Wetand News

There has been a great deal of interest in hurricane prediction this week with the landfall of Hurricane Ian, so this week's podcast discusses progress in hurricane forecasting.  The story is a nuanced one.  Hurricane track prediction has gotten much better over the past decades, with position errors at 72h decreasing by roughly 75%! (see below) But on the other hand, the intensity forecasts, although improved, have not advanced anywhere as much as the track predictions (see below). In my podcast, I explain why the difference in skill between track and intensity forecasts, telling you about some of the challenges. And I also talk about the forecast for Hurricane Ina.  The European Center and UKMET office models did far better than the U.S. model for the 3-6 day forecast, but amazingly BOTH forecast a major storm in the area NEARLY TEN DAYS OUT (see below for the proof). US Model 20 day forecast European Model 9 days out And in the first segment, I provide the forecast. Warm, dry,

European weather prediction models proved to be substantially superior to U.S weather prediction systems predicting the track of Hurricane Ian. >blogged about and written papers about in the past, with the most well-known past case being Hurricane Sandy in 2012.   And it reflects the decline of U.S. national weather prediction skill versus leading international centers--a situation that is a national embarrassment and must be fixed. Let me show you the unfortunate details for Hurricane Ian. I will start with a graphic of forecast track error by Professor Brian Tang of the University of Albany ( website here ).  This figure presents the track error (in km) for various forecast lead times. The main US global model (the GFS) is shown by the dark red color (AVNO), while the leading weather prediction center in the world (the European Center) is shown by blue (ECMF).  The high-resolution US hurricane models (HWRF and HMON) by purple and cyan, and the official forecast (with human inpu

A dry Pacific Northwest in July and August is the normal state of affairs, but this year was particularly arid. Some media outlets have claimed this is Seattle's or the region's driest summer on record.  Is that true? Let's find out.   At Seattle's SeaTac Airport, this summer (June 21-September 21) was the driest in a record doing back to the late 1940s (.50 inches) .  2017 was right behind (.52 inches).   What about a nearby station with a longer record (Kent), going back to 1912?  That is shown below with a trend line.  2022 was the driest summer on record but some came close in the 1925-1945 period.  The trend shows a slight decline (maybe a half-inch) over 110 years.  The very small long-term trend will turn out to be important. What about east of the Cascades?   This is important because of the agriculture there and the frequent wildfires.   A different story from the west.   Spokane (going back into the late 1800s) was dry but six other years were drier. And Kenn

The number one question I have been asked the past few weeks is certainly this:  when will the rain return? And I can answer that now: the middle of this week. Today was another nice warm day, with the origin being a strong upper-level ridge over the West Coast (see upper level map at 5 AM this morning, below).  Yes, another ridge. This ridge was associated with low level easterly flow that pushed more of the smoke from the smoldering Bolt Creek fire into some communities on the eastern side of Puget Sound country (see noon satellite image below) You can view the air quality implications wutg  the Purple Air map around 3 PM (orange and red are worst).   Not as bad as last week, but some haze is apparent on the east side.   Some have smelt smoke. Tomorrow will be the last warm day in the sequence.   Everything changes on Wednesday, as a moderate upper-level trough moves in (see upper-level map at 5 AM Wednesday).  And it won't be the last. Light rain is forecast for Wednesday into e

Here in Seattle, the smoke was amazingly thick on Wednesday morning, only exceeded by the extreme event of Sept. 2020 and equaled by the smoky period in summer 2018 (see small particle levels at Lake Forest Park over the last 5 years ago). The intense smoke was associated with a dying fire (Bolt Creek) in the Skykomish Valley.   How could this be? The explanation is found in my podcast (see below).  The "perfect storm" of meteorological conditions. And talking of perfect, consider the weather conditions over the Northwest this weekend. ANOTHER ridge of high pressure will develop over the West Coast this weekend (see upper level map , 500 hPa--about 18,000 ft late Sunday below).  And you know what that means.... warmth and sun. But this time of the year we can't get really hot...so highs will only get into the upper 70s in the west.  Nearly perfect.  It won't last though...cooler temperates for mid-week, but little rain in the forecast.  My podcast goes into the detail

 I walked outside this morning in north Seattle around 6:45 AM and the smoke smell was very strong.   The expected worst (and last) day of the smoke is here and it is nasty. The Seattle PanoCam this morning at sunrise clearly showed the shallow smoky miasma over the city.  Even the tops of some of the tall buildings are above the worst of it.    The calibrated Purple Air air quality sensors this morning shows the plume of terrible surface air quality exiting from the Skykomish Valley from the Bolt Creek fire, which then heads south over Seattle.   Purple colors indicate truly bad air quality.   Red is just bad.    The plume is relatively narrow...head east or west and you can get out of it. The Puget Sound Clean Air Agency has a ceilometer in Marysville that shows the vertical structure of the smoke plume at that site (which is a bit north of the worst of it).  The graphic (shown below) shows that the worst of it (yellow colors) was down low and moved in last evening.  Yuk. The latest

A narrow plume of relatively dense smoke from the Bolt fire has been pushing into western Washington the last few days. And today may be the worst of the period. The 11 AM surface air quality network run by Purple Air shows the smoky air (red colors are the worst) moving westward out from Steven Pass highway into Everett and north Seattle.  I can smell the smoke here at the UW. The high-resolution visible satellite image this morning clearly shows the plume of smoke following through the relatively narrow Skykomish River valley and spreading out as it hits the lowlands. Near sunrise this morning, the smoke plume was apparent looking northward by the Seattle PanCam. Although not spread horizontally, the Bolt Fire is still smoldering and burning internally, producing significant smoke, as evident from WSDOT cams on Route 2. The meteorology is interesting. Cool air produced by the longer nights drains into river valleys (like the Skykomish) and then jets out into the lowlands, injecting t

 There is a lot of weather happening in the eastern Pacific. First, an unusually powerful low-pressure center, with intense rain and hurricane-force winds, is hitting northwestern Alaska (see surface pressure map at 11 AM Saturday).  A deep, 963 hPa low center.   This storm developed out of Typhoon Merbok, which underwent extratropical transition :  converting from a tropical storm to a midlatitude storm. https://oregonams.wordpress.com/2022/09/06/columbus-day-storm-60th-anniversary-meeting-with-professor-cliff-mass/ Reminder: I will be teaching ATMS Atmospheric Sciences 101 this fall. Like last year, I am teaching atmospheric sciences 101: a general introduction to weather and climate, this fall. You can learn more about the class on the style="color: #2288bb; text-decoration-line: none;"> class website . I talk about everything from the basics of the atmosphere to weather prediction, thunderstorms, hurricanes, and local weather to global warming and climate. I will be

My podcast today will both provide the weekend weather forecast and talk about the history of wildfires in the Pacific Northwest. Wildfires and associated smoke are a major concern in the region, and some media, politicians, and others have suggested that wildfires and wildfire smoke are not normal and are a potent sign of a changing climate. They are not correct.  Wildfires and their smoke are a natural part of the Northwest ecosystem. What was not normal was the period of suppressed fire during the later portion of the 20th century. A good illustration is the visit of Mark Twain in August 1895, a summer in which the U.S. Weather Bureau noted "the sun was almost entirely obscured by excessive smoke from wildfires."   Twain was invited to speak in Olympia, where the chairman of the reception committee apologized for "smoke so dense that you cannot see our mountains and our forests, which are now on fire".  Twain retorted “As for the smoke, I do not so much mind,  I