Gravity Waves over New Hampshire/Vermont


by WeatherFlow meteorologist Shea Gibson.

October 15, 2014 proved to be an interesting setup over the central United States and Ohio Valley region. We had a significantly tight dipping of the jet stream from Canada down to Florida and back up – also known as a Rossby Wave.  A closed upper level Low was caught in the dip and was occluding with pressure around 1000-1008 millibars with fluctuations until the majority of the frontal activity was ripped away and pulled eastward. One of the visible results from this activity was “Gravity Waves”, which are a unique and interesting cloud pattern developed from an inversion of the atmosphere where air warms instead of cools as it ascends. The environment for Gravity Waves is favorable when a warm stable layer forms where warmer air rides along a quasi-atmospheric river of sorts – particularly in the Upper Troposphere Lower Stratosphere (or UTLS Region).  The clouds become visible as water vapor saturates in the areas where air is ascending – becoming a more buoyant stratified fluid and appearing as ripples.  In this case, the ripples remained for quite some time and appeared stationary as convective outflow from the south pushed cloud tops to the north from the Troposphere up into the Stratosphere.

First let’s take a look at the 300mb (~30,000ft. up) polar jet stream showing the Rossby (tight dip southwards in the jet stream) for a 2 day run. We can guestimate about ~100-120kt winds up at that height:

October 15th – 16th

Jet Stream 300mb 10-15-14


 Now let’s take a quick peek at the surface maps:

sfcmap (2)


So looking again at the surface map, here is what is going on:

Gravity Waves 10-15-14

Here are the key elements for Gravity Waves to form – as discussed by Frank Azheimer with the US National Weather Service, Charleston WFO.


 So when we break it down we have:

1. A well edged and well defined upper level trough to the west – present

2. A strong jet stream on the eastern side of the trough  – present

3. Occured between the inflection point of trough to the west and ridge axis to the east –  present

4. Occurrence north of warm front activity extending east ahead of Low – somewhat present extending just east along Canada/US border  (upstream warm air and moisture suffices for the warm front activity)

Here is a visual:



Here you can see the ripples form and remain stationary while the rest of the activity streamed north and east.  Land features such as the Adirondack Mountains also assisted with this. Some of this rippling you can even see extending up into the northern Maine and New Brunswick areas just near the end of this loop.

(The “H”‘s in this GIF are supposed to be “L”‘s for Low pressures – seems there was a technical issue that day with the NOAA GOES site).

GW's 10-15-14


Even though they look a little more impressive from satellite view from overhead, they still look unique from the ground. Here are some examples:













And this one was another event up in the Northeast United States, where the region systematically encounters multiple fronts converging ahead of dips in the polar jet – especially in the cooler months. Might be something to look for any time we see a Rossby Wave bulging southwards into the United States.



Other cool ones, including waves in the wake of the mountain tops of the Sandwich Islands and an arc’ing of waves off the coast of California…











Posted in Massachusetts North Coast

Autumn, geese and North Pacific High depart to the south.

NW winds fade on the California coast.NPHautum

by Mike Godsey

Its that time of year. The average location of the NPH drops south of the Bay Area and focuses west of the Southern California coast. And in the coming weeks the NPH will continue to shrink and move further south. Sometimes it will move towards the Baja Coast other times it will abandon the entire west coast. Today in this video we can see the NPH shoved south of the Bay Area by a storm system passing to the north.

Posted in Los Angeles, San Diego, San Francisco

North Pacific High takes refuge in winter vacation home.

San Carlos, Baja Norte is center of the wind universe.SanCarlosNWbaySW

by Mike Godsey,

Ever wondered where the North Pacific High goes to when it abandons the California coast in late fall? Sometimes it just disappears from the pacific but more often it moves closer to the equator. And at times it lurks near its winter vacation home just west of Baja. And on those day Punta San Carlos has great wave sailing.

In this animation you can see most of the Pacific is a mess is you are looking for quality wind. The Bay Area is preparing for weak southerly storm winds. Hawaii is bracing for hurricane Ana. And there just west of Baja sits “our” North Pacific High creating NW winds for the hardy souls camped on the bluff enjoying perfect side offshore wave sailing.

Posted in Columbia River Gorge, Los Angeles, San Diego, San Francisco

Battered North Pacific High sulks west of Southern California and Baja

So NW clearing winds between storms.StormTinyNPH

by Mike Godsey,

As you know the waters between California and Hawaii are dominated by the clockwise winds of the North Pacific High most of the summer. But as winter approaches huge counter-clockwise spinning storm systems like the one you see in this video shove the NPH far to the south. And in this case hurricane Ana has taken over the southern parts of the North Pacific High’s home waters.

This time of the near the ITCZ which gives birth to the North Pacific High is also moving southward so the average location of the North Pacific High keeps moving to the south even as the North Pacific High weakens.

Oh…. you are wondering what the heck ITCZ means? Google it and next spring, when the ITCZ moves northward and the NPH moves towards California I will do a blog on it.

Posted in San Francisco

Hawaii and hurricane Ana…

HurricaneAnnaTodayTrade winds

give way to

Hurricane winds.HurricaneNearHawaii 

by Mike Godsey,

Hurricane Ana currently a modest hurricane SW of Hawaii should have at least 75 knot winds by this weekend. And it’s modeled trajectory has it coming right over Maui.

The first video shows Ana’s current location while the second video shows Ana’s modeled location on Oct, 18.

When hurricanes are near land or currents like the Gulf Stream the models lose accuracy but over the open ocean they are pretty accurate so if you are kiting or windsurfing the North Pacific High’s trade winds today get ready for smaller gear by Sunday. Probably GUSTY UP AND DOWN winds…..

Posted in Columbia River Gorge, Los Angeles, San Diego, San Francisco

Watch North Pacific High retreat in the face of a wintry storm system.

NPH’s wind turn from NW to NNW and Bay Area winds weaken. Then southerly storm winds.NPHretreatsStrom

by Mike Godsey,

At the beginning of the video  notice the date of Oct 11 and how the North Pacific High dominates the lower 2/3 of the screen creating NW wind on the California coast. Then abruptly as the date changes to Oct. 12 a storm system drops from the Gulf of Alaska and the North Pacific High retreats southward. Notice as this happens how the Northern California coast winds switch from the typical summer NW wind to unfavorable NNW winds that are much less likely to  make it into the Bay Area. And by Tuesday Oct. 13 those weak southerly storm winds will begin to come over the Bay Area.

Posted in San Francisco

To the west Super Typhoon Vongfong, to the east the North Pacific High

We tend to think that strong things come in big packages but…Typhoon

by Mike Godsey,

Looking to the east in this video from Oct. 11, 2014 notice the North Pacific High. The NPH spans well over 3000 miles from the Oregon Border to pass Hawaii. But its clockwise spinning winds are maxing out at about 25 knots. To the west find Super Typhoon Vongfong. This storm spans several hundred miles buts its counter-clockwise spinning winds are averaging 150 knots with gusts far stronger. This is a huge storm larger than the state of Texas but it is tiny compared to the NPH. But far stronger!

Posted in Columbia River Gorge, Los Angeles, San Diego, San Francisco

North Pacific High winds build on coast. But…

Inbound storm poised to bring an end to NW coast winds

by Mike Godsey,


Posted in San Francisco

Typhoon Vongfong as seen from ISS Flyover

by Weatherflow Meteorologist Kerry Anderson

Here is an incredible view of Super Typhoon Vongfong as the Internation Space Station passed overhead on October 9, 2014. At that time the storm was at the height of its strength with reported sustained winds of 178 mph and gusts to 190 mph. Notice how perfectly symmetrical the eye looks.

                                                                                                                                                                                                                                   Vongfong with Okinawa

 The latest satellite picture shows the center of the storm just to the north of the Okinawa.  Winds are now (Saturday Oct 11, 2015 9am PDT) being reported just over 100mph.

Hurricane VongFong

Posted in Weather Blog

Año Nuevo clearing suggest modest NW wind from Waddell to Natural Bridges

What in the world is Año Nuevo clearing?

by Mike Godsey,

Año Nuevo clearing2Those of you who make the drive to Waddell and points south are well acquainted with Año Nuevo clearing and the racing of your heart as you finally round a fog shrouded curve and see impossibly blue skies near Año Nuevo. But for Bay sailors the frequent comment about Año Nuevo clearing in the forecast may seem cryptic. So I made this animation so you can see what it looks like. The reason Año Nuevo clearing is so important to Santa Cruz area winds is complex and one day I will  do a blog on super critical flow and  the magic Waddell’s complex wind machine.

And even if you do not ply the coast waters early Año Nuevo clearing is a good sign for Crissy, Coyote & 3rd. since it typically is a harbinger of clearing at those sites.

Posted in San Francisco