An important change is taking place this week with respect to the southern branch of the jet stream that will allow for two separate Pacific Ocean storms to slam into drought-ridden California with some much needed rain and snow. Both of these California systems will then travel across the country and, while the first system may be inhibited in growth by an extensive Arctic air mass, the second system may end up playing an important role in the eastern U.S. in about a week or so.
The first storm to hit California this week from the Pacific Ocean is destined to arrive in the Wednesday/Thursday time frame. The second, and most likely stronger system, should move into California in the Friday/Saturday time frame. The combination of these two systems will probably dump several inches of rain on coastal and low-lying sections of California over the next 5 or 6 days along with several feet of snow on the Sierra Nevada Mountains. This rainfall will not end the drought, but it will help quite a bit and perhaps be a sign of better things to come.
The first (weaker) system will then cross the country and it could spread some snow into the eastern states early in the weekend. However, an extensive cold and dry Arctic air mass will be entrenched in the eastern states at this time and this will likely reduce the threat for anything too significant although there are still several days to go and this system needs to be monitored.
The second and stronger system that should hit California at the end of the week is likely to have a bigger impact in the eastern states early next week. This system will also traverse the country in a west-to-east fashion and it should generate precipitation in the eastern states in about a week’s time. Strong high pressure to our north appears to be part of this potential atmospheric scenario early next week and this would increase the odds that enough cold air sticks around for at least some snow in the eastern states and it also would help to set up a “cold air damming” environment that can lead to significant “overrunning” precipitation.
Bottom line… it appears that the second and stronger system to hit California later this week in an newly activated southern branch of the jet stream could produce important precipitation amounts in the eastern U.S. in about a week’s time. The 00Z Euro model forecast maps show the location of the second California storm in the west on Friday night (above) and then in the east on Monday night (below). Stay tuned.