SUNDAY MORNING UPDATE ON FACEBOOK ► CLICK HERE
An Icy Mess For Areas Away From The Shorelines
For those that have followed this column all week, none of this should be a surprise to you. Forecast guidance has latched onto the idea that I have been mentioning for the past few days that cold air is likely to get the upper hand at lower levels over interior areas, which with a set up like this, can cause problems.
For overnight Saturday into early Sunday, freezing fog & drizzle will be an issue over much of the state as temperatures have remained cold outside of the anomaly which is the Rockland airport. Watching observations closely today, temperatures ranged roughly 10° cooler than what was predicted over the state. This was the first red flag to fly that my suspicions were coming true the the cold air was going to get the upper hand.
Looking the NAM3km model idea above for 7 AM Sunday shows the textbook cold air damming situation which I spoke of earlier this week. The White Mountains do an amazing job keeping cold surface air locked in at low levels over the western foothills and mountains. This is a classic situation where Mount Washington could record a summit temperature in the 40s and nearby Fryeburg could be in the 20s at the same observation point.
Another indicator that cold air may get the upper hand is a weaker system. For most of the week models indicated a storm around 996mb near the St. Lawrence River, just east of Montreal at roughly this time. This model, and most others, indicate a system running around 1002mb and further south, essentially cutting across the center of Maine and into New Brunswick. Six millibars may not sound like a whole lot, but in this case, it is very concerning. The system may not have the power to flush out the cold at the low level, which sets up the idea of a chance for more ice to build up.
The consistency of the short term models today over proposed ice accretion and where it is most likely to occur has been important. I will say under no certain terms that forecasting ice accretion is the most difficult of any precipitation. I will say that these model ideas are a bit bullish, but the general idea of a tenth to three tenths of an inch of ice is a reasonable idea for the western foothills & mountains, across to Southern Aroostook & Northern Washington Counties by the time this event ends Sunday afternoon.
If the cold air stays entrenched as I have been very concerned that it could, power outages may happen Sunday night as a cold front slides through behind the departing system. Anytime there is ice followed by wind in a forecast, I really hope to be wrong, but the signals are there that it is real possibility to occur.
Flash Freeze & Back To The Bitter Cold To Start The Week
As the Sunday system departs, it will intensify and drag a cold front through the region in its wake. This is likely to touch off some spotty snow showers and squalls which may accumulate a dusting to an inch or two predominantly in the higher elevation regions.
Any coastal areas that manage to get above freezing should be on alert for flash freezing late Sunday into Sunday night as wind increases and temperatures plummet on very short notice. Roads, parking lots, porches and walkways will ice up very quickly. Expect slick spots on secondary roads Monday morning.
A large dome of high pressure will move in for Monday, giving the state quiet but below normal cold through midweek. Our next potential system will arrive Thursday into Friday, and this may impact travel to open the Christmas holiday weekend.
~ Mike Haggett
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.
Always Stay Weather Aware!