GFS can be 5 hours "late" and it's okay

3 hour delays are typical.
4.5 hours delays are moderately common.

example/aitf/ancil.py

@@ -57,7 +57,7 @@ SST = csppfetch.Downloader(
     )
 
 
-################################################################################
+###############################################################################
 #
 # Data: Global Forecast System
 #
@@ -78,6 +78,18 @@ class GFSDownloader(csppfetch.Downloader):
         local_filename = "gfs.t%Hz.pgrbf{priority}"
         localdir = "gfs_grib2_0.5deg/%Y/%m/%d/"
 
+        # Why 5 hours?  
+        #
+        # Examination of geodb in 2019 covering 2019-03-01 through 2019-06-12 
+        # and 2021 covering 2021-07-02 through 2021-09-01, suggests the data
+        # usually available within about 65 minutes, and is almost always 
+        # available within 4 hours and 30 minutes. Round up to 5 arbitrarily.
+        #
+        # As we don't really have use for the data until 3 hours after
+        # nominal generation and don't _need_ it until 6 hours, this seems
+        # a reasonable number.
+        expected_newest = dt.timedelta(hours=5)
+
         super().__init__(
             name="Global Forecast System",
             package_env_id = PACKAGE_ENV_ID,
@@ -85,9 +97,9 @@ class GFSDownloader(csppfetch.Downloader):
             url_relative = CSPP_GEO_AITF_URL_DIR_PART+remote_filename,
             local = localdir+local_filename,
             period = dt.timedelta(hours=6),
-            epoch_start = dt.datetime(2010,1,1,0,0,0)
+            epoch_start = dt.datetime(2010,1,1,0,0,0),
+            expected_newest = expected_newest,
             )
-            #expected_newest = dt.timedelta(hours=1) - TODO, what's the age?
 
         # Fields we're not using:
         # oldest_usable - Not meaningful; the limit is how far into the future
@@ -165,7 +177,7 @@ class GFSDownloader(csppfetch.Downloader):
             urls_to_files.update(self.url_to_file_for_time(generated_time, forecast_start))
             urls_to_files.update(self.url_to_file_for_time(generated_time, end))
 
-            expected = self.is_expected(forecast_start) and self.is_expected(end)
+            expected = self.is_expected(generated_time)
             startstr = str(int(forecast_start.total_seconds()/(60*60)))
             endstr   = str(int(           end.total_seconds()/(60*60)))