Update variable name forecast_is_valid()
Update variable name forecast_is_valid()

Updated Date to date to match prediction files.

sdtaylor/portalPredictions,davharris/portalPredictions,sdtaylor/portalPredictions,sdtaylor/portalPredictions,weecology/portalPredictions,gmyenni/portalPredictions,weecology/portalPredictions,weecology/portalPredictions,gmyenni/portalPredictions,davharris/portalPredictions,gmyenni/portalPredictions