The word that best defines hydrology in New Mexico during 2018 is ‘drought’. A weak La Nina developed in late 2017 and the impacts for the Southwestern and the Southern Rockies were near textbook. By January 1^st 2018, many locations in the state had already reported 60+ days without any measurable precipitation.  

This trend continued through much of northern New Mexico into mid-February when a Valentine’s Day system brought the first measurable precipitation for some areas since mid-October 2017. The dry trend generally continued into early monsoon season as convective activity began to increase over New Mexico. However, most of this precipitation was focused over eastern New Mexico, missing the parched Northern Mountains and Four Corners region. Even in areas that precipitation did develop the character of the rainfall was very “hit or miss” with some areas seeing repeated thunderstorms and other areas a short distance away continuing to see dry conditions. Convective activity continued to increase late in the monsoon season with well above normal precipitation totals over the middle Rio Grande Valley and portions of the Pecos and Canadian River Valleys.

Precipitation totals continued to increase through October with a widespread two day rain event on October 23-24. This event produced widespread event totals of 1.50” or more of rainfall with 45 stations reporting more than 2.00” with Jemez Springs receiving 3.62”!  October 2018 closed out with an early season winter system, which provided an early jump on snowpack over the Northern Mountains. While the precipitation was welcome in some of the hardest hit areas through the state, precipitation totals were not large enough to make any significant change on the USDM.

With the increase in precipitation over the region in September and October, a large portion of New Mexico was able to see improvement on the US Drought Monitor. Many areas along the middle Rio Grande Valley and Eastern Plains saw significant improvement in their designation on the USDM or complete removal.

The wet period of September and late October came to a halt over the Southwest in November as a cold and dry pattern settled into the area. A few storm systems over the Eastern Plains produced near to somewhat above normal precipitation totals, but largely the majority of New Mexico saw little, if any measurable precipitation. The below normal temperature pattern, however reduced evapotranspiration demands as well as the loss of any existing snowpack. This helped to prevent any further deterioration in drought conditions.

December saw a return to an active pattern with several significant winter weather systems moving through the state.  The most significant of these systems occurred in the last week of the year, with significant snowfall totals over much of New Mexico. While the widespread precipitation was welcome, little impact on drought conditions in New Mexico. First, while impressive in the amount of snow that was produced, the late December systems produced snowfall with high snow to liquid ratios, often as high as 30:1. This produces “dry” snow that while excellent for winter recreation, does little for drought conditions. Secondly, many of the D3/D4 areas received lower snow totals than those areas in less severe designations on the USDM. Finally, due to the deep deficits over the previous 12-15 months, the liquid equivalent precipitation from the late month events were not high enough to meet the thresholds for any drought improvements.

Although drought was the rule over the Land of Enchantment in 2018, there were several significant flash flooding events throughout the area:

Ute Park:

After the destructive Ute Park fire was contained and under control, the threat for the area transitioned from wildfire to post-wildfire flooding.  The Ute Park area saw repeated thunderstorms through July and August with 10 confirmed flash flood events in the Village of Ute Park and along US Highway 64. The most significant events were on July 13 and August 2. During both of these events, heavy rainfall fell upstream of the Village of Ute Park, causing flash flooding and debris flows into Ute Park. Up to 21 structures were damaged on the August 2 event, 12 of them having already been damaged on the July 13 event. Almost all of the flood events created a surge of water down the Cimarron River, with the USGS river gage near Cimarron reaching minor flood stage 5 times in July and August.

Santa Fe Flooding:

Strong thunderstorms produced heavy rainfall in the Santa Fe Metro Area in the afternoon of July 23. Significant flash flooding was reported in Santa Fe with 10 roads closed and 100 homes damaged due to flooding. Of those 100 homes, 33 experienced major damage with 6 destroyed. Rapid rises to near minor flood stage were observed on the Santa Fe River near Cochiti Lake that evening. This was the highest stage at this gage since July 10, 1996.

Rio Rancho/Belen Flooding:

A series of thunderstorms produced flash flooding through the middle Rio Grande Valley with significant impacts in Rio Rancho and Belen. In Belen, runoff from heavy rainfall filled an irrigation canal beyond capacity which caused a failure of the levee surrounding the canal. Reports from the City of Belen reports that around 1000 homes and businesses were impacted by the flood waters from the canal.

Further north, thunderstorms also created flash flooding in portions of Rio Rancho. Several roads in northern Rio Rancho were impacted and closed from flash flooding. Several vehicles were damaged in the flooding. Southern Sandoval County Arroyo and Flood Control Authority also reported significant rises through several arroyos through the city.