Southern Connecticut Weather
  • Home
  • Forecaster Discussion
  • SCW Social Media Hub
  • SCW Facebook
  • About Us/Contact Us

Grading the December 16/17 Winter Storm Forecast

12/19/2020

Comments

 
Good evening from Southern Connecticut Weather. 

What a week! After a minor appetizer at the start, the major winter storm that we had been seemingly tracking forever impacted our state on Wednesday and Thursday. For many, it was the largest snowfall since March 2018. Now that the storm has passed and we have had time to breathe, it's time to post our grade. 
Picture
Our verification map using NWS spotter reports. Note that the locations are approximate. 

As you know, we grade ourselves to get better and hold ourselves accountable. For this storm, we are using the following criteria from our final forecast: snowfall accumulation, timing, wind, power outages, and overall impact.

​
For this storm (and perhaps moving forward) I decided to weigh the snowfall accumulation twice as much as the other elements. I think this may be a bit more fair given this is what the general public cares about the most. Let's dive in. 

Snowfall Accumulation

As the map above shows, we decided to go pretty big with out snow accumulation forecast. We upped our numbers from our original forecast of 8-16" and with the benefit of hindsight, that didn't work out. That said, it wasn't a surprise that some areas inland received less snow, as we communicated that the banding nature of the storm could bring some variation in snow totals. We did particularly well with our SE zone forecast, and did ok with our inland forecast with a number of towns ending up at the 12" mark.

However, there was a bit too much variation with dry slotting and a real surprise to us with far SW CT doing poorly relative to the rest of the state due to the combination of dry slotting and mixing with sleet. I'm a little disappointed personally since it was my call to take the numbers up, but it wasn't a disaster. 

Grade: B-

​Timing
We did well here. We expected snow to break out late afternoon and early evening and that's what happened. SA noted that heavy snow would would cross the state in the evening hours and that was right with the first big band that rolled through the state shortly after our call for snow for everyone after 8-9pm. We were right on the snow banding after midnight, and the burst of moderate to heavy snow early Thursday. Great job here. 

Grade: A

Wind
Despite some of the guidance trying to bring blizzard conditions and high winds, we were confident that we would not verify blizzard conditions and wind would be relative pedestrian. We thought 35-45 mph would be the max gust along the shoreline and both Bridgeport and Groton gusted to 47 mph. To be within 2 mph is an excellent call.  

Grade: A 

Power Outages 
Not much to say here. We didn't expect widespread power outages due to the snow being lighter (it was in most places but not everywhere which I'll get to below) and there being less wind. There were no major power issues from what I saw. 

Grade: A 

Overall Impact

We did end up seeing a major winter storm. This was a high impact event despite the timing. Most places saw double digit snowfalls, as we expected, and conditions were hazardous Wednesday night and Thursday morning, as expected.

However, we need to deduct points for the under forecast of mixing. We were fine in northern CT and much of inland CT, but more areas along the shoreline mixed than expected, which caused heavier wetter snow to fall. For anyone that expected to shovel powder but ended up shoveling concrete, that's a meaningful forecast miss. 

Grade: B+

Overall Grade
Overall, we did very well. The snowfall forecast was off for too many in SW CT, but it wasn't a bad forecast. We were spot on for many of the other elements, and while we under forecast the mixing in coastal CT, it could have been a lot worse. Factoring all the elements in and weighing the snow accumulation forecast 2x, we did well. That's important, because reputations are build on the high impact forecasts. 

Final Grade: B+
Picture
Above, the final result. Snow across New England as a result of our major storm.

​A​s always, please like, share, and interact with us on our social media--on 
Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for trusting SCW. 
​
-DB​  
Follow @SouthernCTWX
Comments

    Archives

    July 2022
    June 2022
    May 2022
    April 2022
    March 2022
    February 2022
    January 2022
    December 2021
    November 2021
    October 2021
    September 2021
    August 2021
    July 2021
    June 2021
    May 2021
    April 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014

    Categories

    All
    Tropical Weather
    Winter Forecast

    Authors

    Southern Connecticut Weather is brought to you by Timothy Wrightington Jr. (TW), Spencer Aronstein(SA), Greg Petridis (GP), and Don Bell (DB).

Picture
Copyright Southern Connecticut Weather 2018, all rights reserved. 
For website related inquiries, email us at support@southernconnecticutweather.com

Privacy Policy/Terms of Service