Data Quality for Old Line Weather - CWOP ID: C3900

Temperature Graph
Madis Value:	99%
Data Span: 3 Days	24 Hours	Daytime	Nighttime
Average Temp Error:	-1.5 °F	-1.0 °F	-2.1 °F
Error Standard Deviation:	1.9 °F	1.9 °F	1.7 °F

Dewpoint Graph
Madis Value:	100%
Data Span: 3 Days	24 Hours	Daytime	Nighttime
Average Dewpoint Error:	0.0 °F	0.3 °F	-0.2 °F
Error Standard Deviation:	1.5 °F	1.5 °F	1.5 °F

Barometer Graph
Madis Value:	99%
Data Span:	3 Days
Average Barometer Error:	-0.4 milliBars
Error Standard Deviation:	0.4 milliBars

Wind
Madis Value:	96%

About this Data:
Oldlineweather.com is a proud member of the Citizen Weather Observer Program (CWOP). The above charts represent data reported to CWOP for Ellicott City, MD (C3900 actuals in blue) with the predicted data based on surrounding stations (C3900 Analysis in red).

Data Quality:
The MADIS value represents the percentage of observations that have successfully passed the MADIS QC checks. If the Madis rating is within the acceptable limits, a green check will appear. Otherwise, a red x-mark will appear indicating that the data has not passed quality control.

Errors:
If the above errors are POSITIVE, this means that the analysis variable is HIGHER than the reported variable. This means that the sensor is reading a variable lower than expected. If the above errors are NEGATIVE, this means that the analysis variable is LOWER than the reported variable. This means that the sensor is reading a variable higher than expected.

CWOP:
The Citizen Weather Observer Program (CWOP) is a private-public partnership with the National Oceanic & Atmospheric Administration. Its three main goals: 1) to collect weather data contributed by citizens; 2) to make this data available for weather services; and 3) to provide feedback to the data contributors so that they have the tools to check and improve their data quality.

Calculations/Data courtesy of Phillip Gladstone. Script courtesy of Michael Holden