PHOENIX (3TV/CBS 5) -- While it's still fall, according to your wall calendar, Dec. 1 is the first day of the meteorological winter, which should last until February. Astronomical winter -- your wall calendar -- is a bit different. Why? Here is how the National Oceanic and Atmospheric Administration (NOAA) breaks it down.
“In short, it’s because the astronomical seasons are based on the position of Earth in relation to the sun, whereas the meteorological seasons are based on the annual temperature cycle."
So, let’s talk winter and what it may or may not bring to Arizona. Typically, when looking at winter weather patterns, we look at El Niño or La Niña. However, this year, according to NOAA, neither will develop. Instead, the El Niño Southern Oscillation (ENSO) will be neutral. ENSO is a weather pattern that typically influences winter. This type of pattern leads to warmer-than-normal conditions and drier-than-normal conditions. At least for the Desert Southwest, as noted on the graphics, other areas will be wetter than normal.
Although this is not the first time, Arizona has been in a neutral pattern for winter. Look at what the National Weather Service (NWS) office out of Flagstaff put out about ENSO's neutral patterns previously in Arizona. It looks at the last 10 years and how many were above- and below-average snowfall. We had more years with below-average snowfall.
In a neutral phase, the equatorial water in the Pacific Ocean does not push the atmosphere toward an El Niño or La Niña pattern. That makes it difficult to say whether we will be above or below average. It also makes it difficult to predict the weather pattern over the next several months.
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This weather pattern is just a general idea of what we could see. As we just saw the past two weeks with our back-to-back storms, sometimes Mother Nature does not follow the rules and gives Arizona some good storms.
[THE WEEK BEFORE: Storms bring rain, hail, snow to Valley and northern Arizona]