GAN/MET/M1 - Intermittent PWD alarm

Intermittent backscatter alarms were tripping on the PWD suggesting something was blocking 
(dew) or getting into the measurement path (spider or ants).  Problem resolved 10/9 with 
no clear indication of the cause.

• 15 min present weather code(pwd_pw_code_15_min)
• Present weather detector ID(pwd_id)
• Average 10 min visibility(pwd_avg_vis_10_min)
• Cumulative snow(pwd_cumul_snow)
• 1 hour present weather code(pwd_pw_code_1_hr)
• PWD instantaneous present weather code(pwd_pw_code_inst)
• 1 minute average water intensity(pwd_avg_H2O_int_1_min)
• Average 1 min visibility(pwd_avg_vis_1_min)
• PWD alarm(pwd_err_code)
• Cumulative water(pwd_cumul_water)