So far I have encountered 2 issues with the mod. The first issue is with optifine the particles completely break and the tornadoes appear to look like lava and water. The next issue is a much bigger one which is the mod doesn't work with multiplayer. I attempt to spawn in a tornado and it closes the server, and then the server crashes. Please look into the last one as soon as possible, thanks.

Crash Report:
---- Minecraft Crash Report ----
// I just don't know what went wrong :(

Time: 8/25/16 7:49 PM
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: net/minecraft/client/particle/Particle
at CoroUtil.util.CoroUtilEntOrParticle.getPosX(CoroUtilEntOrParticle.java:19)
at weather2.weathersystem.storm.StormObject.spinEntity(StormObject.java:1879)
at weather2.weathersystem.storm.TornadoHelper.forceRotate(TornadoHelper.java:583)
at weather2.weathersystem.storm.TornadoHelper.tick(TornadoHelper.java:194)
at weather2.weathersystem.storm.StormObject.tick(StormObject.java:417)
at weather2.weathersystem.WeatherManagerBase.tick(WeatherManagerBase.java:124)
at weather2.weathersystem.WeatherManagerServer.tick(WeatherManagerServer.java:40)
at weather2.ServerTickHandler.onTickInGame(ServerTickHandler.java:76)
at weather2.EventHandlerFML.tickServer(EventHandlerFML.java:29)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_10_EventHandlerFML_tickServer_ServerTickEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:72)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:168)
at net.minecraftforge.fml.common.FMLCommonHandler.onPreServerTick(FMLCommonHandler.java:274)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:602)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.particle.Particle
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 16 more
Caused by: java.lang.NullPointerException

A detailed walkthrough of the error, its code path and all known details is as follows:

-- System Details --
Details:
Minecraft Version: 1.10.2
Operating System: Linux (amd64) version 2.6.32-431.el6.x86_64
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 224665400 bytes (214 MB) / 507576320 bytes (484 MB) up to 2077753344 bytes (1981 MB)
JVM Flags: 4 total; -Xincgc -XX:+DisableExplicitGC -XX:MaxPermSize=128M -Xmx2048M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
FML: MCP 9.32 Powered by Forge 12.18.1.2073 7 mods loaded, 7 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
UCHIJAAAA mcp{9.19} Minecraft Coder Pack
UCHIJAAAA FML{8.0.99.99} Forge Mod Loader
UCHIJAAAA Forge{12.18.1.2073} Minecraft Forge
UCHIJAAAA CoroAI{v1.1.6} CoroAI
UCHIJAAAA ExtendedRenderer{v1.0} Extended Renderer
UCHIJAAAA ConfigMod{v1.0} Extended Mod Config
UCHIJAAAA weather2{v2.3.13} Localized Weather & Storms
Loaded coremods (and transformers):
Profiler Position: N/A (disabled)
Player Count: 0 / 45; []
Is Modded: Definitely; Server brand changed to 'fml,forge'
Type: Dedicated Server (map_server.txt)

Another issue Is that i seem to have extreme lag when high wind storms and any progressing stages after seem to cause unbelievable lag that has caused my whole computer to crash, minecraft and logs have been erased till 20 minutes before the crash, so no minecraft crash report.

I have the same problem. With opdifine and with the server. My server only crashes if I use a siren. If I place a siren its OK but as soon as it goes off the server crashes.

That actually may be the cause of my crash, but as for the lag, it remains

One thing I found is Windows 10 Minecraft fixes and also I changed to 1.8. But that also lags. Less though.

Confirmed issue, server trying to do particle work, never a good thing, working on fix.

Also suspicious about performance myself, going to give my mod a try on my less beefy laptop and do some performance profiling.

I did also find a critical issue for client running on server where it would be spamming console as some reflection is broken for that scenario, that might explain part of the performance problem, however that specific problem doesn't happen in singleplayer at the moment.

Now fixed with commit 0de207e

New build pushed to website.

Going to close this issue, please make a new issue if you notice significant performance issues still, interested to hear about that.