tag:blogger.com,1999:blog-19673832.post4872777311200139924..comments2023-11-02T06:10:29.606-07:00Comments on Atmospheric Insights: The Devil Deals the Atmosphere; PNA Retrogression or Bust!!!Ed Berryhttp://www.blogger.com/profile/00969068496887623697noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-19673832.post-88140429007465243912009-01-17T14:22:00.000-08:002009-01-17T14:22:00.000-08:00Hello Greg, I just posted a discussion. Perhaps t...Hello Greg, <BR/><BR/>I just posted a discussion. Perhaps that may answer a few of your questions. The +PNA was linked to a strong +East Asian mountain torque, working with the MJO. AAM is starting to flux poleward (zonal mean) across the Northern Hemisphere. That suggests a tilt toward a +NAO (and/or relaxation of the recent negative phase)the next few weeks. <BR/><BR/>EdEd Berryhttps://www.blogger.com/profile/00969068496887623697noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-61760265315484079072009-01-16T14:55:00.000-08:002009-01-16T14:55:00.000-08:00Thank you for your response.I went to search for y...Thank you for your response.<BR/><BR/>I went to search for your recommended article and wow is it long and ambiguous for my impatient and laymen eyes. <BR/><BR/>I am a much better learner as I go along more than reading, but I will spend a lot of time reading that article in trying to comprehend what it states.<BR/><BR/>From what I have gathered from your blog, the +PNA ridge is forcing the subtropical and pacific jet up and around the west coast ridge. In tern, this is causing -mountain torque anomalies. <BR/><BR/>Is this why we the eastern U.S hasn't felt the brunt of La-Nina conditions?<BR/><BR/>Also, I was looking over the flux convergence reanalysis and it appeared to me that there were positive anomalies in the higher latitudes. Wouldn't this indicate easterly propogation moving poleward and thus an early step for a -NAO?<BR/><BR/>Thank you for your insights as I find them very interesting. <BR/><BR/>GregGreghttps://www.blogger.com/profile/01178598985507215566noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-43588445484182169792009-01-15T19:11:00.000-08:002009-01-15T19:11:00.000-08:00Hello Greg, I hope you can attend our GWO workshop...Hello Greg, <BR/><BR/>I hope you can attend our GWO workshop to answer some of your questions. It is impossible for me to "educate" in this medium. If you already have not done so, please read our papers and go through the references. A particularly good one is Peixoto and Oort, Chapter 11. <BR/><BR/>The R1 data climatology is from the first reanalysis data set per Kalnay and others (1996), and goes from 1/68-12/97. <BR/><BR/>Hope this is helpful.<BR/>EdEd Berryhttps://www.blogger.com/profile/00969068496887623697noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-89853919757213846552009-01-15T19:02:00.000-08:002009-01-15T19:02:00.000-08:00Hello Jim, You are correct about the models strugg...Hello Jim, <BR/><BR/>You are correct about the models struggling with what is likely to be a GWO/MJO 7-8-1-2 transition leading to PNA retrogression. The details are unclear, and maybe until it "practically occurs". <BR/><BR/>I think the initial westward shift will be linked to the Indonesian forcing, with perhaps a more robust western USA trough once the MJO comes back into the Eastern Hemisphere. The former will be in ~7-10 days with the latter ~week-3. The MJO signal is well into the Western Hemisphere with South America and S. Africa becoming active and the SPCZ shutting down. <BR/><BR/>I am not at all surprised by the central and eastern USA cold. I did discuss this possibility in earlier postings since I thought our La-Nina would not be as strong as 2007-08. However, I did not anticipate the strength of the current MJO, which has contributed the current cold regime. While currently significantly perturbed, the La-Nina is also a bit stronger than I would have thought. <BR/><BR/>EdEd Berryhttps://www.blogger.com/profile/00969068496887623697noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-56474364476043399022009-01-15T18:33:00.000-08:002009-01-15T18:33:00.000-08:00Hi Ed,Do you buy the GFS solutions showing a patte...Hi Ed,<BR/><BR/>Do you buy the GFS solutions showing a pattern deamplification as opposed to a true PNA retrogression? I am thinking the models are having real problems with the MJO wave that has developed. Also...are you surprised to see such a severe Eastern cold wave with the Pacific in such a favorable state for Western troughing?<BR/><BR/>Thank you!<BR/><BR/>JimUnknownhttps://www.blogger.com/profile/00888619348972375129noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-76913617678777700692009-01-12T13:11:00.000-08:002009-01-12T13:11:00.000-08:00I am relatively new to the avocation of long term ...I am relatively new to the avocation of long term pattern forecasting. I read the models such as the GFS, NAM etc. on a regular bases.<BR/><BR/>I know that you are a busy man, but I have a few question and would be grateful for you to answer them during some of your spare time.<BR/><BR/>I don't quiet understand the concept of the AAM. <BR/><BR/>What causes the phases to alternate? <BR/>What are the ramifications of the phases (+AAM, -AAM), and what would happen during a phase change?<BR/><BR/>For example, the global AAM would be a +30 Hadley's in one month, and change to -20 Hadleys in the next.<BR/><BR/>And lastly, what is R1 Data Climatology?<BR/><BR/>Thank You Very Much <BR/>GregAnonymoushttps://www.blogger.com/profile/16946327162949292166noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-43983936330167017752009-01-11T15:54:00.000-08:002009-01-11T15:54:00.000-08:00Hello Linda,Thank you for the comment! You are es...Hello Linda,<BR/><BR/>Thank you for the comment! You are essentially correct about the phase of the PDO based on the available data sets. My understanding is that the current negative phase is the most robust in ~57 years. <BR/><BR/>In any case, GCM studies show that extratropical SSTs are forced by the tropics, which easily makes sense physically. Another way of understanding this is the tropical SSTs tend to force the atmosphere and vice-versa for the extratropics. The point is a good portion of the PDO is a response to the extratropical circulation that, in turn, is forced by global-scale dynamical processes (such as ENSO variations). <BR/> <BR/>How long this negative phase will persist is unclear. The PDO (like, for ex., the NAO) is red noise, meaning care should be taken attempting to predict it. I certainly agree with your drought concerns, which tend occur in the central/southern High Plains during a low AAM/La-Nina situation. <BR/><BR/>The following is a link to some PDO stochastic modeling work done folks at ESRL/PSD. You may want to surf around for additional information. <BR/> <BR/>http://www.cdc.noaa.gov/forecast1/PDO.html<BR/><BR/>Hope this helps. Please feel free to ask more questions.<BR/><BR/>Ed BerryEd Berryhttps://www.blogger.com/profile/00969068496887623697noreply@blogger.comtag:blogger.com,1999:blog-19673832.post-26636552521235949602009-01-11T13:22:00.000-08:002009-01-11T13:22:00.000-08:00I am a complete weather novice. I'm concerned abo...I am a complete weather novice. I'm concerned about the PDO. I've read that it's in a negative phase and that it will probably remain in a neg phase for at least 5-20 years!!<BR/>(I live in Texas and we're in exceptional drought. Drought is made worse in negative PDO) <BR/><BR/> I got two different sources of raw data for PDO. Both models show a long neg phase from 1944-1978 (30 yr) and long pos phase from 1978-1998. (20 yr) <BR/><BR/>Data from 1900-1940 seems to be "graphed" as a postive phase, but the raw data shows that it was basically in a "neutral" phase during that time period. <BR/><BR/> The PDO fluctuated frequently between 1900-1940.<BR/><BR/>(It seemed to fluctuate as frequently as ENS0.) <BR/><BR/>I believe the PDO went through a negative phase around July 1998-July 2002. (The last major La Nina) It entered a postive phase from July 2002-August 2005. It then seemed neutral from Aug 2005-Aug 2007. Then, it entered it's current negative phase (with the current La Nina) in August 2007. <BR/><BR/>Therefore the last PDO cycles lasted only 3 years. <BR/><BR/>Here is the link to the data:<BR/><BR/>http://jisao.washington.edu/pdo/PDO.latest<BR/><BR/>Some models are forecasting the PDO to be negative for another 20 years. <BR/><BR/> However, I wonder if this prediction could be somewhat biased? <BR/><BR/><BR/>Are 20 year predictions of the PDO reliable? <BR/><BR/><BR/>Thank You Very Much<BR/>LindaAnonymoushttps://www.blogger.com/profile/05062540964412552374noreply@blogger.com