Tuesday, August 23, 2016

Radium Springs heavy rain event on August 21, 2016

Intense rainfall upwards of 4 inches fell on Radium Springs, New Mexico from a late Sunday evening storm on August 21. Two CoCoRaHS observers in Radium Springs recorded impressive amounts of rain from this storm. The observer at Leasburg Dam State Park measured 4.04 inches by the morning of August 22. Another observer northwest of the park measured 3.83 inches. Observers to the south measured respectable amounts but not nearly as much as that in Radium Springs.

The Santa Teresa radar indeed verified a rainfall hotspot in this area. Below is a screenshot of the 24-hour radar based precipitation by the morning of August 22. The marker in the map below is an approximate location of the park where the 4.04 inch was measured.
The evening sounding (6 pm) at Santa Teresa showed the deep moisture over the area and a precipitable water amount of 1.18 inches. The morning sounding had a precipitable water of 1.33 inches. Vertical structure of the convective clouds over the area were impressive this late in the evening. Radar estimated cloud tops were in the ballpark of 34,000 feet based on the plot below.
An animation of the radar reflectivity shows the storm's trajectory from the west.

Cold cloud tops from this GOES infrared map also indicated the strength of this storm.
The radar also picked up hail signature at the height of the storm. The dual polarization radar product (HHC) shows hail in this plot as red. When I visited the park I verified hail with the campground host. The size of the hail was about pea size or 1/4 inch.
A snap shot of the radar base reflectivity was high at the peak of this storm and extended across the area.
A flood advisory was issued by the El Paso National Weather Service office in the area about the time of this event.

I visited the State Park on Monday afternoon and wanted to view the impacts of this amount of rain on the area. By the time I started my trek it was about 12 hours after the storm. I first drove along Valley Drive (highway 185) from Las Cruces toward Radium Springs. Stopping along the way to view the Rio Grande as it crossed Picacho Avenue (highway 70) I noticed the high level compared to what I am used to. This is the Rio Grande looking north at the Picacho bridge.
The next stop was a viewpoint of the river just north of Dona Ana as the road was close to the water. The river level was about the same as the Picacho crossing.
A few miles north of Radium Springs from the road provided a nice vista overlooking a very full river. However I didn't see any flooding but it was right up to the bank.
I did notice a location where there had been water flow over highway 185 north of Radium Springs. No water remained when I was there but the debris left over from last night was still present and it was obvious that water had flowed over the road at this location.
At that same location I did see a little erosion of the banks upstream from this storm.
There were some ponding on the side of the road driving into Radium Springs on the west side of the village near the post office. In this part of town there was not a lot of ponding remaing 12 hours after the rain but it was evident it rained.
Runoff and debris on the roads within the Radium Springs community was much more severe. At a few locations up to a foot of soil was deposited on the road and by the time I arrived a county road grader was already on the job clearing the roads. The photo below was on DeBeers Road.
and looking in the other direction
Flowing water on the access road to the Masson Farms had eroded part of the area under the railroad.
Some erosion undercut a retaining wall and fire hydrant at the corner of Hurt and Desert Edge Roads.
The most ponding that I saw was along the railroad on Tres Amigos Road and it appeared impassable with a normal vehicle due to the depth of water.
A few parcels had standing water remaining after the storm.
In the park I didn't see any major damage or flooding although Leasburg Dam was very full and one log remained on the top of the dam. I was told that there was another log on the dam but that was pushed downstream by the time I was there.
From the hard work of our CoCoRaHS observers we were able to know about this rainfall and document the impacts from an exceptional event. Below is our CoCoRaHS observer at the park, Park Manager Evaristo Giron who measured the 4.04 inch storm.

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