Another significant-impact freezing rain event across the USA has demonstrated once more what this underrated hazard can do. Mid-week, a strong Arctic cold front pushed deep into the continental United States east of the Rocky Mountains. As strong warm advection from the south commenced and impinged on the artic air, freezing drizzle and freezing rain broke out from west to east.
The first major impacts were seen in Oklahoma City, Oklahoma on Thursday night (December 15th), where bridge icing resulted in at least 81 injuries and 3 deaths. The most stark of the incidents happened in Baltimore, Maryland on Saturday morning (December 17th), where during a 70-vehicle pileup, a gasoline tanker tumbled off of an icy bridge at highway speed and exploded/burned. In between, significant impacts were seen in many major metro areas including St. Louis, Indianapolis, Cincinnati and Columbus.
The characteristics of this event were typical of freezing rain/freezing drizzle:
It created a very thin, hard-to-see glaze of "black ice" that was treacherously slick, more so than any other type of winter precipitation
Accidents happened at higher speeds due to the ice being difficult to see
Crashes were more serious in nature than with other types of winter precipitation due to higher speeds
Metro areas and interstates were gridlocked
Emergency responders were overwhelmed
Many multi-vehicle pileups occurred
911 call centers were unreachable
Many people were forced to park on main roads and walk home, their vehicles unable to travel up even slight inclines
Many did not make it home, forced to spend the night in hotels and in some cases their vehicles
In the southern (warmer) portions of the event, bridge icing produced the majority of the incidents
In Oklahoma City and St. Louis, barely a trace of precipitation was officially measured during this event - yet another example of high-impact icing that does not always meet standard NWS criteria for winter weather watches/advisories. The NWS did have advisories out in time from Missouri eastward, but the public and even many DOTs were clearly unprepared. For example, in Missouri, MODOT was caught completely off guard by the event, not deploying salt trucks until the gridlock from the icing was well under way.
Preliminary statistics and facts
I queried dozens of news media coverage pieces online (from local newspapers, TV stations and national news outlets) to count the number of fatalities from the event. As of the time of this article publishing, the minimum death toll is 35. Missouri clearly was hit the hardest by this event, with at least 11 fatalities, 1,522 reported accidents and 171 reported injuries. This fact sheet breaks down the numbers by state. As a reminder, these stats reflect minimum numbers, that is, only the incidents reported in the news media. The actual death toll is likely far higher, but will require more in-depth research at a state and county level to derive.
Bridge icing from freezing rain is very predictable. It is why I have been able to capture many videos of accidents as they happen! If something is that predictable, it is easily preventable. If radar and/or surface observations show rain/drizzle AND freezing temperatures, bridges WILL ice! I have never seen a below-freezing precipitation case where unsalted bridges did not ice.
When the aforementioned conditions are expected or even if they are possible, DOTs and the NWS should mobilize. When the conditions are imminent or in progress, the public should be warned and the bridges treated immediately.
The Baltimore incident, and many others like it, could have easily have been prevented. Freezing rain never unexpectedly ices bridges - it ALWAYS ices bridges. If I, having no meteorology degree, can easily predict exactly where and when accidents will happen and be there to catch them on video, there is no reason that officials who are equipped to respond could not take action in plenty of time. It is not complicated, and I hope the lives lost during this event are enough reason to rethink the way we all approach this hazard - NWS, DOTs, EMS and the driving public alike.
Educational videos relevant to this event
Bridge icing and freezing rain were prominent factors in this event. The following videos explain the hows and whys of these two hazards and what the public can do to prepare: