April rains brought much needed moisture to Southwest Colorado after a particularly dry and warm winter, although the Durango area still received less precipitation than average.
An April forecast from the Climate Prediction Center showed an El Niño pattern could surface sometime this summer – that’s not a guarantee of wetter weather to come.
Lucas Boyer, National Weather Service meteorologist in the Grand Junction office, said recent rains were a refreshing change after a winter plagued by above-average temperatures.
“It has been a fairly common thing this past winter that we were 10 to 20 degrees above average,” Boyer said.
In March, a stubborn ridge of high atmospheric pressure blocked the jet stream – a fast-moving current of air high in the atmosphere that carries storms from the Pacific Ocean over the continental United States – from the northern regions of the United States. That accounted for the long stretches of hot and dry weather, he said.
“Once April came along, we had that ridge breakdown,” Boyer said. “Last month, we saw a really active weather pattern evolve under that jet stream, which we didn’t have in March.”
According to the Community Collaborative Rain, Hail and Snow Network – whose Durango station provides data for month-by-month precipitation totals for the area – zero measurable precipitation fell in the month of March. April, on the other hand, saw 1.96 inches of rainfall.
Boyer said compared to historical norms, Southwest Colorado received less precipitation than average for April. But still, that was a vast difference compared to March.
“Down south, we stayed warm and dry,” Boyer said. “And then to the north, precipitation and cloud cover kept temperatures a little closer to normal.”
So far, May is off to a wet start. On Tuesday, the National Oceanic and Atmospheric Association issued a winter weather advisory for the San Juan Mountains that lasted until 6 p.m. Wednesday, and lower elevation areas saw intermittent rain storms.
The Climate Prediction Center’s forecast for a possible El Niño pattern in the summer could point to wetter weather, but Boyer was hesitant to say that El Niño would bring an atmospheric gravy train to Southwest Colorado.
An El Niño pattern is characterized by a southerly shift in the jet stream and can increase the chances that storms move in over the southwest portion of the country. What gave Boyer pause is broad atmospheric trends don’t actually account for specific regional forecasts.
“El Niño will have an impact on a seasonal scale when it's all said and done,” he said. “But it doesn't necessarily paint the picture down to the mountain-valley scale.”
Boyer said just how the El Niño pattern will effect precipitation in Southwest Colorado remains to be seen.
The NWS’ current outlook shows equal chances for the state to see above- or below- average precipitation.
“Our seasonal outlook has much of Western Colorado in kind of an equal chance of wet and dry through the May, June and July time frame,” Boyer said.
As for temperatures through midsummer, he said there is a 70% to 80% likelihood the state will be above the historical average.
sedmondson@durangoherald.com
