12/5/19 – Today’s Forecast and Storm Recap

Good morning! This is a two part post: the forecast for today and tomorrow, and a summary of the winter storm from earlier this week.

Today will be mostly sunny and 40, with a west wind of 5-10 mph. Tonight will be mostly clear and 19, with a northwest wind of 5-10 mph.

Tomorrow will be mostly cloudy and 32, with a chance of snow showers, and a light west wind. A coating to an inch of snow is possible if we get any snowfall out of this.

Speaking of snow, we are coming off the heels of what would be a major storm for any time of the year, but especially early December. This unusual two-part system recorded a total of 20.2″ snowfall in Dracut, with 12.3″ falling in the first part of the system (before midday Monday, but primarily Sunday evening) and 7.9″ in the second part of the system (after midday Monday, primarily Tuesday morning). Amounts ranged from 20-30″ in most of northern Massachusetts and southern New Hampshire, as well as much of southern Vermont; total snow was 12-20″ in southeast, central, and far southwest New Hampshire, parts of interior northeast Massachusetts (east of Methuen, as well as south of I-495), and south-central and southwest Massachusetts. The Greenfield, Mass. area saw a local minimum snowfall, with an area of amounts below 20″ surrounded largely by higher amounts. Most of the immediate Massachusetts coastline saw 6-12″, with 3-6″ and lower for coastal southeast Massachusetts.

Post Event Snow Analysis - 12-01 to 12-03-19.png

All this snow fell despite sleet cutting in at points during the storm. Sleet (and rain) resulted in a significant drop in snow amounts south of the Mass Pike and at the coastline. Further inland, brief sleet mixing in interior locales resulted in a minor decrease in amounts compared to the potential, but still well above my forecast from Saturday morning:
Slide6.jpg

The overall forecast from midday Monday (below), which was adjusted to include what had already fallen and what was forecast to occur, was closer, but still fell short in many spots because many locations – especially in western and central spots – vastly over-performed on the back-end of the system. 7-14″ was a hair too high in a handful of coastal locations, but woefully low almost everywhere else – particularly locations that did not see as much snow during the first part of the system. Of course, southwestern Massachusetts isn’t my main area of focus, but Springfield ended up with 18″ of snow, including 11″ in the second half of the system. The second half forecast is what killed the whole forecast; the forecast for the whole system from Saturday (above) is not an unreasonable representation of what actually fell during the first half in most locations.

Screen Shot 2019-12-02 at 12.24.48 PM (2).png

Screen Shot 2019-12-02 at 12.24.52 PM (2).png

This system was fairly unusual in its two-part nature; given precipitation stopped in most locations for a while, it could have been treated as two separate systems for forecasting purposes. I attempted to partially fulfill that by creating two maps, but as you can tell by the remaining snow map (which is for anything after noontime Monday), things went sideways. The eastern 4-10″ zone did reasonably, but the interior forecast was way too low in general.

With that in mind, these two-part systems don’t occur quite like this one too often; on to the next one!

Have a great day!
-Nathan

Published by Nathan Coram

Hello! I'm Nathan Coram, a 19 year old meteorology student and weather geek, and am going into my junior year at UMass Lowell as a meteorology major. I am the current Vice President of the UML American Meteorological Society Local Student Chapter. Prior to at UML, I attended the Dracut school system for my K-12 years, having graduated from Dracut High in 2018. I first got into weather with the December 2008 ice storm, which knocked out my electricity for 4 days. I had no idea how it could be raining and becoming ice immediately, and how rain can knock out power. (Now I do - warm layer aloft, cold air at surface). But I didn't really get into it until the heat of July 2010 and specifically a few severe weather events during that month, followed by the year 2011, which featured several high profile weather events. Since then I have had a growing interest, and am hoping to make it into the meteorology field, preferably with NOAA/NWS. But for now, I'm blogging here, helping with the UML Weather Center social media, and tweeting about the weather on my own account as well. Thanks for visiting!

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