Temperatures at lower elevations averaged near normal, but over the higher terrain, temperatures averaged warmer or much warmer than normal. This pattern reflects the temperature inversions which were prevalent during the month.
No temperature records were broken or tied.
Precipitation was sparse for the month as a whole. But ironically, a storm at the end of the month brought heavy snow to some areas.
Following a period of cool northwest flow aloft at the beginning of the month, an upper level high pressure ridge which resided over the west coast kept our weather mainly dry.
On the 16th a low pressure system weakened as it moved through the ridge. It produced only traces of rain.
On the 19th and 20th another unremarkable system split as it moved inland, with the strongest portion heading south toward southern California and Arizona. Following this system, the ridge rapidly rebuilt over the northwest U.S.
By the 24th a pattern change was underway as the ridge shifted west over the Pacific, allowing an upper level cold low pressure trough to deepen over the Intermountain Region. On the 25th a weather system from the Gulf of Alaska moved into the trough, dropping traces of snow at a few valley locations before heading for the four corners area.
The next system was much more dramatic. As the storm intensified over the northwest coast on the 26th, it generated a steep pressure gradient across southeast Oregon and southwest Idaho, creating strong southeast surface winds. Gusts exceeded 50 mph at many locations. A spotter near Hollister in Twin Falls County measured a gust of 69 mph.
Yesterday's system produced 106 mph gusts at Cape Blanco, and the lowest unofficial pressure on record in CA. The storm continues to weaken and will redevelop into a different system on Friday. The threat of snow exists through Sat. Stay tuned for updates! #orwx #idwx pic.twitter.com/1XifbhsCMx
— NWS Boise (@NWSBoise) November 28, 2019
The storm also produced appreciable amounts of snow, not only at higher elevations, but also at a few valley locations. On the 27th there was an unofficial report of 10 inches at Baker City. A spotter at Burns measured 7 inches. At Weiser 5 inches fell, and Midvale got 7 inches. Even a few locations in the lower Treasure Valley got an inch or two. Amounts in the upper Treasure Valley were generally less than half an inch, leaving only traces on the ground.
❄️Snow amounts from this past storm. Trinity Mountain in Elmore County cashed in with the most snow at 20". Up to 15" fell in the mountains of Baker County Oregon. #idwx #orwx pic.twitter.com/gsr5nV9rZn
— NWS Boise (@NWSBoise) November 28, 2019
Snow continued to fall before the trough jumped the Rockies and headed across the Midwest. Lower elevation reports on the 29th include 2 inches at Buhl and Glenns Ferry, 3 inches at Hammett and near Mountain Home, and 4 inches at Gooding. In Malheur County 5 inches fell at Rome and Jordan Valley.
The 30th brought partial clearing under a transitory high pressure ridge.
