Tuesday, September 22, 2015

Last Days of Summer and Legendary Winters?

"Everyone talks about the weather, but nobody does anything about it!"

You have probably heard that quote before, and suspect it comes from one of our more irreverent figures in history (such as Samuel Clemens or Benjamin Franklin). Alert historians out there know that in the spirit of Paul Harvey, we should share the "rest of the story" in these footnotes: (photo credit: PBS.org)

  • The quote, often attributed to Mr. Samuel Clemens (aka Mark Twain), was actually a statement by his co-author and writing partner Charles Dudley Warner. Thus, as the tattered pages of history sometimes become, this little line over the years morphed into a Twainism. Here's source material you can check, and you don't even have to wait 5 minutes for it either ;-).  
Sloane, Eric. (2013) Weather Almanac, pp. 195. Dover Publications 
  • In honor of Mr. Clemens and his borrowed quote, we ARE doing something about the weather! We track and assess summer-into-fall climate indicators and compare past data to previous winter outcomes in order to explore early clues on how the upcoming season may kick off. We also scale the potential severity against standard probabilities of outcome or another, and let the climate "look fors" guide whether we reinforce or dissuade a seasonal hypothesis. Ready for all that? Here it comes:
The Foot's Forecast pre-winter question for 2015-16:

In years during which a weak-to-strong El Nino was in place from summer into fall, and significantly above normal temperatures were observed in the week just prior to the Autumn Equinox, did the following winter experience higher-than-normal snowfall and frequent periods of storminess?

SYNOPSIS OF OUR FINDINGS (as of 9/22/2015)
  • Fall 2015 should be marked by extended periods of above-normal temperatures, which in turn could delay the arrival of wintry conditions in the eastern U.S. We expect the bulk of significant winter weather to occur primarily in January and February. (see NOAA 3-month temperature outlook)
  • If December presents notably above normal temperatures for several weeks, this may not only exacerbate the usual snow and cold for Jan-Feb, but may delay the Spring recovery, extending below-normal temperatures well into March and April. This would be similar to the pattern of unusual cold observed in the eastern U.S in March 2013 and 2014.
  • Climate indicators underpinning this report include a resurgent El Nino, the North Pacific's "blob" of above normal sea surface waters, a quiet Atlantic hurricane season, a higher than normal meltoff of Arctic sea ice (compared to recent years) and interestingly, a currently larger extent of Canadian and Siberian snow cover than recent years. (See 2011 NOAA Climate Test Bed Paper on Eurasian Snow Cover Variability)

ORIGIN OF THE SEASONAL "LOOK FORS" IDEA: This question actually harkens back to my early days teaching science at Dundalk HIgh School in Baltimore County. This was in the bad old days when air conditioning was found only in the library or the office. Upon coming to the school in 2001, I was able to strategically select my classroom such that it was right across the hall from the library. By keeping my door and a few select west facing windows open - on days the library door was also open, we could harness the fine art of fluid dynamics and create a channel of cool air flow into the classroom. Thus, even on the warmest days in June or September, the room temperature could be maintained around 78 F -- in stark contrast to the 90 F+ conditions of the second floor blast furnace rooms.
(And all these years, you thought students flocked to my classes for the insightful and uncanny forecasts.;-)    *Photo credit of Dundalk High School : Patch.com
THE CONNECTION TO WINTER? In the fall of 2002, pre-dating this website, my Earth Science students and I were working our way through the weather & climate unit. Exploration of El Nino's impacts was one of the components. It just so happened that year featured resurgent warming in the equatorial Pacific, and led to the first moderate El Nino episode since the early 1990s. Early fall was particularly warm, as October 2002 in Maryland launched with several days in in the 80s, continuing a trend of above normal temperatures in the mid and late weeks of September that year.
The fluid dynamics trick (aka sapping library air) to keep the classroom cool was having technical issues (librarians were keeping the doors closed) and students were lamenting the prolonged heat. To distract us all away from the warm conditions, students and l surmised a wild hypothesis that perhaps El Nino was a factor. If so, could this also have an impact on snow days? To keep the gravy train going, I would occasionally pepper the lesson with tales of how my high school weather club nailed a big storm in January 1987 -- also during a Nino period. As you can imagine, the students were totally thrilled.
But the skiers and snowboarders in class were particulary concerned... with the weather so warm so late, how would that affect the opening of ski season? In fact, by early December of 2002-- a Foot brothers ski trip had to be canceled for lack of snow -- in Vermont! Was El Nino going to dash all our hopes for having a reasonably snowy winter in the mid-Atlantic? Those who recall what happened in winter 2002-03 know the rest of that story. (Photo credit: New York Times, snowless ski slopes at Mount Snow in southern Vermont, December 2002)
The real question is...a legendary winter or not?

For new readers to this website since 2010, the format of this post may be unfamiliar, as it has been written in our narrative format that mixes data analysis with a human interest element. If you're a long time reader from the pre-blizzard days, this post is a signal that until we reach significant winter weather events, we will bring back these popular approaches to weather stories. It may even feel like the "good old days are here again" at FF. (LeftDundalk High School, Baltimore County MD is snowed shut at the height of the February 2003 blizzard
1) El Nino is on track to equal or exceed the strongest event since records began in 1950. While Powderhounds might just simply leap with estatic joy at that pronouncement, we must temper with caution. The 1997-98 event topped at 2.3 degrees C above normal, and BWI airport saw a measly 4.8" of snow the following winter. Guess what friends and fellow teachers? Sea surface temperature anomalies from the equatorial Pacific are ALREADY 2.3 degrees C above normal at present for the universally-accepted region 3.4 where Nino temps are measured. Compared to Region 3.4 data from September 2009, this is nearly 300% stronger. 
2) Analysis of high temperatures in 8 select years since 1957 at BWI airport during mid- and late September revealed interesting clues. In all the years where Sept. temps went at least 5 degrees above normal in the week leading up to the Fall Equinox -- and in some years, when an El Nino was already developing -- the following winter produced a range of significant to historic snowstorms in the Mid-Atlantic. Part 2 will present our data more specifically, but the analog years reviewed were 1957, 1977, 1984, 1993, 1997, 2002, 2009 and 2012 among others. 
3) Siberian snow cover in September-October (and amount of summer meltoff of Arctic Sea Ice) are two of the most important early indicators of how winter might kick off in North America. If you're a new teacher or high school senior gaming for lots of snow days, the only piece of encouraging data so far is that as of September 20, 2015 Siberian snow cover (shown left) is already at a greater extent than was observed on 9/20/2009 (shown below) preceding the epic Mid-Atlantic snow show of 2009-2010.

Awesome. So all that means...what exactly?

  • FROM SEPTEMBER INTO OCTOBER: Arctic Circle "look fors" will make or break the winter forecast. As October rolls along, if snow cover in Canada, Alaska and Siberia has a hard time building up, the already strong El Nino combined with a potentially warm Fall suggests winter weather would have a late start in the Mid-Atlantic. A larger and earlier snow cover extent allows for a reservoir of cold air to develop over extreme northern latitudes, an initial ingredient necessary for a big winter kickoff.  
  • NOVEMBER INTO DECEMBER: If you have specific fall or early winter plans that rely on cooperative weather, El Nino may present a rainfall wild card. Given that much more moisture than normal tends to evaporate from the Pacific in Nino-influenced patterns, when the current warm/dry pattern flips, we expect a long duration period of frequent heavy rains to drench the Mid-Atlantic starting the late Fall. The advantage is that a cold dreary rain in November along I-95 can mean snow cover build up in the favored areas of southern Canada to the Great Lakes.

Take-away messages from Part 1:
  • For educators, administrators and students, don't bank on December delivering enough fluff to grant you a day off. Past El Nino data suggests a less than snowy last month of the year for the Mid-Atlantic south of the Mason-Dixon line.
  • For homeowners and property managers, this Fall should present many opportunities to wrap-up a final outdoor improvement. The only risk of interruption would be from fast-moving, but not prolonged periods of rain.
  • For Emergency Management and Public Safety officials, indications are above normal temps this Fall should translate into time to prep for mitigating winter weather once it does hit. 
  • For retailers, shippers and contractors, an extended Fall could have a range of impacts, from slow-to-start holiday shopping but countered by having more time to engage customers on capital exterior improvements. 
We hope you enjoyed the kick-off Part 1 of our Pre-Winter Assessment, and warm wishes for bright skies as we close out the last days of summer. To be in the know before the snow, you can register in our Powderhound email update service with a simple message to winter@footsforecast.org. A printer-friendly PDF version of this report will be issued on or before October 1 to all new and current Powderhounds in the email list. 

-Forecaster Foot and the Long Range Team, including Forecasters Connor Meehan, Jason Mitchell and Troy Arcamano.


Patricia said...

I think this means it might be a feast or famine winter. We will not know until late October which way it is trending .

Carrie said...

So glad to see you all are back! Hoping for a repeat of those legendary winters but we'll just have to wait and see. Right now, I'm looking forward to a beautiful fall!