Severe Thunderstorm Watch Until 9 PM Friday May 29

Friday May 29 2020

The heat and humidity have already develop strong and severe storms in our region. More are in the way. This was expected (see my morning report), but now we have a Severe Thunderstorm Watch that includes northern Maryland and much of Pennsylvania until 9 PM. Some of the storm cells are expected to reach limits to bring damaging winds, large hail, and an isolated tornado.

Here is a look at the surface map, satellite and radar loops, and radar simulation model to use as a rough guide. But first,

Severe Thunderstorm Watch

 

• Watch means it might happen; Warning means it is happening NOW!
• Winds over 58mph = the biggest threat
• Hail over 1 inch (size of a quarter)
• Tornados may develop, but should be isolated.
• Flash Flooding
• Dangerous Lightning

 

Afternoon Weather Conditions

 

Surface Weather Observations

Note the cooling with the storms in the west. Also the wind flow. As I mentioned this morning (and many other times), when there is a southeast wind near the Bay, it can enhance storms east of the mountains.

 

Satellite Loop

 

Radar Loop

 

Radar Snapshot

I need to point out that the image here is at 3:45  PM. This has the storms over Frederick and into Carroll Co MD and into York County PA. This at least 1 hour sooner than the best short range model simulation below.

The outflow boundary is a signal of the colder air being pushed ahead of the storm. You may see a shelf cloud and this could spawn a new line of storms.

I’ve identified the movement of the individual cells and the entire line.

 

Radar Simulation —> slider

This model is already wrong…. Lagging in time. I want to show you how it develops the storm. But with a timer frame 1 to 2 hours sooner, we may see both the arrival for your area sooner AND more robust in metro areas.