diff --git a/lib/xmet/raob.py b/lib/xmet/raob.py
index 6b7a955..8e7ef6b 100644
--- a/lib/xmet/raob.py
+++ b/lib/xmet/raob.py
@@ -572,16 +572,13 @@ class RAOBReader():
         self.soundings = dict()
 
     def sounding(self, station: str, timestamp: str) -> RAOBSounding:
-        key = station + '.' + timestamp
+        if station not in self.soundings:
+            self.soundings[station] = dict()
 
-        if key in self.soundings:
-            return self.soundings[key]
+        if timestamp not in self.soundings[station]:
+            self.soundings[station][timestamp] = RAOBSounding(station, timestamp)
 
-        sounding = RAOBSounding(station, timestamp)
-
-        self.soundings[key] = sounding
-
-        return sounding
+        return self.soundings[station][timestamp]
 
     def parse_chunk(self, text: str) -> RAOBChunk:
         meta = {
@@ -667,12 +664,17 @@ class RAOBReader():
                                                    data.get('wind_speed'),
                                                    data.get('wind_dir'))
 
-        for key in self.soundings:
-            sounding = self.soundings[key].finish()
+    def each_sounding_by_station(self, station: str):
+        for timestamp in self.soundings[station]:
+            sounding = self.soundings[station][timestamp].finish()
 
             if sounding is not None:
                 yield sounding
 
+    def each_sounding(self):
+        for station in self.soundings:
+            yield from self.each_sounding_by_station(station)
+
     @staticmethod
     def each_sounding_from_fh(fh: io.TextIOBase):
         reader = RAOBReader(fh)