Many people don’t realize that the western part of the United States is generally arid to semi-arid. The Pacific Northwest gets biblical amounts of rain, of course, because of the coastal mountain ranges wring the water out of the wet air. Every range of mountains east of the coast catches the ever drier air, and squeezes a bit more moisture out of it. In summer, this water usually falls as rain.
But in winter, the moisture falls in the mountains as snow. The snow builds up over the course of the winter into a thick covering called snowpack. The snowpack only begins to melt in the spring. Depending on how deep the snowpack is, it often lasts into mid summer, giving regional cities and farms a long lasting reservoir of water.
The most important river in the Southwest is the Colorado River, fed by the Green, Upper Colorado, Gunnison, Uncompahgre and San Juan basins. The entire Southwest, including Arizona, Los Angeles, San Diego and the Central Valley of California depend on the rain and snow that fall in these basins that feed the Colorado.
So about this time of year, I begin to watch the snow pack in the mountains to see how dry our summer is going to be. Red is below average, green is above average, white is average, and grey is non-reporting either because it doesn’t have snowpack or there was a glitch.
In January, it was looking pretty grim. (January Snowpack) Only the Northern Rockies were in good shape. That didn’t actually surprise me, because we in Colorado hadn’t had any real snow falls in November, December or January.
But starting in February, we’ve had a bunch of little storms. Most of them have dropped less than 3 inches of snow, but it has begun to build up. (February Snowpack) The snowpack isn’t deep enough to make anybody breath easy yet. But the storms have added enough to give us hope that we won’t have water restrictions this summer.
NRCS National Water and Climate Center
It all depends on the next three months. Spring is our wettest season, by far. If mother nature is kind, we can make up the deficit.