April 9-15 Multiple Potentially Significant Storm Systems

I'm seeing the threat arise for not one, but two potentially significant storm systems.

Tropical Tidbits

The GFS model has been consistently bringing in a strong upper level low into Japan around April 4th, beginning to attain a negative tilt on the image above, valid for the afternoon of April 4th (for more information on negatively-tilted storms, please click on this link to see the post published yesterday on this topic). 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. If we take the April 4th day and extrapolate it out 6-10 days, we arrive at the April 10-14 timeframe for what could be a hefty storm. I say it could be strong, as the strength of these East Asian systems has been reflected in the resultant United States storm . For instance, a strong storm over Japan does usually result in a strong storm in the US 6-10 days later, and that's what we're looking to see in this April 10-15 timeframe.

But we're not just looking for one system. This time, there are indications we could see two systems.

Tropical Tidbits

About a full day after the original system moves out from Japan, we see another swath of significantly below-normal heights enter Japan. The GFS image above, now valid for April 5th, reflects this, and we can see our first storm system that was discussed above now located just west of the ridge in the Bering Sea. This second storm system is kind of a tricky one. I'm watching closely here, as it could end up being one storm with residual cold weather just hanging behind. However, this forecast says we are in for two storm systems, and since we're entering spring, these strong storm systems can create nasty severe weather. For that reason, I'll err on the side of caution and highlight two storms in this post, but do realize that this may switch back to one significant storm.

The pattern I had highlighted earlier last week, which showed how the Northeast was at the most risk, is now a bit more hazy than when we last analyzed this timeframe. Model guidance is no longer as favorable for an East Coast impact, but rather than drop that region from a potential impact zone, I'll still tentatively keep the Central and East US in line for this storm. We should know much more about what this storm(s) could do in about 4 or 5 days from today.

As you can tell, there's a lot of uncertainty. Let's sum up what we do know.

- There is the potential for at least one significant storm system around the April 9-15 period.
- Severe weather does look to be a potential factor in this timeframe.
- Cooler and unsettled weather can be anticipated for this timeframe.

Andrew