January Thaw Isn't All Good News; Ice Jams, Flooding Will Continue Through Saturday

Linda Lam
Published: January 13, 2018

The January thaw that took hold of areas from the Midwest to the Northeast and South had many rejoicing. However, in some areas, the warmer conditions resulted in ice jams and flooding as Winter Storm Hunter tracks eastward.

The prolonged period of record-breaking cold was finally replaced with above-average temperatures from the Plains to the East. Highs in the 50s reached as far north as the southern Great Lakes and northern New England late this past week. These much milder temperatures, however, brought flooding to parts of the Northeast.

(MORE: January Thaw Forecast)

Happening Now

Rain has ended across the Northeast, but flooding concerns will linger into this afternoon.

Saturday morning, some evacuation were reported due to flooding along Route 15 near Johnson, Vermont.

Numerous street flooding and basement flooding has been reported in eastern Massachusetts late Friday night into early Saturday morning where numerous locations have seen more than two inches of rainfall. In some spots more than three inches has fallen, with up to 3.71 inches measured in East Freetown.

For additional flood reports scroll to the bottom of this article.

Concerning Setup

One of the consequences of this brutal cold was the development of ice on rivers in the Northeast and Midwest. Even the Great Lakes saw a rapid advancement of ice cover over the past two weeks.

The Arctic cold also created frozen ground across the northern tier, even where snow cover is lacking.

(MORE: First Week of 2018 Was the Coldest on Record in Dozens of Cities in the East)

With this cold air in place late last week, Winter Storm Grayson was able to bring snow and ice to parts of the South, and then rapidly intensified off the East Coast. Incredible coastal flooding also occurred in eastern New England from this intense storm.

More than a foot of snow and strong winds then impacted portions of New England, much of which remained on the ground ahead of Winter Storm Hunter.

(RECAP: Winter Storm Grayson)

Snow depth on the morning of Jan. 10. 2018.
(NOAA)

Snowmelt and Rainfall

Warmer temperatures infiltrated the Northeast mid-to-late week and much of the existing snowpack has melted as of early Saturday.  

In addition, Winter Storm Hunter spread snow, sleet, ice and rain into the Northeast. The mild conditions ahead of this system resulted in the precipitation mainly falling as rain along the East Coast, including much of New England.

(MAPS: Weekly Planner)

The combination of the rainfall, snowmelt and the potential for snow-clogged storm drains could result in some urban, poor-drainage and small-stream flooding.

Another thing to keep in mind is that temperatures in New England will drop on Saturday afternoon after the cold front moves through. The dropping temperatures bring the potential for any water on surfaces to freeze late Saturday into early Sunday.

Ice Jams

An additional concern is for ice jams in portions of the Northeast, even in areas where less rainfall occurs. This is due to the increase in runoff due to the melting snow and frozen ground, which has resulted in some rise in rivers. The rising rivers could potentially force ice to break up and move, creating ice jams.

 

Ice chunks accumulated on the Kennebec River in Augusta, Maine, in February 2016.
(Facebook/Dave Dostie)

Ice jams typically occur when temperatures above freezing cause ice to begin to thaw into big chunks. When rivers rise or there is an increase in flow due to rainfall and/or melting snow, the ice begins to move. 

(MAPS: 10-Day Forecast)

The pieces of ice can get stuck and pile up near bridges and river bends. This results in the water flow of the river being blocked, and the river can overspill its banks and flood the surrounding area.

The flooding resulting from ice jams can be serious, both due to the water as well as damage from chunks of ice.

Consequently, the National Weather Service has issued flood watches from northeastern Pennsylvania into parts of New York state and New England.


Flood Alerts

These flood watches are for the risk of quick and significant river and stream rises near ice jams, as well as for urban and street flooding. Basement flooding also is expected.

Storm Reports

More than an inch of rain fell in Upstate New York, western Pennsylvania, southeastern Ohio and parts of West Virginia which combined with the melting snow has resulted in numerous reports of flooding, including river flooding and ice jams.

South of Pittsburgh in Monessen, Pennsylvania four inches of rainfall was reported, while almost three inches of rain has been reported in areas north of Pittsburgh, including Bell Acres and Nixon which measured 2.92 inches and 2.82 inches, respectively.

A water rescue occurred in Powhatan Point, Ohio when a car drove into a flooded roadway early Friday. Houses were flooded in Cameron, West Virginia and numerous roads were closed due to flooding in Wheeling, West Virginia.

(LATEST: Flooding Impacts)

Near Lewis Run, Pennsylvania an ice jam resulted in one house and one vehicle flooded.

Flooding in western New York was also reported Friday morning with houses surrounded by water in parts of South Buffalo.

A few basements were flooded in parts of Connecticut late Friday.


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