If you set the "Valid for" to zero for the above, then the satellite image has to be loaded every time, which won't help your bandwidth!
In the overlay version some posts previously, the icons enlarge ridiculously past zoom 6, so how about an overlay like this:
<provider id="11711" type="0" visible="false" background="-1">
<name>Overlays</name>
<mode>Clouds</mode>
<url><![CDATA[http://mts{s}.google.com/vt/x={x}&y={y}&z={z}&lyrs=weather_0cloud]]></url>
<serverPart>0;1</serverPart>
<zoomPart>{z}-8</zoomPart>
<zoomMin>8</zoomMin>
<zoomMax>14</zoomMax>
<tileSize>256</tileSize>
<attribution><![CDATA[(c)2011 Google - Map data (c)2011 Tele Atlas]]></attribution>
<extraHeader><![CDATA[User-Agent#Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1]]></extraHeader>
<extraHeader><![CDATA[Referer#http://maps.google.com/]]></extraHeader>
</provider>
<provider id="11712" type="0" visible="true" background="11711">
<name>Overlays</name>
<mode>Weather - Clouds and Icons</mode>
<url><![CDATA[http://mts{s}.google.com/mapslt?x={x}&y={y}&z={z}&lyrs=weather_c_kph|invert:0]]></url>
<serverPart>0;1</serverPart>
<zoomPart>{z}-8</zoomPart>
<zoomMin>8</zoomMin>
<zoomMax>23</zoomMax>
<tileSize>256</tileSize>
<attribution><![CDATA[(c)2011 Google - Map data (c)2011 Tele Atlas]]></attribution>
<extraHeader><![CDATA[User-Agent#Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1]]></extraHeader>
<extraHeader><![CDATA[Referer#http://maps.google.com/]]></extraHeader>
</provider>
Clouds only appear up to zoom 6, which seems the most usable arrangement, as they then do not obscure map detail when you want it.
The "Clouds" layer 11711 in my code above does not appear in the Locus menu, but is used to build the overlay.
PS It might be best to set "Valid for" to 1 hour in any case, as weather really doesn't change that quickly, even in England.