Friday, April 4, 2014

April 10-14 Potentially Major Storm System

I'm monitoring the April 10-14 timeframe for some stormy weather.

Tropical Tidbits
The image here shows a GFS forecast map, valid on the morning of April 4th, earlier today. We observed a negatively-tilted storm system hitting Japan this morning, and if you've been reading this blog lately, you know that that means we're in for a storm here in the US in just a few short days. There is a rule, well explained by Joe Renken, that states a weather phenomenon in East Asia will be reciprocated in the United States 6-10 days later. This means that if there is a storm system in Japan on a certain day, we can expect a storm in the US 6-10 days after that. The same goes for high pressure and warm weather. With this negatively tilted storm hitting Japan on April 4th, we're watching April 10-14 for a storm system in the United States.

There's a reason why I keep bringing up the negatively-tilted aspect of this trough in Japan. We may expect a negatively-tilted trough here in the US around April 10-14 in response, and there's a reason why the negative tilt is concerning.

USA Today
As the graphic shows, there are two types of tilts to a trough- positive and negative. The positive tilt trough sees the jet stream bending towards the southwest, as the Energy Pocket, also known here as the 500mb maximum vorticity, pushes in that direction. The negatively tilted trough indicates the system has reached maturity, as the vorticity maximum now pulls the system to the southeast. The mature storm now produces more vigorous storms, hence why we are concerned more when a negatively tilted trough comes around, compared to a positively-tilted trough. Since we might expect a negative trough to impact the US in the April 10-14 timeframe, it's plausible we also see a decent severe weather event in response to the negative tilt.

It's a bit too far out to tell an exact track for this storm, but as always, I'll update the situation in the next day or two with new information on this storm.