Stormy New Year’s Day for Arizona!

The atmospheric ingredients are set for a stormy New Year’s Day over Arizona! A dynamic weather pattern is in play over the Desert Southwest to kick off the new year with nature’s version of fireworks, so to speak. The southwestern U.S. has had ample moisture to work with for several days now and this is an important consideration. Evidence of higher moisture readings have been observed by ongoing mostly cloudy conditions, extended foggy periods in mountainous zones, and moderated temperatures in general at all elevations as afternoons are cool, but overnights are seasonably warm. In other words, the atmosphere is primed to deliver decent precipitation should large scale lift commence. That’s exactly what we are going to get for those living in Arizona starting 2023!

Prime time for widespread heavier precipitation, gusty winds, and pockets of thunderstorms will be late morning through the afternoon period. Looking at the situation top-down, we have a dip in the main jet stream overhead stretching from California that is entering Arizona as of sunrise. The jet stream’s southward “dip” represents a vigorous, cold, and unstable low pressure trough. Accompanying the advancing upper-level low pressure trough, a main catalyst for the unsettled weather we will experience today is from an associated surface cold front moving west to east. Recall that a cold, dense air mass moving into a warmer and moist air mass will force the warmer one, and its water vapor content, vertically. Condensation and deeper clouds to support precipitation then become likely, especially when the vertical temperature profile aloft in the troposphere is cold.

The tradeoff for excessive moisture, indicated by warmer dewpoint temperatures, is higher snow levels ahead of and up to the time when the cold front passes through your local area. Behind the cold front, the freezing altitude can plummet to reach the surface for the mountains and a sudden transition to wintry precipitation results, even if only briefly as drier air behind the cold front filters in. Atmospheric instability overhead likely keeps scattered heavier shower activity going tonight. Be mindful of deteriorating road conditions!

Data Source: College of DuPage