This guide is targeted at NMHSs and is intended to demonstrate the benefits that NMHSs gain by participating in WWIS, and to provide step-by-step guidance for a National Meteorological or Hydrometeorological Service (NMS) wishing to either join the WWIS i
World Meteorological Organization. Guidelines on Participation of National Meteorological and Hydrological Services in the WMO World Weather Information Service. 2012-01-01.