Moondogs and Southern California Storms
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Category: Weather Blog
Why are we talking about Bombs?
by Meteorologist, Kerry Challoner Anderson
The media is talking about a “Bomb Cyclone” on the West Coast. Does this mean imminent destruction? View the following presentation for more info on this very interesting storm and how it relates to all the eddies we had this past summer.
West Coast Fog Brings Localized Winds
West Coast Wind Blog: Eddy, 950mb. winds and Bodega
by Mike Godsey, mike@iwindsurf.com
On this day the WF-WRF barely showed a hint of an eddy. The NAM surface had a better hint. But, as I have noticed again and again for larger elongated eddies, the 950 & 975 NAM do a very good job forecasting existence
of an eddy and its duration.
Also notice how a subtle shift in the eddy location can radically change the wind direction at Bodega. Also notice how such movement made the fog in the Hwy. 92 gap suddenly disappear due to SE winds. Normally such clearing foretells good NW wind at 3rd.
West Coast Wind Blog: Forecasting UP AND DOWN Gorge winds.
A Slack discussion: Learning to recognize a pattern for very up and down winds in the Columbia River Gorge
by Matt Sounders & Mike Godsey
Here is a animation I am working on to help explain the UP AND DOWN winds today. Even over the ocean at dawn you can see the instablity.
look at all of those vertical strat-cus west of the Cascades
Notice reform clouds on eastern mountains
indeed
Luv how the marine layer clouds and wave clouds get wiped out.
they erode and are replaced by that garbage strat-cu
I really like how these animations allow you to review things over and over in motion.
very clearly replacing the cool stable layer with a cool unstable mid-level layer
Shud try to grab and compare Troutdale 7AM and 7 PM profiler and skew t
that could actually be pretty amusing
very…very-weak top-of-boundary-layer inversion in the morning, then immediately wiped out by steep lapse rates in the midday period
Actually looking at the satellite more closely there was not much of marine layer over Troutdale
it looks very muted even on that profiler chart
So even at dawn unstable air had moved to Troutdale.
so it would appear. 
no inversion at all
This would make a good tutorial for Gorge mets. I will grab this conversation and imagery and put into a blog. Then you can add texts. Not all blogs have to be aimed at customers. We can publish it just for internal use.
modeling as of late Monday had a little bit of an upper ridge over the NW US…instead it’s a little bit of an upper-trough
We have to get better at forecasting winds beyond the typical up and down.
yes
new messages
D-Day Weather
by Meteorologist, Kerry Challoner Anderson
As we recognize the 75th Anniversary of the D-Day invasion it is interesting to look at the role the weather and meteorologists played in the success of the operation. According to How D-Day was Delayed by a Weather Forecast, “The planning team responsible for the invasion of Normandy had to consider the weather, the moon and tides when assigning a date for D-Day. Air Operations required clear skies and a full moon for good visibility. Naval Operations required low winds and calm seas to safely transport troops ashore. Ground troops needed to land at low tide, when German beach obstacles were exposed and easier to deal with.”
Seventy-five years ago, the weather conditions were not ideal at the first chance to start but meteorologists forecast a window of improvement so the invasion began on June 6. Interestingly conditions are quite similar today. Skies cleared for awhile over the Channel but they didn’t last long and by morning a system rotates up from the south bringing cloudy skies and increasing winds.
One requirement for a successful crossing was visibility but a major issue in the Channel is fog, especially at this time of the year. Like California the fog forms due to the cold ocean temperatures. Today’s sea surface temperatures show a very chilly swath of upper 40s and low 50s. As we move into summer warm, moist air moving over the water is cooled as it comes into contact with the ocean’s surface and advection fog forms. Once the fog forms it is hard to clear as the air is dense and remains close to the surface unless a storm system moves through with strong enough winds to force the air to mix. But while we need the wind to clear the fog, too much wind would have caused the flotilla to struggle as they crossed the Channel and on the landings. With a front arriving from the south, winds have been increasing today as they likely did 75 years ago.
As I think about this historical day I give thanks to those who were willing to serve their country, both the fighting men and the meteorologists that provided the forecasts that allowed commanders the ability to plan for the greatest success.
Kite Surfer Rescue
by Weatherflow Meteorologist, Kerry Challoner Anderson
Last night I was out walking near sunset, checking out the marine layer development north of Santa Cruz, California when I noticed a Kite Surfer struggling to make it back to shore.
The winds were quickly fading as the temperature over the land cooled off. High pressure over the Pacific had strengthen and moved closer to shore which turned the winds along the California shoreline more northerly. Consequently the coastal winds were well offshore at Santa Cruz.
It was interesting to take a look at the observations at this time and see how quickly the wind dropped as the temperature dropped, which showed that the coastal winds were not in play and the only fuel for the Bay winds were sea breezes. Once the temperature cooled over the land the convection cell vanished and the winds died.
Fortunately rescue crews arrived just before the light faded to provide assistance back to shore.
Severe weather in the Northeast
Thunderstorm season in the Northeast US is off to an eye opening start after yesterday’s severe weather outbreak. A strong squall or line of thunderstorms passed through MA down to NJ in the late afternoon and evening bringing damaging winds and localized hail. 
In the radar image below, note the gust front ahead of the thunderstorms and the high dBZ signatures (in purple) over CT as thunderstorms barrel through. Dime to golf ball sized hail was reported in parts of NY and CT.
WeatherFlow stations recorded several gusts around NY and CT exceeding 60 miles per hour!
Honorable Mention: WeatherFlow station, Eaton’s Neck Lighthouse measured a 50 knot gust (~57.5 mph).
Let’s remind ourselves to stay safe when severe weather approaches and heed the watches and warnings issued by your local NWS offices.
Sources:
Wind data courtesy of WeatherFlow
http://www.spc.noaa.gov
http://www2.mmm.ucar.edu
College of DuPage: http://weather.cod.edu/
Waves arriving from Down Under
by Weatherflow, Meteorologist Kerry Challoner Anderson
A cold outbreak for Eastern Australia has not only meant that I am preparing this from under the warmth of some extra blankets but also has brought record wave heights, epic winds for Wind and Kite Surfers here in Brisbane and the potential for great surf later in the week for Californians.
Usually I am forecasting from my home in California but this week I am back in my childhood home in Australia. Watching the weather patterns here has been a great reminder of how connected we are in this world especially when it comes to winds and waves.
This past weekend a series of intense storms have pushed down from Antartica across Tasmania, Southern Australia and New Zealand with very strong winds, severe weather and flooding and sending the mass of cooler air across Eastern Australia.
Campbell Island a remote location south of New Zealand recorded winds in excess of 50 mph and a 78 foot wave.
For Eastern Queensland these storms have meant that the “windy westerlies”, as they are called here, were cranking. These are cold dry winds that blow from the deserts of Central Australia. I remember them well from my childhood as we are pretty thin-skinned here and so it meant for a cold day on the playground. I enjoyed being here for a Westerlies event as they also mean some epic wind conditions wind surfers and kiters at Wellington Point.
Here’s a shout out to our mates down under. It was great to visit and find out how you use our data and models.
And Californians surfers should benefit from all this energy down under. Waves models show that this energy travels across the Pacific and will arrive in California later in the week.
Picking the Right Model
Yesterday’s forecast was a tough one so I made sure to check back this evening to verify. We know we may not always be exactly right and so the process of verifying helps us to learn and improve and also to understand the eccentricities of each model. WeatherFlow has a suite of models to chose from, each having its own strengths and weaknesses.
As I looked through this event of strong NNW flow spilling over the mountains of Southern California it was interesting to see how each model responded. It became very clear how valuable a fine mesh model is when forecasting winds in this terrain.
Here is how the winds looked at 9pm. Belmont has seen over 30 knots for much of today while just a few miles west Cabrillo’s winds have been more northerly and lighter, in the upper teens to low 20s.
The map above shows the forecast for the Long Beach area as predicted by the North American Model using a 12 km grid while the map below shows the same model but using a 3 km grid. You can clearly see that the smaller grid is able to predict the strong winds that are created as the NNW flow pushes through the LA Basin and then offshore south of Cabrillo. However it is clear that the 30 knot winds for Belmont are not predicted.
While the NAM 3 obviously did a much better job than it’s 12 km counterpart, it was interesting to see the output from WeatherFlow’s Wf-Wrf which was run on a 1km grid. The map below shows that this model picked up on the both the higher speeds and the wide variation due in large part to the higher resolution of the grid.
