diff --git a/py_src/low_delta_t/handler.py b/py_src/low_delta_t/handler.py
index 474776d..f7fe833 100644
--- a/py_src/low_delta_t/handler.py
+++ b/py_src/low_delta_t/handler.py
@@ -5,7 +5,7 @@
 from datetime import timedelta
 import numpy as np
 from requests.exceptions import ConnectionError as RequestConnectionError, HTTPError
-from python_lib.utils import parse_event, fetch_trends, build_index, build_df
+from python_lib.utils import parse_event, fetch_trends, build_index, build_df, AnomalyError
 
 # the minimum acceptable length of the datapoints array
 MIN_DATAPOINTS_LENGTH = int(7 * 24)
@@ -46,6 +46,8 @@ def run(event, _context):
         # compute estimated design load from max(tons) over past year
         max_tons = max(tons[point_name].values())
         model_df = build_df(recent)
+        if any(x not in model_df for x in recent_points):
+            raise(AnomalyError(f"Missing trends from {recent_points}"))
         # model partial load ratio for the recent period from all fetched data
         model_df["PLR"] = model_df[tons_name] / max_tons
         # model partial temperature ratio
@@ -53,15 +55,19 @@ def run(event, _context):
         # DTpred = PLR^0.173 * PT^0.067 * 15.603
         model_df["DT_PRED"] =  (model_df["PLR"] ** 0.173) * (model_df["PT"] ** 0.067) * 15.603
         # compare actual delta-t with modeled normal, and detect anomaly if it falls below model by more than variance
-        actual_dt = np.sum(model_df[rtemp_name] - model_df[stemp_name])
-        model_dt = np.sum(model_df["DT_PRED"])
+        actual_dt = np.mean(model_df[rtemp_name] - model_df[stemp_name])
+        model_dt = np.mean(model_df["DT_PRED"])
         if actual_dt < model_dt * 0.9:
-            response[ "body" ] = f"""{point_name} actual_dt {actual_dt} model_dt {model_dt} for the period {start_time:%Y-%m-%d %H:%M} to {now:%Y-%m-%d %H:%M}"""
+            response[ "body" ] = f"""{point_name} actual_dt {actual_dt:.2f} model_dt {model_dt:.2f} for the period {start_time:%Y-%m-%d %H:%M} to {now:%Y-%m-%d %H:%M}"""
     except RequestConnectionError as err:
         response[
             "body"
         ] = f"""{point_name} ConnectionError:
              {err.response.text} {start_time:%Y-%m-%d %H:%M} to {now:%Y-%m-%d %H:%M}"""
+    except AnomalyError as err:
+        response[
+            "body"
+        ] = f"""{point_name} Error: {err} {start_time:%Y-%m-%d %H:%M} to {now:%Y-%m-%d %H:%M}"""
     except HTTPError as err:
         response[
             "body"
diff --git a/py_src/python_lib/utils.py b/py_src/python_lib/utils.py
index abf2dc9..50733ca 100644
--- a/py_src/python_lib/utils.py
+++ b/py_src/python_lib/utils.py
@@ -12,6 +12,8 @@
 PORTAL_API_URL = os.environ.get("PORTAL_API_URL", "/")
 QUERY_URL = f"{PORTAL_API_URL}query"
 
+class AnomalyError(Exception):
+    "Anomaly Exception class"
 
 def parse_event(event):
     """