Rain Moving Different Directions on Norfolk Radar

There is an interesting situation going on, on the Norfolk, VA radar this afternoon. Notice how there are small storms near the center of the center moving southwest, while the larger line of precip to the east is steady or moving northeast!

What accounts for this? I admit, I had to check with some of the meteorologists on our Operations Floor (who were more in tune with today's weather) to be sure. But what they told me made sense and I've downloaded some maps to help explain the situation. It all stems from what moves storms. Normally, large weather systems are driven by the "500 mb flow" - the wind direction at around 15,000 feet, which is "southwest" this morning according to the 500mb chart below (the wind barbs point at the compass direction where the wind is coming from), meaning that the wind is coming from the southwest, moving towards the northeast. That makes sense for the rain from the "non-tropical" low pressure system.

The showers moving southwest are too "short" to poke up into the 500mb layer, and instead are being driven by the winds at 700mb, which happen to be the opposite - "northeast winds" coming from the northeast moving things southwest.

Sure enough, a check of the "Echo Tops" product from the Norfolk NEXRAD shows that the storms moving southwest topped out at only about 5-10,000 feet, so they would be immune to the 500 mb flow.