What does a historically cool June and early July mean for Winter 2009-2010

By:  Lionel Hutz
July 9, 2009 10:39 am | Category: Weather

As the north country endures another round of upper level low induced summer suckage you have to wonder exactly what that means for the upcoming winter.

First the answer is it has nothing to do with the upcoming winter. Any historical stat – espically with winter is just an expression of what happened in the past. As anybody knows – if you flip a coin 50 times and it lands on heads 50 times that doesn’t mean it will land on heads the 51st time. Now you say-well it should tell you that something is up with the coin and you can expect heads…and you might be right. Perhaps the coin is weighted funny. Perhaps you’re playing a cheater. Who knows. Well the same goes for the weather. Looking at historical data should only tell you that something is afoot. It should give you a guide for watching how things develop.

And so with that crap out of the way let me begin.

I noticed that the Artic Oscillation (AO) is extremely negative and has been so since early june.

AO observed and forecasted

In fact it’s been strongly negative. Since 1950 only seven other years have featured a june with such a strongly negative AO.
They were: 1951, 1957, 1958, 1982, 1987, 1997 and 1998.

So taking those years I figured lets look at what Mt. Mansfield shows as snowfall for the winter following those years.

1958


Total snow depth 1958

1959


Total snow depth 1959

1983


Total snow depth 1983

1988

Total snow depth 1988

1998



Total snow depth 1998

1999


Total snow depth 1999

Sadly examining this snow stake data is inconslusive. Early years showed a slightly below normal snow depth and the later years show a slightly above average snow depth. Clearly no conclusion can be drawn.

Perhaps we can draw some conclusions regarding what the weather might be based on comparing the years above with the AO in the corrseponding winters.

As you can see from the chart below, A negative AO generally leads to below average temperatures for the East and North east when the Negative AO occurs in J/F/M.

AO to US Surface Temp

So what did these years have for the AO? (Numbers are D, J, F, M)

51/52: -1.9, -.85, -.4, -1.9

57/58: .8, -1.4, -2.2, -2.5

58/59: -1.67, -2.013, 2.5, 1.4

82/83: .967, 1.359, -1.806, -.567

87/88: -.534, .265, -1.066, -.197

97/98: -.071, -2.081, -.183, -.254

98/99: 1.353, .110, .482, -1.492

Looking at these numbers again is not conclusive BUT they do show that 75% of the time these winters exhibted a negative AO which is a good thing for our temperatures.

With a building “west based” el nino, which leads to cooler east coast temps the best guess at this time is that the signs point to a cool winter. Wish I could say all signs point to constant bombed out coastal lows but that’s reality!

Related Stuff:

  1. Feb. 2010…analog discussion of what’s in store:
  2. Dang…it’s wet and cool this summer!
  3. Cool it Bro. Seasonal Cold Air to Return. UPDATED: Potential Major Winter Storm “Delta”
  4. Summer Series: July 30 to August 1
  5. Winter Outlook (2010-2011)
  6. Interesting Developments in Long Range Winter Forecasts

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