Keith's Weather Notes: Storm Update

3:21 PM, Dec 27, 2012   |    comments
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For the most part the forecast is on track for moderate to heavy snow statewide through this afternoon...but there are two notable "twists":

1) Coastal Front for the win!- Parts of York and Cumberland counties, including Portland, that we expected to change over to all rain at some point...aren't going to. (Sidenote: I know some places near Kittery and along the beach over York County have changed over to rain, but that's the exception rather than the rule). This is because of the formation of something known as a "coastal front." It's a small scale boundary that divides the relatively warm ocean influenced air from the colder continental air to the west. When the boundary sets up a bit inland, the coast changes to rain...when the boundary sets up offshore like it did today, the coast remains snow. This setup will continue through the afternoon and bring some very heavy bands of snow to spots along the coastline and just inland. There will be some sleet mixed in at times and even a little freezing rain, but overall the cold air is winning this battle. Because of this front, and the enhancing of convection along it, some of the heaviest snowfall totals from this storm will be just onshore.

2) Dry slot Developing to our south- The crusher of many of my childhood snow dreams, a dry slot, has developed over Massachusetts as of the latest radar data. These dry slots tend to lighten up the precipitation for a period during the middle of the storm, and in this case, totally shut it for several hours. As a result look for things to quiet down across southern Maine in a few hours as the dry air works in. Farther norther the dry slot will be a factor later this afternoon. The computer models have the dry slot "filling back in" by this evening but in my experience the bands of snow never totally regain the same strength. (Again another bitter disappointment as a child who loved snow. I can't tell you how many times I waited for dry slots to fill in and it never happened)

Even with the dry slot, snowfall totals in the 10-18" range are likely in most spots. There will be some local variation of course but I decided to just cover most of the state with the same range due to the way the radar trends are unfolding.

Timeline for snow ending: 9-10 PM over southern and western Maine. Midnight over the Midcoast. 4-5 AM over Downeast and northern Maine. The snow will lighten up some before these times, but these are the "it's really over" time estimates.

After some snow showers over northern Maine tomorrow morning look for clearing for Friday afternoon with windy conditions and blowing snow.

Saturday will feature increasing clouds as we watch another storm for Saturday night. At this point that storm looks like it will just brush coastal Maine with some snow as it will be a bit too far east. Still time for that to change of course but it doesn't look like a major event for us at the moment.

I will be on air doing live cut ins about this storm all afternoon and will update this post if anything changes.

Twitter: @KeithCarsonWCSH



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