Cold overnight lows

Craig Oswald, Field Meteorologist, 509-786-9256


Overnight low temperatures during the next few nights look to become cold enough to cause some concern for growers who reside within locations that typically run colder than surrounding areas in eastern Washington. This is due to an upper low that continues to move into the Pacific Northwest from the northwest. Current progs indicate that air temperatures aloft will begin dropping through the night tonight (Wednesday). Projected upper air temperatures suggest that areas such as the upper and lower Yakima valley as well as the Okanogan have a potential for frost on a calm and clear night, even this late into the season.

HOWEVER, a combination of relatively elevated dewpoints due to recent rain showers, light to breezy winds, and mostly to partly cloudy skies are expected to regulate overnight low temperatures. These factors look to keep overnight lows in the upper 30s throughout the typical cold locations with a handful of mid 30 lows possible in spots that find breaks in the cloud cover. Low 40s can be expected elsewhere.

Friday night is anticipated to have slightly more widespread temperatures in the mid 30s. This is due to an expected decrease in cloud cover and easing of the wind through the overnight, even though upper air temperatures are indicated to be slightly warmer than the previous night. Dew points continue to look to remain elevated, also helping to prevent overnight lows from cooling lower than the mid 30s in the coldest locations.

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