--- a/net/minecraft/server/WorldData.java
+++ b/net/minecraft/server/WorldData.java
@@ -11,6 +11,11 @@
 import java.util.Set;
 import java.util.Map.Entry;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import org.bukkit.Bukkit;
+import org.bukkit.event.weather.ThunderChangeEvent;
+import org.bukkit.event.weather.WeatherChangeEvent;
+// CraftBukkit end
 
 public class WorldData {
 
@@ -64,6 +69,7 @@
     private final Map<DimensionManager, NBTTagCompound> T;
     private NBTTagCompound U;
     private final GameRules V;
+    public WorldServer world; // CraftBukkit
 
     protected WorldData() {
         this.f = WorldType.NORMAL;
@@ -304,6 +310,7 @@
         nbttagcompound2.setBoolean("Snapshot", false);
         nbttagcompound.set("Version", nbttagcompound2);
         nbttagcompound.setInt("DataVersion", 1631);
+        if (org.bukkit.craftbukkit.util.CraftMagicNumbers.DATA_VERSION != 1631) throw new AssertionError(); // CraftBukkit - sentinel
         nbttagcompound.setLong("RandomSeed", this.e);
         nbttagcompound.setString("generatorName", this.f.b());
         nbttagcompound.setInt("generatorVersion", this.f.getVersion());
@@ -389,6 +396,7 @@
             nbttagcompound.set("CustomBossEvents", this.U);
         }
 
+        nbttagcompound.setString("Bukkit.Version", Bukkit.getName() + "/" + Bukkit.getVersion() + "/" + Bukkit.getBukkitVersion()); // CraftBukkit
     }
 
     public long getSeed() {
@@ -478,6 +486,16 @@
     }
 
     public void setThundering(boolean flag) {
+        // CraftBukkit start
+        org.bukkit.World world = Bukkit.getWorld(getName());
+        if (world != null) {
+            ThunderChangeEvent thunder = new ThunderChangeEvent(world, flag);
+            Bukkit.getServer().getPluginManager().callEvent(thunder);
+            if (thunder.isCancelled()) {
+                return;
+            }
+        }
+        // CraftBukkit end
         this.z = flag;
     }
 
@@ -494,6 +512,16 @@
     }
 
     public void setStorm(boolean flag) {
+        // CraftBukkit start
+        org.bukkit.World world = Bukkit.getWorld(getName());
+        if (world != null) {
+            WeatherChangeEvent weather = new WeatherChangeEvent(world, flag);
+            Bukkit.getServer().getPluginManager().callEvent(weather);
+            if (weather.isCancelled()) {
+                return;
+            }
+        }
+        // CraftBukkit end
         this.x = flag;
     }
 
@@ -643,6 +671,12 @@
 
     public void setDifficulty(EnumDifficulty enumdifficulty) {
         this.G = enumdifficulty;
+        // CraftBukkit start
+        PacketPlayOutServerDifficulty packet = new PacketPlayOutServerDifficulty(this.getDifficulty(), this.isDifficultyLocked());
+        for (EntityPlayer player : (java.util.List<EntityPlayer>) (java.util.List) world.players) {
+            player.playerConnection.sendPacket(packet);
+        }
+        // CraftBukkit end
     }
 
     public boolean isDifficultyLocked() {
@@ -723,4 +757,12 @@
     public void c(@Nullable NBTTagCompound nbttagcompound) {
         this.U = nbttagcompound;
     }
+
+    // CraftBukkit start - Check if the name stored in NBT is the correct one
+    public void checkName( String name ) {
+        if ( !this.levelName.equals( name ) ) {
+            this.levelName = name;
+        }
+    }
+    // CraftBukkit end
 }