Thursday, July 8, 2010

Tropical Depression or Not?

That is the question today. Yesterday I posted reasoning as to why I did not consider 96 L to be a tropical depression at the time of the upgrade which was 11 PM EST.

In order to answer this question ..One has to know what a closed low is. SO what exactly is a closed low?

A low pressure system that is completely encircled by an isobar. 

Notice that a closed low is a low pressure that is completely circled by an isobar..

Now lets look at a surface map from 03 Z or 11 PM

3

Notice the low off the California coast is completely circled by an isobar? Hence you have a closed low… However, take notice to the area circled in yellow. You have an open area of low pressure at 11 PM at the time that NHC declared this a Tropical Depression!

Now lets look at 6 Z

namsfc06wbg

Now, as of 2 AM we have a closed low ..so now we have a tropical depression at 2 AM. What happened at 9 Z?

namsfc09wbg

It appears to have opened back up and this was during the time that i noticed that it was weakening and no convection and clear skies were being seen in the satellite right around the center.

Finally by 12 Z it had closed back off once again and then stay closed off and this would be when it had actually obtained TD status which it was able to maintain.

Now either HPC does not know what a closed low is and there graphics are just erroneously wrong or …someone jumped the gun at National Hurricane Center.

Readers be advised that I am not afraid to go against the grain when the data lies on my side. Its quite clear that at 11 PM we did not have a Tropical Depression. We briefly maintained that status at 6 Z.. but it continued to waver between an open wave and a closed low there after up until 12 Z.

Regardless it remains that so far for the 2010 Tropical Season we have had 1 named storm with no tropical action forseen in the next 10 days.

No comments:

Post a Comment