Ed Kieser presents Weather Outlook The 2004 Season March 9, 2004

Global Weather

South America Highlights: Argentina soil moisture has improved. Southern Brazil has dry pockets, but many areas will receive rain this week. Northern growing areas of Brazil remain way too wet. Yields have been reduced.

South Africa Highlights: Crop conditions remain better than usual because of frequent rain of late. Dry and warmer weather is needed for crop maturation.

U.S. Weather

U.S. Midwest Highlights: Concern about a possible wet start to the planting season. A favorable start to crop development is expected once plants are planted and established. More uncertainty about later into the summer.

U.S. Delta Highlights: The soil is saturated in many areas. Pre-planting fieldwork and early planting will remain slow.

Central Plains Highlights: Drought continues in southwestern Nebraska, eastern Colorado, and far western Kansas. Other areas not as dry. Winterkill suspected in some areas.

Northern Plains Highlights: Soil moisture generally favorable from melting snow and recent precipitation. Some areas may be a little too wet in April and May. Spring wheat planting may be slow, but improved soil moisture has prospects good for an improved crop this year.

Climate Outlook - Temperature March 2004

Long-Lead Outlooks How to read them: EC – Equal Chances – Chances are 1/3 A, 1/3 N, 1/3 B. A – Above Average. N – Near Average. B – Below Average.

Long-Lead Outlooks Example: “40” around “A”: Chance for “Above Average” increases to 40%, meaning: A – Odds for Above Average: 40%. N – Odds for Near Average: 33 1/3%. B – Odds for Below Average: 26 2/3%.

Climate Outlook - Temperature March 2004

Climate Outlook - Precipitation March 2004

Climate Outlook - Temperature April-June 2004

Climate Outlook - Temperature June-August 2004

Climate Outlook - Precipitation April-June 2004

Climate Outlook - Precipitation June-August 2004

Climate Influences

El Niño When does it occur? Every 2-7 years. The interval between events is irregular. Maximum warming of the Pacific waters is generally observed between December and February.

Normal Conditions Convective Loop Equator 120ºE 80ºW

El Niño Impacts Midwest: Bottom Line: There is little correlation between El Niño and weather in Illinois, especially in summer. Winters are often milder than average during a STRONG El Niño. There is a good chance of less snowfall than average during a STRONG El Niño.

Pacific Decadal Oscillation What is it? Know as the “PDO.” It’s a long-term ocean fluctuation of the Pacific Ocean, with a cycle of about 20 to 30 years.

Pacific Decadal Oscillation What is happening? Evidence suggests that the PDO switched to the “cool” or “negative” phase in the eastern Pacific Ocean in 1999. It appears that this will act to steer the jet stream farther north over the western U.S. The “warm” or “positive” phase appears to have lasted from 1977-1998.

Pacific Decadal Oscillation

Pacific Decadal Oscillation Cool Warm

Pacific Decadal Oscillation Cool Warm Cool Warm

Pacific Decadal Oscillation PDO Index:

Pacific Decadal Oscillation PDO Index: - + - + -

Pacific Decadal Oscillation Impacts - Negative Phase: The average national summer temperature ranking tends to be lower than average. Annual precipitation tends to be less in the Midwest, Tennessee Valley, southern New England, and West. Trend toward more precipitation in the northern Rockies, Oklahoma, eastern Texas, and the Mid-Atlantic Coast.

North Atlantic Oscillation What is it? Large scale oscillation of atmospheric mass between the subtropical high and the polar low.

North Atlantic Oscillation When does it occur? The NAO occurs in the winter. It varies from year to year, but can remain in one phase for several years.

NAO – Positive Phase Stronger than usual subtropical high pressure center and stronger than usual Icelandic low. Increased pressure difference causes stronger winter storms, crossing the Atlantic on a more northerly track. Warm, wet winters in Europe and cold, dry winters in northern Canada and Greenland. Mild and wet winters in the eastern U.S.

NAO – Negative Phase Weaker than usual subtropical high pressure center and weaker than usual Icelandic low. Reduced pressure difference causes fewer and weaker winter storms crossing the Atlantic on a more west-east pathway. Moist in the Mediterranean and cold in northern Europe. More cold air outbreaks and, thus, more snow along the U.S. east coast.

Final Thoughts

No Simple Answers Beware! The atmosphere operates on many time and space scales. They all influence the weather. PDO, El Niño, NOA etc. do influence the jet stream (and the global scale), with the greatest impact on weather near the oceans and in and near the tropics. The impact is much reduced here.

Decision Making Some Advice: Listen to the weather rumors as they impact the markets in the short term, but remember in the long term the actual weather is most important. Follow the weather on a daily basis and follow meteorologists that you can trust. All long-range weather forecasts have little skill. Don’t make “all or nothing” decisions based on long-range forecasts.

New Website Illinois State Water Survey: www.sws.uiuc.edu/warm On left column, click on agriculture. Has information about growing degree days, 30 different pests, and more.

Tune to In-Depth Weather: 5:35, 6:35, 7:35, 8:35, 9:35 AM 12:35, 4:33, 5:33 PM

Tune to In-Depth Weather: 5:35, 6:35, 7:35, 8:35, 9:35 AM 12:35, 4:33, 5:33 PM Special Ag Weather Reports: 8:51 AM 2:32 PM

Tune to On the Web at: www.will.uiuc.edu

Tune to Thank You!

Tune to Thank You! Questions?