The spring and early summer 2014 outlook from the Climate Prediction Center (CPC) suggests a continuation of the colder than median climate, with equal chances for below, above, or median precipitation for April, May and June. However, the climate patterns as forecast at this time do not support an exceptionally stormy pattern this spring. However, as the spring is a volatile period and weather patterns can rapidly change, one cannot make firm assumptions. What we can do is make scientifically based predictions using the latest dynamic (computer) forecasts, statistical analysis (composite / analog), and trend based (climate change) tools. Climate predictions are different from the day-to-day weather forecasts in several significant ways. 1) We cannot provide the specificity in a climate outlook that the daily predictions contain e.g. climate outlooks deal in generalities; 2) Climate outlooks provide the weather 'averaged' over many weeks or months, providing the most likely scenario for the next one month or three month season; 3) Climate outlooks cannot provide specific temperature ranges or precipitation amounts, but can provide the most likely category that will dominate the weather over the next month or season.
Current atmospheric and oceanic conditions remain ENSO-neutral and the latest ENSO outlook favors ENSO-neutral conditions to continue through the Northern Hemisphere spring of 2014. However, an El Nino Watch has been issued which indicates conditions are favorable for El Niño development within the next six months. Over the last several weeks, considerable changes have occurred across the Equatorial Pacific Ocean, both in the atmosphere and in the ocean that have increased probabilities for the development of El Niño later in 2014. Sea Surface Temperatures (SSTS) across the Equatorial Western Pacific have increased and anomalies are now positive from near New Guinea to just east of the Dateline and range from +0.5 to +1.0 degrees Centigrade, with some areas near the Dateline greater than +1.0 degree Centigrade. Moreover, there have been two strong westerly wind bursts over the western Pacific, one occurring during late January and another spanning late February and early March. The first westerly wind event initiated a strong oceanic down-welling Kelvin Wave which is in the process of traversing the Pacific Ocean as of mid-March 2014. At depth, positive ocean temperatures are evident for the majority of the Pacific Basin from 150 East to near 110 West at depths ranging from 75 m to 200 m. The greatest positive anomalies reach +6.0 degrees Centigrade near 160 West at a depth of 150 meters (nearly 500 feet in depth).
Anomalous Equatorial convection (thunderstorms and showers) have continued to slowly evolve eastward with time over the Indo-Pacific warm pool region since late 2013. Enhanced convection during the last month has been centered over the western Pacific with suppressed convection that had been dominant near the Dateline during late 2013 having shifted slightly east and weakening considerably.
Below are the April - June 2014 seasonal temperature and precipitation outlooks from the CPC
Click on the image for a larger version
Downscaled/Experimental Outlook: As earlier mentioned, one of the techniques used in the outlook process is Composite Analogs (various analog techniques are detailed by following the link). This technique simply looks at the current and recent trends in the climate and the general atmospheric conditions that helped create them. Looking through the historical database, previous years that approximate the current year and recent history are selected. Then, a composite of the average climate for those years is projected into the next three months. The primary assumption is very simple: since weather and climate are somewhat cyclical in nature, what has occurred in the past may be used as a guide to the next season's weather. The major assumption is the atmospheric conditions of the past will approximately repeat in the near future. The major problems include 1) This technique does not take climate change / trends into account, and 2) Presumes the same 'weather' will be approximately repeated.
However, there is sufficient evidence to support this process, provided the user understands this is not an official outlook, and the conditions presented be used as historical guides only. Below is the locally generated Experimental Outlook using the Composite Analog technique, focusing on the "net climate" during the April - June years where the ENSO shifted from cool phase to warm phase as is currently forecast by the CPC.
Click on the image for a larger version
The four panel image above represents the temperature anomaly (upper left) and precipitation anomaly (upper right) for the April - June period. Based on the years where conditions in the Pacific changed from cool phase to warm phase ENSO, there was a bend towards cooler and slightly wetter conditions. In the 6 years chosen, the mean departure from normal temperatures was -1 degree Fahrenheit. This is statistically on the cool side of normal, but not drastically so. Precipitation totals were around 1.0 to 1.5 inches above median, which is well within the "normal range" for the three months.
The images in the lower half of the panel represents the upper level pattern in the mid-troposphere for January 1 to March 15, 2014 (lower left) and the Composite Analog derived April - June (lower right). Based on the shape and distribution of the centers of high / low pressure in the lower left panel, the cold winter of 2013/14 can be explained. The green arrow represents the mean flow from across the North Pole, through the Hudson Bay area then south into the U. S. This flow consistently brought colder than average air into the region. Based on the shape and distribution of the centers of high / low pressure in the lower right panel, a shift in the upper air pattern will occur this spring. The upper air pattern would retrograde, or shift west. The region would remain under lower than normal heights keeping our weather "cooler than normal". However, the flow would shift from northwest to more west or southwest at times - very common in the spring - bringing an enhanced risk of rain or snow to portions of the plains.
Overall the local outlooks agree with the CPC Outlook, supporting the tendency for below normal temperatures the next three months. While the outlook has a bend towards wetter than normal, this wetter pattern falls within the net climate common during ENSO transition years.
Spring Flood Implications: The overall weather patterns do not currently suggest any widespread heavy snow or rains the next few weeks. Also, the generally below median temperature pattern will favor a gradual melt. More information is available by clicking here.
For more information on the Climate Outlook email Mark Ewens Climate Services Focal Point at 701.795.5198