Last updated: October 20, 2021
Article
Wild Winter Weather
The winter of 2017-2018 was an interesting one at Acadia National Park. The weather was comprised of warm and cool periods that may well have been within the normal range of winter temperatures but it was significant because of the magnitude and rate of change of the transitions between those periods. The sequencing of those warm and cool periods also had a major impact and caused significant flooding of park areas and resources.
This flooding event cannot be tied to one storm as multiple ingredients came together at once. However, what caused the widespread heavy rain and flash freeze were of the same system. Flooding and the subsequent freeze-over at Sieur de Monts was caused by a few primary factors.
NPS Photo
January 13th, 2018 - Sieur de Monts and Great (Ice) Meadow
This flooding event cannot be tied to one storm as multiple ingredients came together at once. However, what caused the widespread heavy rain and flash freeze were of the same system. Flooding and the subsequent freeze-over at Sieur de Monts was caused by a few primary factors.Frozen Ground
During the last week of December 2017, air temperatures fell out of the 40s into a deep freeze. Air temperatures only touched 20F once on McFarland Hill, while daily highs struggled to get into the teens for the rest of December. On Cadillac, temperatures were more extreme, with 60 hours straight of below zero temperatures (Dec 27-Dec 30). Additionally, snowpack prevented solar radiation from heating immediate ground cover, creating a less permeable surface for runoff. With potentially more frozen ground on high terrain, snowmelt would be prone for quicker runoff into low-lying areas.
Snow Melt
On January 4, 2018, additional snowfall of 5-7 inches fell on MDI increasing the overall snow depth to about 10-12 inches. A transition to freezing rain further saturated the snow, enhancing a snow water equivalent of approximately 4 inches on MDI.
On January 9, temperatures rose above freezing for the first time in the New Year, and would continue rising into the mid-50s through Friday January 12th as strong warm air advection took place. With the warm unseasonable temperatures, snowpack began to melt
On January 4, 2018, additional snowfall of 5-7 inches fell on MDI increasing the overall snow depth to about 10-12 inches. A transition to freezing rain further saturated the snow, enhancing a snow water equivalent of approximately 4 inches on MDI.
On January 9, temperatures rose above freezing for the first time in the New Year, and would continue rising into the mid-50s through Friday January 12th as strong warm air advection took place. With the warm unseasonable temperatures, snowpack began to melt
Heavy Rainfall
Overnight January 12, strong southerly flow provided excellent tropical moisture transport from the Deep South, which placed Downeast and mid-Maine in persistent rains overnight Friday. Total rainfall at McFarland Hill was 2.82” in a 16-hour period.
Flash Freeze
Associated with the same system that brought well above normal temperatures and heavy rain, was a trailing arctic front with a tight temperature gradient. With the frontal passage around noon on January 13, McFarland Hill and Cadillac Mountain both recorded a drop of 24 degrees (F) in 2 hours from the lower 50s, to upper 20s (Fig 6). Temperatures would continue to fall into the upper single digits overnight and Sunday night.
Overnight January 12, strong southerly flow provided excellent tropical moisture transport from the Deep South, which placed Downeast and mid-Maine in persistent rains overnight Friday. Total rainfall at McFarland Hill was 2.82” in a 16-hour period.
Flash Freeze
Associated with the same system that brought well above normal temperatures and heavy rain, was a trailing arctic front with a tight temperature gradient. With the frontal passage around noon on January 13, McFarland Hill and Cadillac Mountain both recorded a drop of 24 degrees (F) in 2 hours from the lower 50s, to upper 20s (Fig 6). Temperatures would continue to fall into the upper single digits overnight and Sunday night.
NPS Photo
January 17-24, 2018 – Nature’s Zamboni
The event between January 17-24, 2018 was similar to the initial freeze of the Nature Center and Great Meadow just a week prior. With only a couple days of solid ice coverage, a coastal low-pressure system developed off the east coast and tracked northeastward. Bar Harbor and Downeast were originally forecasted for a 5-7 inch accumulation on the 17th with changeover to rain, but a further south track kept the region in moderate snow for the entire event. A total of 9.1 inches of new snow was reported between the 17th and 18th . On the 23rd, a large storm system underwent cyclogenesis in the Central Plains and slowly tracked eastward. With a warm front lifting through the region, temperatures on McFarland hill warmed to 50 F as rain fell. Strong moisture transport along the warm conveyor belt would drench Downeast in 1.66 inches of rain by the next morning. All of the 9.1 inches of snow had melted with the warm temperatures and rain with a Snow Water Equivalent of approximately 2-4 inches. While there was no strong arctic front to flash freeze the new precipitation, much of the ice at Sieur de Mont was still in place and retained the new snowmelt and rainfall. With temperatures falling into the teens above the standing water and a giant ice cube beneath it, the new water refroze on top increasing the ice pack.
This storm was described by local media outlets as a once in five hundred year flooding event. Although this weather event created memorable conditions for those who got to experience it; severe damage to park resources accompanied it as well. Trails, buildlings, the Wild Gardens of Acadia brand new sprinker system, and many other resources in the Sieur de Monts Springs area of the park were damaged during this weather event.
As the climate continues to warm and change, its impact on weather will leave drastic changes throughout Acadia National Park. Since this winter flooding in 2018, two other flood events have caused damages at Sieur de Monts Springs and other locations within the park.
As the climate continues to warm and change, its impact on weather will leave drastic changes throughout Acadia National Park. Since this winter flooding in 2018, two other flood events have caused damages at Sieur de Monts Springs and other locations within the park.