High temperatures Sunday exceeded the 90’s both west and east of the Cascades. Monday will be the hottest day of the week before afternoon highs begin to gradually decline through Friday. Monday will also mark the first day of the incoming thunderstorm threat.
An upper level cut-off low sitting just off the coastline of California combined with an area of high pressure across the four corners, will work together to drive moisture north in the coming days. This along with increasing instability, will bring favorable conditions for thunderstorm development across the viewing area.
Precipitable water values will exceed 1” by the middle of the week. This is a weather parameter measuring the moisture content in the air, and values for this region exceeding 1” are high. For this reason, storms that do develop will be heavy rain producers and will certainly help improve air quality. On the other hand, the cloud to ground lightning (mainly on outlying areas) will require close monitoring. Because air is so dry near the surface, it is typical to see strong outflow winds as storms dissipate, also something that will require close monitoring. Hail will be likely as well this week.
Thunderstorms are going to be isolated Monday, and mainly across Siskiyou County and southern portions of the Basin. By Tuesday, the entire Basin, Cascades and Siskiyou County will see a good chance for thunderstorm development. Wednesday, the threat expands west to the valleys and by Thursday, Curry County could hear a rumble or two.
Meteorologist Alyssa Caroprese