WXinCanton Posted March 15, 2015 Share Posted March 15, 2015 What did we end up averaging for DJF? Been looking around but can't seem to find it. TIA Link to comment Share on other sites More sharing options...
ORH_wxman Posted March 15, 2015 Share Posted March 15, 2015 What did we end up averaging for DJF? Been looking around but can't seem to find it. TIA December: 0.413 January: 1.092 February: 1.043 Average was a bit under 0.85 Link to comment Share on other sites More sharing options...
donsutherland1 Posted March 15, 2015 Share Posted March 15, 2015 What did we end up averaging for DJF? Been looking around but can't seem to find it. TIA The DJF average for the AO was +0.813. 76% of days had positive AO readings. Link to comment Share on other sites More sharing options...
WXinCanton Posted March 15, 2015 Share Posted March 15, 2015 The DJF average for the AO was +0.813. 76% of days had positive AO readings. Thanks Don! So the OPI hasn't been so hot the last couple of winters. Between that and SAI, looks like they off a good bit in regards to the AO. Link to comment Share on other sites More sharing options...
donsutherland1 Posted March 15, 2015 Share Posted March 15, 2015 Thanks Don! So the OPI hasn't been so hot the last couple of winters. Between that and SAI, looks like they off a good bit in regards to the AO. I agree. It's really tough to know right now whether either approach yields a significant advantage in trying to forecast the predominant winter state of the AO. Link to comment Share on other sites More sharing options...
Rainman Posted March 15, 2015 Share Posted March 15, 2015 Complete failure to predict the mean state of the DJF AO. But then again, what index does perform well? None. That'll teach everyone to go ape over the introduction of the next new seasonal outlook index Link to comment Share on other sites More sharing options...
GaWx Posted March 15, 2015 Share Posted March 15, 2015 December: 0.413 January: 1.092 February: 1.043 Average was a bit under 0.85 Considering the longterm mean DJF AO of -0.30, 2014-5 ended up at ~+1.15 above the mean. That's quite a solid +AO for 2014-5. Looking back to 1950-1 (65 winters), only 9 had a higher AO for DJF than 2014-5's +0.8: They were as follows: +2.7, +1.8, +1.3, +1.1, +1.1, +1.1, +1.0, +1.0, +0.9 Link to comment Share on other sites More sharing options...
Absolute Humidity Posted March 17, 2015 Share Posted March 17, 2015 Question is why did OPI and SAI fail and fail miserably? - Late October Eurasian snow melt 700K during the last week? - relatively strong solar flux with -QBO during critical late Nov and December? - Typhoon Nuri allowing the PV to reconsolidate strong at worst possible time? Link to comment Share on other sites More sharing options...
GaWx Posted March 17, 2015 Share Posted March 17, 2015 Question is why did OPI and SAI fail and fail miserably? - Late October Eurasian snow melt 700K during the last week? - relatively strong solar flux with -QBO during critical late Nov and December? - Typhoon Nuri allowing the PV to reconsolidate strong at worst possible time? I don't know if this is at all relevant but: Despite the huge fail of the OPI/SAI with regard to the AO, the E 1/3 of the US still had its coldest winter overall since at least 1950 for such a +AO/NAO! Other than 2013-4, nothing else was close for such a solidly +AO and NAO. Link to comment Share on other sites More sharing options...
CoastalWx Posted March 17, 2015 Share Posted March 17, 2015 Question is why did OPI and SAI fail and fail miserably? - Late October Eurasian snow melt 700K during the last week? - relatively strong solar flux with -QBO during critical late Nov and December? - Typhoon Nuri allowing the PV to reconsolidate strong at worst possible time? The atmosphere is a chaotic system. While the physics behind the snow cover argument are there, clearly other factors can influence and override it. Always important to not fall in love with an index. We have been in a base state of a +AO for awhile now. Sun influence perhaps? Probably part of it. This also could be one if the few cases where this index didn't work out and it may nail the next 15 winters. Who knows. Sample size needs to be part of the research. Link to comment Share on other sites More sharing options...
GaWx Posted March 17, 2015 Share Posted March 17, 2015 The exact equation hasen't been revealed, but it appears to calculate a number based on the 500mb height anomalies in the northern hemisphere. I hope these charts from the first page of this thread explain it: It seems like using the OPI for DJF AO rather than the simple October AO is more accurate because it includes the Aleutian low/+AO that both correlate with a -AO in DJF. Other than that, it seems the north-central siberian ridge is the most important feature of a -OPI October. Well, I guess the correlation dropped a bit from 0.91 after this past winter. But it probably is still quite high (probably still will into the 0.80's) since one winter, alone, has relatively little weight out of almost 40 winters even if a really big miss. Not surprisingly, it would appear that this miss was way bigger than all of the winters shown on the graph. I'm still a bit suspicious about some kind of retro fitting having occurred when this 0.91 correlation was released. That sounds way too high for any index. Link to comment Share on other sites More sharing options...
weatherwiz Posted March 18, 2015 Share Posted March 18, 2015 The state of the stratosphere I"m sure had to have played a huge role in the record cold which occurred across a good chunk of the east in February. 70mb and 50mb temperature anomalies where quite warmer than average which really helped to make for very low heights to be possible across the east and the 500mb patter that was in place was extremely favorable for cold to continuously drain into the east Link to comment Share on other sites More sharing options...
Absolute Humidity Posted March 18, 2015 Share Posted March 18, 2015 I don't know if this is at all relevant but: Despite the huge fail of the OPI/SAI with regard to the AO, the E 1/3 of the US still had its coldest winter overall since at least 1950 for such a +AO/NAO! Other than 2013-4, nothing else was close for such a solidly +AO and NAO. The atmosphere is a chaotic system. While the physics behind the snow cover argument are there, clearly other factors can influence and override it. Always important to not fall in love with an index. We have been in a base state of a +AO for awhile now. Sun influence perhaps? Probably part of it. This also could be one if the few cases where this index didn't work out and it may nail the next 15 winters. Who knows. Sample size needs to be part of the research. Without a doubt! The past two years have been phenomenal winter wise eastern 1/3 to 1/2 CONUS. Was just throwing out some possible cause and effect possibilities as to what happened? Despite the sample size being small, the potential for traditional blocking (AO NAO) was huge given that this was the 2nd highest Oct. eurasian snowfall cover seen in that sample. The base state of +AO is also intriguing given how strongly negative the previous years 2009-2011 were. Atmosphere balancing out? +AO regime heightened by the current double solar maxima, albeit weak. Regardless, we'll see how things work out in the years to come. Link to comment Share on other sites More sharing options...
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