Frost/Freeze in Central Gunnison and Uncompahgre River Basin, Colorado

The minimum temperature recorded at the KMTJ ASOS at the Montrose Regional Airport was 28F, while the minimum recorded at any of the available 14 sensors was 23F. A total of 13 out of the 14 sensors recorded at least 3 hours of temperatures at or below 32F, with an average duration of 6 hours, a maximum of 9 hours and a minimum of 2 hours. Therefore this event qualifies as a standard freeze. Temperatures at or below 28F were recorded for an average of 2.5 hours, which does meet the 3 hour minimum to qualify as a hard freeze. However, the maximum duration of temperatures at or below 28F being 10 hours does indicate that localized hard freeze conditions occurred. No reports of crop damages or losses were received.

Once the growing season is underway, freeze products are needed even when a widespread freeze or hard freeze has occurred as recently as the night before, if conditions warrant. Such was the case on the night of the 19th to the 20th, as continued cold air advection behind a departing low pressure combined with good radiational cooling conditions to lead to widespread temperatures at or below 32F in the lower valleys.