Potential Winter Storm For This Weekend
Update (Wednesday noon): I will release a forecast map later this evening.
For the past couple of days we have been following a potential winter storm that could impact the area this weekend. It’s slowly starting to look like there will be a system off the east coast which could bring wintry weather to ENC.
The energy for this potential system currently sits off the NW US coast and over the next several days it will become the most watched weather feature in the country. The potential wintry precipitation could impact areas as far south as Louisiana. So what impact will it have on ENC?
While things could still change over the next couple of days, right now it does look like ENC could in fact see wintry precipitation. The CMC, GFS, and Euro all have the shortwave diving southeastward initiating cyclogenesis over the Gulf of Mexico. The exact location and track thereafter will matter greatly.
For the GFS, the past couple of runs have the low developing further south and slower than the CMC and Euro. The overall track out of the Gulf of Mexico and into the Atlantic is also further south, further offshore, and slower still. Over ENC, there is sufficient cold air available for frozen precipitation. The problem is the low will be further away from the coast and a lot of that moisture would stay offshore. It will still be close enough for some of the moisture to move inland but not as much. Since it will be further away from the coast, warm air off the coast won’t nose inland as much leaving most of the precipitation as snow from beginning to end.
Update (Tuesday night 11:00PM): Little change in the 00Z GFS. No changes made to forecast. Will update in the morning. Keep in mind when you look at forecast model accumulation forecast: some snow forecast in the models don’t handle ice very well which leads to an inflated forecast. View where the ice is forecast to be and compare it with the forecast totals.
The CMC and Euro are closer together but with some subtle differences. First, both of these models is roughly 6 hours faster than the GFS. Second, they are further north over and both are much closer to the east coast than the GFS. This means both would be close enough to spread moisture inland further and in greater amount. With the counter-clockwise flow around the low, winds to the north of the low will flow inland from the warmer ocean, increasing low level temperatures which would lead to rain as opposed to snow at the beginning of the event especially areas closer to the coast. Areas far from the coast would not experience this problem thus increasing their snowfall totals significantly. As the low begins to pass to the east, winds wrap back around drawing cold air back eastward behind the low just in time to transition the rain into snow.
This means with the CMC and Euro models, precipitation over coastal sections and coastal plains would start as rain or a rain/snow mix before transitioning to all snow later.
The 12Z Euro is similar to the 12Z CMC since I can’t post that here.
Update (Wednesday morning): Models are a little closer together than previous runs. The GFS has picked up the speed of the low though its still a little further offshore than other models. The NAM is the least aggressive with the system this weekend. The surface low in this run is much closer to the coast than other models which would bring in warmer temperatures inland from the ocean making rain the dominant precipitation type. It does show a transition to snow before departing Saturday night. It will be interesting how the NAM responds as the weekend approaches but until then, this solution remains a slight outlier though not impossible.
The Euro is quicker than its 12Z run but still inline with yesterday’s 00Z run. The thing to watch for is the amount of cold air available when the precipitation arrives. There seems to be a growing consensus that precipitation will start as rain for ENC. How long it stays as rain will be determined by the track of the low. As mentioned in this discussion location is key. I will be back online later today and will give another detailed forecast later this afternoon.
Bottom line: there is still a ways to go before we can know more details about this storm. It does appear that a system will impact ENC this coming weekend and the potential of frozen precipitation is elevated.
I will continue to monitor this system over the next several days and will update as new information becomes available. If this trend continues, I will post a forecast total map in the next day or two.
