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.

Wind speed and direction for the Northern California coast on May 17, 2018

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.

This image was taken in Milford, Ma before thunderstorms passed through. These are mammatus clouds, formed by cold dense air sinking downward into warmer air causing groupings of ominous lobes. These types of clouds are often seen out ahead of thunderstorm clouds and are therefore harbingers of imminent severe weather. Source: WF Forecaster Tim Nicholas.

Wind data courtesy of WeatherFlow
College of DuPage:

West Coast Wind Blog: Local low pressure and eddies:

Good eddy, bad eddy.

by Mike Godsey, mike AT

There are several scenarios for creating micro to mesoscale eddies. Two of the more common factors is a very localizeed low pressure area and wind shear as wind rounds a point or  cape. Southern California kiters and windsurfers are very familiar with the wind killing Catalina Eddy and the Mid Channel edies off Santa Barbara that deepen the marine layer and often block the inbound WNW to WSW ocean winds. The situation is more complex with the increasingly common Golden Gate Eddy off the Golden Gate. Those plying the waters north of the Bay Bridge love to hear about the Golden Gate Eddy since it usually means solid wind especially at Pt. Isabel and Sherman Island. While those south of the Bay Bridge or on the coast know that and eddy often means W to WSW winds that are weak near shore.

The following imagery shows an eddy with very simple causation. It often occurs in  the morning in the extreme northern end of Baja’s Sea of Cortez near San Felipe.

Notice NNW winds from the North Pacific High streaming down the west side of Baja. Looking closely notice how a bit of that winds turns and is sucke into the eddy in the Sea of Cortez. Likewise wind from the San Diego and Nogales regions are sucked into the the counter-clockwise spinning eddy.

The next image shows the proximal cause of this eddy. In the morning a low pressure area often forms in this region since the Sea of Cortez water is warmer than the surrounding land mass that cools rapidly over night. So wind is sucked towards the pressure gradient and is set aspinning by the coriolis effect. Later in the morning as the land warms rapidly the the low pressure disappears and the eddy fades away.

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.

Forecast minimum temperature for Saturday, May 11, 2018

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.

Cape Verde von Kármán Vortex Streets

By WeatherFlow meteorologist Shea Gibson 5/12/18

One of the great things about the new GOES-16 satellite imagery is the ability to see microscale events in high definition far beyond our coast to the east over the Atlantic ocean.

Check out these ripples called  “von Kármán vortex streets” created from NE flow across the Cape Verde Islands just west of the African Coast. This is caused by the separation of moisture over the mountains of these island as the winds blow across them.

This process is very much like how wind would whip across a powerline and create the vortices on the other side, giving it the ripple-like effect (and that “singing” effect as well).Just as a FYI….another hot-spot for this to occur is Jeju Island off the coast of the Korean peninsula during strong cool Northerly winds across its tall volcano peak.

Just another one of those neat-o things that occurs in the atmosphere that lets us know how the surface and atmosphere can work together to create beautiful patterns. Until next time, take care and keep up with our forecaster blogs at – make sure to toggle the varous regions for lots of valuable information from our team!

Shea Gibson
WeatherFlow Meteorologist/Wind Forecaster
Outreach & New Station Projects
SE Region/East Coast
Twitter: @WeatherFlowCHAS


West Coast Wind Blog: Rio Rips but mild gradients to Sacramento and Redding but…

Strong pressure gradient to the Great Basin!

by Mike Godsey

So we all learned in on-the-beach meteorology 101 that the pressure gradient to Sacramento is critical in Sherman Island winds.

Then in advanced beach lore you may have heard that the gradient towards Redding is also important in setting up the SW flow that Sherman Island thrives on.

And looking at this satellite animation from 9AM this morning, May 3, you can see the fog burying the greater Bay Area and even streaming over Sacramento and turning northward.

Also, notice the fast burnoff that is just starting. We will come back to that.

In the next image of the Bay Area wind map you can see strong winds blowing from Benicia to Sherman Island.

Also, notice the overall SW wind flow inside the Bay despite the weak West ocean wind at the ocean buoys.

Then check out the pressure gradients from SFO airport to Sacramento. It is actually quite modest at 9:30 AM and the pink line that shows the modeled pressure gradient is also mild.

The same is true of the pressure gradients from SFO-Redding and the gradient from the ocean buoy to SFO. So where is all of this wind coming from?

To get the answer check out the very strong pressure gradient from SFO to Winnemucca in the northern Great Basin and the SFO to Reno gradient on the western edge of the Great Basin.

It is those strong pressure gradients that are shooting the streamer of fog across the Central Valley. Meanwhile, the pressure gradient towards Chico and Redding is producing the turn to the west you see in the fog streamer.

The last image comes from the Bodega  Bay 449 Mhz profiler. The blue area you see in the bottom of the image roughly shows the depth of the marine layer.

Notice how it increased overnight. Now notice the lighter color area above the marine layer. This is the inversion layer of warmer air above the marine layer.

In the summer this layer would be much warmer and would try to keep the marine layer clouds intact. Since this is a weak inversion I would expect the clouds to burn back fairly fast today.

That is part of the reason I am forecasting weaker PM winds for Sherman Island and better clearing today at Crissy compared to yesterday. And that means stronger Crissy winds.



West Coast Wind Blog: First eddy of the year brings…

Southerly winds at the ocean buoys!

by Mike Godsey

Strong NNW winds from the North Pacific High blow just west of our ocean buoys today but with low pressure to over the far North Bay and weak NNW winds aloft it was clear the last few days we were heading in to eddy conditions.

The satellite imagery of the eddy is imperfect today. First find the Golden Gate. Then note the streaming of the clouds from the NNW in the #1 annotation. Then look carefully in the area around #2 and you can just discern the spin of the eddy in the clouds. Much easier to see is the impact of the eddy on the ocean buoy winds and the winds inside the Bay. 

Typically when the North Pacific High is close to the Bay Area we have NW wind at the ocean buoys. So the winds flowing into the Bay towards the  Central Valley have a bias to head towards the sites from Treasure Island southward. But with an eddy in play the bias is more towards sites north of the Bay Bridge.

Most of the time the eddy fades mid day but if lingers it blocks NW wind from reaching the Peninsula and Waddell. Plus it tends to funnel winds towards the north tower to Point Blunt to Pt. Isabel to Sherman Island axis.

The story of how the eddy is created is complex but the following images will give you some  hints of the major players in eddy creating. Note the weak northerly flow aloft in the Bodega  profiler image.

The in the next image note the surface low pressure trough over the far North Bay. With low pressure to our north there is a S. to N. pressure gradient in the Bay Area.

All of this favors eddy formation in the AM. And all of these variables fade in the afternoon. The key to our afternoon winds is how fast or slow these variables  fade which determines the edd resulting eddy fades



West Coast Wind Blog: East and West winds at the same time on the Columbia River

How can that happen?

by Mike Godsey

Check out today’s Gorge forecast.

Strong Easterly and strong Westerly winds along the Columbia?

Since winds are largely driven by pressure gradients how can you have two different pressure gradients at the same time?

Looking at the isobar map you can see there is low pressure off the coast and high pressure to the east.

This pressure gradient is what creates the easterly wind you see today in the wind map image.

This animation of model data shows these easterly winds pretty accurately.

But looking at the animation for this afternoon you can see westerly winds from the coast to near Portland.

So how do westerly winds develop from the coast to Jones Beach near Portland?

Looking at the next image from 9:07 AM today note the strong easterly winds especially at Rooster Rock.

But also notice the 13 knot WESTERLY winds already at Jones beach.

Afterall there is low pressure to the west of Astoria.

The answer has to do with the density of air and its pressure. The low pressure storm to the west is creating southerly winds at the coast. As Ben mentions in his forecast this low pressure is creating the southerly coast winds you see in the animation above. This southerly flow pushes a lot of cool dense foggy air towards the coast and inland along the river. Cool air is denser than warm air which means it creates high pressure along the coast and up the river. Today, especially in the afternoon, this high-pressure zone creates a hefty pressure gradient for westerly winds.  At the same time, the easterly winds weaken as they typically do in the afternoon. This means that starting this morning and continuing through at least early afternoon we have both E. and W. winds at opposite ends of the Columbia River.

News Flash at 4PM. Since I posted this blog this morning it has become clear that Ben had a spectacular forecast. Check out this wind maps frm 3:50 PM… No words needed!


West Coast Wind Blog: Most of the check boxes are checked for a marine surge today but…

Pressure gradient to N.Central Valley vs. gradient to Bakersfield limits southerly surge winds.

by Mike Godsey

Hi cTuna,

Funny you should ask! Looking at the thermal trough along the California coast and the low pressure off Arcata conditions almost looked ripe for a strong marine surge. Even the ocean buoy winds were southerly.

But the devil is always in the details. The low pressure was mostly just offshore so looking at the pressure gradient charts below notice that the gradients from SFO to Arcata, Redding and Sacramento are pretty mild. So it is hard to get really strong wind all the way Sherman Island. Plus there is a strong pressure gradient to Bakersfield. And this funnels a lot of the wind into the Peninsula.

This meant no real marine surge with fog blasting through the Golden Gate all the way to Sherman Island. Instead we got what I call a combo day with useful winds at many sites from Sherman Island to the Peninsula.

This time of the year the S. half of the Central Valley towards Bakersfield is usually hotter than towards Redding. So marine surges are not very common. That will change in the next 2 months.

West Coast Wind Blog: Classic high pressure vs low pressure setup today…

This should mean strong winds for most of the Bay Area and Southern California, but…

by Mike Godsey

Take a look at my forecasts for today, April 19, for the Bay Area and Southern California. Both forecasts call for strong wind as a combo of the North Pacific High’s surface NW winds and a strong pressure gradient to the Great Basin bring strong winds to the coast.

But both forecasts have nagging copouts (in green) to cover my rear. Let’s first look at those winds and then why I need some wiggle room in the forecasts.

This animation shows a classic spring type pattern for strong NW clearing winds along the California coast.

First note the North Pacific High west of California and check out the clockwise winds spiraling out of the high. Notice how the NPH is a bit enlongated towards the Pacific Northwest. We will come back to that. Now notice the strong NW winds from the NPH along much of the California coast. Next find the low pressure in the Great Basin. See how the winds spiral into the low pressure in a counter-clockwise fashion.

Following the streamlines you can see how having the low pressure in the Great Basin adds a bit of extra velocity to the winds hitting the Bay Area, Central California coast and Southern California. And this low pressure also speeds up the winds just aloft which also impacts the surface wind a bit. All in all a classic strong wind day for the California coast.

So why the copout in both forecasts? Notice how the isobars of the NPH lean into far Northern California. Tomorrow that lean turns into a surface ridge from the NPH. This creates a N. to S. pressure gradient over the interior of California. Which in turn promotes weak NNW to NNE winds inland from the coast both at the surface and just aloft. And for both Southern California and the Bay Area that can delay and weaken the wind. AND, there is a slight chance that this process could start late this afternoon and spoil my forecasts!