were the same, but surface temps were actually cooler...but I don't think temps were cooler than average over the entire world
Thinking about it, I think our instability "averages" are too high. If data only goes back to 2000, and we've been in the upside cycle of hurricanes, of course the "averages" will be too high, because it does not incorporate the downside cycle. It has been over a decade since we entered the "up" cycle, perhaps we are starting to swing back into the "down" cycle?
If the times from 2000 - 2010, the vertical instability was "100", and that is the only time period we have, then the "average" is "100". So of course getting a reading of "20" is going to look extremely odd. But if the 100 year average is "50", then that "20" doesn't look so odd in the long run.
Cooler surface temperatures being a factor is highly unlikely. Since we're talking about a basin comprised almost entirely of water, the low level temperature anomalies will invariably mimic SSTAs, which were largely positive.
0 likes
Who is online
Users browsing this forum: Cat5James, Category5Kaiju, Cpv17, Google [Bot], Google Adsense [Bot], nijay, skyline385, Stratton23, tolakram, Wampadawg and 37 guests