An upper level trough will cross the northwest Pacific states Fri/Sat and eject into the central Plains on Sun. This will bring periodic windy conditions across the western US and cooler weather for the northwest. No critical widespread critical fire weather is expected, although some areas will have enhanced conditions that will aid in fire spread, especially with drought conditions across the west. Continued heat is expected for the southwest with dry conditions prevailing.
The primary fire threat across the US will focus on warm temperatures and low RHs in the western Great Basin Fri and Sat. Breezy westerly winds are expected Fri/Sat especially across much of NV due to the approaching upper level trough. As the trough shifts eastward, wind conditions will move across northern UT and southern WY/northern CO into Sun/Mon. Dry conditions over much of WY/CO will provide an increased fire risk with these strong westerly winds.
The southwestern US will remain dry and hot through the period. Portions of central/eastern CA/NV/AZ will have poor RH recovery overnight. Though no windy conditions are expected across this region, above average temps and below average precipitation will lead to conditions conducive to human caused fire starts and challenges for suppression
A cold front crossing WA/OR will bring breezy conditions Fri, however, temperatures are expected to remain cool and RH is expected to remain above critical levels. A lack of upper level moisture will prevent any thunderstorm development, however some light rains are possible along western slopes. A stable post-frontal air mass will provide quiet conditions for the Pacific Northwest and eastward with the front’s advancement through the weekend. Cooler weather is expected to continue through the period for WA/northern OR/MT/northern ID with warming conditions likely Tues in advance of the next system.
Long term into mid-week, a summer type pattern looks to return for the central US with another trough pushing into the west. This may develop enhanced fire weather conditions across the western US mid-week and central Rockies mid-to-late week and should be monitored.
Eastern CA/NV: Breezy westerly winds Fri/Sat with low RH and warm temperatures. Locally critical fire weather is possible, otherwise generally enhanced fire weather is expected across the region. Winds will be decreasing Sun.
WA/OR: Breezy conditions are likely today across central portions of OR/WA on the eastern sides of the Cascades. Moderate temperatures and RH should prevent any increased fire risks. Warming with decreasing RH across southern OR late weekend and moving northward into next week.
Southern WY/northern CO/northern UT/southern ID: Developing strong westerly winds Sun/Mon. Combined with warm and dry conditions, this will lead to an enhanced fire threat continuing into mid-week.
Southern/central CA/AZ: Continued warm and dry with poor RH recovery. Some breezy winds Fri in eastern CA, otherwise no significant winds/thunderstorms.