While working on my winter outlook, I checked on some data from last years various snowfalls. For some reason, I wondered how this heavy snow event compared to others as far as the heaviest snow in an hour and other short specific durations.
In general-
Heavy snow is an inch an hour or more, moderate snow is about a half inch an hour
One unique fact is that the biggest snows on record (Jan 1996, Dec 09, March 93) often give the best depth, but its the duration that wins, not ONE heavy hour. Visibilities associated with these would be Heavy snow--less than a quarter mile, moderate snow-- about a half mile.
My search of the data is limited by the resources online and more importantly, the lack of ALL the hours of data pre 2000--
I'd bet that I am accurate 20 years, likely accurate 30 years and at that point the data is missing WAY to much.
The snow from Jan 30th was about 2 inches an hour between 7 and 8 am, with about 3.3 inches falling between 7 and 9 am.
The heaviest snow of the past 20 years comes down to 2 dates--
1. March 2, 2009. The storm that broke the 13 year double digit snow drought also had ONE of the heaviest snowfalls in the past 20 years. Between 12 am and 2 about 5.1 inches of snow fell. This was part two in a two part system. Part one pass through the area Sunday afternoon. Places Lynchburg south and east had about 2-3 inches of heavy wet snow. As the upper piece of energy passed through, the temps dropped at every level of the atmosphere and the snow bands set up over town for 2 hours. This was a powdery snow--so the liquid equivalent was .27 and the snow ratio was about 19-1. (Inch of liquid would make 19 inches of snow) The heaviest snow fell between 12-1 am with about 2.6 inches falling with a two hour total of 5.1 inches.
2. January 25, 2000- This storm is called the Carolina Crusher as a largely unforecasted and then under forecasted storm developed which brought locally 8-12 inches of snow with upwards of 20 inches in the
Raleigh, NC region.
Local forecasters struggled with a 1-2 inch call issued at 8 PM, upgrade to 2-4 inches at 10 PM and then 6-12 well after the onslaught of snow was on. There was a tremendous amount of dry air to the northwest of this storm, so it only snowed when the heaviest of snows hit the area. From 8 PM on, there was snow in the clouds evaporating as it fell. Snow first trickled out of the clouds around 3 am and it meant business. Between 3:45 and 4 AM a half inch of snow fell. The next two hours 4.7 inches of snow fell-- with 2.6 inches falling between 4 and 5 am.
(On a side note-- My old roomates, Mike, Chris and Jeremy can testify that I was all over this storm, promising them at least 6 inches of snow that night---one look at radar at 2 pm with the classic negative tilt radar presentation sealed the deal for me. I was right, but not by much. 10 miles west of Lynchburg had nothing more than flurries.)
Special mention-
Jan 22 87 had 5 inches fall in 3 hours.
Most other events max out between 1 and 1.5 inches an hour.
Which event had the heaviest---over two hours the March 1-2 09 event does take the cake. However, this was a powdery snow. The Jan 25, 2000 event ended up "officially" as .78 liquid for 7.5 inches of snow. I measure 8.5 inches at my house--which was 4 miles north of the airport. (Not even sure who measured that one)
It is this bloggers opinion that the Jan 25, 2000 storm had the heaviest snow on record for one hour. The fluff from the 09 event was impressive but when you compare 2.6 inches of fluffy snow to 2.6 inches of good ole concrete snow, the concrete wins. However, the 2 hour total of March 1-2 2009 has the 2 hour total lead.
