diff --git a/run_from_github.py b/run_from_github.py
index 012bef0..8831d0c 100755
--- a/run_from_github.py
+++ b/run_from_github.py
@@ -6,64 +6,112 @@
 # Usage: ./run_from_github.py
 #        When prompted, enter a repository URL.
 #        When prompted, enter a branch name.
+#        Alternatively, you can also enter the "--url" and/or "--branch" options via command line arguments
 # 
 # Author: Michael Kavulich, Jr. (September 2016)
+#         Update history:
+#         November 2016: Added command-line arguments for url and branch
 #
 
 
 import os
+import re
+import sys
 import shutil
 import tarfile
 
-url = raw_input('Enter github URL (leave blank for https://github.com/wrf-model/WRF): ')
-branch = raw_input('Enter branch name (leave blank for master): ')
 
-if not url:
-   url = "https://github.com/wrf-model/WRF"
+def usage(exit_code=0): #If no exit code is specified, this indicates successful execution, so return exit code "0" per convention
 
-#In the future we hope to run tests from multiple forks, so we should disambiguate the tar files by adding the fork name
-urlsplit = url.split("/")
-if "http" in urlsplit[0]:
-   fork = urlsplit[3]
-else: # Assume if it is not http then user is using ssh
-   urlsplitagain = urlsplit[0].split(":")
-   fork = urlsplitagain[1]
+   print("usage: " + __file__ + " --url=https://github.com/wrf-model/WRF --branch=branch_name")
+   print("")
+   print("       " + __file__ + " url   : The main URL of the Github repository you wish to test (e.g. https://github.com/username/WRF for your fork)")
+   print("       " + __file__ + " fail  : The name of the branch you wish to test")
+   sys.exit(exit_code)
 
-if not branch:
-   branch = "master"
 
-print "Repository URL is %s." % url
-if "wrf-model" not in fork:
-   print "Fork is %s." % fork
-print "Branch name is %s." % branch
+def main():
 
-os.chdir("tarballs")
+ if len(sys.argv) > 1:
+    for arg in sys.argv[1:]:
+       if "--url=" in arg:
+          url=arg.split("=",1)[1]
+       elif "--branch=" in arg:
+          branch=arg.split("=",1)[1]
+       elif ("--help" in arg) or ("-h" in arg):
+          usage()
+       else:
+          print("Unrecognized option: " + arg)
+          usage(1)
 
-if os.path.isdir("WRFV3"):
-   shutil.rmtree("WRFV3")
+ url = raw_input('Enter github URL (leave blank for https://github.com/wrf-model/WRF): ')
+ branch = raw_input('Enter branch name (leave blank for master): ')
 
-os.system("git clone " + url + " WRFV3")
-os.chdir("WRFV3")
-os.system("git checkout " + branch)
-os.chdir("../")
+ url = url.strip()
+ branch = branch.strip()
 
+ spaces = re.compile(r'\s')
+ if (re.search(spaces, url) is not None):
+    print("FATAL:\nInvalid URL: contains whitespace character(s)")
+    sys.exit(2)
+ elif (re.search(spaces, branch) is not None):
+    print("FATAL:\nInvalid branch name: contains whitespace character(s)")
+    sys.exit(3)
 
+ if "/tree/" in url:
+    print("The URL you typed appears to be a direct link to a branch rather than the top-level URL of a repository. \nYour URL should probably be in the format 'https://github.com/username/WRF/'.")
+    sys.exit(4)
+ if not url:
+    url = "https://github.com/wrf-model/WRF"
 
-out = tarfile.open("github_" + fork + "_" + branch + ".tar", mode='w')
-try:
+ #In the future we hope to run tests from multiple forks, so we should disambiguate the tar files by adding the fork name
+ urlsplit = url.split("/")
+ if "http" in urlsplit[0]:
+    fork = urlsplit[3]
+ else: # Assume if it is not http then user is using ssh
+    urlsplitagain = urlsplit[0].split(":")
+    fork = urlsplitagain[1]
+
+ if not branch:
+    branch = "master"
+
+ print "Repository URL is %s." % url
+ if "wrf-model" not in fork:
+    print "Fork is %s." % fork
+ print "Branch name is %s." % branch
+ 
+ os.chdir("tarballs")
+
+ if os.path.isdir("WRFV3"):
+    shutil.rmtree("WRFV3")
+
+ os.system("git clone " + url + " WRFV3")
+ os.chdir("WRFV3")
+ os.system("git checkout " + branch)
+ os.chdir("../")
+
+
+
+ out = tarfile.open("github_" + fork + "_" + branch + ".tar", mode='w')
+ try:
     out.add('WRFV3') # Adding "WRFV3" directory to tar file
-finally:
+ finally:
     out.close() # Close tar file
 
-os.chdir("../")
+ os.chdir("../")
+
+ user = os.environ.get("USER")
+
+ del(os.environ["MP_PE_AFFINITY"])
+ if not os.path.isdir("/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE"):
+    os.makedirs("/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE")
+ os.environ["TMPDIR"] = "/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE"
+
 
-user = os.environ.get("USER")
+ os.system('bsub < bsub_this_to_run_all_compilers.csh')
 
-del(os.environ["MP_PE_AFFINITY"])
-if not os.path.isdir("/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE"):
-   os.makedirs("/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE")
-os.environ["TMPDIR"] = "/glade/scratch/" + user + "/TMPDIR_FOR_PGI_COMPILE"
 
+if __name__ == "__main__":
+    main()
 
-os.system('bsub < bsub_this_to_run_all_compilers.csh')