An anomalously strong upper-level ridge will push temperatures into the mid-90s Tuesday, setting records across the region, before a powerful Pacific cold front sweeps through Wednesday with wind gusts up to 55 mph and a dramatic temperature drop.
Record Heat Expected Tuesday
After a slight cooling on Monday, Tuesday will be about 10 degrees hotter as the anomalously strong upper-level ridge passes directly overhead. Weather models are in close agreement on high temperatures for Tuesday, with 90s expected in southern valleys and 80s elsewhere. These temperatures will be hot enough to set records for the date across the region.
Powerful Cold Front Arrives Wednesday
The ridge will exit east Tuesday evening as a deep Pacific low moves due east toward the Oregon coast. A steep temperature and pressure gradient will develop between the departing ridge and the approaching low, resulting in the formation of a strong surface cold front.
The front is forecast to reach western Harney County around 10 a.m. PDT Wednesday, the Oregon-Idaho border around 3 p.m. MDT, and south-central Idaho between 6 and 8 p.m. MDT Wednesday evening.
A Wind Advisory has been issued for this event. Sustained winds of 25 to 35 mph with gusts up to 55 mph are expected as the front passes. Rising air ahead of the front will support a chance of showers and thunderstorms right along the frontal boundary. Blowing dust may reduce visibility in areas that do not receive rain.
High temperatures Wednesday will be as much as 30 degrees cooler than Tuesday's highs in Harney County, with less dramatic cooling on the Idaho side. More showers will pass through the region Wednesday night, most numerous in northern areas, with snow on the higher peaks by Thursday morning.
Cooler and Unsettled Weekend
An upper-level trough will move east of the area on Thursday, leaving the region under drier northwest flow with a 20 percent chance of showers over the mountains of southwest Idaho. Breezy west to northwest winds will continue Thursday, especially across the Magic Valley, with daytime highs around normal.
Friday will be dry with temperatures trending up a few degrees. The weekend will bring cooler weather and a 20 to 30 percent chance of rain and snow showers to the northern mountains, with snow levels between 5,000 and 6,000 feet. Weekend temperatures are expected to be 5 to 10 degrees below normal with breezy northwest winds across the Upper Treasure and Magic Valleys. Conditions will dry out Monday with temperatures trending upward.
Tonight
Partly cloudy, with a low around 55. North northwest wind 5 to 7 mph becoming calm in the evening.
Tuesday
Sunny and hot, with a high near 96. Calm wind becoming east southeast around 6 mph in the afternoon. Winds could gust as high as 20 mph.
Tuesday Night
Mostly cloudy, with a low around 63. East southeast wind around 6 mph becoming calm in the evening.
Wednesday
A slight chance of a shower or storm otherwise partly sunny and becoming windy later in the day, with a high near 82. Winds could gust as high as 32 mph. Chance of precipitation is 30%.
Wednesday Night
A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 46. Breezy, with a west wind 15 to 20 mph decreasing to 8 to 13 mph after midnight. Winds could gust as high as 37 mph. Chance of precipitation is 20%.
Thursday
Sunny & cooler, with a high near 73.
Thursday Night
Clear, with a low around 47.
Friday
Sunny & pleasant, with a high near 76.
Friday Night
Mostly clear, with a low around 46.
Saturday
Mostly sunny, breezy & cooler with a high near 66.
Saturday Night
Partly cloudy, with a low around 41.
Sunday
Sunny & breezy with a high near 68.
Sunday Night
Mostly clear, with a low around 42.
Monday
Sunny, with a high near 75.
