As you know, we like to grade our forecasts. It is a way for us to look back and identify how we can be better. With a number of active threats, including one tomorrow, time is hard to come by. As a result, we're going to grade the two most recent storms here, without the standard map that you see after a storm. Rest assured, however, I did review the storm reports in relation to our final call forecasts. Let's start with the January 31st event.
January 31, 2021 Event
We took the numbers up modestly from our first call, and for the most part that worked. It's always difficult to get double digit accumulations statewide, and we saw a relative minimum in NE CT. That said, we could have gone higher with snow totals in SW CT. We saw multiple reports of 15+ in SW and central parts of the state, including 15.2" in Bridgeport!
We weigh snow accumulation twice to account for the fact that most people only care about what falls in their backyard. Here, we did well. Of the 60 reports I counted, only 6 (10%) deviated from our forecast upper bound of 14" by 2 inches or more. Only one report ended up higher than our maximum isolated number on our map of 18". I think that puts us in a good place.
Overall the timing was good, though we did struggle a bit with onset. The worst of the storm was when we said it would be.
This area was mixed. We did a great job highlighting wind potential and blizzard conditions in southern CT, and that's what happened. Inland CT winds were not as strong as I expected, and the southern CT winds were within our range, though on the lower bound.
As for power outages, while I did say I didn't expect widespread power outages, I went with scattered outages for southern CT. They were more isolated. That's splitting hairs, but it matters to me.
This one wasn't too hard. Road conditions were terrible for a while, as you always see with a heavy snow event with blizzard like conditions.
We called for high impact, and it was high impact. We nailed the worst impact timing and for many this was the worst winter weather event since 2018. Very happy with this aspect of the forecast.
Taking everything into account, this was an excellent forecast. There's no better feeling than coming through with a great forecast during a high impact event.
Overall Grade: A-
Super Bowl (2-7-21) Event
This forecast was much more difficult than the January 31st event. This forecast had a lot more uncertainty with the guidance being all over the place in track.
After putting a large part of the state in the 6-10" zone, we downgraded that to a map which featured a large 3-6" zone and a smaller 4-8" zone at the shoreline. We thought that the heaviest banding would remain just to the SE of Connecticut, and that was wrong. We did tell everyone to expect a period of moderate to heavy snow, and we saw an afternoon full of heavy snow. We thought the highest totals would be in SE CT, and they ended up a bit further west and north.
Here, we had 3/55 (5%) of the relevant reports fall two inches or more out of our zone, which is excellent, but we did have one report well out of our 3-6" range and we could have stood to be more aggressive in the overall map in eastern CT, among the other issues I mentioned earlier. For that reason, what would have otherwise been a higher grade gets downgraded harshly.
Our timing forecast was a mixed bag, and is also graded more harshly because although we were accurate in start and end time, we were off by a few hours in how quickly the heavy snow would begin. I was surprised by how quickly we went from light snow to heavy snow. This would be an A otherwise, but we lose a letter grade for failing to pinpoint how quickly things would get.
We were right on the money in saying the roads would be where the highest impact would be felt. We had snowfall rates of 1-2+ inches an hour, and we did correctly forecast that road conditions would begin to deteriorate by late morning and the worst being from 1-5pm on the roads. Great job here, which makes me even more annoyed that I missed the timing forecast for the onset of heavier snow.
We were right on this one too. It was a moderate event because it was a Sunday, but high impact on the roads. There were no significant wind or power outage issues here, and it was a quick mover. Good job.
Using the formula we did with the first event, we did alright. With a higher degree of difficulty came some misses that cost us significantly on the overall grade, but I don't view this forecast too poorly. It would have been worse if GP didn't convince me to drag that 4-8" zone across the shoreline! Thanks, GP!
Overall Grade: B
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