03/05/2026
SIGNIFICANT WARM-UP EXPECTED WITH SOME RAINFALL ELEVATED RISK OF ICE JAMS AND SPRING FLOODING
DURING THE NEXT 2 – 4 WEEKS
Temperatures this winter have been below normal consistently since December. Snowfall has been above normal. The following data is from Bradley International Airport and is representative of the state.
The cold temperatures (winter average of -4.2 F) combined with above normal snowfall (52.3”) has generated thick ice on many state rivers. The Connecticut Civil Air Patrol flies weekly ice patrols across the state. Ice coverage is currently estimated at 70 – 90% on most rivers. Ice thickness is estimated at 8 – 14”. The current snowpack is above average across Connecticut and most of New England. Snow/Water Equivalents (SWE) currently range from 2.0” along the coast up to 7.0” in the Northwest and Northeast Hills.
SWE’s in Northern New England range from 5” – 15” depending on elevation. Ice Jams occur when rainfall and/or snowmelt cause rivers to rise more than 3 times the thickness of the ice. This breaks up the ice sheets and they begin moving downstream. If the floating ice encounters a barrier such as a bridge or bend in the river the ice can pile up. If the ice also encounters a shallow enough area the ice blocks can become grounded in the riverbed.
In March, the ice sheets will typically “rot” as the stronger March sun melts the sheets from above and also penetrates into open areas of water. This solar energy warms the water which melts the ice sheets from below. With average March temperatures It takes approximately 7 – 14 days to completely melt a foot of ice.
If a significant rainfall event (over 2” of rain) combines with a sudden warmup of 2 or 3 days, rivers can rise suddenly from the runoff and dislodge existing ice. The ice then flows downstream until it hits an obstruction such as a bridge or runs into a shallow area that causes the ice to ground into the riverbed. Water then piles up behind the jam.
During a typical spring flooding season, the smaller rivers in Connecticut will rise first and feed into the medium sized and larger rivers during the middle of March. As seasonal warming continues the upper basin of the Connecticut river starts to receive meltwater and flooding may occur from late March into April. The timing changes slightly each year depending on snowpack, temperatures and rainfall.
Major flooding can occur if a significant warmup is accompanied by heavy rainfall causing the entire snowpack to melt at once across New England.
The Army Corps of Engineers maintains several flood control dams in Northern New England that can hold back some of the meltwater (approximately 17%) to help reduce major flooding. The 6 – 10 Day (shown to the right) and 8 – 14 Day outlooks from NOAA are both indicating above normal temperatures and above normal precipitation (mainly in the form of rain).
Long range models are indicating a significant warmup over at least the next two weeks. Temperatures could reach the upper 60’s to low 70’s early next week before cooling back down for a day or two. Another warmup is expected next weekend into the beginning of the following week.
On average, temperatures are forecast to range from +4 to +6 F above normal for the next two weeks. The EURO (shown to the right) and other models are forecasting several small rain events over the next two weeks. Total rainfall for the next two weeks is expected to range from 2” – 3” across the state which is approximately 150% of normal.
Several light to moderate rain events are expected over the next two weeks. There are no imminent threats from large rain events in the next 14 days. However, the threat level will remain elevated until most of the ice cover has broken up on state rivers in approximately 10 – 15 days.
Flooding along the Connecticut river resulting from Northern New England runoff will is expected to remain an elevated threat for the next 4 – 6 weeks. Three risk factors (Thick River Ice, Deep Snowpack and Warm Temperatures) are expected to be present for the next few weeks. If a large rainfall event occurs, widespread ice jams and/or significant river flooding could occur.
In the absence of any large rainfall events, minor flooding and a few ice jams are possible in the next 14 days.
