Storm Potential – 4-5 days away

Considering it’s still a bit early, I’m going to keep this brief. Yes, there is a growing storm potential for next week. No, I don’t know who will get snow, rain, or nothing at all. But, I’m getting increasingly concerned about a major coastal flooding event midweek regardless of the exact track of this storm.

12z GFS forecast for sea-level pressure and 6-hour accumulated precipitation valid at 7 pm EST on 03/07/13.
12z GFS forecast for sea-level pressure and 6-hour accumulated precipitation valid at 7 pm EST on 03/07/13.

The 12z GFS from this morning showed a rather scary scenario with a moderately strong low pressure system strengthening near the Delmarva Peninsula by 7 pm EST next Wednesday. This would lead to very strong winds along the coast and inland, heavy rain along the NJ coast, and heavy snow from Richmond up through Philadelphia.

18z GFS forecast for sea-level pressure and 6-hour accumulated precipitation valid at 7 pm EST on 03/07/2013.
18z GFS forecast for sea-level pressure and 6-hour accumulated precipitation valid at 7 pm EST on 03/07/2013.

To contrast the morning GFS run, the afternoon (18z) GFS run just came out and looks very different. In this scenario, the storm passes far enough south to completely miss NJ, Philly, and DC. I think this is too suppressed based on the pattern, but it’s certainly still a possibility. Other computer models have been averaging between Charleston, SC and Cape May, NJ for low position. So why all the model mayhem?

GOES-15 water vapor image of the East Pacific valid at 2330 UTC on 03/01/2013.
GOES-15 water vapor image of the East Pacific valid at 2330 UTC on 03/01/2013.
18z GFS initial 500 mb potential vorticity valid on 03/01/2013.
18z GFS initial 500 mb potential vorticity valid on 03/01/2013.

The GOES-15 water vapor image above shows the culprits for the potential storm over the northeast Pacific. The disturbances highlighted with the red and black circles will combine in the next 24 hours and move over an amplifying ridge (bubble of warm air aloft) over the West Coast. The 18z GFS initial 500 mb potential vorticity (a fancy way of showing the disturbances in the water vapor image with values) shows the combined areas of energy that will lead to our big storm. Over the weekend, I would expect the models to flip back and forth a bit more. We will have a much better idea by Monday, but my hunch is that this will be a big deal. I have been wrong before. . .

Thanks for reading!

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