The stormy leading edge of a collapsing Mesoscale Convective System (MCS), with origins Wednesday in Iowa and Illinois, moved across the Baltimore area Thursday morning. The heaviest rains along with some hail were north of I-70, Baltimore City and I-95.
The track of this storm complex was similar to last year’s derecho but the system was not nearly as strong so it did not meet derecho criteria.
The area is still under the gun for some heavy weather on Thursday.
Maryland is in the warm, humid airmass. A deep low pressure area will track across Pennsylvania with a cold front trailing to the southwest. This system will likely trigger strong storm activity in the warm, humid, unstable airmass this afternoon.
The morning storms did help to stabilize, to some extent, the airmass in northern Maryland. This has most likely shifted the highest severe weather probabilities a bit to the south of the Baltimore/Washington metro areas but it doesn’t mean the area is completely out of the woods.
The two charts below show CAPE and Lifted Index values as of mid-morning.
CAPE is, in essence, an expression of energy in the atmosphere for making storms and when values are in the thousands there is a severe potential. As of mid-morning the highest values have been pushed south by the early morning storms.
Lifted Index is an expression of stability/instability in the atmosphere. Negative numbers are unstable indicators. As of mid-morning the higher valued negative numbers are also concentrated to the south of the metro area because of the morning storm activity.
The bottom line, the Baltimore area will likely be on the northern edge of severe storm activity this afternoon and evening. It all depends on how much destabilization can occur before the cold front comes in. Sunbreaks will help but cloud cover will be considerable for the rest of the day.
The National Weather Service has issued a Severe Thunderstorm Watch for the area until 7:00pm.
As storm activity develops, the Watch area could be extended to the Eastern Shore counties.
The latest updates are available anytime on the web at wbaltv.com/weather. Join Tom Tasselmyer for the latest at 5-6 & 11pm on WBAL-TV 11 and at 10 pm on WBAL+.