Retired senior lecturer in the Department of Meteorology at Penn State, where he was lead faculty for PSU's online certificate in forecasting.
By: Lee Grenci , 2:57 PM GMT on February 16, 2013
In my last blog, I presented research showing that the long-term average of strong East-Coast winter storms (wind speeds of at least 45 knots) was highest during February. I also noted that February had the greatest number of "full coast" storms, which provided more opportunities for the southern and northern branches of the jet stream to constructively interact and produce intense nor'easters. By "interact," I meant that two 500-mb short-wave troughs (one in each branch) phase or deliver a one-two punch. I had indicated that today's follow-up blog would elaborate on the one-two punch, but the meteorology is pretty straightforward (here's my definition).
The surface analysis at 12Z on February 2, 1976. Note the 964-mb low centered over Maine. Courtesy of the National Meteorological Center (NMC).
So I decided to switch gears, although I'm still sticking to the theme of strong East-Coast winter storms during February. Indeed, the topic of today's blog is the infamous Groundhog Day Gale of February 2, 1976 (see the analysis of mean sea-level isobars above at 12Z on this day; details will be forthcoming). I chose this storm for three reasons. First, the storm certainly fits the motif of strong February nor'easters that I wrote about in my last blog (and an interesting topic Stu Ostro broached earlier in the week). Second, two 500-mb short-wave troughs, one in the northern branch and one in the southern branch of the jet stream, merged (phased) to set the stage for explosive cyclogenesis. Last, but not least, I'm wondering whether the Groundhog Day Gale of 1976 would have been named by The Weather Channel.
The surface analysis above indicates an intense low-pressure system centered over southwestern Maine at 12Z on February 2, 1976 (the minimum pressure at the time was 964 mb). During the next 18 hours, the bottom fell out of local barometers as the minimum pressure plummeted to 944 mb by 06Z on February 3 as the storm headed northeastward into the Canadian Maritimes. To this day, all-time records for low barometric pressure set in Maine (957 mb at Caribou, for example) during the Groundhog Day still stand. At Boston, Massachusetts, the barometric pressure of 965 mb ranked as the second lowest on the city's all-time list.
It doesn't take a rocket scientist to infer that the rapidly deepening low produced very strong winds, ranking the Groundhog Day Gale of 1976 as one of the fiercest windstorms on record in the Canadian Maritimes (and rivaling the Saxby's Gale of 1869). According to Environment Canada, winds gusted to 188 kilometers an hour (117 miles an hour) at Saint John, New Brunswick. Waves as high as 12 meters (almost 40 feet) and swells to 33 feet were observed in the Bay of Fundy. There was also surge flooding in Maine (I recommend reading this compelling NOAA account). Freezing spray from crashing waves coated everything with ice as far as four miles inland from the bay, and eroded chunks of coastline disappeared into surging seas (YouTube documentary of damage).
Coarse analyses of 500-mb heights (solid contours) and 500-mb absolute vorticity (dashed contours) at 00Z on February 1, 1976 (upper left), 12Z on February 1 (upper right), 00Z on February 2 (lower left), and 12Z on February 2 (lower right). Short-wave troughs (circled in red) were traveling in the northern and southern branches of the 500-mb westerlies. The two troughs phased by 12Z on February 2, 1976. Larger image. Courtesy of Robert S. Gaza and Lance F. Bosart.
As I suggested in my last blog, strong, "full coast" storms typically involve the phasing of short-wave troughs traveling in the northern and southern branches of the 500-mb westerlies. The evolution of the surface pattern from 00Z on February 1 to 12Z on February 2. 1976 (larger image), confirms a low-pressure system developing along the Gulf Coast and eventually moving up the East Coast (so it was a "full coast" storm). The pattern of 500-mb heights and vorticity (above; larger image) shows distinct short-wave troughs and their associated vorticity maxima (circled in red) embedded in the northern and southern branches of the 500-mb westerlies. Note that the short-wave troughs moved closer to each other from 00Z on February 1 to 00Z on February 2, eventually phasing by 12Z on February 2 (lower-right panel) and setting the stage for explosive cyclogenesis.
On The Weather Channel's Web site, there are three guidelines for naming winter storms:
1) Significant impact due to snow or ice within three days
2) Significant disruption to road and air travel
3) Life-threatening conditions from wind, snow, ice and cold
Given that the Groundhog Day Gale of 1976 didn't make the NESIS Top-46 list and that the Groundhog Day Gale's primary impacts were strong winds and surge flooding, I'm wondering if the Groundhog Day Gale of 1976 would have been named (to be fair, there were some pretty heavy lake-effect snows in the wake of the storm). Maybe I'm just plain wrong, but, taking the three criteria used to name winter storms at face value, I don't see how this storm could have been named (I recognize that "Groundhog Day Gale of 1976" is a name; I'm obviously referring to a name on a TWC list). What do you folks think?
I'm not trying to stir the pot here (well, maybe a little). I'm asking this question respectfully. Indeed, naming Nemo was very helpful, in my view. But the Groundhog Day Gale of 1976 was also one heck of a storm. It gained its infamy, however, from wind and surge flooding, not from snowfall. So I think a discussion about whether the Groundhog Day Gale of 1976 would have been named is a compelling topic. I'm looking forward to reading your opinions.
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