PGH/MET/M1 - PWD spikes and missing data prior to revised install

The PWD was not installed efficiently, leading to occasional spikes and a period of 
missing data from 7/6 - 7/12 until revised installation took place and the programming was 
updated.

Use available PWD data with caution.

• pwd_id
• pwd_pw_code_1_hr
• pwd_avg_H2O_int_1_min
• pwd_err_code
• pwd_cumul_snow
• pwd_avg_vis_1_min
• pwd_cumul_water
• pwd_avg_vis_10_min
• pwd_pw_code_15_min
• pwd_pw_code_inst