Wetand News

 One of the backbones of the meteorological observing network is the radiosonde , a balloon-launched weather station that rises to around 110,000 feet before the balloon bursts and the instrument package plummets back to Earth, slowed by a small parachute. Such radiosondes are launched twice a day at approximately 1000 locations around the world. Most U.S. National Weather Service sites use a radiosonde made by the Finnish company Vaisalla, and specifically, the RS 41 unit shown below.  The projection at the top has the temperature and humidity sensors, a digital barometer is inside, and winds are derived by tracking the movement of the unit. One of the great pleasures of doing this blog is the emails I receive from many of you, with all kinds of observations and questions.   Well, today I got an email from Ian Cruickshank; while he was hiking in the forest in the Sooke Hills near Victoria, BC, guess what he found?  An American radiosonde unit (see the proof below). He asked me where i

The weather wisdom of the ancients. Red sky at night sailors delight, red sky in the morning sailor take warning. Or perhaps from the Book of Job. Fair weather cometh out of the north Weather proverbs and sayings are found in virtually every human culture.  Based on modern meteorological knowledge, do they make sense? The answer is found in my new podcast.  And so is the latest forecast, which includes rain on Sunday and a cool, but generally dry, next week. To listen to my podcast,  use the link below or access it through your favorite podcast service. Some major podcast servers:     Like the podcast? Support on Patreon 

Like many days this week, this morning dawned with low clouds and fog trapped under an inversion (see image for this morning).  Eastern Washington and interior western lowlands were pretty much covered in a thick blanket of white. But although low clouds might seem unremarkable, there are subtleties to the observant eye that reveal much about our local meteorology.  And there is beauty there as well. Take sunrise.   The visible satellite image taken just as the sun was coming up reveals the long shadow of Mount Rainier extending over the low clouds, like a dagger pointing to the northwest (see below). The tip of the point is just south of Tacoma. An hour later, the image around Hoquiam is revealing.   A narrow jet of fog is pushing westward into Grays Harbor.  And there are waves on the low clouds.  The fog exists in cold, dense air and this layer acts like a water body with waves undulating on its top. And then there are the tendrils of fog moving up river valleys.  For example, highe

 Inversions, in which temperatures INCREASE with elevation,  suppress vertical mixing, which in turn allows pollutant concentrations to increase near the surface. And with a strong inversion over western Washington and Oregon the last few days, air quality has degraded to moderate levels at several locations.   To illustrate, below is a map  (at 7 PM today) showing the concentrations of small particles (less than 2.5 millionths of a meter) that are capable of passing deep into your lungs. Nasty stuff.  Low concentrations are green, with moderate values in yellow and orange, and red being even higher.  The Puget Sound region has degraded air quality and it is even worse around Portland.  Generally good in the mountains. Graphic provided by PurpleAir You can see the declining trend of air quality in Seattle with a plot of the small particle concentration during the past few days (below).  A progressive upward trend in small particles. The sources of the particles include combustion from

Update at the end! High pressure and a super-inversion have developed over the Northwest, and jaw-dropping weather contrasts have developed-- both in the horizontal and the vertical. For example, yesterday (Saturday) temperatures zoomed up to near 80F on the southern Oregon coast, with 79F at Brookings, Oregon (see yesterday's max temps, below, click on the image to expand).  The forecasts were right. At the same time, temperatures were in the 40s in eastern Oregon and BELOW FREEZING in large sections of the Columbia Basin of Washington (see Saturday's high temps below).  If you were in frigid, sub-freezing Wenatchee yesterday and wanted to warm up by 20F you could do it-- by going up into the mountains.   This morning, the Puget Sound lowlands are enshrouded in fog, but clear skies are only about 1000 feet above.   Want proof?  Here is a picture from around 1200 ft in Bellevue, looking west, provided by Dr. Peter Benda.  Fog covers the lowlands, but blue skies are aloft. Or th

 High pressure has built over the region and will strengthen on Saturday (see surface map for 4 AM Saturday morning). Strangely enough, high pressure during the winter can have two localized impacts on our region:  cool, foggy conditions in the western lowlands, OR very warm, sunny conditions where downslope flow is forced by regional terrain. Such will be the situation this weekend, where northern Puget Sound will be dank, cloudy and cool, while the Oregon coast (and to some degree the southern WA coast) will enjoy sun and warmth.  The Columbia Basin will also be caught in the murk and cold. To illustrate the wildly varying situation, here is the forecast surface air temperature for 1 PM Sunday.  Some places on the Oregon coast will get into the lower 70s, while Puget Sound will be in the lower to mid-40s.  BELOW FREEZING in the Columbia Basin.  Quite nice on the Long Beach Peninsula.  COLD over Northwest Washington. Want to know why such extremes occur over our region during high-pre

 Don't worry,  this time code red is a good thing. Below is the latest high-resolution surface temperature forecast for Saturday at 4 PM.  Red colors are temperatures above 60F along the Oregon coast!    The kind of code red I like.  And near Brookings, just north of the Oregon/CA border temperatures surge into the mid-to-upper 60s. On Sunday, the code red temperatures are even more extensive along the coast as well as extending along the western slopes of the Oregon Cascades, The highly skillful European Center model is going for 66F in Brookings, Oregon on Saturday....and 62F on Tuesday.  Brookings is well known for being the warmest location in the southern Oregon "banana belt."  And there is a reason (more later). Our "code red" temperatures are associated with a high-amplitude upper-level (500 hPa) ridge over the northeast Pacific, with two "bookend" troughs on both sides (see below).  This is a very stable pattern. Why does high pressure alo

After months of jet streams, atmospheric rivers, snowstorms, cold waves, and low centers, a huge persistent ridge of high pressure will soon form along the West Coast. But you will have to be patient.  For three more days, a series of weak systems will bring precipitation to the area. But then the region will turn dry, and in one area, the Pacific Coast, the temperatures will rise to very pleasant levels.  Book your room now! First, the ridge. On Friday, high pressure will explode over the eastern Pacific and by 1 AM Saturday, the mother of all ridges will be evident aloft (500 hPa pressure level, about 18,000 ft) shown below.   Two troughs of lower pressure/heights are found on the sides.   This produces an OMEGA pattern, which is very stable. UW Model Forecast for 1 AM Saturday This pattern will hold in for the weekend and beyond.  At the surface, high pressure will be centered just offshore of Vancouver Island and inland, producing moderate easterly flow over the coastal zone of O

Yesterday, around 0400 UTC 15 January (8 PM PST 14 January), there was a massive, explosive eruption near Tonga, in the southern tropical Pacific, about 5642 miles from Seattle (see map). The volcano was clearly evident in satellite imagery from the massive ash cloud (see below, about 1-h after the eruption) The explosive eruption created shock waves in the atmosphere (pressure waves) that rapidly propagated away.  These waves are evident in some infrared (water vapor channel) imagery as concentric rings (shown below). The oceanic eruption also pushed away a massive amount of water, which created a tsunami on nearby islands (such as Tonga) and deep water waves that moved away at the speed of a jet plane, reaching the West Coast this morning.  This is why some local tsunami warnings went out this AM. The Pressure Wave Reaches the Northwest Local barometers indicated a well-defined pressure wave passing over our region around 4:30 AM this morning.  Here in Seattle, the University of Was