LaTeX Error: Something's wrong--perhaps a missing \item when using {description}

The following section of my code is producing the following error ! LaTeX Error: Something's wrong--perhaps a missing \item., but is still producing a PDF with the output I desire. The program I am using, Texmaker, will move the cursor to the second array I created.

Additionally, the sections where I am using flalign is producing the following warning Underfull \hbox (badness 10000) in paragraph at lines 16--18

The code below is part of the first LaTeX code I have ever created. I am wondering what I am doing wrong to create these errors and warnings. Please let me know where I can improve.

\documentclass[fleqn,10pt,pdftex]{article}
\usepackage[margin=.75in]{geometry}
\usepackage{amsmath,amsthm,amssymb}

\begin{document}

\subsubsection{Wind load from IEEE Std 605, Section 11.2}

\begin{quote}
In the case of extreme wind speed (without ice), the wind load by unit length on a conductor (or a slender structure such as support or isolator) is given as follows:
\begin{flalign} \tag{8}
F_{W} = C V^{2} D_{o} C_{f} K_{Z} G_{f} I
\end{flalign}
where \\

\begin{description}
\begin{math}
\begin{array}{ll}
F_{W} & \mbox{  is the wind load by unit length, [lbf/in]} \\
C & \mbox{  is a constant, (British: 2.132 $$\times$$ 10\textsuperscript{-4})} \\
V & \mbox{  is the extreme wind speed without ice, [mi/h]} \\
D_{o} & \mbox{  is the conductor outside diameter or the height of the profile used as conductor, [in]}\\
C_{f} & \mbox{  is the force coefficient} \\
K_{Z} & \mbox{  is the height and exposure factor} \\
G_{f} & \mbox{  is the gust response factor} \\
I & \mbox{  is the importance of the structure}
\end{array}
\end{math}
\end{description}

In the case of high wind with ice, the wind load by unit length on a conductor is given as follows:
\begin{flalign} \tag{9}
F_{WI} = C V^{2}_{I} (D_{o} + 2r_{I}) C_{f} K_{Z} G_{f} I
\end{flalign}
where \\

\begin{description}
\begin{math}
\begin{array}{ll}
F_{WI} & \mbox{ is the wind load with ice by unit length, [lbf/in]} \\
V_{I} & \mbox{  is the high wind speed with ice, [mi/h]} \\
r_{I} & \mbox{  is the equivalent uniform radial thicknesses of ice due to freezing rain, [in]} \\
G_{f} & \mbox{  is the gust response factor which is equal to 1.0 for ice and concurrent wind} \\
\end{array}
\end{math}
\end{description}

\end{quote}

\end{document}


The following MWE contains two different possibilities. The first one uses a tabular and automatically sets the fist column in math mode, while the second is normal text. The second variant uses the description environment instead.

\documentclass[fleqn,10pt]{article}
\usepackage[margin=.75in]{geometry}
\usepackage{amsmath,amsthm,amssymb}
\usepackage{array}
\begin{document}

\subsubsection{Wind load from IEEE Std 605, Section 11.2}

\begin{quote}
In the case of extreme wind speed (without ice), the wind load by unit length on a conductor (or a slender structure such as support or isolator) is given as follows:
\begin{flalign} \tag{8}
F_{W} = C V^{2} D_{o} C_{f} K_{Z} G_{f} I
\end{flalign}
where

\begin{tabular}{>{$}l<{$}l}
F_{W} &   is the wind load by unit length, [lbf/in] \\
C &   is a constant, (British: 2.132 $$\times$$ 10\textsuperscript{-4}) \\
V &   is the extreme wind speed without ice, [mi/h] \\
D_{o} &   is the conductor outside diameter or the height of the profile used as conductor, [in]\\
C_{f} &   is the force coefficient \\
K_{Z} &  is the height and exposure factor \\
G_{f} &  is the gust response factor \\
I &  is the importance of the structure
\end{tabular}

In the case of high wind with ice, the wind load by unit length on a conductor is given as follows:
\begin{flalign} \tag{9}
F_{WI} = C V^{2}_{I} (D_{o} + 2r_{I}) C_{f} K_{Z} G_{f} I
\end{flalign}
where

\begin{description}
\item[$F_{WI}$]  is the wind load with ice by unit length, [lbf/in]
\item[$V_{I}$]   is the high wind speed with ice, [mi/h]
\item[$r_{I}$]   is the equivalent uniform radial thicknesses of ice due to freezing rain, [in]
\item[$G_{f}$]  is the gust response factor which is equal to 1.0 for ice and concurrent wind
\end{description}

\end{quote}

\end{document}