Santa Gertrudis Source February 2025

PRODUCTION TIPS & TOOLS • Randy L. Stanko, Ph.D. • Texas A&M University-Kingsville

One More Month of Possible Cold Weather

O ne of the reasons we like living in a Gulf Coast state and why others love to share their winters with us is the typical winter weather pattern. For the most part, our cattle do not acquire a wooly haircoat like we see on cattle residing in the northern states – partially due to cattle genetics and partially due to the fact that we can have flies on Valentine’s Day. It has been four years since the “The Great Texas Freeze” (Feb. 11 20, 2021) for which no one was prepared. We dealt with a billion-dollar weather disaster and hauled water for seven days. It was the coldest winter storm in Texas since Decem ber 1989. Having a brush with cold weather last month has piqued my interest in “weatherology” and prompted me to think about preparing for one more month of possible cold weather. Do a quick check on the status of the three most important items needed by cattle when it is cold – feed, water and some type of shelter. The first item on my weather-understanding list was to become familiar with proper terminology. We must un derstand arctic oscillation, polar vortex, polar jet stream, stratosphere, troposphere and quasi-biennial oscillation to become “weatherologists.” Many factors were to blame in 2021, but the most notable was a strong negative arctic os cillation (AO). The AO influences winter weather in North America and is a back-and-forth shifting of atmospheric pressure between the Arctic and both the North Pacific and North Atlantic oceans. A negative AO allows for a weaker jet stream, which can dip south, whereas a strong, positive AO promotes a strong jet stream and ensures storms (cold air) stay north of us. A second factor was the polar vortex. The polar vortex is essentially a low-pressure, cold-air cap on both poles that “hangs-out” in the stratosphere (>10 miles up). The polar vortex has a dancing partner known as the polar jet stream. In this case (polar jet stream), we are in the troposphere or the area between the earth’s surface and three to six miles

above our ranch. When the polar vortex is strong and sta ble, the polar jet stream stays north and out of our concern. However, a disrupted or weakened polar vortex often leads to a very wavy polar jet stream. A wavy polar jet stream al lows warm air to flood into the Arctic and, in turn, sends us cold polar air. Third and fourth factors that can wreak havoc on our winter weather is the quasi-biennial oscillation (QBO) and the El Niño/La Niña weather pattern. The QBO describes an approximately two-year cycle of alternating easterly (from the east) and westerly (from the west) winds in the tropical stratosphere. An easterly QBO can result in a weaker polar vortex – warm air travels north and cold air moves south. A westerly QBO supports a strong polar vor tex and reduced chances of sudden warm air flowing into the Arctic. As of December 2024, NOAA is projecting that the La Niña weather pattern plus a westerly QBO gives us the lowest chance of sudden stratospheric warming mov ing into the Arctic (45 percent chance). Taken another way, there is a 55 percent that Texas will not relive February 2021 this month. Regardless, let us do a quick check on the status of the three most important items needed by cattle when it is cold – feed, water and some type of shelter. In general, cattle can handle temperatures down to about 20° F. Feeding cattle in the late afternoon will help them get through cold nights. Rumen heat production will peak approximately six hours after consuming feed. Cattle will need access to good qual ity hay or stock-piled forage and possibly some easily di gestible energy feed (corn) to generate heat. Fresh water is also critical, not too cold though. I would rather haul water twice per day rather than once per day only to find out that it turned into ice overnight. A good es timate of cow water intake would be at least 10 to 15 gallons per head per day during severe cold weather. As far as shel ter, each ranch would best know their owns needs or man agement plans. Minimum requirements would be bedding (like around a round-bale hay ring) for insulation from the cold ground. Hopefully I have prompted you to do your own “table top” exercise, just in case! I am going to town for a few items I may or may not need.

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SANTA GERTRUDIS SOURCE

FEBRUARY 2025