Thundersnow may occur 1/hour dealing
(1d10)d8 Electricity damage.
OGL v1.0a . Send suggestions and bug reports to:
For Pathfinder: non-specific Skill penalties from Wind apply per
GM discretion, possibly stacking with Perception penalties.
cap708g at hotmail.
Thunderstorm Wind Speed is listed even when Tornados and
Hurricanes are present. Tornado and Hurricane events that occur
during or after Thunderstorms and must be
Due to days with constant sunlight or darkness, errors may occur
for areas near a Pole experiencing Summer or Winter.
Day or Night
Alterations to Published Rules:
Baseline Winter temperature for Tropics was
increased to 65 degrees to greatly decrease the chance of frozen
precipitation at night.
"Stable Temp Biome?" option was added
to decrease temperature variations by either 1/3 or 2/3 for moderate Biomes
such as Mediterranean.
"Drizzle" renamed to "Light
Rain" and "Rain" renamed to "Medium Rain" to create
a consistent naming convention.
"Windstorm" Wind Speed set to 51 to 74
as opposed to "51+" as "Hurricane" threshhold is 75.
"Sandstorm". Duststorm and Haboop and may occur in Deserts when
there are high winds and no Precipitation. Duststorm otherwise follows Rain
Couldcover descriptions changed to
"None", "Light", "Medium", and
"Heavy" to create a consistent naming convention.
Maximum temperature for "Thunderstorm with
Hail" limited to 79 to better mirror such events.
Average Night temperature drop roughly doubled
depending on Climate and Biome.
Previously absent Blizzzard effects added by
extrapolation from other snow events.
For temperatures and wind with ongoing durations,
a twice-daily variation of -5 to 5 was added.
Precipitation frequency for most categories was
increased by 5% each due to the common elimination of Fog events by Wind.
Further decrease of Precipitation for
"Drought" areas was ignored, as Precipitation Frequency and
Intensity were already very low for those areas.
Added "Force Precipitation?" option to
manually adjust Precipitation frequncy. Per rules, precipitation events are
limited to one per 24-hour block, but often persist into the following
Added "Adjust Temperature?" option to
manually increase or decrease temperatures. The numbers shown are in
Fahrenheit but final results can still be in Celcius.
Added "Weaker Winds?" options to
decrease frequency of extreme Wind by either 1/3 or 2/3.
Added Wind Chill to output. I invite GMs to use
this as the effective temperature when determining cold weather effects on
characters outside of shelter.
Eliminated Tornados for Highlands and High
Desert temperatures increased moderately for Day
and decreased moderately for Night.