NOAA September 6, 2007 — Scientists with NOAA’s Climate Prediction Center, in today’s release of its monthly El Niño/Southern Oscillation (ENSO) Diagnostic Discussion, say that La Niña is on its way. (Click NOAA image for larger view of observed sea surface temperatures on August 29, 2007. Please credit “NOAA.”)

“While we can’t officially call it a La Niña yet, we expect that this pattern will continue to develop during the next three months, meeting the NOAA definition for a La Niña event later this year,” said Mike Halpert, acting deputy director of the Climate Prediction Center in Camp Springs, Md.

La Niña refers to the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific that occur every three to five years. NOAA declares the onset of a La Niña event when the three-month average sea-surface temperature departure exceeds -0.5 degrees Celsius (-0.9 degrees Fahrenheit) in the east-central equatorial Pacific [between 5 degrees North and 5 degrees South and 170 degrees West - 120 degrees West].

The development of La Niña conditions is supported by increasing below-normal-sea surface temperatures across the central and eastern equatorial Pacific and stronger-than-average easterly winds across the west-central equatorial Pacific. “Nearly all operational dynamical models, including the National Centers for Environmental Prediction’s Climate Forecast System and many of the statistical models also favor a La Niña event,” said Halpert.

(Click NOAA image for an animation (mov) of sea surface temperature (SSTs) anomalies across the Eastern Pacific as depicted by NOAA’s Polar Operational Environmental Satellite. The blue and purple colors indicate areas of colder-than-average SSTs, indicative of a developing La Niña. Click here for high resolution version of the still image to the right. Please credit “NOAA.”)

With La Niña developing, seasonal forecasters expect wetter-than-normal conditions in the Pacific Northwest and drier-than-normal conditions in the already drought-stricken southwestern U. S. this Fall.

“These conditions also reinforce NOAA’s August forecast for an above normal Atlantic hurricane season,” said Gerry Bell, Ph.D., NOAA’s lead seasonal hurricane forecaster.

The Climate Prediction Center routinely publishes an assessment of ENSO conditions each Monday and the next official ENSO Diagnostic Discussion will be issued on October 11, 2007. The El Niño/Southern Oscillation Diagnostic Discussion is a product of the Climate Prediction Center in association with its funded institutions.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation’s coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

Relevant Web Sites
NOAA

ENSO Diagnostic Discussion & Weekly Update

FAQs on ENSO

CPC ENSO Page

Atlantic Hurricane Season Outlook Update

Behind the Scene: NOAA’s North Atlantic Hurricane Season Outlook

Seasonal Outlooks

Media Contact:
Carmeyia Gillis, NOAA Climate Prediction Center, (301) 763-8000 ext. 7163

Tropical storm activity increased again this weekend so we’ll be adding another named storm to our tracking maps on Monday. Interestingly, Monday is also the peak date for hurricane season and there are now 3 tropical disturbances developing that we should monitor. Click on the image below to see the most recent activity.

I want to give you a heads up that you have a test on hurricanes coming up. Of course all of you are going to want to do some additional studying and I’ve made it easy. Here’s a link to a great site that I think you’ll enjoy and also learn from. Try it out and let me know what you think.

When you go to the site you’ll see an image like that below. You will have to register in order to view the activities. Clicking on the image below will also take you to the site.

Here’s another way you can study for the test — read pages 9 and 11 in your notebooks and view the videos listed below. These are the same videos we watched in class.

• The Science Behind Hurricanes
• El Nino And La Nina Weather Patterns
• Lessons Learned From Previous Hurricane Seasons
• What To Do When A Storm Hits
• Behind The Scenes Tour Of Hurricane Hunter Plane

Here we go again. Friday Felix formed just North of South American as a Tropical Depression with winds of 35 mph and a barometric pressure of 1008 mBar. By today, Sunday, it’s pressure dropped to 980 mBar with sustained winds of 105 mph and is rated as a category 2 hurricane.

Look at the global sea surface temperatures. What are they telling you? What does the blue color off the western coast of South America mean? Click on the image and explore Weather Underground, a great site for weather information. Look at the projected path for Felix, find where the jet stream is, and look at the paths of other hurricanes.

You can begin tracking hurricane Felix on your tracking maps (page 9 in your interactive notebook). Also monitor tropical disturbance 98 over the next few days and look for further development.