2010 CAPPING INVERSION

[Matt Gingery]

I have a question that I have been mulling over in my mind regarding the cooler than normal Gulf temperatures. Gulf SST's in comparison to averages are running 10-20 degrees below normal in many areas. I want to limit this to severe weather and not tropical, so I titled the thread Capping Inversion. My questions are dealing with the relation to severe dynamics and below normal Gulf SST's. What effect will these below average Gulf waters have on the capping inversion this coming season? California deals with a capping inversion on nearly a daily basis as the colder air from the pacific pushes in over the warmer drier land SFC temps creating an inversion layer (Fog). I understand that these SST's may rebound some, but it would seem that won't happen til late May at the current readings. What effect will this cooler than normal Gulf flow have if we experience downslope warming across the S CONUS and as a formidable system develops on the lee side of the rockies bringing in this cooler than normal gulf flow across the warmer land SFC temps? It would appear to me that if the land SFC temps are warmer than the moist air coming in off the gulf it would create a stronger capping inversion aloft. Does soil saturation levels play into the moisture levels? Taking this counter-intuitive approach would the soil moisture levels combined with the cooler gulf flow lead to a more buoyant SFC level? One thing that we are in right now is an active storm track, and if that continues we would have the upper forcing needed to break this cap. Would this lead to more explosive development? Am I correct in saying that as the SFC temps rise over land and in comparison, if the waters trend cooler over the large open gulf waters, should this lead to higher pressure in the gulf induced by cool waters? Having this high pressure in the gulf, would that play a role in a more enhanced role of the subtropical jet? I will limit it to those questions and build from there. It would seem to me that there would be adverse effects in the cooler SST's of the Gulf. I see many climatological comparisons in the El Nino in 1997 and the current El Nino. Thanks for all the input

GULF TEMPS COMPARISON TO AVG:

http://www.nodc.noaa.gov/dsdt/cwtg/egof.html

http://www.beachhunter.net/thingstoknow/gulfwatertemp/index.htm


Edit: I had to edit this because one of the moderators felt as if I came across as shouting. Sorry for that! I have poor vision and many times it helps me to write larger.

 

[David Wolfson]

I'm not convinced that the the Gulf is especially colder than normal: http://www.osdpd.noaa.gov/data/sst/anomaly/2010/anomnight.1.4.2010.gif

That said, I think the focus is that the surface temperature of a large water body sets the moisture content of the surface air. Cold Gulf water results in proportionately lower Gulf dewpoints. Since moisture content is an important CAPE generator for severe weather, I think you can take it from there.

 

[JF Massicotte]

My first guess would be that it will have an impact mostly on mositure quality availlable in the Gulf. We would then have a hard time getting good, deep, moisture up in the plains.

Impact on capping inversion is that it will not erode from below as easy as with better moisture.

This is only a guess, some veteran here may have better answers...

 

[rdale]

I don't think the marine layer in California is anything close to the same as the mid-level cap inversion in the severe weather states. Two dramatically different processes and outcomes.

 

[cdcollura]

Good day all,

The Gulf of Mexico SST will be cooler than normal because we have had well-below-normal temperatures sitting over it for almost a week (as of today, 1/6).

We can still have above normal temperatures in the early spring / late winter which can actually make up for it, and that's usually what happens ... It all balances out come May / June, hopefully.

As for the "marine layer" and capping inversion, as mentioned, they are two different processes. The marine layer is the cooler and moist air layer over cold water, like off California, and is a low-level inversion (the cool air only very close to the ground, less than 3,000 feet or so deep). A capping inversion is in the mid-levels, from 5,000 to 10,000 feet or so, and is usually caused by dry air at mid-levels (such as air from higher desert terrain over spreading the plains and lower moisture).

Having cooler air (and less moisture) in the low levels due to a cooler Gulf only may affect the cap being overcome by convection, which is dictated by instability and relative to the moisture content and temperature.

 

[Matt Gingery]

Thanks for all the input on this. I understand that the SoCal example is different, and the basic point that I spoke of has some similarities. I am trying to elude to a more counter intuitive approach. Is there a link in similarities to the 1997 El Nino and this El Nino. 1998 was a very active season, and the winter of 1997 was similar to this winter. I understand that trying to compare different events is difficult, although that is climatology. Gulf cooling was an issue in winter 97-98, although I am not sure how the storm track compares. Lately we have been in an active storm track pattern. I am trying to overlook the obvious reasons to forecast a below normal spring severe season. Soil saturation should play a role in moisture content. What I should be asking you is "Why was the spring of 1998 so active?" Also, am I heading in the wrong direction by trying comparisons in El Nino seasons? I have alot of ideas churning and trying to connect the dots on what understanding I do have of the atmosphere. I am absolutely fascinated with these patterns and am breaking my head to try to connect the dots. Thanks for helping me understand things better. What is going on with the gulf temperatures is going to play a role in the coming season. Having high pressure induced by the cooler waters of the gulf this spring would seem to keep the storm track active across the Alley as well as making the subtropical jet a player. Capping should be an issue, and if ridging occurs in the gulf I think that should shield much of the deep south and E. Texas from severe weather as well.



Edit: I did compare the averages of gulf temperatures where data was provided. In many areas the temperatures are running some 10-20 degrees below normal.

 

[rdale]

What is going on with the gulf temperatures is going to play a role in the coming season. Having high pressure induced by the cooler waters of the gulf this spring would seem to keep the storm track active across the Alley as well as making the subtropical jet a player. Capping should be an issue, and if ridging occurs in the gulf I think that should shield much of the deep south and E. Texas from severe weather as well.

You're connecting WAY too many dots. Some dots are better left without lines drawn, since we don't know what is in between. To begin with - you are saying that the cooler waters will develop a massive high pressure system that deflects all storms? Doesn't make sense. Why would capping be an issue? We all just pointed out that your interpretation was incorrect, and the cooler waters won't increase the 700mb cap.

 

[Matt Gingery]

You're connecting WAY too many dots. Some dots are better left without lines drawn, since we don't know what is in between. To begin with - you are saying that the cooler waters will develop a massive high pressure system that deflects all storms? Doesn't make sense. Why would capping be an issue? We all just pointed out that your interpretation was incorrect, and the cooler waters won't increase the 700mb cap.

I have to disagree with you on your abundant negativity. First of all I wasn't interpreting, I was pondering. I understand in your pescimistic world you are always right. In the weather community I think that everything is a learning experience. Cool waters do in fact tend to induce high pressure, and that is a fact. Although, I never noted that a death ridge would settle in over the gulf and block every system from entering. The symphony of weather systems is going to play out however. I think we need to lay out all the dots and draw all the lines in a fashion to develop a better understanding of the large symphonic scheme of things. You have a totally different perspective than I do, and personally I don't think someone as short sighted as yourself should delve into climatology, or research. Stick to software, drinking coffee or lack thereof. There will be capping issues every year in many different places. First of all reading involves comprehension. I never at anytime in that post disputed whether or not any of those questions (theories) was FACT. YOU HAVE DECIDED THAT YOU LIKE ME SO MUCH, SIMPLY BECAUSE I AM SOMEONE WHO GIVES YOU THE ATTENTION THAT YOU FEEL YOU NEED. SINCE I AM NEW TO THE SITE AND DON'T KNOW YOUR ANTICS LIKE THE SEVERAL DOZEN THAT HAVE TOLD ME THAT THIS IS YOUR STYLE, I WILL TRY TO ENTERTAIN YOU UNTIL I CANNOT STAND IT MYSELF. So, as of now Mr. Rdale I will continue to try to entertain you with these back and forth arguments so you attain the skills needed to debate with a Meteorology student as opposed to someone on your level. I rest my case. . . That was a compliment by the way. I can take it all day long pal, so feel free to pack a lunch and bring it. I do feel that you are above my level. I really really really like your comments. Please indulge yourself in responding as much as possible. I feel we could develop a truly exciting friendship. I cannot wait to read your insight into the questions I posted in the thread.


I have a question for you. What is your feelings on what the outcome of this coming season will be? Please answer some of the questions for me in your words. You didn't answer any of the questions before. So, please help me understand what it is that I don't. I ask questions to learn. I AM GOING TO LAY IT OUT RIGHT NOW FOR EVERYONE TO SEE. Rdale? Will you be my storm chase partner this coming spring? When I am not arguing with my wife, you could fill the gaps! Ha Ha Ha



SERIOUSLY THOUGH! All joking aside I really am curious as to the effects of the cooler gulf waters impact on the coming season. Thanks for all the serious answers. I don't want to turn this thread into a debate with my pal here.

 

[rdale]

All joking aside I really am curious as to the effects of the cooler gulf waters impact on the coming season. Thanks for all the serious answers.

IF the waters remain cooler than normal, it will have an impact on moisture return. Not capping inversions.

 

[Matt Gingery]

Yes indeed, but without upper forcing I was trying to understand any relations there might be between the effects in California and if there is any correlation.

The direct effect of cooler Gulf of Mexico waters would likely be to slightly reduce the moisture content (dew point) and air temperature of the flow coming onshore. This would tend to reduce the buoyancy slightly, but that can often be overwhelmed by inland warming and evapotranspiration. This is what I was eluding to when I mentioned the effect of downslope warming. Creating abundance of land warming prior to the gulf temps rebounding. Still, it would tend to slightly decrease the temperature (theta-e) of the boundary layer air beneath any cap, so – for equal cap temperature – would make the cap effectively stronger than if the Gulf air was warmer and moister. Thus, I would think that the most direct effects might be to slightly reduce severe storms.



That said, there could be other effects – some related to and some independent of the Gulf water temperature. There could be some ridging over the Gulf of Mexico induced by the cooler water – which would tend to give a bit of “shielding” for east TX and the Gulf Coast states.



But the strength, frequency, and positioning of the mid-latitude upper-air systems that trigger severe weather are likely to be the dominant factors, as always – and are generally independent of the Gulf water temperatures.



El Nino is currently running at moderate strength, which tends to suppress tornadoes and outbreaks somewhat in the central US, but El Nino is expected to weaken, so its impacts are unclear.

What I was getting at in my post was simply trying to get a counter-intuitive approach. Sort of trying to list all the dots, and draw all the lines. So often we follow paths that end up leading us away from the true forecast. Glass half empty sort of. . .if that makes sense.

 

[Matt Gingery]

IF the waters remain cooler than normal, it will have an impact on moisture return. Not capping inversions.

You can do better than that! If you connect lines to the dots you would have figured out that there is in fact a connection between capping and cooler waters. Haven't heard from you in a while, are you ok?

 

[Jeff Duda]

Good day all,

The Gulf of Mexico SST will be cooler than normal because we have had well-below-normal temperatures sitting over it for almost a week (as of today, 1/6).

We can still have above normal temperatures in the early spring / late winter which can actually make up for it, and that's usually what happens ... It all balances out come May / June, hopefully.

Keep in mind that the specific heat capacity of liquid water is around 4100 J/Kg*K whereas that for sand, soil, and other earth materials is around 900 J/Kg*K and that for air is 1005 J/kg*K. Thus, even a week of well below normal air temperatures probably won't have that large an effect on SSTs. Now, if this pattern continued for a month or so, then there could be significant, widespread cooling of Gulf of Mexico seawater. I don't think the GoM is screwed quite yet. Let's see how February goes.

 

[Matt Gingery]

Very valid point Jeff. I honestly don't think the GoM is screwed either. We don't see extended periods of cooler than normal waters in the GoM very often. There will be rebounding that takes place, but at what point will this happen? Will this effect the early spring season? The fact that some temp readings in the Gulf are flirting with the high 30's raises my brow. Thanks for the input Jeff!

 

[Mike Johnston]

Matt,

I think if your trying to project the strength of the capping inversion over a whole season, that's a pretty tall order. I've never seen any studies re: inter-annual variations of the avg. cap strength, but that would be an interesting and challenging pursuit.

However, I agree w/ most of the previous replies that SST's in the Gulf don't have much to do with the cap. Let's take a step back and look at the bigger picture. For the areas most prone to severe weather in the spring, the source region for the (dry) air mass affecting the capping inversion is over the high terrains of the desert southwest and Mexican plateau - continental tropical air, not the maritime tropical air over the Gulf. You will often see this referred to as the elevated mixed later (EML).

Re: some of your other questions. Yes, the soil moisture content can directly effect surface dew points by evaporation and indirectly through transpiration. Although evapotranspiration can be important in overall surface moisture , advection from warm, moist regions is most often the "difference that makes the difference."

If it were like March 10th or so, and we had had weeks upon weeks of below-normal Gulf SSTs, I would be concerned about the quality of the source region of the moisture so important for severe weather over the plains. However, it's only January 8th, so it's too early to draw conclusions, IMO.

 

[Chris C Sanner]

It's really hard to draw conclusions about the cap, quality of gulf moisture, and such the day before the event much less 3-5 months before any specific event. I'd love to see a seasonal analysis of the EML done and then maybe attempt correlate that to severe reports across the plains. I'm pretty sure that on any given year, you'd end up with an EML that is pretty variable in location and strength given mesoscale variables far beyond that of just the EML, but of course I'm not 100% sure on that.

It'd be an interesting study, but I don't think any attempt to draw lines to things which don't connect will lead very far right now with so many missing pieces in between. So really, IMHO, it is still very hard to anticipate how any specific event will unfold in regards to the EML, moisture quality, etc. much less try to tie those variables to seasonal severe production well before the doldrums of winter have passed.

Good discussion though, this is what Stormtrack should be here for gents