WHAT COULD LA NINA MEAN FOR WINTER?
Written by: Bob Metcalfe
A few weeks ago, the NWS office in Buffalo released a little bonus climo info in regards to La Nina winters and what it could mean for us. It got lost in the shuffle and I've been meaning to post it here on the blog. This does not reflect the News 8 forecast, but this definitely plays a large role in our thoughts. Here it is:
THE CLIMATE PREDICTION CENTER (CPC) HAS BEEN CLOSELY MONITORING A
STRENGTHENING LA NINA OVER THE EQUATORIAL PACIFIC. THE CURRENT LA
NINA IS ALREADY MODERATE IN INTENSITY. AS A RESULT OF SEVERAL KEY
INDICATORS...INCLUDING ANOMALOUS UPPER LEVEL WESTERLY WINDS AND
CONTINUED ENHANCEMENT OF LOW LEVEL EASTERLY WINDS...CPC IS
FORECASTING THAT THIS LA NINA COULD FURTHER DEVELOP AND BECOME
STRONG DURING THE UPCOMING WINTER MONTHS. WHAT DOES THIS MEAN FOR
WESTERN NEW YORK?
LOOKING SIMPLY AT LA NINA EVENTS...THERE HAVE BEEN 7 WINTERS SINCE
1950 WHERE MODERATELY STRONG LA NINAS HAVE BEEN IN PLACE. A MAJORITY
OF THOSE WINTER MONTHS HAVE FEATURED ABOVE NORMAL TEMPERATURES
ACROSS OUR REGION...ESPECIALLY DURING NOVEMBER AND FEBRUARY. THERE
HAVE BEEN 3 WINTERS WHERE THERE WAS A STRONG LA NINA. THE MONTHS
DURING A STRONG LA NINA WERE EVEN MILDER WITH ROUGHLY 80 PERCENT OF
THE MONTHS RECORDING ABOVE NORMAL TEMPERATURE DEPARTURES. IN OTHER
WORDS...HISTORICALLY SPEAKING THE STRONGER THE LA NINA...THE GREATER
THE POTENTIAL FOR POSITIVE TEMPERATURE DEPARTURES. THOSE TEMP
DEPARTURES ARE TYPICALLY MORE ANOMALOUS AS WELL.
DURING A LA NINA...THE UPPER LEVEL FLOW IS MUCH MORE MERIDIONAL THAN
IT IS DURING EL NINO. THIS ALLOWS FOR MORE COLD OUTBREAKS...BUT ALSO
OPENS THE DOOR FOR VERY MILD PERIODS. IN OTHER WORDS...A MUCH
GREATER SWING IN TEMPERATURES THAN DURING THE MORE ZONAL FLOW
PRODUCED DURING MODERATE TO STRONG EL NINOS.
WHILE THE MEAN POSITION OF THE MAIN LONG WAVE TROUGH IS FOUND
OVER THE NATIONS MID SECTION DURING STRONGER LA NINA...A
DIFFERENCE OF JUST A FEW HUNDRED MILES IN THE LOCATION OF ITS BASE
WILL DETERMINE WHETHER WE HAVE COLD ARCTIC AIR OR MODIFIED SRN
PLAINS/GULF BASED AIR.
ONE HAS TO ALSO LOOK AT OTHER GLOBAL TELECONNECTIONS THOUGH WHEN
ATTEMPTING TO FORECAST SEASONAL TEMPERATURE TRENDS. THIS INCLUDES
THE NORTH ATLANTIC OSCILLATION...WHICH HAS A STRONG INFLUENCE OVER
OUR REGION. THE GREATEST INFLUENCE OF THE NAO IS FELT DURING TIMES
OF WEAK OR NEUTRAL ENSO CONDITIONS IN THE PACIFIC. THAT WILL NOT BE
THE CASE THIS SEASON THOUGH AS A MODERATE TO STRONG LA NINA WILL BE
IN PLACE.
does that mean we are going to get a lot of snow? or no snow? and warm or cold temperatures?
ReplyDeleteIt means it will be another crappy winter for snow lovers.
ReplyDeleteActually no it doesn't mean "it will be another crappy winter for snow lovers." Historically we tend to average above normal with La Nina winters, but it will be more important on how the storm path will be this winter.
ReplyDeleteAs I have said many times before. I don't do well with long range forecasts. I tend to be a more analog when it comes to forecast which isn't the best but it helps me get a better understanding of what we could expect.
As for temperatures we tend to also be above average historically. That doesn't mean all winter will be warm. Just mean the average by the end will be warmer. Plus in the discussion from the NWS they mention we could see a lot more swings in temperatures.
We will have our winter outlook coming out soon. Until then we might issue parts or our thoughts or other forecasts from time to time.
-Brian