The Winter Solstice is now 52 days away and it is time to release my Washington Area 2019-2020 Winter forecast. Sea Surface Temperature (SST) anomalies currently depict neutral El Nino Southern Oscillation (ENSO) conditions across the Equatorial Pacific indicative of neither dominant El Nino (warmer) or La Nina (cooler) conditions.
Current SSTs (image below courtesy NOAA): My winter forecast featuring temperature and precipitation trends is based solely on historical analog years where SSTs match up with current conditions.
The historic analog years (1978, 2003, 2004, 2013 and 2014) in the image below match-up “fairly” well to the current SSTs in the image above; this is not a perfect science and part of that problem is that we do not have a complete picture of oceanic SST data.
The majority of the forecast models (in the graph below) predict that ENSO conditions will remain neutral with several outliers depicting a potential resurgence of weak El Nino conditions developing in December.
Temperature anomalies (departure from average) may run about 1.5 to 2 degrees below-normal during the upcoming Meteorological Winter (December 1, 2019 through February 28, 2020) across the Washington D.C. Region.
Precipitation anomalies may run near to slightly above normal during the upcoming Meteorological Winter (December 1, 2019 through February 28, 2020) across the Washington D.C. Region:
November 2019 through March 2020 potential Temperature and Precipitation Anomalies (based off of five historic Analog Years):
While December 2019 may turn out “warmer” than average, look for a potential return of colder than average temperatures from January through March 2020 along with a decent shot of several winter storms January through March. If these analog years are a good match, January and March could produce several decent winter storms across the National Capital Area.
Analog Years and Seasonal Snowfall at National Airport:
- Two winters (2003-04, 2004-05) featured below-average snowfall
- Two winters (1978-79, 2013-14) featured well-above average snowfall
- The Winter of 2014-15 featured average snowfall
Tim’s 2019-2020 Seasonal Snowfall Forecast for the National Capital Region:
Washington Metropolitan Area:
Average Snowfall Across the Washington D.C. Region:
A few thoughts on this upcoming Winter forecast:
Some of you may be thinking if temperatures are forecast to run near to below average and precipitation is forecast to be near to above normal then why isn’t Tim predicting a lot more snowfall across the D.C. Region?
- There has been a very dominant sub-tropical ridge of high pressure off of the southeast United States coast this Fall and if this feature were to hold on through the upcoming winter then some of the storms could produce the dreaded wintry-mix of sleet and freezing rain versus pure snow events (the D.C. Area is well overdue for a nasty ice storm).
- It’s always impossible to know if the arctic outbreaks (which are expected this year in January, February and March) will coincide with moisture.
- For those of you snow-lovers (like me) the good news is that the SSTs near Greenland are above normal this year (unlike last year) which would favor a negative NAO (North-Atlantic-Oscillation) through portions of the upcoming winter. A negative NAO features blocking in the North Atlantic ocean favoring the development of Nor’easters on the Mid-Atlantic and New England coast.