Wetand News

 The media has been going a bit crazy about a very common and usually benign meteorological phenomenon.    A weather satellite feature called a baroclinic leaf- -a thickening of the jet-stream clouds that is associated with the incipient development of midlatitude low-pressure centers. This tempest in a teapot all started with a tweet by the National Weather Service on Tuesday that mentioned the baroclinic leaf (see below).  The purple arrow points to the feature, which is characterized by a curved mass of clouds.     Some folks think it looks like a leaf.  I am not convinced.   Below is an infrared satellite image showing the baroclinic leaf at a slightly different time (I put a red oval around it). We see such features over the Pacific dozens of times each autumn and winter.  The term "baroclinic" indicates it is associated with a horizontal temperature gradient (or change with distance).   A well-known meteorological term. As noted above, the media went silly about this ru

Some of the most ferocious storms of the planet develop in our backyard:  the Gulf of Alaska. Storms that are not hurricanes or typhoons but capable of producing winds and waves comparable to Category 3 tropical storms. And one will occur in a few days. The satellite imagery of these storms is remarkable, as illustrated by a powerful example from September 26, 2012.  Masses of frontal clouds swirl into the low center, not unlike water circling into a drain.  The low center is in the center of the swirl.   The energy source of these powerful storms comes from contrasting cold and warm air, with warm southerly flow in front of the storm and cold air circling behind.  The popcorn-like, modeled cloud field south and west of the low center in the above picture indicates cold, unstable air.  This storm had plenty of fuel The central sea-level pressure in Gulf of Alaska low centers can drop as low as 930 hPa (hectopascals, also known as millibars).    Such pressures are similar to the central

There have been a lot of stories about heatwave deaths this summer and the latest Washington State Department of Health (DOH) statistics indicate that the June 2021 heatwave contributed to 91 deaths.    The DOH also noted that 39 individuals died from heat-related complications from 2015-2020.  Nearly all of those who lost their lives were either elderly or suffered from serious pre-existing conditions. Heatwave deaths are all tragic losses and we should do all we can to prevent them, including expanded use of air conditioning, cooling centers, and more. But it is also important to understand the other "side of the coin", about deaths resulting from cold waves, both in the Northwest and the rest of the nation. And the facts may surprise you.   Far more people die from cold than heat.   Furthermore, cold waves sometimes kill young people, often on icy roads. Consider the national statistics provided by the U.S. Environmental Prediction Agency .  Based on hospital records, the

Weather and climate modelers like myself use a lot of technology for weather prediction, and that technology has become very capable. But we should not forget that there is a lot of information available by simply being a good observer and my podcast will give you a prime local example:  "cap clouds" over our major mountain peaks. Cap Cloud over Mount Hood.  Courtesy of Steve Rawley My podcast will explain why cap clouds and lenticular clouds are often a potent sign of upcoming clouds and precipitation. And my podcast will also supply the latest forecast, describing the warm weather today and Saturday, followed by an extended decline into clouds and rain.  The totals over the next week will be substantial, with over five inches in the Olympics, North Cascades and the mountains of southwest BC (see total below).  Wow. You can listen to the podcast below or through your favorite podcast server. Or access the podcast on all major services.     Like the podcast? Support on Patreo

We are now enjoying a short period of relatively dry conditions before the next surge of moisture reaches our shores, starting later on Sunday.   With the expected precipitation,  September precipitation over the region will come in way above normal . And the recent cool, wet weather has had one positive impact:  local wildfires are rapidly declining, with MUCH less smoke apparent in satellite pictures. Compare the NASA MODIS visible satellite imagery for Tuesday (Sept. 21) with earlier this month (Sept. 7)--see below.  A LOT more smoke two weeks ago!  And with the upcoming rain, the remaining Northwest fires will become history. Sept. 21 Sept. 7 River levels and streamflow are generally near normal around the region, which is good for supporting local salmon runs around the region. The Soggy Story for Next Week     The dry conditions today through Saturday are associated with a ridge of high pressure aloft over the eastern Pacific (see below).  You can see the large high pressure/heig

We have had a dry spring and summer and people are concerned.  Completely understandable. And people's discomfort and fears have been unnecessarily worsened by the incessant drumbeat in the media and some politicians that Northwest summers are been getting drier.   And they are not shy about suggesting the cause:   climate change or what was previously known as human-caused global warming. But is this really true?  Do observations REALLY show that our region is getting progressively drier over the past decades and century?   The facts are clear:  there is no long-term trend towards drier summers in the Northwest.   And the effects of climate change (global warming) will be very small, with some locations receiving more summer precipitation.  But as in real life, there are details and nuances that are generally not provided in the media.....let me provide them to you here. Fact 1:  The Pacific Northwest is climatologically one of the driest locations in the U.S. during summer. Few

  Nearly 100,000  Washington State  power  customers lost power last night as strong winds first hit Northwest Washington and then spread across the remainder of the western interior as a powerful front crossed the region during the late evening.  Trees are very vulnerable to the first windstorm of the season, particularly if they are fully leafed out. Winds gusted to around 60 mph over Northwest Washington, 40 mph over the lowlands of the South Sound, and reached 103 mph at Camp Muir on Mount Rainier. The power outage map from Puget Sound Energy last might shows the damage, centered around NW Washington and the south Sound towards the Cascades. Here are the top wind speeds on Friday (click to expand).  A gust to 63 mph a Whidbey Island Naval Air station, nearly the same at Port Townsend, and nearly 50 mph on the San Juans.   These winds occurred during the afternoon before the front made landfall.    Strong winds over NW Washington are very typical for winter weather systems around he