 The water vapor image captured at 4 AM Wednesday shows two of the three main pieces that work together to bring a storm into Maine for Thanksgiving. While confidence is there for an impactful snow event over the interior, questions are certainly there for the coastal plain, and where that question lies is with the cold injection piece over Alaska.  Wednesday 7 AM (12z) to Friday 1 AM (06z) – The cold injector is where the dynamic cooling of the atmosphere takes place to turn rain into snow. The upper low over the northwest is what pinwheels it in. The timing of the arrival of it and how it interacts with the developing ocean low will be the difference in how much, if any, snow builds up on road surfaces south and east of the foothills.  Thursday 5 AM (10z) to Friday 1 AM (06z) - As the cold injector arrives on the scene, the “thump” with the snow banding comes in. The short-term models are picking up on that potential but disagree on the intensity and timing just enough that it could throw a wrench into the outcome, either busting snowfall amounts on the high end with a cooler result or lower with a slightly warmer result. The difference of a couple of degrees is critical here. The other piece in this is the idea for a mix of sleet that may come into play as a warm nose works in off the ocean. This all has to do with the storm track, as a few miles difference closer or further away from the shorelines also affects the outcome.  Thursday 5 AM (10z) to Friday 1 AM (06z) – As snow develops, there is a decent agreement that the heavier banding holds off until later in the day. After sunset, this helps the atmosphere cool down quicker. The window between roughly 3 PM to 10 PM for the west and south and 7 PM to 11 PM for the east appears to be when the better chance for thumping is expected to take place. For those traveling, daytime is the safer period to go where you need to before the sun sets. After that, road conditions could be a challenge.  The slop factor is typical of early-season snowfall events, and with a surface low tracking through the Gulf of Maine to boot, it comes into play. North of the mountains will be a higher snow-to-water ratio, bringing drier snow, and then the ratios become lower closer to the coast, which brings the paste factor into play. With wetter snow comes more compaction. While wind gust speeds during the storm appear manageable (20-30 mph), where snow sticks may be a concern for power outages on Friday as the storm intensifies on its way into the Canadian Maritimes and a relatively stiff northwest flow develops. The bottom line is confidence is good for snowfall amounts to verify over the interior, but below the line of 6-10” is where questions remain. Given the setup, it all boils down to the timing of the cold injection and consequent dynamic cooling that will dictate how much accumulation comes with it.  Another round of much-needed water content is on the way, regardless of whether it falls frozen or liquid. Any banding that occurs could raise amounts locally, and where that does not occur, they could be lower. After this storm, there are no other storms of concern in the pipeline until perhaps later next week.  Please help to keep PTW going into 2025... Always have MULTIPLE ways to receive weather alerts. Stay aware, stay on alert, and stay safe. - Mike PRINT MEDIA: Feel free to quote and cite my work here for your stories. Please give me the professional courtesy of knowing that you are referencing my material so I can read your final product and acknowledge it on my media and link it on the PTW IN MEDIA page here on the website. Feel free to send me a message via the Facebook page or Twitter (X) to get my phone number if necessary. Thank you! NOTE: The forecast information depicted on this platform is for general information purposes only for the public and is not designed or intended for commercial use. For those seeking pinpoint weather information for business operations, you should use a private sector source. For information about where to find commercial forecasters to assist your business, please message me and I will be happy to help you. |
Mike Haggett
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