Thursday, February 18, 2016

Playing with Weather

I doubt this is at all realistic, and it's probalby too fiddly for most people, but here's a draft of a general weather chart that I'm considering using for the campaign.


Table: Random Weather
d20
Weather
Wind Table
Temp
Table
Precip
Table
Cold Climate
Temperate Climate
Desert
1-13
Normal weather
1d10
1d10
1d6-1
Cold, calm
Normal for season
Hot, calm
14-15
Abnormal weather
2d6
2d6
2d4
Heat wave (01-30) or
cold snap (31-100),
1d8+12 on Temperature Table
Heat wave (01-50) or
cold snap (51-100)
1d8+12 on Temperature Table
Hot, windy
16-17
Inclement weather
3d4
3d4
1d4+6
Precipitation (snow)
Precipitation (normal for season)
Hot, windy
18-19
Storm
1d10+6
1d10+6
1d6+6
Snowstorm
Thunderstorm, snowstorm
Duststorm
20*
Powerful storm
1d10+10
1d10+10
1d4+8
Blizzard
Windstorm, blizzard, hurricane, tornado
Downpour
* Roll d20 again if abnormal weather is indicated (14-19), the storm is a powerful storm as listed below, if a second 20 is rolled, the storm is a “storm of the century” table listed below.

Wind Table
Temperature Table***
Precipitation Table****
1
No Wind 0 mph
1
10 degree change
0
Very dry, cloudless
2-3
Light Wind 0-10 mph
2-3
5 degree change
1
Dry, clouds
4-7
Moderate Wind 11-20 mph
4-7
No change
2-3
Dry, very cloudy
8-10
Variable Winds**
8-9
5 degree change
4-5
Partly cloudy, brief drizzle
11-12
High Winds 20-50 mph
10
10 degree change
6
Rain, 2d4 hours, overcast
13-14
Severe Wind 50-70 mph
11-12
15 degree change
7
Heavy Rain, 3d4 hours
15-16
Dangerous Wind 70-90 mph
13-15
20 degree change
8
Soaking Rain, 2d6 hours, overcast
17
Deadly Wind 90-120 mph
16-17
25 degree change
9
Hard Rain, 3d8 hours, thick cloud cover
18
Hurricane Winds 120-150 mph
18
30 degree change
10
Hard Rain, 2d12 hours including 1 hour of hail, sun-blocking clouds
19
Tornado Winds 150-200 mph
19
40 degree change
11
Hard Rain, 6d4 hours, flooding, sun-blocking clouds
20
Unnatural Winds 200+ mph
20
50 degree change
12
Hard rain, 24 hours, flooding, extreme lightning, sun-blocking clouds
** Variable Winds: Winds blowing from 10-40 (1d4x10) mph with gusts 50-90 mph (1d4+4x10). Check for gusts any time something is attempted that might be adversely affected by winds
*** Temperature changes are based on the previous day’s temperatures. Unless otherwise directed, a 50% chance of raising and 50% chance of lowering temperatures.
**** In temperate climates, use the table as is. In cold climates, consider rain to be snow unless a heatwave is indicated. In desert climates, use cloud cover only unless 20, powerful storm has been rolled on the weather table, then include the rain as well.



Storm of the Century
1d8
Cold Climate*****
Temperate Climate
Desert
1
Temp drop 30 degrees, 6d8 inches of snow lasting 1d4+3 days
Hurricane/Tornado cluster (2d4 tornadoes touch down)3d6+12 inches of rain over 24 hour period, massive flooding
Snow on the Sand an impossible combination of events occurs, causing 1d4 inches of snow per hour to fall in the region, temperature drops to 30 degrees during the day and -5 degrees at night. Snow falls for 1d4+3 hours and melts at a rate of 1” per hour once the snow stops. Unprotected creatures take 1d4 hp damage per turn.
2-4
Temp drop 30 degrees, 2d12+12 inches of snow lasting 1d6 days
1d8+4 inches of rain falls for 1d12+12 hours, flooding, cluster lightning
Downpour 1d4+4 inches of rain falls in a 6 hour period causing massive flooding.
5-7
Temp drop 40 degrees, 4d6 inches of snow lasting 1d4 days
Hail the size of grapefruits falls for 10d6 minutes (each does 1d6 damage), +1d4+8 inches of rain over 12 hour period, flooding
Duststorm and rain 100+ mph winds drive a massive dust storm for 1d4 hours ahead of a huge storm front, which will bring 1d4 inches of rain in 2 hours.
8
Temp drop 40 degrees, 2d6+24 inches of snow lasting 1d6+5 days
Golf ball sized hail for 10d4 minutes (1 point of damage each), +12d6 inches of rain over 20 hour period, cluster lightning
Black Blizzard dust storm so thick that it blocks out the sun for 2d12 hours, any living creature caught in a Black Blizzard has a 1d10% cumulative chance per hour of dying due to exposure
***** In a cold climate storm of the century, creatures left exposed to the elements will take 1-4hp damage per hour (creatures born/bred in cold climate get a save, half damage if failed, no damage on successful save)


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