function syncButtons() {
  var fileName = window.top.rightframe.location.href;
  var region;
  var product;
  var viewtype;
  var alternate;
  var overlays;

//---- get file name, minus the file extension ------
  fileName = fileName.substr(fileName.lastIndexOf("/") + 1);
  fileName = fileName.substring(0,fileName.lastIndexOf(".htm"));

//---- parse filename -----------------------------
  var textArray = fileName.split('_');

  region = textArray[0];
  if (textArray[1] == 'extrapbref1') { 
    viewtype = 'extrapbref1'; 
    if (textArray.length > 2) { alternate = 'cc'; }
  } else {
    product = textArray[1];
    var viewtype = textArray[2];
    var txt = textArray[3]; 
    if (txt == 'cc') { 
      alternate = txt;
    } else if (txt == 'no') {
      overlays = txt;
    }
    txt = textArray[4]; 
    if (txt == 'no') {
      overlays = txt;
    }
  }

//--------- synchronize button state in left frame with what is actually being viewed -----  

  var n = window.top.leftframe.document.form1.region.length;
  var index;
  for (index = 0 ; index < n ; index++) {
    if (window.top.leftframe.document.form1.region[index].value == region) {
      window.top.leftframe.document.form1.region[index].checked = true;
      break;
    }   
  }

  n = window.top.leftframe.document.form1.viewtype.length;
  var index;
  for (index = 0 ; index < n ; index++) {
    if (window.top.leftframe.document.form1.viewtype[index].value == viewtype) {
      window.top.leftframe.document.form1.viewtype[index].checked = true;
      break;
    }   
  }

  n = window.top.leftframe.document.form1.product.length;
  var index;
  for (index = 0 ; index < n ; index++) {
    if (window.top.leftframe.document.form1.product[index].value == product) {
      window.top.leftframe.document.form1.product[index].checked = true;
      break;
    }   
  }

  if (alternate == 'cc') {
    window.top.leftframe.document.form1.alternate.checked = true;
  } else {
    window.top.leftframe.document.form1.alternate.checked = false;
  }

  if (overlays == 'no') {
    window.top.leftframe.document.form1.no_overlays.checked = true;
  } else {
    window.top.leftframe.document.form1.no_overlays.checked = false;
  }

 // ---------- HIDE BUTTONS --------
  if (viewtype == "loop" || viewtype == 'extrapbref1') {
    hideButton("no_overlays1","no_overlays1_dis");
    hideButton("no_overlays2","no_overlays2_dis");
  } else if (viewtype == "latest") {
    hideButton("no_overlays1_dis","no_overlays1");
    hideButton("no_overlays2_dis","no_overlays2");
  }

  if (region == "midwest" || alternate == "cc") {
    hideButton("storm1","storm1_dis");
    hideButton("storm2","storm2_dis");
  } else {
    hideButton("storm1_dis","storm1");
    hideButton("storm2_dis","storm2");
  }

  if (region == "midwest") {
    hideButton("rad1","rad1_dis");
    hideButton("rad2","rad2_dis");
  } else {
    hideButton("rad1_dis","rad1");
    hideButton("rad2_dis","rad2");
  }

  if (product == "storm" || product == "radial") {
    hideButton("midwest1","midwest1_dis");
    hideButton("midwest2","midwest2_dis");
  } else {
    hideButton("midwest1_dis","midwest1");
    hideButton("midwest2_dis","midwest2");
  }

  if (product == "storm") {
    hideButton("alt1","alt1_dis");
    hideButton("alt2","alt2_dis");
  } else {
    hideButton("alt1_dis","alt1");
    hideButton("alt2_dis","alt2");
  }

  // ---------- SET PRODUCT TO BASE REFLECTIVITY IF VIEWTYPE IS EXTRAPBREF1 ---------
  if (viewtype == "extrapbref1") {
    window.top.leftframe.document.form1.product[0].checked = true;
  }
}