Monday, February 2, 2015

February 10-15 Potential Winter Storm

I'm watching for the potential for wintry weather in the February 10-15 period.

Tropical Tidbits
The image above shows 500mb geopotential height values for the morning of February 5th, with mean sea level pressure (MSLP) contours superimposed. In this graphic, we see two areas of low pressure over the Western Pacific. The more dominant system is located south and east of Japan, with another piece of energy just west of this island nation. In the forecast hours after this graphic, it appears the energy west of Japan transfers to the storm east of Japan. From there, the dominant low moves generally northeast, away from Japan. When we use the Typhoon Rule, which states weather phenomena occurring over Japan is reciprocated in the US 6-10 days later, a storm in the US might be expected in a February 10-15th period, adding a day for some uncertainty I have on timing. Additionally, the transfer of energy over Japan tells me we could be looking at a transfer scenario from the Midwest/Great Lakes/Ohio Valley into the Northeast.

We can take a look at teleconnections to get a glimpse at what this storm might do. For this post, we'll pay attention to the top-right North Atlantic Oscillation (NAO) outlook. Notice how the index rises from negative to neutral territory right in the timeframe of this potential winter storm. The NAO switching phases is known to be a red flag for snowstorms in the Northeast, as the risk of snow events in that area tend to rise when this switching of phases occurs. This could support the idea of a transfer storm to the Northeast, like the GFS showed (in a likely overdone projection) in its 12z forecast:

Tropical Tidbits

To summarize:

- Model guidance is indicating a winter storm may impact the country in a February 10-15 period.
- As of now, a transfer low from the North-Central US to the East Coast may be a likely solution.
- As usual, high uncertainty still exists.