Past Conditions

I hope everyone had an enjoyable Thanksgiving holiday, despite chilly temperatures and rain across the area. Normal highs for late November run in the low to middle 50s across much of Kentucky (upper 40s across the Northern Bluegrass). Lows average in the low to middle 30s. Looking back at this past week, it was difficult to find temperatures close to seasonable norms. We started the week with highs limited to the 40s on Monday and Tuesday with northerly flow in place. As I mentioned in last week’s update, Kentucky saw the coldest temperatures of the fall season so far on Tuesday morning. Most of Kentucky saw lows in the upper teens to low 20s, but some even dipped into the middle teens. Wednesday was probably the nicest day of the week, preceding a cold front when high temperatures ran near to above seasonable norms with gusty southerly flow in place.

The frontal boundary led to a wet Thanksgiving for the Commonwealth. Widespread showers produced accumulations of a quarter to half inch across the area, which was the only rainfall event for the week (map below). Behind the boundary, chilly air returned to Kentucky with highs on Friday limited to the upper 30s to mid-40s for almost everyone. Friday and Saturday mornings had temperatures in the 20s. Looking at preliminary data through the 29th, this will likely be the first month since July that the state average temperature has run below normal.

Data for the Past 7 Days

Forecast

Conditions have been dry since Thanksgiving Day across the Bluegrass State. Excluding isolated to scattered light rain showers associated with a weak disturbance on Wednesday, dry conditions will prevail through the end of the workweek. The best chance for accumulations looks to stay across the northern half of Kentucky at mainly under a tenth of an inch (map below).

If you’re hoping for warmer temperatures, you are in luck! Temps are on an uphill climb for the first half of the week. Current temperatures as of 2:30PM EST on Tuesday (11/30) are in the middle 50s to around 60 across the state. After similar temperatures tomorrow, we jump well into the 60s for Thursday and Friday. Rain chances then look to return over the weekend, but confidence on timing and amounts are still low at this point. Temperatures take a step back into the 50s, which is not significant. Outlooks hint that warmer than normal temperatures will be here into the second week of December (maps below).

Read the Kentucky Ag Weather Synopsis

2021 Winter Forecast & Climate Trends

December 1st marks the start of meteorological winter, and that brings about the #1 question to meteorologists everywhere: What will winter be like this year? Obviously, we can’t provide a perfect forecast, but we can give an idea based on previous years and worldwide climate patterns. Below is a look at the latest winter outlooks from the Climate Prediction Center. These maps hint at higher confidence in above normal temperatures and precipitation over the next three months for much of Kentucky. This DOES NOT mean the entire winter will be warm and wet. We’ll still have some bouts of cold air and dry periods, but when looking at the winter as a whole, forecasters hint that the wet and warm periods will outweigh those drier and cooler periods. A sliver of Southeastern Kentucky is even in the "equal chance" category, meaning that chances are equal for near, above, and below normal precipitation.

Darker shades on the maps above correlate to higher confidence. You can see that the shades across Kentucky aren’t the darkest. This indicates the uncertainty in the forecast. The focus this year is on a “double-dip La Nina,” meaning this is the second year in a row for La Nina conditions over the winter months. "La Nina" is associated with the El Nino-Southern Oscillation (ENSO) climate pattern. The Southern Oscillation can take one of three phases: neutral, El Nino, or La Nina. El Nino and La Nina phases are known for causing disruptions to large-scale weather patterns, such as the jet stream, most significantly during the winter months. La Nina is the cool phase and is associated with cooler sea surface temperatures in the equatorial Pacific Ocean. Below is a look at the conditions we expect across the United States during a typical La Nina winter. Here in the Ohio Valley, we typically see warmer and wetter conditions during a La Nina. Notice that this map is quite similar to the outlooks.

The problem is that La Nina for winter 2021-22 is considered "weak.” So, the map above will most likely have deviations, which complicates the winter forecast further. The map above is most probable during “strong” events. I recently read a great article from Mike Halpert, deputy director of the NOAA Climate Prediction Center, which discussed winter precipitation and temperature patterns associated with the second year of a double-dip La Nina. I included a look at the maps developed by climate.gov below. Most, but not all, of the time, we see wetter than normal winters in the Bluegrass State with a double-dip La Nina. Warmer winters have also been more prevalent than cooler winters. One caveat he pointed out: We don’t have a lot of data on these double-dip La Nina episodes, since they have only happened seven times since 1950.

Our winters have been trending warmer and wetter over the past decade. This makes the warmer and wetter outlook a familiar scenario. Using data from the Midwestern Regional Climate Center, I've looked at the temperature and precipitation statistics over the past ten winters. Since our exceptionally cold winter of 2014-15, five of our past six winters have seen near to above normal temperatures. The only exception came this past winter when a very cold and active February pushed us solidly below normal for the season. Overall, four of the top-10 warmest winters on record (data going back to 1895) have occurred over the past decade in Kentucky. 2016-17 sits at #2, 2019-20 at #5, 2011-12 at #6, and 2015-16 at #9. Looking at precipitation, Kentucky has now seen six straight winters of above normal precipitation. Some years have been much more significant than others. 2018-19 ranked as the 4th wettest winter on record, while 2019-20 was #12.

I combined these two aspects of temperature and precipitation for the past 30 years in the time-series scatter plot below. Each year is plotted based on the average winter temperature and accumulated precipitation for that respective year. The graph is then divided into four boxes based on the 1991-2020 Kentucky temperature (red line) and precipitation (blue line) normals for the winter season. Here's how to understand the chart. Upper right: Contains any years with above normal precipitation and temperatures. Upper left: above normal precipitation and below normal temperatures. Bottom left: both below normal precipitation and temperatures. Bottom right: below normal precipitation and above normal temperatures. Then I highlighted the last five years in red. Outside of this past winter, the previous five have all hovered within or very close to that upper right box of above normal precipitation and temperatures.

The warmer and wetter winters have proven impactful to Kentucky agriculture in a variety of ways. Based on the outlooks, we could be in for similar problems in winter 2021-22. Kentucky is in a good spot compared to other states in the northern plains when it comes to soil moisture, but that could come at a cost with a wetter-than-normal winter on the way.

One impact could be an overwhelming amount of mud. Below is a picture from Dr. Josh Jackson, a UK extension livestock systems specialist and livestock producer in Mercer County. He took this in February of 2019, which was the second wettest February in Kentucky history when the state averaged 9.39 inches. This was one of many mud-filled scenes that were observed that year; mud has become more prevalent with warmer and wetter winters in place. Heavy mud can create a stressful environment for animals, causing feed requirements to go up to maintain proper body condition. Luckily, hay production was high this year, with extended dry windows that were absent in recent years, especially 2020. Also, according to the latest Kentucky Crop Progress and Condition Report on November 29th, livestock condition is running predominantly in the good to excellent category. Despite that, a warm and wet winter could cause livestock issues.

With the prevalence of wet conditions over recent years producers may want to consider mitigation strategies. Dr. Jackson installed all-weather surfaces on his farm, specifically in feeding areas that see a lot of foot traffic. More information on siting and materials suitable for your own operation can be found in the following extension publication, AEN-115 – Appropriate All Weather Surfaces for Livestock. Rotational grazing structures are another option, with more info in ID-188 – Strategic Winter Feeding of Cattle Using a Rotational Grazing Structure. Steve Higgins and Lee Moser also take a look at fenceline feeder systems in the following publication: AEN-134 - Fenceline Feeder Systems for Beef Cattle.

Another impact we’ve seen with warmer winters is that crops like winter wheat move into more advanced growth stages earlier in the year. This in turn makes the crops more susceptible to spring freezes sooner in the season. I discussed this subject at the UK Winter Wheat Meeting early in 2021. One way we can see this phenomenon over recent years is by looking at growing degree day accumulations (GDD). GDDs are essentially used to relate temperature to crop or insect development. In calculating GDDs, you take the average temperature for the day and subtract a base temperature, which is the minimum temperature required for growth. This base can vary among crops and insects, but in the graphs below, I used 32 degrees as it relates to winter wheat. When you see the lines increase in the graphs, daily average temperatures exceeded the base temperature for growth and GDDs are accumulated. You can assume no growth when the line levels or when the average temperatures for the day equals or is less than the base temperature. In the graphs below, I included a look at GDD accumulations for Lexington and Paducah on a yearly basis between 2011 and 2021. I then color-coded the years 2011 – 2015 in blue, 2016 – 2020 in red, and 2021 in black. Just focusing on the 500 GDD level, you’ll notice that the years in red have consistently hit that mark much earlier than the previous five years of 2011 – 2015. Yes, 2021 did level out in February. Even though we’ve been trending warmer in Kentucky, we still can get a cold shot now and then.

The potential for flooding also deserves monitoring. Kentucky, especially eastern portions of the state, got hit hard late last February and early March following intense rainfall across the region. Warm temperatures combined with wetter winter climates and dormant vegetation is a recipe for more runoff. Livestock producers and horse owners need to prepare for the potential for flooding during the winter season. In the August 24th edition of the Ag Weather Update, I discussed several steps a producer can take to better prepare themselves for the threat of flooding. Be sure to take a look since now is the time to prepare!

In the end, winter forecasting is definitely not an exact science. Despite outlooks hinting at above normal temperatures and precipitation across the Lower Ohio Valley, we’ll still have our ups and downs through the year. Overall, it's good news. Combined with climate trends, the oulooks do hint we are NOT in for a VERY cold winter in the Bluegrass State. My parents always told me about the winter of 1978, but the winter of 2014-15 is my '78. February 2015 was the fourth coldest February on record. The coldest temperatures were seen on February 20th when several across the state dipped between 10 and 20 degrees below zero (map below from NWS Jackson, Ky.). The Richmond, Ky. Mesonet station dipped to -32! That was only five degrees away from tying the all-time record low for Kentucky, set in 1994 in Shelbyville. I don’t know about you, but I’ll definitely choose a warmer outlook over that kind of winter any day!