For the second consecutive time in two years, La Niña (translated from Spanish as “little girl”) is back and she means business. New data from Climate.gov indicates La Niña conditions have formed just in time for winter weather in the Northern Hemisphere.
On Thursday, the Climate Prediction Center confirmed La Niña after analyzing October ocean temperatures cooling along the equatorial eastern and central Pacific Ocean. La Niña is often declared when sea surface temperatures in the region (just stated) decline by 0.5 degrees Celsius.
John Morales, Chief Meteorologist WTVJ NBC-6 Miami, shows the progression of cool water over the equatorial Pacific Ocean responsible for La Niña formation.
The cooler waters have an influence on atmospheric conditions by decreasing evaporation in the tropics, which is a major driver of global weather.
According to the Weather Channel,
A typical La Niña winter in the U.S. brings cold and snow to the Northwest and unusually dry conditions to most of the southern tier of the U.S., according to the prediction center.
The Southeast and Mid-Atlantic also tend to see warmer-than-average temperatures during a La Niña winter. New England and the Upper Midwest into New York tend to see colder-than-average temperatures.
Climate Prediction Center /NCEP/NWS Full Report: La Niña conditions are predicted to continue (~65-75% chance) at least through the Northern Hemisphere winter 2017-18.
During October, weak La Niña conditions emerged as reflected by below-average sea surface temperatures (SSTs) across most of the central and eastern equatorial Pacific Ocean [Fig. 1]. The weekly Niño indices were variable during the month, with values near -0.5° C during the past week in the Niño-3.4 and Niño-3 regions [Fig. 2]. Sub-surface temperatures remained below average during October [Fig. 3], reflecting the anomalously shallow depth of the thermocline across the central and eastern Pacific [Fig. 4]. Also, convection was suppressed near the International Date Line and slightly enhanced over parts of the Maritime Continent and the Philippines [Fig. 5]. Over the equatorial Pacific Ocean, low-level trade winds were mainly near average, but the upper-level winds were strongly anomalously westerly and the Southern Oscillation Index was positive. Overall, the ocean and atmosphere system reflects the onset of La Niña conditions.
For the remainder of the Northern Hemisphere fall and winter 2017-18, a weak La Niña is favored in the model averages of the IRI/CPC plume [Fig. 6] and also in the North American Multi-Model Ensemble (NMME) [Fig. 7]. The consensus of forecasters is for the event to continue through approximately February-April 2018. In summary, La Niña conditions are predicted to continue (~65-75% chance) at least through the Northern Hemisphere winter (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).
La Niña is likely to affect temperature and precipitation across the United States during the upcoming months (the 3-month seasonal temperature and precipitation outlooks will be updated on Thursday November 16th). The outlooks generally favor above-average temperatures and below-median precipitation across the southern tier of the United States, and below-average temperatures and above-median precipitation across the northern tier of the United States.
La Niña weather phenomenon easily explained:
Ben Noll, Meteorologist, National Institute of Water & Atmospheric Research of New Zealand, compares the equatorial sea-surface temperatures in 2016 and 2017. His findings indicate 2017 waters “not as large farther west” when compared with 2016. Basically he validates NOAA’s “weaker La Niña” claim...
Compare early November equatorial SSTs in two consecutive #LaNina years.— Ben Noll (@BenNollWeather) November 10, 2017
2016: Coldest anomaly in central Pacific, above normal near South America.
2017: Coldest anomaly near South America, anomalies not as large farther west.
An important difference as we go forward! pic.twitter.com/2fjXfjjVOD
NOAA’s winter weather outlook indicates normal participation for the mid-tier of the United States. The southern-tier is forecasted to see much drier conditions. Meanwhile, the Great Lakes region and Northwest of the United States appear to have much wetter conditions.
Temperature outlooks for this winter include at-least 2/3 of the United States well above average. Below average to normal in regions, such as the Great Lakes region and Northwest.
Bottomline: What do weather forecasters and Dennis Gartman both have in common?... Well you guessed it– terrible forecasting...