Data: Daily PPH
      MAM 1955-2018
      92 days each MAM
      64 years 
      1x1 over US
      value x 100  --> PPH percentage value

The data will be extended to 2019 and the paramenters for
calculating PPH will likely be modified.

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Tornado 
Data file: td-PPH_1955-2018_MAM.92d.1x1.gr
ctl file:  td-PPH_1955-2018_MAM.92d.1x1.ctl

Hail
Data file: hl-PPH_1955-2018_MAM.92d.1x1.gr
ctl file:  hl-PPH_1955-2018_MAM.92d.1x1.ctl

Land-sea mask
Data file: us.land.1x1.gr
ctl file:  us.land.1x1.ctl

Example
s6.read.1981-2010.f
  To read data and derive event days for MAM (10% for Tornado or 30% for Hail)
  To calculate climatology and standard deviation of event days for 1981-2010

Map of 1981-2010 climatology and standrad deviation:
  MAM.clm.sdv.1981-2010.eventday.gif