La Niña came in with a punch through Hurricane Priscilla, even impacting the aridified lands of the San Luis Valley with swelling rivers and a low danger of flash flooding the week of Oct. 12.
The storm originated from western Mexico with heavy rain and strong winds, with remnants moving through the southwestern U.S. and southwest Colorado and overpowering the San Juan River.
The San Juan through La Plata County and into Archuleta County took the brunt of the storm. An evacuation of hundreds of homes around Vallecito Reservoir near Durango and highway erosion east of the Wolf Creek Tunnel that forced weekend closures of Wolf Creek Pass were the biggest impacts.
The eastern San Juan region could see another 3 to 4 inches of rain this week, which has put emergency managers, including in the six-county San Luis Valley, on alert.
When the lands have become aridified as they have in the San Luis Valley, from decades of drought, they become less capable of handling swelling riverbeds caused from the heavy rains to the west. The result is flash flooding events like in Pagosa Springs, and warnings of low flash floods as the San Luis Valley is seeing, due to soil erosion and poor groundwater recharge.
The communities of Creede and South Fork remained on alert Monday with more rain possible, and the Rio Grande through Del Norte saw flows of 2,630 cfs.
The Colorado Department of Transportation’s southwest regional office said it is monitoring the San Juan Bridge on the east end of Pagosa Springs and would take a closer look once water levels recede. The state transportation agency said it was confident of the structure given that it is built on a fixed foundation.
The early forecast from the National Weather Service was for a weak La Niña season once it materialized. Now that it has, the predictions remain for a weak La Niña season through mid-December – meaning temperatures still above normal and below-normal levels of moisture for the season.
