Wetand News

While the Northwest has been drier than normal, it has been drenching wet a few hundred miles to the north. An unusually strong atmospheric river ....a long current of moisture stretching southward to the subtropics...has been in place for days, bringing large amounts of water vapor to Alaska.   And the atmospheric river will be in place for several more days, slowly moving southward. To illustrate, the scale and beauty of the atmospheric river, here is a water vapor satellite image for 11 AM today. The lighter areas have more water vapor.  You can see the current of moisture extending from near Hawaii into central BC.  This current is the result of low pressure over the Gulf of Alaska and high pressure offshore of California.   A forecast of total water vapor content in the atmosphere for 11 PM tonight shows a healthy atmospheric river (white and blue colors indicate the higher amounts of moisture). As this atmospheric river slams into the mountainous West Coast, the air is forced to

  Most of the time, you can not see the air move.   You can feel it, but the complex, turbulent motions are invisible to you, except when it interacts with leaves and branches on trees and plants. But for a few weeks of the year, the sky is full of small, cotton-like tuffs that like a natural MRI machine reveals the complex three-dimensional motions of the atmosphere.   Cottonwood season.  And we right in the middle of it.   Being cottonwood aware is of particular value this year.  It reveals the active dispersion and movement of air that makes the outdoors essentially COVID safe, and thus should be of some comfort for those nervous about transmission outside. Cottonwood seeds are embedded in small cotton-like fibers.   A million seeds weigh about 3 pounds.  Yes, each seed and tuff weights about .000003 pounds.   And that fact, plus the cottonwood tuff, means that these seeds fall VERY, VERY, VERY slowly.   So slowly that they are excellent markers for the three-dimensional flow of the

  The key technology of weather forecasting is numerical weather prediction , using powerful computers to simulate the future evolution of the atmosphere. The first numerical weather prediction--using a digital computer to solve the equations describing the physics of the atmosphere-- occurred in 1950 using the ENIAC computer (see below) And numerical weather prediction was immeasurably improved with the advent of weather satellites that can provide a three-dimensional global view of atmospheric structure. TIROS-1 the first weather satellite is shown below. My podcast describes the history and technology of numerical weather prediction and provides a very favorable Memorial Day weekend forecast.  Listen to my podcast below or through your favorite streaming service. Here is my podcast, with more streaming information at the bottom of the blog. Click the play button to listen or use your favorite streaming service (see below) You can stream my podcast from your favorite services:   List

 Y ou start with a late spring day after fields have been plowed for a number of crops. You add a relatively dry spring, with rainfall less than 50% of normal over most of the region. And you throw in strong winds, gusting to 40-70 mph in some places. The result:  blowing dust, obscured roads, and even some visibility-related accidents. Eastern Washington There is dust blowing right now around the Tri-Cities and around I90 from roughly Moses Lake to Spokane.   Check out this video from WA State Trooper C. Thorson (click on the link) taken in Richard (I82 and Dallas Rd).  Make sure you have the sound on! https://twitter.com/i/status/1398041775210598403 Or check out this WSDOT cam in Davenport--pretty hazy. The visible satellite picture at 4PM clearly shows the dust--- I put on an arrow to make it clear.  The blowing dust is a light brown color. Now springtime dust storms are not that unusual in eastern Washington.  Unfortunately, it happens every year. Western Washington But less usual

 A few days ago, a blog reader emailed about atmospheric pressure.   He asked:  Since can't feel it or sense it, why should we care? I was surprised by the question since atmospheric pressure is so important in meteorology and weather prediction.     So let me give you a lowdown on pressure--by the time I finish,  you will run out and buy a barometer! Atmospheric pressure at the surface of our planet is not negligible.   On average, pressure at sea level is about 14.7 pounds per square inch!   That is like a bowling ball pushing against every square inch of your body! Since the human body has about 2600 square inches of surface area, the is equivalent to the force of several thousand bowling balls.  Or 38,000 pounds of force or 19 tons! Why aren't we CRUSHED???      Because the pressure inside our body balances the external force from atmospheric pressure.    But you can tell that this massive pressure is there by lowering the pressure inside an object---it is summarily crushe

The Pacific Northwest has a Mediterranean climate, with wet winters and very dry summers. Thus, it is important for us to approach summer with full reservoirs, ample mountain snowpack (which provides melt water during the summer and early fall), and a nice late spring dousing to wet down the vegetation and soils. And it looks like we will have all three. As most of you know, we have had a dry spring so far, with the eastern part of the state receiving 0-3 inches less than normal and larger deficits in the west (as much as 9-16 inches below normal)--see below. On the other hand, there is good news.  With a relatively cool, wet, and snowy La Nina late winter the key reservoirs serving our region are looking good.   The critical Yakima River reservoir system, so important to agriculture in eastern Washington, now possesses above-normal water levels (see below, blue is this year and red is normal). Seattle's reservoirs are near normal and the snowpack above Seattle's reservoirs ar

The Cherrywood Fire of southern Nevada.  DOE image. My New Podcast My new podcast is out, providing the latest forecast for this weekend, and in the second part, I describe the history of weather forecasting over the past 200 years. Here is my podcast, with more streaming information at the bottom of the blog. Click the play button to listen or use your favorite streaming service (see below) First Smoke of the Season I was a bit surprised when I saw the visible satellite imagery this morning:  there was clearly significant wildfire smoke over the eastern portion of Washington State (see image below).  This smoke is aloft and not reaching the surface. This is confirmed by air quality monitors around the region, which are all green (good air quality). The Cherrywood fire is now about 15,000 acres in size and is burning in mainly grass, so I suspect it will be short-lived (grass fires generally burn fast and are accessible to fire-fighting).   You can see the movement of the smoke from th

  This is the season of large cumulus clouds over the Pacific Northwest.  And they are often stunningly beautiful. There is a reason why these majestic clouds are so frequent this time of year:  the atmosphere is most unstable and turbulent during the spring, for reasons I will explain below. And with strong sun and long days, the illumination is excellent, and the potential for rainbows ever-present. Consider an image from the Seattle PanoCam for yesterday evening as the setting sun illuminated the underside of a large cumulus cloud east of Seattle.  There is an extensive cirrus anvil-like structure aloft (with wispy edges) and downward protuberances called mammatus clouds extending downward from the anvil.  These features are associated with heavier air that is sinking. A few hours earlier, the PanoCam caught a growing cumulus cell south of Seattle with a shaft of rain falling beneath it. And here is an extraordinary photo of a large cumulus cell over the South Sound yesterday take

Three weeks ago, there were fears that COVID was increasing again and Governor Inslee was thinking of backtracking on reopening the State.    Local papers were carrying stories warning that herd immunity was impossible. But a careful analysis of the numbers, as  >provided in my blog of May 1st , showed the opposite:  that Washington COVID cases were about to plummet . And that is exactly what has happened.    Consider a plot of Washington COVID cases from March 1st to May 16th below, showing both daily cases and a 7-day average (data from the WA Department of Health website). The daily cases (and 7-day average) peaked in late April and then declined rapidly by roughly 40% through mid-May.  Note there is a weekly cycle of collection, with some days with better collection than others. Washington State COVID is collapsing.   And it makes perfect sense. If you read my earlier blog, the analysis started by trying to get a measure of the percentage of residents (of each state) that poss