Projected ENSO Model Data
Neutral conditions are expected to take hold during the spring and continue into the summer. In Neutral conditions, little if any effects from ENSO are anticipated across the country. That being said, I expect our La Nina pattern to fade as a "the song is ended but melody lingers on" type of pattern for the near term with the atmosphere still reeling from some of the La Nina effects. I feel we are seeing a good example of this with the recent notable early severe weather across the center and southern portions of the country. La Nina's do tend, on average, to be busier in the severe weather department.
Of course; the strongest influence by far on our weather continues to be the NAO/AO oscillation which has been nearly consistently positive since last Autumn (check it out; Fig -1 below). This was the main reason the winter was so mild as explained in earlier blogs. Looking at the Winter 2012 preliminary statistics at Detroit all data includes leap day, 2/29.
Ave High: 39.5 Precipitation
Ave Low: 26.4 7.70"/ +1.26
Wntr Ave: 33.0 /6th warmest/ Snow thru 2/29th
(warmest winter since 2001-02 @ 33.8) 25.8"/-8.3"
Ave High: 38.1 Precipitation
Ave Low: 24.2 5.85/ +0.82
Wntr Ave: 31.2 /5th warmest/ Snow thru 2/29th
(warmest winter since 2001-02 @ 31.7) 32.3"/-6.3"
Ave High: 36.9 Precipitation
Ave Low: 24.2 5.85/ +0.82
Wntr Ave: 30.6 /3rd warmest/ Snow thru 2/29th
(warmest winter since: 2001-02 @ 30.5 41.9"/+7.6
1997-98 @ 30.9)
Solar Variation and WeatherThere are some suggestions that there may also be regional climate impacts due to the solar activity. Measurements from NASA's Solar Radiation and Climate Experiment show that solar UV output is more variable than the total solar irradiance. Climate modelling suggests that low solar activity may result in, for example, colder winters in the US and southern Europe and warmer winters in Canada and northern Europe, with little change in globally-averaged temperature. More broadly, links have been suggested between solar cycles, global climate and events like El Nino. In other research, Daniel J. Hancock and Douglas N. Yarger found "statistically significant relationships between the double [~21 year] sunspot cycle and the 'January thaw' phenomenon along the East Coast and between the double sunspot cycle and 'drought' (June temperature and precipitation) in the Midwest."
Recent research at CERN's CLOUD facility examined links between cosmic rays and cloud condensation nuclei, demonstrating the effect of high-energy particulate radiation in nucleating aerosol particles which are precursors to cloud condensation nuclei. Dr. Jasper Kirby, a team leader at CLOUD, said, "At the moment, it [the experiment] actually says nothing about a possible cosmic-ray effect on clouds and climate, but it's a very important first step."
1983–1994 data from the International Satellite Cloud Climatology Project (ISCCP) showed that global low cloud formation was highly correlated with galactic cosmic ray (GCR) flux; subsequent to this period, the correlation breaks down.Changes of 3–4% in cloudiness and concurrent changes in cloud top temperatures have been correlated to the 11 and 22 year solar (sunspot) cycles, with increased GCR levels during "antiparallel" cycles. Global average cloud cover change has been found to be 1.5–2%. Several studies of GCR and cloud cover variations have found positive correlation at latitudes greater than 50° and negative correlation at lower latitudes. However, not all scientists accept this correlation as statistically significant, and some that do attribute it to other solar variability (e.g. UV or total irradiance variations) rather than directly to GCR changes. Difficulties in interpreting such correlations include the fact that many aspects of solar variability change at similar times, and some climate systems have delayed responses.
As mentioned, analogue data was virtually useless with the main driver of the winter the NAO+/AO+. However, in the analogues years where the patterns seemed the closest to our recent mild winter conditions and prevailing NAO+/AO+, the springtime temperatures and precipitation are shown below. In addition, included is the the springtime precipitation for all the previous winter analogues. The data maps show the warm weather continued to prevail from the Plains eastward across the country. Below normal temperatures were found out west. Overall; precipitation averaged normal to above east of the Mississippi in both sets of years of the analogue data.
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian