In the image above is the vLAPS model maximum base reflectivity is evaluated verses observed radar over the Mid-Atlantic region. The top left pane is 0.5 deg reflectivity from the LWX radar at 2017z. The top right pane shows the 2 hour forecast of the 18z run of the vLAPS model surface layer maximum base reflectivity with 1km resolution. Overall the model continues to forecast convective mode very but location is still a bit off.

The model shows a wavy convective band extending north-south to the west of Washington DC along with discrete individual cells between the line of storms and the Chesapeake Bay. Location of the band of storms in the vLAPS model is about 20-40 miles too far west. The location of the highest model reflectivity correlates with the stratiform rain behind the leading edge of the bowing line not handling the eastward progression of the bowing segments very well.

Shawn Smith