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SNOW AND COLD FOR EASTERN UNITED STATES LINKED TO NORTH ATLANTIC OSCILLATION
So far, it has been a very cold and snowy winter. The usual suspect is El Nino. However, the real culprit appears to be hovering over the Northern Atlantic. We haven’t had an early winter this cold since 1976, when the last North Atlantic Oscillation (NAO) was as strong as it is now.
THE REAL SUSPECT, NORTH ATLANTIC OSCILLATION
The current El Niño is an unlikely driver for the cold and wintry weather over the Northeastern United States. The North Atlantic Oscillation could be the major contributor to winter events like the US January arctic blast. Differences in the normal pressure between the high-latitude and sub-tropical North Atlantic are the signature of the NAO The current phase of the NAO tends to produce colder and more wintry weather in the Northeastern US by allowing the moisture in the Gulf of Mexico and subtropical Atlantic to made available to cold air that makes its way southward from Canada a result of the NAO. The Quik Scatterometer (QuikScat) satellite along with data from the National Weather Service shows circling wind anomalies over the North Atlantic drawing that cold air over the US and moist air from the south, meeting over the northeast US. These anomalies are part of the North Atlantic Oscillation (NAO). For more information on the North Atlantic Oscillationclick here.
SUSPICIOUS TRAITS OF 2002-2003 EL NINO
On the other side of the world, El Nino continues to exert its suspicious traits. The 2002-2003 El Nino is much weaker and unlike the recent El Nino of 1997-1998. Images 2 and 3 show that the warmest sea surface temperature (SST) anomalies are concentrated in the Central Equatorial Pacific. Anomalies are a departure from normal. These images only show where the water is warmer than normal or cooler than normal. Areas in red indicate warmer than normal temperatures and areas in blue show cooler than normal temperatures. During 1997-1998 El Nino, the warmest SST anomalies were right up against the South American coast. Historically, El Nino's effects on United States weather are greatest when the warmest SST anomalies are near the coast of South America. Thus, history would suggest the present El Nino effects on United States weather might be moderate.
The Advanced Microwave Scanning Radiometer (AMSR-E) on
board the Aqua satellite sees through the clouds to monitor sea
surface temperature (SST) associated with 2002-2003
El Nino. AMSR-E was developed by Japan's National Space
Development Agency. Data for this image were provided through
Remote Sensing Systems.
WIND'S EFFECTS ON SEA SURFACE TEMPERATURE ANOMALIES
The wind anomalies associated with the 2003 El Nino are quite different from past observed El Ninos. The Quik Scatterometer satellite (QuikScat) along with data from the National Weather Service shows trade winds weakening over the Central Equatorial Pacific Ocean. Image 4 shows wind anomalies converge near the middle of the equatorial Pacific Ocean. The converging wind anomalies are keeping the warmest SST anomalies in the middle of the equatorial Pacific Ocean. During the 1997-1998 El Nino, wind anomalies flowed from west to east across the Equatorial Pacific. This allowed the warmest SST anomalies to push up against South America.
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