Historically wet California, unusually warm temperatures for Chicago?
The Yolo Bypass south of Sacramento has been flooded for the first time in nearly a decade. Water managers opened a number of weir gates on the Sacramento River on January 10 (constructed in 1916), diverting massive amounts of water into the floodplain known as the "Yolo Bypass". This type of flooding prevents the city of Sacramento (and other cities downstream) from catastrophically flooding. This chart from the California-Nevada River Forecast Center shows the Yolo Bypass water level well exceeding flood stage and projected to remain that way for a number of days (with more storms on the way, see below):
The photo of water spilling over the weir into the bypass is incredible (from WIRED):
Speaking strictly in numbers, the heavy rains this year are starting to break the drought. Here is a comparison chart showing the drought index during the peak of the drought (LEFT: October 2015) and now (RIGHT: January 2017). As you can see, the region of extreme drought has shrunk to only 2% of the state. With more rains next week, this will probably shrink even more:
The city of Sacramento has so far received 16.66" of rain this water -year (since October 1), which is 220% of normal. Many other stations in Northern California are running 150-250% of normal (or, in some cases exceeding 300%!), including the all-important stations in the Sierra Nevada. Here's a map showing the Percent-of-Average precipitation for the state as of January 13:
Looking closer to home, Los Angeles has actually received more rain at this point in time than during the very wet 1997-98 El Nino!
The Week ahead:
The next week will be pleasantly warm and dry with lots of sun. But the next series of storms should start moving into the area on Thursday. Stay tuned.
Shifting gears to Chicago: after a cool weekend, the early part of next week looks unsettled, with a rain/ice storm plowing through the area on Sunday evening. However, a bifurcation in the jet and a deepening trough in the western US will allow the Chicago/Midwest area to warm considerably toward the latter half of the week. Here's an image of the upper level wind pattern on Thursday afternoon:
The wind map shows a deepening and very strong trough on the west coast which will bring unsettled weather once more to California but will serve to push up a strong ridge in the central US, with the jet pushing up into central Canada! A little closer to the surface, here is a map of forecast 850mb temperatures during the same time frame:
You can see very warm temperatures stretching all the way up into southern Canada! These factors should work to push surface temperatures up close to 50 on Thursday and Friday and 60 near Chicago on Saturday! The best part: the sun may be out, too :)