High pressure takes over Maine for Sunday. A backdoor cold front brings cold air back to the region Sunday night into Monday. A storm system responsible for severe weather in the south organizes off the Mid-Atlantic coast on Monday, and brings snow, sleet, and ice into the area Monday night into Tuesday.
Sunday is more or less a carbon copy of Saturday as far as cloud cover, but temperatures nudge up a few degrees to bring most of the state above freezing at the high point of the day.
A backdoor front returns the cold air back to the state overnight Sunday into Monday morning. A slight chance of a snow shower is possible over the north and mountains, but any accumulation appears to be a dusting at best.
Cold Air Monday Sets The Table For The Storm
Where most of the state climbs above freezing Sunday, temperatures fall back to near their seasonal average for the state on Monday. While this model indicates the southwest coast may climb above freezing, if it does, it may be only by a degree or two.
Outflow ahead of the storm to the south may kick off some ocean enhanced snow showers for York & Cumberland Counties during the day. This may bring an inch or two in spots and could slick the highways up during the morning. This activity may continue into the afternoon. For southern areas, this is a precursor to the main event on the way Monday night.
Wind Concerns Monday Night Into Tuesday
As the storm moves off the DelMarVa peninsula early Tuesday, the storm intensifies and brings gusty winds to the shorelines. Snow develops Monday evening and may blow around for a time causing intermittent whiteout conditions along the coast. Wind advisories and perhaps high wind warnings are likely to be issued for the shoreline counties as a strong low level jet indicates wind speeds near 65-70 mph at around 1700 feet above ground level early Tuesday morning.
Tuesday Morning Commute A Rough One
For those working the day shift on Tuesday, chances are good that the commute will feature some sort of a wintry mix. By this time, a good 1-4″ of snow appears on the ground for western & southern areas with sleet and freezing rain mixing in along the coast and coastal interior by the height of the morning commute. For eastern areas, it appears to be slick in spots as well, but with lesser amounts of snow, and more in the way of sleet and freezing. With the exception of the far northern areas, who will get in on the action by mid-morning, greasy roads are very likely to start the day.
Why There Could Be Many Surprises With This Storm
What will happen in the mid- and low levels of the atmosphere temperature wise is going to indicate the final outcome once the precipitation reaches the surface. Each model has its own ideas, and each are showing different outcomes… some with stark differences, others with subtle ones. Anytime warm air invades the airspace over a below freezing ground level, the outcome often ends up as sleet or freezing rain, pending on just how low the warm air inversion goes. In the NAM model idea above for air temperature at roughly 5,000 feet, not only is it blowing between 40-60 knots, it is also running between 37°- 40°F for an actual temperature. The picture at the surface is much different.
Thanks to northeast winds at 10-20 mph, cold air is dammed in thanks to high pressure above northern Maine. It could be another example of Mount Washington seeing hurricane force winds, rain on the summit and a temperature in the 40s while areas below are seeing freezing rain and/or sleet with temperatures in the 20s.
Predicting actual snowfall amounts with this event with sleet & freezing rain playing a factor in the outcome is also a daunting task. It is still early to get into the fine details as far as how much snow, sleet and/or ice will cover the surface, but there is a reasonable idea where the impacts will be.
Cold air damming is going to be a force to be reckoned with for this event, as it almost always is in wintry mix storms. As it appears at this point, all areas have a reasonable chance of seeing at least some snow and some ice.
Coastal areas are likely to see 1-3″ of snow before changing over to a short period of freezing rain and/or sleet before going to rain… that is IF the coastal front can make headway onto land.
The interior areas away from the shorelines up through the foothills on into northeast Maine may see a few inches of snow before changing over to a period of icing and/or sleet before ending as rain near the end of the event.
For the High Peaks region over to the Moosehead / Baxter State Park area up to the Allagash, snow is likely to be the primary feature in the 4-8″ range but the outcome will be dictated in how much sleet and/or freezing rain occurs during the event toward the end Wednesday morning
I will have another update with more details Sunday evening.
~ Mike Haggett
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Special thanks to Tropical Tidbits and Pivotal Weather for their written permission to use their graphics in this post. Use of WeatherTAP images used within their written permitted terms of media use policy. Additional forecast information supplied by the National Weather Service, WeatherBELL Analytics and AccuWeather Professional.
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