Snow and rain showers to wrap up the holiday weekend While it won't be an event of significance, interior areas could pick up enough snow to make the roads slick. Model ideas have trended a bit warmer, which will make the snow sloppier, and have knocked down the amounts. The ski hill summits should do well with this, with upwards of 6". The interior valleys may only end up with an inch or two of paste. Northern areas could end up with 2-4" in the Allagash region, with lesser amounts over eastern Aroostook. As far a liquid equivalent for the event, totals range from ¼-½" (locally higher/lower) with DownEast areas favored to be on the high end.  Sunday 7 AM (12z) to Monday 7 AM (12z) - Snow begins to break out over interior areas mid to late morning and expands to the south and east mid to late afternoon. As the precipitation picks up, so will the wind. MidCoast and DownEast coastal areas may experience southerly wind gusts in the 35-45 mph range with the low-level jet overhead. A cold front passes overnight, flipping the wind direction to the northwest. Any liquid on roads, driveways, sidewalks, and parking lots is likely to freeze by Monday morning, away from the immediate shorelines. Expect a breezy and cold day on Monday. The verdict on snow for Tuesday remains up in the airThe European deterministic model and its ensemble are a clear outlier versus other model ideas, indicating the potential for little to no snow over the interior and less than 6" of snow for the coastal plain. As noted in Saturday's post, the driver energy has made landfall on the continent in southern Alaska/western British Columbia, but the kicker energy remained near the Arctic Circle.  The European model has jogged slightly north in the overnight run, but most of its ensemble members are running south of the benchmark 40°N/70°W point and continue to track the storm south of Nova Scotia. With the delay in the arrival of the kicker, the storm is later in development, allowing the trough entering the region on Monday to sink further south and keeping the bulk of the moisture offshore. With the wind more out of the north, the shorelines may see minor accumulations as ocean influence is cut off. The European AI model, along with other guidance and ensembles, is more bullish on the kicker forcing the issue earlier, and thus creating a more impactful snow event.  There is an interesting game of liar's poker going on due to how guidance interprets the influence of the kicker and the trough. Cold air fools models, as the bias is toward warmer, more progressive outcomes, and in situations like this, that needs to be accounted for. Having two of those wrenches to contend with isn't anything new, but it is rather peculiar how the European model and its ensembles are treating them in this scenario. Has more of a cold bias crept into the recent upgrade, allowing the AI version to exploit it? A part of me hopes so, as models have been running warm for years in the chase of tropical storms. Cold bias is good to see for comparison. Looking at 150+ ensemble ideas and factoring them all in has me seeing a middle-of-the-road outcome.  Tuesday 7 AM (12z) to Wednesday 7 AM (12z) - Where guidance agrees, the storm is progressive with no blocking high to the north. There is variance in the start and end times. The European idea starts later, with less snow. Most other ideas are like this one, with snow breaking out mid to late morning on Tuesday, bringing impacts to the afternoon commute and into the evening. Precipitation ends from west to east Tuesday night into early Wednesday morning.  This is my idea for now, subject to change. Coastal areas are likely to see plowable amounts of snow. Further inland, it's a toss-up. Gifts for the ski or bike bum in your life Outlook through SaturdayExpect a breezy and cold day on Wednesday. A weak clipper brings snow showers with possible squalls on Thursday. The deep cold rushes in behind Thursday night. Storm potential is possible for Saturday.  The PTW Weather Wall updates 24/7 Your financial support keeps the lighthouse lit |
Mike Haggett
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