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Ag Weather Update

Matt Dixon, Meteorologist, UK Ag Weather Center

Updated July 26, 2021

Past Conditions 

Our wet first half of July seems like a distant memory after this past week, when the the state averaged just 0.08 inches. Sunday was the only day that offered any rainfall, and even that was limited to scattered coverage. A number of locations recorded nothing for the week. This was the driest week for the Commonwealth since the second week of May, breaking a streak of three straight weeks with the state average above normal. Temperatures ran slightly below seasonable norms for most of the workweek before rising over the weekend. Combined with high humidity, heat indices topped the century mark in some places on Sunday.

The main highlight of the week was the smoky haze in the air originating from wildfires across the western United States (more on this below). While this led to some air quality concerns, it did produce impressive sunsets and sunrises. The satellite image from the National Weather Service in Charleston, WV, below shows the haze across the area on Monday morning.


Data for the Past 7 Days 


7-Day Observed Precipitation 

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The forecast doesn’t offer much promise for significant rainfall moving forward. Following isolated to scattered coverage across the southern half of Kentucky on Monday, we turn dry through at least Thursday. The lack of rainfall will be accompanied by increasing heat. Some of the warmest temperatures of the summer season so far will be in play. Highs Tuesday through Thursday are expected to run in the low to middle 90s statewide. The highest temperatures will be across the western half of Kentucky, with some seeing the heat index top the century mark. I included a look at forecast highs on the warmest day (Thursday) from the National Weather Service below. Livestock heat stress will continue to run in the “Danger” category during the afternoon and evening hours. Some across Western Kentucky could briefly see an uptick into the “Emergency” category. Be sure to take precautions as necessary. 


We will have chances for rainfall on Thursday night into Friday and then again late in the weekend. The map below from the Weather Prediction Center shows the better potential for higher accumulations across the eastern half of Kentucky (> 1 inch) and much lower across the western half (< 0.5 inch). Based on the latest model runs, I’m leaning toward a second straight week of below normal rainfall for the Bluegrass State. We’ll see temperatures decrease with these rounds, back into the middle 80s to around 90.

Read the Kentucky Ag Weather Synopsis

How Did the Smoky Haze Get There?

You are probably well aware that the haze in the sky this past week was the result of smoke from wildfires out west, but you might be wondering how it got here. After all, we are about 1,500 to 2,000 miles away from the source. Typically, we’re only worried about what we see at the surface, but a few key components higher up in the atmosphere ultimately determine the weather that we see at the surface. The main one is the jet stream, which has the fastest winds aloft and is found several miles up in the atmosphere. In general, it divides cold, drier air to our north and moist, warmer air to our south. Ultimately, the jet stream steers our storm systems. It blows from west to east across the United States with some north and south bends in the flow. As smoke rises, it can get caught up in this jet stream and transported large distances. 

Below is an image from NOAA’s Global Systems Laboratory showing the movement of smoke across the United State according to a high-resolution forecast model last week. I made a couple of edits, one showing the source of the smoke from the wildfires out west and another showing the flow of the smoke across the United States (blue line). This blue line followed the same path of the jet stream at the time, which for comparison purposes can be seen in the upper-level map just below. The jet stream ended up directing the smoke northeast into South Central Canada and then southeast into the Ohio Valley Region.


Related News from UK and Beyond

Kentucky grain producers adapt to new climate normals – Katie Pratt, July 20, 2021

New “Destructive” Severe Thunderstorm Warning category to trigger Wireless Emergency Alerts on mobile phones – National Weather Service, July 22, 2021


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