This is an experimental forecast that will look at the month of May and examine the types of weather trends that can be expected in Mid-Missouri, rather than a day-to-day forecast.
There are many things to analyze when putting together a long range forecast. One of the biggest players in a long range forecast is looking at current and future ocean temperatures, particularly in the central and tropical Pacific. Meteorologists look here to tell us what phase of ENSO (El Nino Southern Oscillation) we are currently in; in other words, are we in an El Nino phase, La Nina phase or somewhere in-between.
Currently, we are in a neutral pattern in terms on ENSO phase, but we are making a move toward El Nino for the upcoming summer. El Nino is classified as a warming of the tropical Pacific by 3-5 degrees Celsius. Being in a transition period between the two phases makes forecasting the upcoming month a bit more challenging.
Temperatures & Precipitation
So far in 2014, the average temperature is 5.8 degrees below average (not including temperature data from the month of April). The Climate Prediction Center (CPC) has Missouri in the "equal chance" range when it comes to a temperature outlook as seen in the picture below. Equal chance means there is an equal chance we could see temperatures below or above average. Overall, spring will be in full-force across the area. However, it does appear that May will start off a little bit below average in the way of temperatures ?? especially the first week. However by the middle and end of the month, I expect temperatures to be above normal ?? I also expect to see a few hints of summer-like temperatures as well.
May 2014 temperature outlook from the Climate Prediction Center (CPC).
In terms of precipitation, the CPC shows that Missouri has an equal chance for below or above normal rainfall for the month. I expect rainfall to be slightly below normal when the month is said and done. Statistically, May is our wettest month with 4.75 inches of precipitation on average, but it will likely be a bit lower this year for the month. Expect to see a few rounds of showers and thunderstorms, with a few shots of severe weather in the mix as well. Overall in 2014 (through March), Mid-Missouri is nearly 2 inches below normal for precipitation. Not all of the April's numbers are in the books yet, but we are currently sitting about one-half inch above normal in precipitation.
May 2014 precipitation outlook from the Climate Prediction Center (CPC).
Flooding & Drought
Widespread flooding will not be a concern this May as it has been in past. Coming out of a drought over the past few years we are a little bit behind in overall precipitation. Average yearly precipitation for Mid-Missouri is 42.62 inches. Below is how much we have had the last three years:
Total precipitation over the last three years has been 111.88?? which is only roughly 85% of what we would normal get between 2011-2013. Drought conditions currently in Missouri are almost non-existent, however, it could become a concern for the summer.
Drought monitor of Missouri from the National Climate Data Center (NCDC) as of 22 April 2014
Looking ahead to the summer, an El Nino pattern would favor a cooler with slightly more moisture than normal weather pattern, but look for more on the upcoming summer in my next long range forecast for June.