National Weather Service United States Department of Commerce

Slow Moving Storm to Impact California and Dampen Western States

A slow moving system off the California coastline will bring rain, mountain snow, and coastal impacts. Locally heavy rain may cause flash flooding, especially, on burn scars in from central California to southwestern Oregon. Snow up to 3 feet will be possible in the Sierra-Nevada Mountains. Rain with mountain snow can be expected from the Northwest to the Northern Rockies and into the Plains. Read More >

Proper Siting

The Coop network has provided climate and weather data for over 100 years. Consistency of the measurements is an attribute of the network, and it has been maintained by rare and/or gradual change, and established standards for exposure, of instruments over the life of the network. In order to preserve the integrity of the network, NWS has established standards for equipment, siting, and exposure.

Temperature sensor siting: The sensor should be mounted 5 feet +/- 1 foot above the ground. The ground over which the shelter [radiation] is located should be typical of the surrounding area. A level, open clearing is desirable so the thermometers are freely ventilated by air flow. Do not install the sensor on a steep slope or in a sheltered hollow unless it is typical of the area or unless data from that type of site are desired. When possible, the shelter should be no closer than four times the height of any obstruction (tree, fence, building, etc.). The sensor should be at least 100 feet from any paved or concrete surface.

Precipitation gauge siting: The exposure of a rain gauge is very important for obtaining accurate measurements. Gauges should not be located close to isolated obstructions such as trees and buildings, which may deflect precipitation due to erratic turbulence. To avoid wind and resulting turbulence problems, do not locate gauges in wide-open spaces or on elevated sites, such as the tops of buildings. The best site for a gauge is one in which it is protected in all directions, such as in an opening in a grove of trees. The height of the protection should not exceed twice its distance from the gauge. As a general rule, the windier the gauge location is, the greater the precipitation error will be.

                                               Compatibility Determination for Site Moves

Station moves where the new equipment location is within 5 miles of the original site and the difference in elevation is 100 feet or less are also assumed to be incompatible unless they pass a data compatibility evaluation. While most re-locations are expected to exhibit data incompatibility, there may be cases when the data record from the new location may be a faithful continuation of the climate record from the old location. However, the compatibility evaluation will be conducted for all relocations of less than 5 miles and/or 100 feet unless the move is deemed incompatible by the NWSREP.

The NWSREP will convene an ad hoc committee to conduct a thorough evaluation. The committee hereafter referred to as the WFO Data Continuity Committee (DCC) (one DCC for each WFO) will be comprised of one representative from each of the following groups:

       a.  WFO NWSREP (chair).

       b.  NWS Regional COOP Program Manager (co-chair) and Regional Hydrologist if applicable.

       c.  NWS Regional Climate Services Manager (backup co-chair).

       d.  Appropriate Regional Climate Center.

       e.  American Association of State Climatologists Recognized State Climate Office (if a member is available).

       f.  NCDC, only when results of parallel testing are available for the evaluation, or when a new station identifier issued.

The DCC determines compatibility on an advisory basis by applying a compatibility checklist. Relocations that satisfy the conditions on the checklist may then be declared data compatible by the NWSREP (chair, DCC). The checklist will be entered into the official metadata record for the station and be available as part of the site’s historical record as funds are available.

For climate data continuity purposes, the establishment of a station near the site of a previously closed site will be treated in the same manner as other relocations. That is, the station number of the previously closed station can only be used again if data continuity is found to be maintained between the two locations through the checklist process of the DCC. In such cases, there will be an acceptable period of missing data between the closure of the historic site and the opening of the new site.