Excessive Rainfall Potential for the Southeast; Heat Expands for Center of the Nation; Critical Fire Weather for Pacific Northwest

Flash flooding threatens areas from the Tennessee Valley to the Carolinas as storms repeat along a stalled front. Monsoonal storms may trigger flooding in the Southwest. Dangerous heat expands across the Desert Southwest, Plains, mid-Mississippi Valley and Southern Tier. Critical fire weather for interior Pacific Northwest. Cooler, drier air brings brief relief to the Great Lakes and Northeast. Read More >

A Record High and Record Low Temperature was Set Today in Alamosa, Colorado

A new record high temperature of 92 degrees was set in Alamosa, Colorado on July 10th, 2020. This breaks the old record high temperature for July 10th of 91 degrees, last set in 2003.
In addition, Alamosa also set a record low temperature for July 10th, when the temperature fell to 37 degrees in the morning. This ties the record low temperature for the day which was set on July 10th, 1982.

Additional Similar Records
The Science

Additional Similar Records

This has happened 3 times before in Alamosa during the extreme drought of 2002 (Thanks to James Aydelott's assistance)
- August 24, 2002: Record high of 85°, record low of 33°
- August 25, 2002: Record high of 87°, record low of 30°
- August 26, 2002: Record high of 88°, record low of 31°

The Science

Energy from the sun is transferred through space and through the earth's atmosphere and heats the earth's surface.
Through conduction, the ground heats the air right above it. When you have a very warm air mass in place and sunny skies, hot temperatures will develop.
Additionally, very dry conditions like what are usually observed across most of Colorado, will assist with quickly rising temperatures.
Alamosa (around 7500 ft above sea level) is located in the San Luis Valley, which is a high mountain valley in between 2 mountain ranges. Alamosa is considered to be a high desert climate, with annual precipitation of only 7.31 inches.
With a dry annual climate, Alamosa and other locales across Colorado can frequently see diurnal temperature ranges of 30 to 50 degrees (the difference between the high and low temperature).

Figure 1: Nighttime Radiational Cooling

The San Luis Valley has seen extreme drought conditions develop over the last 6 to 8 months.
Alamosa has received 0.97 inches of precipitation from January through June of 2020 (1.74 inches below normal) and only 3.66 inches of precipitation from July of 2019 through June of 2020 (3.65 inches below normal).
With extreme drought conditions in place, per US Drought Monitor, soil moisture conditions are well below normal across the San Luis Valley. The dry soils, combined with the dry air mass in place, help to quickly heat the earth’s surface during the day.

Figure 2: Extreme Drought Across Parts of Colorado (The U.S. Drought Monitor)

At night, the dry air mass can also help cool temperatures efficiently under clear and calm conditions, due to radiational cooling effects.

Figure 3: Nighttime Radiational Cooling

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Excessive Rainfall Potential for the Southeast; Heat Expands for Center of the Nation; Critical Fire Weather for Pacific Northwest

Record High and Low Set at Alamosa on July 10 2020