UPDATE: Thunderstorms Likely Saturday

Well, yesterday we were all talking about the potential for severe weather and even dangerous storms on Saturday. That threat has lessened, however, there will still be thunderstorms to deal with. Yes, the potential for severe weather is still there, but it will not be as bad as it was looking after Wednesday’s model runs. However, we will continue to watch the weather models in the event that they ramp up again.

The big story yesterday was the NAM CAPE values up to 5000 on Saturday. This has gone down, but not by too much. This is the latest NAM run on Thursday:

NAM CAPE at 00:00 GMT Sunday

NAM CAPE at 00:00 GMT Sunday

This time is one of the highest points of CAPE on the NAM. I’m having trouble with the model skipping time, so this is as close to time as I can show right now. At 00:00 GMT Sunday, the NAM shows CAPE values in NJ from about 2000 to 4000 in isolated spots.

The GFS shows about the same amount of CAPE:

GFS CAPE at 21:00 GMT Saturday

GFS CAPE at 21:00 GMT Saturday

The GFS shows CAPE values in western NJ only up to 2500. So there is a little difference between the NAM and GFS, so we’ll have to keep an eye on these and see where they go on Friday.

Before the “conclusion” discussion, let’s go through the timing on the GFS and NAM models.

GFS at 12z Saturday

GFS at 12z Saturday

GFS at 18z Saturday

GFS at 18z Saturday

4km NAM at 09z Saturday

4km NAM at 09z Saturday

4km NAM at 12z Saturday

4km NAM at 12z Saturday

4km NAM at 00z Sunday

4km NAM at 00z Sunday

4km NAM at 03z Sunday

4km NAM at 03z Sunday

 

DISCUSSION: First off, the severe weather threat will not be as bad as feared yesterday. Although we will see thunderstorms, with still a chance of severe thunderstorms, I think the bigger story on Saturday and all weekend is the heat and the humidity. This, along with the CAPE, also supports strong to severe storms well west of NYC. However, the heat will most likely be more dangerous than the storms. I’m not focusing on the timing too much right now, but currently we need to watch for early Saturday morning, and then again on Saturday afternoon. Sunday could have some afternoon thunderstorms popping up, but that isn’t anything to worry about.

What could be something to worry about is the chance for more widespread thunderstorms, possibly severe, on Monday. @NY_WX points out, that as of now, that is a good possibility:

So be sure to stay tuned for the latest updates on Saturday’s storms, and then we turn our eyes to Monday. I’ll be tweeting my updated Thunderstorm Threat map for Saturday later Thursday night. For now, though, I’ll leave you with my heat indices map for Saturday, since it is more dangerous than the storms right now.

Heat indices for Saturday

Heat indices for Saturday

 

— Jonathon Rocco¬† (@jonathonrocco)

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