Guide for severe weather warning in README

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 2022-03-06
+* Add weather.gov as a forecast and alert provider
+
 ## 2022-01-07
 
 * Add cryptography==36.0.0 to setup. It's used by msal, but version 36.0.1 from piwheels produces [illegal instruction](https://github.com/piwheels/packages/issues/273)

README.md

@@ -139,6 +139,23 @@ As needed, change the temperature format (CELSIUS or FAHRENHEIT).
     export WEATHER_LONGITUDE=0.1963
     export WEATHER_FORMAT=CELSIUS
 
+## Pick a severe weather warning provider
+
+### Met Office (UK)
+
+Go to the [Met Office RSS Feeds page](https://www.metoffice.gov.uk/weather/guides/rss) and pick the RSS feed based on your region.  
+Set its value in the `env.sh` as `ALERT_METOFFICE_FEED_URL`. For example, London would be:
+
+    export ALERT_METOFFICE_FEED_URL=https://www.metoffice.gov.uk/public/data/PWSCache/WarningsRSS/Region/se
+
+### Weather.gov (US)
+
+Weather.gov requires you to [identify your application](https://www.weather.gov/documentation/services-web-api).  This can be any made up string, or an email address. 
+
+    export [email protected]
+
+This provider will use the same latitude and longitude as specified for the weather provider.  
+
 
 ## Pick a Calendar provider
 

alert_providers/weathergovalerts.py

@@ -10,13 +10,16 @@ def __init__(self, location_lat, location_long, weathergov_self_id):
 
 
     def get_alert(self):
-        severe = self.get_response_json("https://api.weather.gov/alerts?point={},{}".format(self.location_lat, self.location_long), 
-                                        headers={'User-Agent':'({0})'.format(self.weathergov_self_id)})
-        logging.debug("get_alert - {}".format(severe))
-        if 'features' in severe:
-            if 'properties' in severe["features"][0]:
-                if 'parameters' in severe["features"][0]["properties"]:
-                    if 'NWSheadline' in severe["features"][0]["properties"]["parameters"]:
-                        return severe["features"][0]["properties"]["parameters"]["NWSheadline"][0]
+        try:
+            severe = self.get_response_json("https://api.weather.gov/alerts?point={},{}".format(self.location_lat, self.location_long), 
+                                            headers={'User-Agent':'({0})'.format(self.weathergov_self_id)})
+            logging.debug("get_alert - {}".format(severe))
+            if 'features' in severe:
+                if 'properties' in severe["features"][0]:
+                    if 'parameters' in severe["features"][0]["properties"]:
+                        if 'NWSheadline' in severe["features"][0]["properties"]["parameters"]:
+                            return severe["features"][0]["properties"]["parameters"]["NWSheadline"][0]
+        except Exception as error:
+            pass
         return ""