Wetand News

 My podcast today deals with cold and snow. And it will give you a foundation regarding the mountain gaps that channel cold air in our region. Tomorrow, an approaching front and associated trough of low pressure will rev up the north-south pressure differences, causing strong southerly winds over Puget Sound (see the pressures at mid-day tomorrow below).  Gusts to 40 mph can be expected. Then a cold front will move through Tuesday morning, bringing lots of snow in the mountains on Tuesday.    Late Tuesday and Wednesday, much colder air will push into Washington state, bringing highs in the 30s and lows in the 20s for western Washington, and ten degrees colder over the Columbia Basin.    Some snow showers will fall over Puget Sound, but feet of new snow will accumulate over the Cascade.    The snow totals through Thursday morning are shown below: The second half of my podcast will talk about the importance of gaps in our mountains, and how they act as critical conduits of cold (and not-

If anyone thought that La Nina would sneak away with little notice, the latest model predictions should disabuse you of that opinion:  an extraordinary cold wave will occur next week, with several daily cold records destined to be broken. But there is more:  huge additional snowfalls will occur over the mountains of the entire West Coast. Let me start with the predictions at Seattle and Pasco, WA for the next week, based on the National Weather Service Blend of Models predictions. There will be warming over the weekend into Monday, with a transition occurring on Tuesday as modified Arctic air pushes in.    The highs on Wednesday through Friday will be in the 30s, and the lows will be at freezing or below every night, bottoming out at 22F Friday morning. For Pasco, even colder, with temperatures dropping into the low teens. Now let me show you the maps of pressure and temperature (at around 2500 ft), which will give you a good feeling about how the Arctic is coming to us!  I have waited

Today, machine learning (ML) applications such as chatGPT are all the rage, with folks worried about the displacement of humans, bogus homework, and more.    So I was not a little curious to evaluate OpenAI's chatGPT abilities in the meteorological realm. My conclusion:  human meteorologists currently don't have much to worry about. ChatGPT can produce reasonable-sounding prose that is often totally wrong . For example, I asked it about the origin of the all-important Puget Sound convergence zone (see below). According to chatGPT convergence zones occur when ocean air collides with drier air from the eastern part of Washington State.  Wrong.  The Puget Sound Convergence occurs when marine air moves around the Olympics and then converges (comes together) east of the Olympics, forcing air upwards (and thus producing clouds and precipitation).   Zero for chatGPT Then I thought I would give it an easy one...why Bellingham is often cold.  The answer is that cold air from the interio

 The models were scary good tonight. As predicted, a double convergence zone formed this evening, producing heavy rain, thunder, small hail, and yes....snow. Snow has been reported around Everett (Paine Field), Marysville, and at SeaTac Airport. And snow was reported earlier on the higher hills around Bellevue (see below) Snow at 1170 ft in Bellevue.  Picture courtesy of Dr. Peter Benda In the radar image above, the orange and red areas indicate heavy precipitation and small hail associated with strong convection, including embedded thunderstorms.  Several have reported thunder. And there are major power outages in south Seattle that I suspect are due to the thunderstorm activity (see below) Expect the precipitation to fade out overnight, making way for a chilly Tuesday morning.

 There are some situations that local meteorologists really worry about:  when both temperature and precipitation are on the margin for snow.    And the situation tomorrow and early Tuesday is just like that....on the edge. The latest UW WRF model run is painting a snowier picture over the western lowlands , as illustrated by the snowfall total through 10 AM Tuesday (below). Several inches over north and south Puget Sound.  General snow over SW Oregon and Portland.  Loads of snow over the Cascades.   The latest NOAA/National Weather Service HRRR model forecast has most of the lowland snow over north Seattle (see below). I should note there is plenty of uncertainty for the Puget Sound snow. In my podcast today, I talk about this situation and describe the complexities of this snowfall event.  The "inner baseball" of westside snow, including rainshadows, convergence zones, and marine influence. To listen to my podcast, use the link below or access it through your favorite podca

 Our military pilots have been busy this weekend, with two more shootdowns of objects floating into U.S. airspace from the west. The first shootdown occurred near the northern Alaska coast late Friday night (0645 UTC 11 February), with the object (a smaller balloon) at around 40,000 ft (12000 m) above sea level. As described in my previous blog, I ran the NOAA Hysplit trajectory model, to calculate the back trajectory over the past few days of air ending at 40,000 ft (12,000 m), as well as 8000 and 16,000 m (shown below). Looking at these trajectories, one worries that this might be a Russian balloon!     The trajectory ending at 40,000 ft started over western Russia, and the trajectory above it originated over Russia as well.  The lower trajectory could have passed over far northern China, but that would assume that the balloon was able to move up and down by command.   Maybe there is a reason that our military is being relatively quiet about this one. The object that ended over the C

 I don't want to hype the situation, but I do think some snowflakes will descend on portions of the western lowlands next Tuesday and Wednesday. To illustrate, below you find the sea level pressure and temperature (925 hPa, about 800 m aloft) for Tuesday at 4AM.    Blue colors are cold enough for snow---and such chilly air extends over much of the region. The daily highs and lows in Seattle for the next week from the National Weather Service National Blend of Models, shows the cooling trend down to highs in the mid-40s.  Not nearly as cold as in December, but Tuesday and Wednesday mornings will be cold enough for snow.   But will there be moisture? A front will move through tonight, bringing rain to the western lowlands and light snow in the mountains.  In fact, the latest radar imagery clearly shows the rain, which soon reaches Puget Sound. The amount of snow in the mountains tonigth will be relatively modest (see total through 1 AM Saturday below).  Only a few inches. The second