Chapter 10 — WATCH ROUTINES 



Table 10-1. — Symbols for weather elements and obstructions to vision for column 5 entries 



TORNADO Tornado 



WATERSPOUT Waterspout 



FUNNEL CLOUD Funnel cloud 



T+ Severe thunderstorm 



T Thunderstorm 



R Rain 



RW Rain showers 



L Drizzle 



ZR Freezing rain 



ZL Freezing drizzle 



IP Ice pellets 



IPW Ice pellet showers 



S Snow 



SW Snow showers 



SP Snow pellets 



SG Snow grains 



IC Ice crystals 



A Hail 



F Fog* 



GF Ground fog* 



BS Blowing snow* 



BN Blowing sand* 



BD Blowing dust* 



IF Ice fog* 



H Haze* 



K Smoke* 



D Dust* 



BY Blowing spray* 



1 



Suffix + to precipitation symbol to indicate heavy intensity and for light intensity. 

 The absence of an intensity symbol indicates moderate intensity. No suffix is attached to 

 "A", for hail or "IC" for ice crystals regardless of intensity or to any obstruction to 

 vision symbols. "T" used alone indicates moderate intensity or less and lightning (LTG) 

 is entered in column 13 as a mandatory remark. 

 *-Denotes Obstructions to vision. 



NOTE: Tornado, waterspout, and funnel cloud are always written out in full in column 5 

 and column 13. 



Intensities of precipitation are determined form of snow or drizzle occurs in combination 



by one of two methods. One method is the with one or more hydrometeors or lithomete- 



rate of accumulation. The other method is the ors, the Intensity of the precipitation is deter- 



degree to which the precipitation affects vlsl- mined on the basis of the rate of accumulation, 



bility. The term "hydrometeors" includes all atmos- 



Intensitles of all forms of precipitation ex- pherlc phenomena composed of liquid or solid 

 cept snow and drizzle are determined by the forms of water. A lithometeor, on the other 

 rate of accumulation. Intensities of all forms hand, is composed of solid dust or sand parti- 

 of snow (snow, snow grains, and snow pellets) cles, or the ashy products of combustion, 

 and drizzle, when they occur alone, are deter- At stations not having recording gages, de- 

 mined by the effect on visibility. When any termine the intensity of rain from the guides 



169 



