Once the satellite map information has been decoded it is possible to see the recorded temperatures as I move the mouse over the map.
From NOAA 19 at 08.10 this morning (BST)

While the ground temperature here (where the salmon coloured cross is on the map) is about 19C the air higher up is in the region of 10C. To the south of the ROI the red / black heavy rain area shows cloud temperatures ranging from -30C to -60C. No wonder the temperature at ground level can drop so sharply in a heavy rainstorm. I assume that area is the one which is forecast to bring heavy showers to Lincolnshire later this afternoon.