June 2012 will be remembered. Numerous locations in the eastern 2/3rd of the country took home climatological gold medals with an onslaught of daily, monthly and all time maximum temperature records, wildfires in New Mexico, Colorado and Wyoming in the wake of intense short-term drought and record or near-record fire danger, tropical storm Debby brought up to 20 inches of rain to moisture-starved sections of Florida, and by month’s end a whopping 70% of the lower-48 was experiencing drought, the most since the advent of the US drought monitor in 2000. The the lack of moisture the last two months in the midwest has farmers very nervous about failing to capitalize on a potentially great corn crop this year that had a huge jump-start on the growing season due to unusually warm temperatures in March.
Meanwhile, while these weather and climate stories were making national headlines, the Inland Northwest had its own story to tell and trophies to hand out. Gold medals were awarded for the wettest and coolest (for daytime high temperatures) June on record for a WSW-ESE oriented swath from Walla Walla, Washington through the northern panhandle of Idaho and toward Glacier National Park. The coupling of wet and cold daytime high temperatures is not a coincidence, but physically consistent with reduced solar heating due to cloud cover and wet ground reducing sensible heating. An extremely wet June on the heels of an extremely wet March has resulted in calendar-year-to-date precipitation amounts in or near record territory across northeastern Washington, the Idaho panhandle and parts of northwestern Montana.
At the broader scale of the western US, we can see that the dividing line separating the haves-and-have nots bisects the region. By the way, you can decide which group you are in depending on your proclivity to precipitation, sunny days and warm temperatures. Drought is by no means acute in the inland northwest, at least relative to other parts of the US; however, the US drought monitor reports that about 47% of Idaho is currently in a benign drought, compared to 0% this time last year, and only 5% three months ago. A similar storyline is also the case for Montana.
In my last post I referred to us turning the corner toward a summer regime characterized by a prolonged period of quiescent weather (no precip, nominal clouds, warm days) where a large upper-level ridge acts like a guardian to ward off the decaying weather systems that dare cross the Pacific.
Bottom line is that we are not only turning the corner to summer, but going to experience some g-forces in doing so. The National Weather Service office in Spokane is anticipating that northern Idaho and eastern Washington will experience their warmest temperatures since August 2009 toward the end of this weekend. The persistent ridge that has been slaying records across much of the central US is retrograding, or moving westward (typical for very large waves during the summer), and will set up shop over the western US for at least the first half of July bring a respite from the heat in the Great Plains. (note, the colormap on this plot is a bit deceiving as grey = warmer than normal conditions). We’ll also keep our eye out for some convection as monsoonal moisture permeates northward into the region. Given the relatively dry conditions in the Great Basin following a wet year in 2011, the potential for dry lightning ignited fires will be elevated.