diff --git a/lib/xmet/series.py b/lib/xmet/series.py
index 2835594..6e502b7 100644
--- a/lib/xmet/series.py
+++ b/lib/xmet/series.py
@@ -1,24 +1,26 @@
+import enum
 from typing import Self
 
 from xmet.util import cmp
 from xmet.list import nearest
 
+class SeriesIntersection(enum.Enum):
+    GREATER = -1
+    EQUAL   =  0
+    LESSER  =  1
+
 class Series(dict):
     def __init__(self):
         super().__init__()
 
-    def intersect(self, series: Self) -> tuple[float]:
+    def intersect(self, series: Self, intersection: SeriesIntersection) -> tuple[float]:
         pairs = nearest(sorted(self.keys(),   reverse=True),
                         sorted(series.keys(), reverse=True))
 
-        sign_last = None
-
         for pair in pairs:
             v1, v2 = self[pair[0]], series[pair[1]]
 
             sign = cmp(v1, v2)
 
-            if sign == 0 or (sign_last is not None and sign_last != sign):
+            if sign == intersection.value:
                 return v1, pair[0]
-
-            sign_last = sign
diff --git a/lib/xmet/sounding.py b/lib/xmet/sounding.py
index 22d373f..c703ab6 100644
--- a/lib/xmet/sounding.py
+++ b/lib/xmet/sounding.py
@@ -4,7 +4,7 @@ import shapely
 from xmet.db     import Database, DatabaseTable, DatabaseOrder
 from xmet.coord  import COORD_SYSTEM
 from xmet.list   import nearest
-from xmet.series import Series
+from xmet.series import Series, SeriesIntersection
 from xmet.thermo import follow_dry_adiabat, \
                         follow_moist_adiabat, \
                         follow_saturated_mixing_ratio
@@ -218,7 +218,7 @@ class Sounding(DatabaseTable):
         saturated_mr_line = follow_saturated_mixing_ratio(self.samples[0].dewpoint,
                                                           self.samples[0].pressure)
 
-        lcl = dry_adiabat.intersect(saturated_mr_line)
+        lcl = dry_adiabat.intersect(saturated_mr_line, SeriesIntersection.LESSER)
         lfc = self.find_lfc(lcl[0], lcl[1])
         el  = self.find_el(lfc[0], lfc[1])