How to Deserialize an XML String Variable

I need to extract XML data from the National Weather Service’s Web Service.  It returns XML data as a text string.  I’m looking for the best way to get values of elements and attributes from specific nodes. The code below throws this error on the last line:

System.InvalidOperationException: <dwml xmlns=''> was not expected.

            // Get weather forecast
            string strWxXml = "";

            gov.weather.graphical.weatherParametersType paramsWX = new detailwindow.gov.weather.graphical.weatherParametersType();
            paramsWX.wx = true;
            gov.weather.graphical.ndfdXML xmlWx = new detailwindow.gov.weather.graphical.ndfdXML();
            DateTime dtStart = DateTime.Now;
            DateTime dtEnd = DateTime.Now.AddDays(5.00);
            Decimal longitude = 39.73M;
            Decimal latitude = -86.27M;

            // Call web service proxy class
            strWxXml = xmlWx.NDFDgen(longitude, latitude, 0, dtStart, dtEnd, 0, paramsWX);

            DataSet dsXML = new DataSet();
            System.IO.StringReader read = new StringReader(strWxXml);
            System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(dsXML.GetType());
            System.Xml.XmlReader reader = new XmlTextReader(read);

            dsXML = (DataSet)serializer.Deserialize(reader);

I have also tried adding this above the partial class statement:

[Serializable, System.Xml.Serialization.XmlRoot("dwml")]