Wetand News

Most weather fronts that reach the Northwest coast are generally wimpy.    Only a slight change in temperature, a minor wind shift, and a modest change in humidity.   Quite a contrast to the often strong fronts of the central and eastern U.S. The reason for our generally unexceptional fronts is two-fold. First, the fronts reaching our coast are generally aged, declining occluded fronts, compared to the prime, active fronts of the western Pacific.   Cyclones and fronts are driven by large temperature gradients  (changes of temperature over distance) and a strong jet stream, something that exists over the western Pacific, where cold air from Siberia meets the warm water of the Kuroshio current.  Not true off our coast. Frontal Image Produced by Dall-E Machine Learning Second, the temperature changes across our fronts are generally weak because they have traveled across thousands of miles of temperate ocean, which progressively warms the cold air following the fronts (see Pacific sea surf

In my new podcast (see information below), I talk about a major weather transition that will occur over the West Coast, with the development of a huge, persistent ridge of high pressure (see upper-level map below for Sunday morning). California will have a chance to dry out. And in the second part of the podcast, I talk about the claims of supposed weather data voids over the Pacific.  Such an absence of weather data existed 60 years ago, but no longer.   Today massive satellite, aircraft, and buoy data provide huge amounts of 3D weather data worldwide (see examples below), and form the basis for a huge improvement in weather prediction.  I  provide details in the podcast. View of the planet in the infrared from geostationary satellites. Atmospheric motion information using wavelengths  in which water vapor is active 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 

We are now at roughly the halfway point of Northwest winter, and it is interesting to evaluate where we are weatherwise. In contrast to California, which is experiencing the wettest winter in a generation...if not longer... most of the Northwest has had a muted winter so far, with the December ice storm being the main exception.  Let's start with the temperature over the past 60 days ( the difference from normal, below).     The entire region was cooler than normal by 0-4F, but eastern Washington and parts of eastern Oregon were MUCH cooler than normal...by as much as 6-8F.     Not particularly surprising for a La Nina year. What about the precipitation difference from normal for the past 60 days (below)?   East of the Cascade crest, a large area was slightly wetter than normal (green color). Interestingly the western slopes of the Cascades were below normal by 4-10 inches. A closer-in view for Washington of the precipitation difference from normal for the past 60 days more clearly

Sometimes you see meteorological imagery and just say wow. Today a huge low center extends over much of the northeast Pacific, while an impressive plume of moisture--an atmospheric river-- stretches southwest-northeast towards the California coast. The infrared satellite image this morning shows the situation, with the white areas indicating higher clouds. Want to be impressed even more?    Here is the water-vapor satellite image at the same time, viewing the emission of water vapor to space.  Scary for northern California! For reference, here is the sea-level pressure analysis at the same time, with low-level temperatures and winds also shown.  Perhaps the largest low-pressure center I can remember spreading over a vast area.  With warm air from the southwest on the southern side (orange colors).  That is the atmospheric river. To really hit that home, below is a map for the same time (this morning) of a potent diagnostic of atmospheric rivers, integrated vapor transport, IVT.   This

La Nina, the periodic occurrence of unusually cool surface waters over the central and eastern tropical Pacific, has a substantial but variable impact on Northwest weather. Generally, La Nina brings wetter than normal and cooler than normal conditions to the Northwest, often with a healthy local snowpack.  Central and southern CA are often dry. But this year La Nina appears to be following a different playbook, with Calfornia being pummelled with uber-moist storms.   And La Nina is about to weaken rapidly, with changes already occurring beneath the Pacific surface. Here is the latest map of Pacific sea surface temperature.  You can see the cool water near the equator over the central/eastern Pacific,   But beneath the surface, temperatures have begun to warm rapidly, something illustrated by the following chart, which displays the different from normal (the heat anomaly) of the subsurface sea surface temperature.   NOAA and other organizations run computer forecast models that predict

 I don't know what to call it. The leviathan of lows?    The Whale Storm?   The Colossus of the eastern Pacific? Whatever you call it, the largest midlatitude cyclone I can ever remember is about the form over the eastern Pacific.  Guinness record keepers should pay attention. Below is the predicted sea level pressure map for Wednesday at 7 AM from the UW modeling system. Just wow.    A deep low-pressure system of enormous dimensions, extending from Alaska to the latitude of Hawaii.   Roughly 2500 miles in diameter. Strong winds will spread over thousands of miles as well (see the wind gust forecast below for the same time). And with its large size and powerful winds over a huge area, this super low will produce immense, dangerous waves. Consider the significant wave height prediction by the NOAA WaveWatch3 model.   The forecast for Tuesday evening predicts waves reaching 45 to 50 feet.  Extreme waves. By Wednesday, the area of large waves greater than 25 ft expands and moves eastw

 My new podcast talks about the origins and importance of atmospheric rivers.    As I describe, atmospheric rivers are relatively narrow plumes of water vapor that extend out of the tropical and subtropics into the midlatitudes (see the example below for Monday morning). California gets it again, as an atmospheric river (red and white colors)  of enhanced water vapor hits the Golden State. Atmospheric rivers result from a specific atmospheric configuration with a trough of lower pressure to the north and a ridge of higher pressure to the south. When the plumes of moisture associated with atmospheric rivers hit land, huge amounts of precipitation can be released, as illustrated by the forecast of 12-h precipitation on Monday (below). A lot more is found in my podcast (see below).  By the way, I am moving my podcast release date to Saturday.  Hope that is ok. To listen to my podcast, use the link below or access it through your favorite podcast service. Some major podcast servers:     Li