There's Something About May

Posted May 17th, 2009 by Jill Reale. 24 comments

 

The National Weather Service visited Georgetown in Madison County today and after surveying the damage, they have concluded that an EF 2 tornado touched down. This date quickly popped into my head since last year, one year to be exact, an EF 0 tornado touched down in Camden. Is this coincidence or is there a reason behind tornadoes in May? I began to research weather in May from 1996 to present and I quickly found out that tornadoes are not unusual for the month of May in NY. Here is a list of Tornado watches/warnings that have been issued since 1996.

May 31st, 1998
Tornado Outbreak South of Rt 20: 8 Tornadoes F0-F3
May 13th, 2000
Multiple Tornado Warnings
May 11th, 2003
Tornado Watch
May 22-24th, 2004
Numerous Tornado Watches/Warnings, Funnel Clouds
May 17th, 2008
EF 0 Tornado in Camden

Even more interesting information about May storms was found in Matt Lanza's Blog entry from May 2007:
Tornadoes
Like we said, the definition is that of a violently rotating column of air that extends from the base of a thunderstorm to the ground. Tornadoes can have wind speeds ranging from 70-80 mph all the way up to 300 mph or more. Strong tornadoes usually destroy most things in their path.
Strong tornadoes, as you saw in the previous entry, are rare in CNY. But we have had instances of strong tornadoes (particularly in 1998) impacting us. We'll go into those cases later.
Tornado Watch vs. Tornado Warning
Again, one of the most confusing aspects people have with severe weather is watch vs. warning.
A Tornado Watch is issued when atmospheric conditions are favorable for the development of severe thunderstorms...some of which could produce tornadoes. A watch means that conditions are favorable....it does not mean that a tornado is coming. A watch means...do just that. Watch. Don't cancel any plans, but be aware of what's going on, and check back in to wktv.co, the Weather Blog, or NEWSChannel 2 throughout the day for updates if you hear that a watch has been issued. Also, be very aware of where you are. Know your county, know your town and know any counties or towns near yours. Geography is one of the most important things you should know, so now is a good time to brush up on things.
A Tornado Warning is issued when either a.) A doppler radar has detected a potentially developing tornado or b.) A storm chaser, spotter or local authorities reported a developing or active tornado actually on the ground. Tornado Warnings are issued by county. Again, with polygon warnings being experimented with, warnings will become much more specific...so if a tornado threatens, say, Boonville and not Utica, the warning will represent that. A Tornado Warning means that your county or area is in danger of being struck by a tornado. It means you need to take action immediately.
What to do if a Tornado Warning is Issued in Your Area
I've taken this directly from the National Weather Service...this is a general overview of what you should do, depending on what scenario you are in:
The key is to remain calm but take immediate action. If you are at home or in a small building go to the basement or to an interior room on the lowest floor. Closets bathrooms and other interior rooms offer the best protection. Get under something sturdy or cover yourself with a mattress.
If you are in a school, hospital or shopping center go to a pre-designated shelter area. Stay away from large open areas and windows. Do not go outside to your car. If you are in a high-rise building, go to an interior small room or hallway on the lowers floor possible. Do not use the elevator, use the stairs instead.
For the best protection, get under something sturdy or drop to your knees facing an interior wall. Lean forward with your hands shielding your head.
Get out of mobile homes or vehicles. They are easily tossed about by strong winds in the tornado. Take shelter in a substantial structure. If there is no shelter nearby, lie flat in a ditch or low spot with your hands shielding your head. Never stay inside the mobile home or vehicle.
The tornado intensity scale is known as the Fujita Scale, which rates tornadoes on a scale of F-0 to F-5, with F-0 being the weakest and F-5 being the strongest. This year, the NWS made changes to the Fujita Scale to show a more realistic depiction of damage. This is known as the Enhanced Fujita Scale.
The biggest changes occurred from F2/EF2 on up. These changes were meant to show a more realistic depiction of actual tornado winds and a better description of damage, using new and updated research on construction and tornadoes.
2003 Storms
A couple of severe events occurred in the region. July 21 saw some significant weather and a mini-tornado outbreak in Eastern New York. An event just missed us to the south in May.
2002 Tornadoes
May 31, 2002 was a busy day. Several reports of tornadoes occurred throughout CNY. More details can be found from NWS Albany. Even more details from NWS Binghamton.
This scenario produced an F0 in Hartwick, Otsego County and an F1 in Johnstown, Fulton County.
May 31, 1998 Tornado Outbreak
The benchmark of tornado outbreaks in CNY. Notice that May 31 seems to come up a lot? New York State averages 6 tornadoes per year. This outbreak spawned 6 separate tornadoes in one day. Details from the NWS Binghamton here. This outbreak dropped an F3 in Milford and an F2 just southwest of the Town of Maryland. Click here for damage info from Otsego County. This same outbreak also caused several tornadoes near Albany, including an F3 which devastated the community of Mechanicville. Click here for the NWS Albany info on this event.
This ranks as one of the worst in New York history. Wikipedia also has an article, which can be found here. This was part of a wide ranging event which brought an F4 tornado to Spencer, SD, essentially wiping the town off the map.
Boonville Tornado May 2, 1983
We just celebrated the 25th Anniversary of the Boonville Tornado last year. Detailed information can be found here on this historic event across the North Country.
Matt actually was involved in some research last year on the specific dates of May 30-31st. Since 1950, the NCDC has reported 363 total tornadic events in New York State.
Of those 363, 32 have occurred within 3 days of May 31 (May 28-June 3). That's 8.8% of all NY tornadoes.
Of those 32, 24 occurred on either May 30 or 31. That 6.6% of all NY tornadoes.
More interestingly... Since 1995, NYS has had 113 tornadic events. Of those, 25 have occurred within 3 days of May 31. That's 22% of all tornadic events in the last 12 years.
If you think that is impressive, take a look at PA: Since 1950, the NCDC has reported 709 tornadic events across PA.
Of those, 108 have occurred within 3 days of May 31. That's 15.2% of all tornadic events in PA!
Of those 108, 65 have occurred on May 30 or 31 (including 41 in 1985 and 21 in 1998). That's 9.2% of all tornadoes in PA. Think about that... 0.5% of the entire calendar year, and nearly 10% of all tornadoes occurs on it.
Even more interesting.
Since 1995, 51 tornadic events have occurred on 3 days either side of May 31st. That's 23.0% of all tornadic events.
Since 1985, 93 tornadic events have occurred on 3 days either side of May 31st. That's 22.8% of all tornadic events.
Of the 57 years of NCDC data, 10.5% have reported at least one tornado on May 30 or 31st in PA.

 Another link listing Tornado Activity divided by County for NY
New York averages 7 tornadoes a year and the peak is between June-August, so what is the deal with May?
On average, May has the most tornadoes across the United States. May is a transition month, a month of changes, where we go from cool weather (like today) to warm weather very quickly due to frontal systems and different boundaries of air. You need very strong thunderstorms to develop (preferably supercells). These usually occur along a cold front, where warm air out ahead of a storm system clashes with the cold air behind. During a strong storm, a downdraft (pocket of air) may develop, where air quickly pushes downward from a storm, dragging down cool air from aloft, which converges with the warm air aloft (warm air is less dense than cold air, so it rises). This motion can cause rotation within the cell and a funnel cloud can form.

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Comments

  1. Laura (Paris Hill):

    Jill, thanks for the good info! I was in Syracuse all weekend and the storms were not that impressive. Chilly morning with a low of 34 degrees.

    Posted May 18th at 8:26 AM

  2. Tony - CNYWeather.com (Westmo):

    Great Info!

    Kinda odd having a Tornado of that strength around here. Any stats on when the last one was?

    Posted May 18th at 10:57 AM

  3. Working in Utica:

    I was at Yankee Stadium on Saturday. My wife and baby stayed home. We had great weather in the Bronx. On the way home, we drove through some very heavy rain. When I got back to the valley, I couldn’t believe that we actually had tornado warnings! My poor wife had a rough day on Saturday. She said she watched the weather blog all day on Saturday to keep an eye on things. She said you guys did a great job. Thanks, WKTV crew. Appreciate it!

    Posted May 18th at 11:02 AM

  4. Jill Reale (Utica):

    We will be near record cold tonight. Our record low for the 19th is 31 degrees so it is in jeopardy

    Posted May 18th at 6:23 PM

  5. Michael- (Dolgeville):

    37.9 degrees here. I’m still in disbelief that an EF2 Tornado did indeed touchdown in Georgetown. Just amazing! I would have never in a million years guessed it was that strong. Looking at radar, the Tioga county storm had much stronger rotation than the Madison county storm, yet that tornado was only an EF-0.

    Posted May 18th at 11:53 PM

  6. Michael- (Dolgeville):

    How many Tornados have been confirmed from Saturday’s storms? SPC has 4 Tornado reports all in NY State. I am assuming it was 3 Tornados on the ground, but the Tioga county storm had two reports with it which is the reason for 4. Summer hasn’t even begun yet! looks like it could be another activer severe wx season for us.

    Posted May 19th at 12:02 AM

  7. Matt (Cold Brook):

    Yesterday was definately not a stelar day.Took till 7 for the clouds to break up.It is 29 degrees here this AM and heavy spotty frost.May 19th and I have to scrape a windsheild.

    Posted May 19th at 5:13 AM

  8. John (Ohio):

    31 here this morning

    Posted May 19th at 6:51 AM

  9. Bill Kardas:

    Widespread frost reported across the region. Most spots fell below 32 degrees. Our unofficial overnight low (we’ll get the official numbers in one hour) was 30 degrees. The record low for the date was 31 set back in 1932.

    Posted May 19th at 7:24 AM

  10. John (Ohio):

    WKTV team – thinking back to how the snow stopped around Feb 1, like someone flipped a switch compared to Dec/Jan, what was the driver of this change to lack of snow past early Feb?

    Posted May 19th at 8:15 AM

  11. MG(Point Rock):

    26.5 degrees here this morning. Not so good for the blossoms on my apple trees. John — up here it seemed like the switch flipped on March 1 — we had plenty of snow in February (most of it lake-effect).

    Posted May 19th at 8:20 AM

  12. John (Ohio):

    Only used the snowthrower once in Feb, and that was marginal. Lake effect never made it into Central Herkimer county except for one brief event, after Feb 1. Both the storm tracks and the lake effect ended. Strange.

    Posted May 19th at 8:25 AM

  13. Bob (Cooperstown) :

    Low last night was 29.0 here

    Posted May 19th at 8:53 AM

  14. Bill Kardas:

    John,

    I think the reason we saw such a major change had to do with the shift of the jet stream in February. In December and January, we had a very favorable pattern for lake effect snow (it was the season, but our weather patterns were good for it too). NAO was slightly negative but PNA was very positive. That’s a good pattern for cold spells in the Northeast (as we saw in the middle of January). The pattern ‘flipped’ around in February fairly abruptly…NAO turned slightly positive and PNA slightly negative. I’m not an expert at climatiology prediction, but knowing those patterns changed I believe is why the weather changed so abruptly too.

    Posted May 19th at 10:39 AM

  15. Bill Kardas:

    Also, keep in mind that the lake effect season naturally changes in late January and February. The lakes are cold, and the difference between the airmass and water temperature becomes marginal. Even when bands do form when the airmass is cold, the bands have a very difficult time moving inland. The higher sun angle also shreds the bands apart during the day. Recalling how cold January was, it’s not surprising that the lake effect season wasn’t exciting after that.

    Posted May 19th at 10:43 AM

  16. John (Ohio):

    Thanks for the explanation Bill!

    Posted May 19th at 10:50 AM

  17. Mel (Westernville):

    Yeah had 41” here in Feb. Season total ended up at 205.3”. 32 degrees this morning. Hope thats the last night for the wood stove.

    Posted May 19th at 11:37 AM

  18. MG(Point Rock):

    I looked back over my Feb records, and I had 54.5 for the month, but a lot of that (24.5) fell on one day (the 20th) in a persistent lake effect band. Season total was 245,5.

    Posted May 19th at 12:15 PM

  19. Adam Musyt:

    Record low this morning at Griffiss. The temperature early today was 30 degrees. The old record was 31, set in 1932.

    Posted May 19th at 5:31 PM

  20. Jeff H (Sherburne Hills):

    down to a low of 22 degrees with a heavy frost this morning.

    Posted May 19th at 5:52 PM

  21. Kenny (South utica):

    Kind of odd out this evening….very brezzy but none of the weather stations are reporting any sort of wind what so ever….breeze even blew some stuff around in my apt with the windows open.

    Posted May 21st at 1:03 AM

  22. Working in Utica:

    Any plans of setting up a Memorial Day Weekend Outlook entry? Thanks, WKTV. You guys rock!!

    Posted May 21st at 8:07 AM

  23. Adam Musyt:

    Ask and ye shall receive, Working :-)

    New entry posted.

    Posted May 21st at 10:32 PM

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    Posted June 18th at 3:41 AM

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