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Livestock Wx for November 17, 2017: Significant cooling in the Pacific is leading to the development of a moderate La Niña
Rapid Equatorial Pacific Cooling
The region of the Pacific (called ENSO 3.4) NOAA uses to track El Niño and La Niña events cooled from an anomaly of -0.4°C last week to -1.1°C this week. That 0.7°C change may seem minor but it matches the largest one-week change since 1990!
This increases the odds of a moderate La Niña—and more typical La Niña weather patterns—over the next 3 months. This is reflected in the seasonal precipitation and temperature outlooks below.
Changes in the U.S. Drought Monitor
For the past 30 days, percent of rainfall for much of Texas and Oklahoma has been 50 to 25 percent of normal. As a result, Abnormally Dry (D0) and Moderate Drought (D1) conditions have continued to expand. The below image shows the latest U.S. Drought Monitor along with how the map has changed from last week to this week. Note areas around the Southwest, Coastal Bend, and the Rolling Plains are seeing some degradation in conditions while the Southern Plains and West Texas have seen some improvement. The gray shading on the map show areas that have not changed over the last week.
Over the next week, the regions east of Highway 277 should see some rainfall so there could be some minor improvement or at least status quo in these areas.
Seasonal Drought Outlook
On Thursday (Nov. 11-16) NOAA released its suite of outlook products. Among those was the Seasonal Drought Outlook. The image below shows the Outlook, which is valid from November through February. Drought is expected to develop for much of Texas. The pattern reflected in the Outlook is being heavily influenced by NOAA’s thinking about how La Niña will influence weather patterns across the U.S. Much of this is based on historical patterns. Since the 2000’s, however, both La Niña and El Niño events have not always “behaved” as expected. So, while it is likely we could see deteriorating conditions around the state it is not a climate slam dunk, so there is always room for a surprise.
Temperature and Precipitation Outlook
As reflected in the Drought Outlook, conditions through winter (December-February) are expected to be above average on the temperature side and below average on the precipitation side of the ledger. Already parts of the state are seeing precipitation deficits so close monitoring will be needed as we move through Winter and into Spring.
If you have any questions about what to expect during this weak La Niña winter please contact us at [email protected].