Record high temperatures have been set across the central United States over the past few days. The hot, dry air has contributed to the wildfire problems in Colorado, Utah, and the rest of the intermountain western United States.
The first image shows the NAM computer model's forecast for this afternoon's high temperatures. At least 15 states will register triple-digit heat, including western parts of Tennessee as Memphis is on the outer periphery of the hottest air. Parts of western Kansas, western Oklahoma and eastern Colorado may approach 110°.
The second image shows the weather pattern tomorrow in the mid-to-upper atmosphere. You can see Tropical Storm Debby down in the northeastern Gulf of Mexico in the second image. It's no mistake that the core of the heat wave is directly underneath the upper ridge of high pressure. By plotting the height of the 500 millibar level, meteorologists identify areas of cool and hot air, indicating areas of low and high pressure.
The third image shows the 500 millibar weather pattern as predicted for Thursday. Nashville will see highs in the upper 90s Thursday, Friday, and next weekend as the upper ridge essentially sits on top of the Mid-South. The increasing presence of some low-level humidity will cause our ridge to become “dirty” by the weekend. That means we'll have heat and plenty of humidity, which will contribute to a dangerous heat index of 100° to 105° by that point in time.