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March 2, 2010

Three big snowstorms all ranked in Top 10

The National Weather Service's Sterling, Va. forecast office has disowned the list of Top 20 Snowstorms for Baltimore that was posted on its Web site for many years. In the wake of the Feb. 5-6 storm, concerns were raised about the scientific legitimacy of the criteria long used for inclusion on the list.

Jim Lee, meteorologist-in-charge at Sterling, told me that one of the problems is that the list does not discriminate among 1-day, 2-day and 3-day storms, not to mention those that seemed to rage on even longer. The No. 1 ranked snowstorm, before the list disappeared from the Sterling site, dropped snow on Baltimore over four days, from Feb. 15 to Feb. 18, 2003.

But Lee told me a few weeks back that, meteorologically speaking, no snowfall that lasts four days can be considered the consequence of a single storm. And in truth, that 2003 event really was a combination of at least two storms, with some time during those four days when no snow was falling. (The Baltimore Top 20 snowstorm list includes two others, in 1899 and 1892, that stretched over four days.)Feb. 10, 2010 snow in Baltimore

So, because climatologists only accept data on 1-, 2- or 3-day storms, the Sterling office will be reassessing its Top 20 list. What we'll probably get will be several lists, broken down by the length of the storm, and ignoring the snow that fell on the fourth day of three former Top-20 storms.

The Sterling office will also be reassessing storms that may have been measured at BWI-Marshall with hourly measurements - in accordance with FAA standards - rather than with the six-hour measurements required by NOAA for climatological purposes. That could reduce official storm totals for BWI going back as far as 1998, when the FAA took over the job of measuring snowfall at the airport from the weather service. There are six Top 20 storms since 1998 at BWI that could be affected.

I'm not sure how all this will come out in the wash. It seems likely that, if the FAA's contractors really have used hourly measurements since 1998, that all our snowstorms since then will get smaller. When the problem was discovered last month, Lee rejected the 28.8-inch total the FAA contractor reported for the Feb. 5-6 storm based on its hourly measurements. He replaced it with the more conservative 24.8-inch measurement the contractor reported as the storm's "snow depth" - the total measured when the snow stopped falling (and after the snow's weight had compacted it). 

On the former issue - revisiting the entire storm record at BWI and Washington and ranking snowfalls in separate categories according to the number of days the snow fell - I suppose they have to abide by the rules set by climatologists.

But, on the latter, it seems to me that those of us who are not climatologists experience snowstorms as discreet events based on how much we have to shovel once the flakes stop falling. I would argue that the February 2003 "storm" - while it may have been two storms - felt like one really long siege to those of us left to dig out from 28 inches of snow.

So, in the interests of continuity ... or nostalgia, or something less than scientific ... here is the old NWS Top 20 Snowstorms list for Baltimore, using the old (now officially discredited) criteria, and updated to include the three big storms from December 2009 and February 2010. Clip and save. You may never see it again after the NWS issues its revised lists.

Some observations: February, while it is not the snowiest month on average at BWI, has seen nine of these Top 20 storms, as many as January and March combined. December has seen just two. But what's most astonishing to me, personally, is that, while the record goes back to the 1880s, my family and I have witnessed 10 of these 20 storms since we moved to Baltimore only 30 years ago. How about you? There should be only three or four that no one living today can recall.

1. Feb. 15-18, 2003:  28.2 inchesClearing the roof of snow

2. Jan. 27-29, 1922:  26.5 inches

3. Feb. 5-6, 2010:  24.8 inches*

4. Feb. 11, 1983:  22.8 inches

5. Jan. 7-8, 1996:  22.5 inches

6. Mar. 29-30, 1942:  22.0 inches

7. Feb. 11-14, 1899:  21.4 inches

8. Dec. 18-19, 2009:  21.1 inches

9. Feb. 18-19, 1979:  20.0 inches

10. Feb. 9-10, 2010:  19.5 inches

11. Mar. 15-18, 1892:  16.0 inches

12. Feb. 15, 1958:  15.5 inches

13. Jan. 25, 2000:  14.9 inches

14. Dec. 11-12, 1960:  14.1 inches

15. Feb. 11-12, 2006:  13.1 inches

16. Mar. 5-7, 1962:  13.0 inches

17: Jan. 22, 1987:  12.3 inches

18. Jan. 30-31, 1966:  12.1 inches

19. Feb. 16-18, 1900:  12.0 inches

20. Mar. 13-14, 1993:  11.9 inches  

* Snow depth measurement. The "true" depth, had it been measured every 6 hours, likely would have been more.

(TOP: AP Photo/Rob Carr; BOTTOM: Sun Photo/Gene Sweeney, Jr.)

Posted by Frank Roylance at 10:29 AM | | Comments (9)
Categories: By the numbers
        

Comments

Your December line item (#8) should be 2009, not 2010. Unless, of course, you feel that confident about a forecast for 9 months from now.

FR: Nice catch. Fixed. Thanks!

February's average snowfall being lower than January's is an artifact of the different number of days in the month. If you correct the February average for the 28.25 days in the average February, the 2 months are equal to the nearest 0.1", although February is a hair higher.

FR: Makes sense to me. Thanks.

I remember after several brutal Februaries in the late 70s, that's when they implemented "energy conservation" week off for schools in mid-late February. Of course, I don't think it ever snowed again during that week. The best laid plans ....

I've been around for all the ones after '57, but only remember those from the mid-60s on. I've worked and driven through all the ones since about '78. The '83 one was most wicked to have to drive in, with white-out conditions during the day and rampant thundersnow and lightning. These past few this year, fortunately occuring mostly on the weekends (or when my employer closed for the last one), I didn't have to drive through.

Official totals are somewhat irritating. While recent storms in Owings Mills are "officially" higher totals than I measured in the back yard, the one in '96, when I lived in Reisterstown, had a reported snowfall of 31", and I believe it. I was fighting my way through snow to my waist, and few 4-wheel drive vehicles could move through the snow.

Crazy stuff. Can we get a break now for a few years? Can you use your pull to arrange that, Frank?

FR: Done.

I've lived here for only 15 years and have experienced seven of these. Three of the top five and five of the top 10. Wow!

LJ Kirk has a good point about how these storms are experienced differently, too. Even this winter, with just over 5 inches difference between the largest (though that is an undercount) and the smallest, that first February snow felt like it was way, way worse than the other two, to me. The wet weight of that snow made it much nastier to deal with. (And then there was the shock of going into my back yard between 6:30-7:00 a.m. to clear snow off some things I didn't want to bear weight and sinking up to mid-thigh, with several hours of snow still to come.)

frank--
i've been in 15 of the 20. so guess how old i am?

most memorable? i suppose #4. i was just promoted to locomotive engineer for conrail, working an orangeville yard job in baltimore, and i developed pneumonia.

but i disagree with the totals and the rankings. i remember #1, and it was big, lumbering sissy compared to #3.

FR: Well, I suspect the NWS will demote No. 1 once they lop off one or two of the four days. And assuming you have lived here all your life, my guess would be that you are between 52 and 66 years of age, born sometime between the Palm Sunday Storm in 1942, and the big storm in February 1958.

8 of the 20 storms have ocurred in the last 20 years. More evidence that climate change is causing extreme weather events--even blizzards.

The first one i remember is the '83. My brother refused to walk outside because he couldn't see over the snow. Rather wise for someone not yet 2, if you think about it.

I was around for 15 of them, too. 1958 was memorable because school was closed for a whole week. And in 1966, several friends were snowbound at our house over a long weekend.

Of course, when I was growing up, the storm everybody talked about was the Palm Sunday snow of 1942.

In the year 2003 I would like to know if there is on record of 2 snowfalls in the month of march that year ? Thanks.

FR: The snowfall for March 2003 in Baltimore was 2.6 inches, all of it on March 30. It set a record for the date.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff
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