Cloud Seeding Program

Cloud Seeding Safety Guidelines

In the event of any emergency which affects public welfare in the region of any seeding operations being carried on by the DRI Cloud Seeding Program, the seeding operations in that region will be suspended until the emergency conditions are no longer a threat to the public.

Seeding suspensions are generally expected to occur due to one or more of the following conditions:

A) When an extreme avalanche danger exists as determined by the U.S. Forest Service.

B) When the National Weather Service (NWS) forecasts a warm winter storm(freezing level >8000 ft.) with the possibility of considerable rain at the higher elevations which might lead to local flooding.

C) When the Project Meteorologist determines that potential flood conditions may exist in or around any of the project areas, the National Weather Service Flood Forecast Services at Reno or Sacramento will be consulted about the possibility of any of the following warnings or forecasts being in effect.

  1. Flash flood warnings by the NWS.
  2. Forecasts of excessive runoff issued by the CA/NV River Forecast Center, including such forecasts for rivers on the adjoining west slope of the Sierra Nevada.
  3. Quantitative precipitation forecasts issued by the NWS that would produce excessive runoff in or around the project area.

In addition to the above, if any of the following conditions or forecasts exist; seeding operations may be suspended, at the discretion of the Project Meteorologist, in and around the areas of concern:

A) When the wind speed is 60 knots or more for over 30 minutes at the 700 mb level (~10,000 ft). For monitoring purposes in the western part of Nevada, the winds measured at Slide Mountain (9,650 ft) are considered equivalent to the 700 mb level winds. The Reno and Elko upper air soundings can also be used to monitor this criterion, as can the Doppler winds from the Reno and Elko NEXRAD radars.

B) When wind directions lie outside of the range between 180 and 330 degrees during ground-based seeding operations on the west side of the Sierra Nevada crest. The winds measured at Slide Mountain or Ward Peak (8,480 ft), and the upper air soundings and NEXRAD Doppler winds from Reno and Elko can be used to monitor wind direction.

C) When the water content of the snowpack in the target area, as measured at existing snow courses or SNOTEL sites, exceeds the accumulation envelope defined by the following percentages to date of long-term averages on the same date. NRCS SNOTEL data and reports are used to monitor snowpacks.

December 1…175% February 1…150% April 1…140%
January 1…..150% March 1….150% May 1….140%

Intermediate limits shall be derived by linear interpolation between the percentages given above.

D) During major holidays such as Thanksgiving, Christmas, New Year’s Day, and President’s Day, in areas and times of heavy traffic on Highways 50 and 80, over the Sierra Nevada.


Frank McDonough, M.S.
Program Director 


Desert Research Institute
2215 Raggio Parkway
Reno, NV 89512


Atmospheric Sciences