Tucson News NowMajor weather change ahead for southern Arizona

The Arctic is sending pulses of cold air into and through northeast Asia (Russia). Those pulses cause ripple effects in the atmosphere, which eventually result in southward dips in the jet stream.

Figure 1: Notice the purple colors over northeast Asia and the Bering Sea. These represent an Arctic airmass.

This is the first ingredient that will bring a significant change from tranquil and warm to cool and unsettled weather during Valentine's Day week.

In addition, an intra-seasonal system, called the Madden-Julian Oscillation, will bring available moisture close to southeast Arizona, increasing our rain chances.

Figure 2: Madden-Julian Oscillation (MJO). For more on MJO, click here.

For the up-to-the-minute forecast, visit TucsonNewsNow.com/Weather.