MIAMI VALLEY, Ohio (WDTN) – Cloudy skies usually block the sun from the Miami Valley much of November. In 2019 we only saw two mostly sunny days. This year Dayton has recorded six mostly sunny days.
More sunshine means less rain. As of Nov. 28, Dayton recorded 1.61 inches of rain during the month of November. This is 2.6 inches below normal.
Looking ahead to winter the Miami Valley typically sees wetter and warmer conditions during La Nina.
The Climate Prediction Service issued a La Nina Advisory after conditions strengthened in the Pacific Ocean. Average sea surface temperatures along the equator were below normal by 0.7 to 1.0 degrees celsius. There is a 90% chance of La Nina continuing through winter and a 50% chance through the spring.
This winter we return to La Nina after a Neutral break in the El Nino Southern Oscillation (ENSO) through the Summer.
There are five years with similar ENSO conditions in the Pacific Ocean. The table below shows how the winter season played out in Montgomery County with data from the National Centers for Environmental Information.
|20th Century Average||29.7°F||8.14″||27.5″|
Average temperatures across December, January, and February were near or above the 20th-century average. 2008 and 1984 were below normal by less than 1 degree Fahrenheit.
Precipitation was above normal every year except for 1984.
Snowfall varied the most. In 2011 we only saw 9.2 inches of snow for the year and in 1974 Dayton recorded 41.1 inches of snow.
Warmer and wetter averages do not always mean less snow. It only takes a couple of cold blasts with enough moisture to produce snow in the area. The average high is 41.5°F in December, 37.1°F in January, and 41.2°F in February. If the upper atmospheric conditions are below freezing right up to the surface we can still see snow with these temperatures. Average lows are in the 20s all three winter months. A warmer winter can still be cold in the Miami Valley.
Since 1950, Dayton has recorded less than two inches of rain in November 16 years. La Nina was present in November six of those years: 1964, 1970, 1971, 1998, 1999, 2017. Winter precipitation was above normal every year except in 1971. The snowfall was just above the normal snow of 27.5 each of these years except in 1971 when Dayton recorded 23 inches of snow. The most snow was 30.6 inches in 1998. The only year from this set to record a winter average temperatures below the 20th-century average is 1970. This trend suggests there are some exceptions but there is a good sign for a wetter and warmer winter with about average snowfall.