I didn’t have time last week to review the U.S. Drought Monitor and provide some analysis for Wisconsin so that will be the first thing in the blog today. Here in Wisconsin the drought situation is not bad, just a few spots indicated as abnormally dry. The amount of the state that was a little dry shrank by just a couple tenths of a percent since the last report. As I have mentioned recently, I am not too worried about drought conditions in the Fall. The growing season is about done and things turned out pretty good, so now we are in the clear except for the possible impact on water levels- if dry weather should persist for most of the Fall. We have only had a trace of rain over the last 8 days and it looks like there will be another 7 days with mainly dry weather before a threat of significant rain develops (next week Monday). The only chance (40%) of significant rain for this week will be in the northwoods this afternoon with a few thunderstorms possible. On Wednesday there could be some sprinkles. So you expect the “abnormally dry” conditions to expand either with this week’s or next week’s Drought Monitor (comes out on Thursday).
In other news, the most recent ENSO diagnostic discussion has arrived and it indicates that a weak La Nina has formed in the Pacific ocean. The La Nina is expected to continue into the Fall and early Winter and it will likely remain on the weak side. A past trend has been for a strong La Nina to be followed by a weaker La Nina. The most interesting part about this month’s diagnostic discussion is that the (human) forecasters have ignored the “advice” of most of the computer model projections, and gone with just one – the NCEP Climate Forecast System (CFS). The CFS has accurately predicted the onset of the current La Nina conditions for the past couple of months, while most of the other models do not even show a La Nina at this point. It is kind-of risky just relying on one model, but when it is out-performing most of the others, it does make more sense.
The CFS is now actually predicting a strong La Nina that would be strongest around January – and be as strong as last winter. Again, the rest of the computer models show neutral conditions and/or weak La Nina conditions. Lately – during the last three episodes - La Nina has meant colder than normal temps and above normal snowfall for our Winter-time. If a strong La Nina forms this Fall, then I would forecast a good chance of “real” Wisconsin winter conditions (cold and snow), at least for the first half of Winter. If La Nina remains on the weak side, then I would say the odds of frigid temps and heavier snow are quite a bit less.
Folks who are probably more interested in the latest ENSO projections are in the Deep South, Gulf Coast, and Desert Southwest. An extreme to exceptional drought is ongoing in many of these areas (like Texas) and another La Nina Winter will likely exacerbate (if that is possible) the record drought.
Computer models are very helpful in producing longer term forecasts, not only of the La Nina/El Nino oscillation but of other weather trends around the world. With better models and more powerful computers researchers at UCLA have now extended the length of “accurate” climate predictions out to 16 months, twice as good as previous models. Which might make one wonder, how many climatologists have been so certain for so long how the climate will be in 2100, when the most accurate models could only “get it right” for 8 months into the future. Now, the issue is more complicated than it seems on the surface, and different models are used for different time frames, but it is still an interesting question. The UCLA researchers also tackled the thorny issue of separating human climate influences from natural variability. Which, again makes one wonder, how many climatologists have been so certain for so long what the climate will be like in 2100 when natural variability has not been adequately quantified. In the end, it is good to see that the computer model forecasts are getting better. With this technology, we should be able to better pinpoint the year-to-year and decade-to-decade changes and adapt appropriately.
On a related follow-up note on climate forecasting, Dr. Roy Spencer’s recent paper has caused more fallout (I first blogged about this here). The editor of the journal Remote Sensing has resigned in shame because the paper was allowed to be published. Many climatologists have claimed that there are potential errors with the Spencer paper and its claim that clouds play a much larger role in climate variability than was thought in the past. I haven’t been able to review the findings myself to add my detailed thoughts, however, as I mentioned previously, it doesn’t look very good from the outside. Spencer’s paper garnered headlines (in fact, he was probably hoping and planning for that outcome) and mainstream climatologists reacted swiftly to openly condemn the paper and its publication. The climategate emails displayed for the world how top climatologists were actively trying to shut out alternative theories and alternative journals on climate science. The most recent Spencer episode, whether an honest appraisal of his paper or not, makes it look like the blacklisting might still going on.
Have a fine Monday! Meteorologist Justin Loew.
This post was written by jloew on September 12, 2011