Catalina Eddy today at 9AM April 17.

Catalina EddyCloseAnimVideo: Why such a large and long lasting Catalina Eddy today?

by Mike Godsey, mike@iwindsurf.comCatalina EddyAnim

The causes of the Catalina Eddy that so often shuts down Southern California winds while creating weak SSE wind are complex. And one of these days I will do a special blog covering that topic. But today let’s focus on why today’s Catalina Eddy is so huge spanning the waters from Ensenada, Mexico to just north of Jalama near Point Conception.

Looking at the video notice the North Pacific High’s surface NW winds roaring down the northern and central California coasts. Notice the kink in the California coast starting at Point Conception. This turn in the coast means that Southern California is typically in a wind shadow and often does not receive the brunt of the NW wind from the NPH unless there is something to push or pull those NW winds so they curve into the beaches as NW to WSW winds. What type of “something”? One factor would be lots of heat in the inland valleys another would be strong NW winds aloft. Today we have neither.

That sets us up for a Catalina Eddy. Now notice how part of the NW wind north of Pt. Conception curves inland and becomes a northerly wind. This wind climbs the Traverse Range of mountains north of Santa Barbara. As this wind “falls” down the ocean side of the mountain in compresses, heats and expands creating a very local low pressure area. In the early morning there is very little wind in the SynopticLOW PRESSUREjazzesCatalina EddyAnimwaters around the Channel Islands but this air begins to march towards this low pressure near Santa Barbara creating a southerly wind. But the bulk of the NW ocean wind has to much momentum to make the sharp turn towards the low pressure. However  further south the NW wind at the edges of the wind shadow is moving much slower and a bit of this NW wind  curves towards the  shore and is swept up into the eddy.

On a typical Catalina Eddy day the low pressure area near Santa Barbara is filled in by the eddy wind mid to late morning and the eddy dies. But today the Catalina Eddy is being turbocharged by 2 factors.

1. Look carefully at the video in the area to the right side and notice the wind flow from Baja’s Sea of Cortez and eastern edge of the Catalina Eddy. Note how the wind is rushing towards this low near Las Vegas. This flow is augmenting the eddy and is making it larger and probably longer lasting than a typical Catalina Eddy.

2. Now look at the 2nd video. We are looking at the pacific for hundreds of miles SW of Southern California. First find the coast and the channel islands in the upper right corner. It is in that area that the Catalina Eddy is still spinning at 11:30AM. Now notice the surface low pressure area that has formed below an upper trough at ≈ 18,000 ft. Looking carefully notice the counter-clockwise spin of the clouds around this low pressure. Now look to the waters where the Catalina Eddy spins and you can see that the spin from this huge low pressure system tends or reinforce the counter-clockwise spinning spin of the Catalina Eddy near shore.

This, along with the high clouds overhead, is why the wind forecast for the Southern California coast is so bleak today.

 

 

 

Posted in Los Angeles, San Diego, San Francisco

Subtropical Ridging effects in the SE Region.

by WeatherFlow meteorologist Shea Gibson

From April 11 – April 14, High pressure entered from the Gulf, expanded across FL/GA and out into the Atlantic north of Bermuda, where it slightly built around the center and then became flattened by two areas of troughing to the north and south. To the north, a stronger frontal boundary had just lifted where the High passed underneath, and then settled back down by laying in an EAST-WEST diagonal pattern. To the south, weaker troughing + lack of significant system activity the western Gulf allowed it to expand the axis inland all the way to Louisiana and perhaps Texas.  The result was mixed SSE/SE winds to the south of axis and S/SW flow to the north of axis.  This made it especially difficult to predict how much angle of SSW/SW directions and potential elevations in speeds we might observe from Seabreeze circulations for several days. We mainly stayed with the weaker synoptic flow to beaches with marine layering effects tied in with our forecasts, but coastal breaks and inland locales had to be mentioned for SW directional influences to perhaps drive up a few elevations in speeds.

 

First let’s take a look at the APRIL 11, 2014 Surface Analysis

 

Subtropical Ridging 4-11-14

 

And the forecasts starting with GA, then SC and SENC

 

FC GA 4-11-14

 

FC SC 4-11-14

FC SC 4-11-14 (2)

 

FC SENC 4-11-14

FC SENC 4-11-14 (2)

 

OUTCOME

Jekyll Island, South GA (ignore the morning spikes) – came up a couple of knots higher late afternoon, but overall target met.

JEKYLL 4-11-14

 

Isle of Palms, (mid SC)

IOP 4-11-14

Charleston Harbor, (mid SC) – escapes some of the ridging effects..notice how well it picks up as winds funnel in between land masses during Seabreezing.

CHAS HARBOR  4-11-14

 

 

4-11-14

 

 

Above Charleston/Georgetown, we see activity north of axis allow for stronger builds off the Seabreezes.

Myrtle Beach, Springmaid Pier (north SC)

MB 4-11-14

 

Oak Island, NC (Cape Fear area)

OAK ISLAND 4-11-14

 

Fort Macon, BC (Cape Lookout area)

FT MACON (C LOOKOUT0 4-11-14)

 

APRIL 12, 2014 Surface Analysis showing the frontal boundaries north and

south of High.

 

Subtropical Ridging 4-12-14

Forecast from GA, SC and SENC:

FC GA 4-12-14

FC GA 4-12-14 (2)

 

FC SC 4-12-14

FC SC 4-12-14 (2)

FC SENC 4-12-14

FC SENC 4-12-14 (2)

 

Outcomes:

 Jekyll Island, (south GA) – again ignore the spikes in the AM hours.

Jekyll 4-12-14

Isle of Palms, (mid SC)

IOP 4-12-14

 

Charleston Harbor, (mid SC) – stayed several knots lower than expected.

CHAS HARBOR 4-12-14

 

Myrtle Beach, Springmaid Pier (north SC)

MB 4-12-14

 

Oak Island, NC (Cape Fear area)

OAK ISLAND 4-12-14

 

Fort Macon, NC (Cape Lookout area)

FT MACON 4-12-14

 

 

APRIL 13, 2014 Surface Analysis shows ridge axis remaining extended across

SE states, with some meandering south to north.

 

Subtropical Ridge Axis 4-13-14

 

 Forecast from GA, SC and SENC:

FC GA 4-13-14

FC GA 4-13-14 (2)

 

 

FC SC 4-13-14

 

FC SC 4-13-14 (2)

 

AND A MIDDAY UPDATE:

FC SC UPDATE 4-13-14

 

 

FC SENC 4-13-14

 

FC SENC 4-13-14 (2)

 

Outcomes:

 

Jekyll Island, (south GA)

JEKYLL 4-13-14

 

Isle of Palms, (mid SC)

IOP 4-13-14

 

Charleston Harbor, (mid SC)

CHAS HARBOR 4-13-14

 

Myrtle Beach, (north SC)

MB 4-13-14

 

Oak Island, NC (Cape Fear area)

OAK ISLAND 4-13-14

Fort Macon, NC (Cape Lookout area)

FT MACON 4-13-14

 

 

Finally, the April 14 Surface Analysis shows continued ridging starting to

show signs of retreat as cold front comes together out west.

4-14-14 (1)

 

 

 

 

 

Posted in Coastal Georgia, Coastal South Carolina, SouthEastern North Carolina

North Pacific High arrives Tuesday!

Watch new North Pacific High approach the California coast.

by Mike Godsey,

mike@iwindsurf.com

North Pacific HighINBOUND

The old wimpy North Pacific High is dying fast along with its useless eddy producing North wind.

A new powerful North Pacific High is inbound with an ETA Monday afternoon or Tuesday.

Here is the story story in images.

Posted in Los Angeles, San Diego, San Francisco

Seesaw pattern … strong easterlies Sunday while westerlies rush back Monday.

Sunday13Apr2014

Monday14Apr2014

Posted in Cape Cod

Gorge and Oregon coast winds April 11

North Pacific High:  why the coast and the Gorge ripped yesterday.

by Mike Godsey, mike@iwindsurf.com

let’s take a quick look at the big picture behind yesterdays wind on the Oregon coast and in the Gorge. First, the simple concept of Gorge winds is the pressure gradient between the west and the east. But to forecast the development of that pressure gradient you have to know what causes it to form.

North Pacific High&GorgeWindsAmim

In the top video first find the Oregon coast and the Gorge. Then notice the North Pacific High and the winds that spiral out of in in a clockwise fashion. You can see why in this set up forecasting northerly winds on the coast is pretty easy. Just plot out the future location of the North Pacific High and when it arrives at the coast and you have a decent wind forecast.

But forecasting for the Gorge is much trickier. The North Pacific High’s wind are surface  winds and when they hit mountains their flow is disrupted, weakened and changed in direction. That is why on a day like April 11 most sites in inland Oregon and Washington did not show winds remotely like what the coast saw. However the North Pacific High still pushed isobars over the 2 states so there was a pressure gradient. And that pressure gradient was strengthened by low pressure in the Columbia River Basin far to the east. So while the NPH’s wind can not flow smoothly from the N. as on the coast there still is a strong West to East pressure gradient. And as you can see, on the right edge of the video, all that west wind blasted through the Gorge and spirals into the Basin.

Now picture the Gorge being a near sea level gap in all those mountains. The northerly winds will blow over that gap but the pressure gradient will make wind rush from the North Pacific High Pressure towards the  low pressure in the Basin. And since the gap is narrow in places you will get a venturi effect further accelerating the WEST wind.

Now looking at the bottom video first find the Gorge and notice the strong WEST wind flow along the river. Now notice that while the northerly flow from the North Pacific

OceanNGorgeNWflowAnim

High is disrupted over land it still stirs the surface wind in all the valleys and hilltops of Washington. Look carefully and you can see what happens when this northerly flow reaches the Gorge. Notice how it “feels” the pressure gradient and flows along the path of least resistance eastward in the Gorge.

You experience this northerly flow as wind shifts and powerful gusts and the westerly wind is enhanced by northerly flow curving into the westerly flow. This addition of northerly flow also determines what sites have the strongest winds and even which side of the river has the strongest winds..

With thanks to http://earth.nullschool.net and http://visual.ly/wind-map?view=true

Posted in Columbia River Gorge

NORTH PACIFIC HIGH: out with the old and in with the new!

Old crumpled NPH fades away while out in the pacific….

by Mike Godsey, mike@iwindsurf.com

Ok, enough of this! Where the hell is the North Pacific High and our NW wind? The Cut-Off Low has passed and that is suppose to mean NW clearing winds in Southern California and the Bay Area. Yet we are seeing Sherman Island SW winds at dawn today April 12. This is not suppose to happen!

For weeks now you have heard me and other forecasters talking about the North Pacific High but rarely have we seen significant NW wind. Why? Basically the current Old&NewNPHanimversion of the North Pacific High has been shoved around mostly to the north by a succession of storm systems too closely packed for the high to have time to move back to the California coast. Worse these systems are distorting the NPH so that it ridges inland over the Pacific Northwest. This is great for the Oregon coast and Gorge wind but it means North wind on the California coast which cannot, given jutting Cape Mendocino,  really fill into the Bay Area. And as you saw in the previous blog this northerly flow favors an eddy west of the Bay Area that creates SW flow.

So why are we forecasting moderate NW clearing winds late Monday and for sure Tuesday?

Looking at the video first find the Bay Area and California to get oriented in this zoomed out view. Then find the “Old NPH”. Ideally the NPH should be a large oval with winds spiraling out in a clockwise fashion. This makes NW wind on the California coast and NE trades in Hawaii. But notice how this ”Old NPH” has been pancaked against the northern west coast. There are still clockwise winds but note how they are NORTH winds on the coast and do not reach the Bay Area. This pancaking continues tomorrow as the next storm system, which you see in the video, presses against the ”Old NPH”. This  new storm finishes off the ”Old NPH” and it disappears from the models as it is absorbed by passing weather systems.

Now looking at the video notice the “New North Pacific High” that has formed north of Hawaii.  The robust NPH is pushing towards the California coast and the NW winds you see on the edge of the high pressure should arrive at the Bay Area late Monday or more likely Tuesday. And this new North Pacific High promises to hang closer to California so expect more reliable NW flow the next week or so.

With thanks to http://earth.nullschool.net

Posted in Los Angeles, San Diego, San Francisco

North Pacific High & Tiny Golden Gate eddy

Gorge rips but location of North Pacific High helps a tiny eddy form west of the Bay AreaNorth Pacific High& TinyEddyAmim

by Mike Godsey, mike@iwindsurf.com

Usually I can discern any eddies west of the Golden Gate by their signature in the satellite imagery and looking at all the coast sensors. But today high clouds are obscuring that view and there are few sensors out in the near shore waters. fortunately today all the models actually capture the eddy so I can factor those counter-clockwise spinning winds into the wind forecast. Basically having an eddy off the Golden Gate gives the winds a more southerly cant which favors the north tower to Point Blunt to Pt. Isabel to Sherman Island corridor.

Looking at this video find the North Pacific High and notice how far north it is of the Bay Area. In this location it creates NNW wind on the Oregon coast and stacks some isobars over the Gorge so The Hatch is seeing mid 20′s wind today. But given the angle of our coast line north of the Bay Area these winds can not fill into the beaches or curve into the gaps in the coast range very well. This creates a perfect scenario of a counter-clockwise spinning eddy. Look very carefully just west of the Bay Area in the video and you can see this eddy.

With thanks to http://earth.nullschool.net

Posted in San Francisco

Inbound Cut-Off Low

2 Videos: Surface low forms below Cut-Off Low and combo push

NPHcrushedCutOffAnim

the North Pacific High to the north. 

by Mike Godsey, mike@iwindsurf.com

I  will add more text the blog later but you can see the big news in those two videos. By themselves these critters are not too exciting wind wise BUT once they depart……

A Cut-Off Low  at ≈ 18,000 ft. and about 900 miles WSW of the Bay Area is moving towards Southern California.

Below the Cut-Off Low at surface the Cut-Off Low has induced a weak surface low pressure storm with the typical counter-clockwise spinning winds.

Looking at the first video you can see this surface storm.

The second video shows the clouds and moisture above 10,000 feet up the the jet stream at about 30,000 feet. This is where this  Cut-Off Low resides.  The dark green areas are where the moisture level is high and given the right conditions these areas can produce rain. Notice the broad band of clouds moving from the SW south of the Cut-Off Low. This is the subtropical jet stream.

Think of the Cut-Off Low and the surface storm as being a double layer cake with one layer right a the surface and the other layer mostly around ≈ 18,000 ft..

 Looking back at the top video you can see ho  they have pushed the North Pacific High and its NW winds to the north. Notice the strong NW wind along the Oregon coast.

This Cut-Off Low is targeting Southern California in the next few days and may mess up the wind there.

BUT once the Cut-Off Low departs to the east this weekend get ready!Cut-Off LowANIM

The North Pacific High, which you see in the video crunched to the north is poised to bring NW clearing winds to much of California as it reclaims it home waters.

With thanks to http://earth.nullschool.net

Posted in Los Angeles, San Diego, San Francisco

Lower Sea Surface Temps show Marine Layering along the SC Coast into the spring.

By WeatherFlow meteorologist Shea Gibson

As we have had a cold winter climate here in the SE Region this year, our waters chilled down into the upper 40’s/lower 50’s and have remained cool between the 58-62 degree mark into the spring, with recent readings more current today, April 10, at ~ 63.5 degrees.   With air temps on the rise and very slow warming of the our cooler shelf waters, we are seeing marine boundary layers develop just along shore to cause inconsistency to builds for immediate beaches. Even with an Atlantic High firmly in place, diurnal Seabreeze circulations have been limited in strength along the shoreline with MBL forming to limit elevations as cool air remains stabilized at the surface. The Gulf Stream 40-50 miles out has held stronger flows over the warmer water currents and as we get towards the cooler shelf waters, we see the layer form.

I will be looking at the Charleston area in particular during the dates April 2-4 for this topic as the stretch of Southerly flow lasted for several days. From April 2nd – April 4th, we had a fairly stationary Atlantic High parked to our SE that slowly drifted to the ENE until Saturday’s front pulled through. Each day, Charleston Harbor speeds at our Fort Sumter Range Front Light sensor showed elevations in periods to upper teens/low 20’s during afternoon builds as winds funneled in through the harbor mouth… but 10kts to low teens with UP’s and DOWN’s prevailed along immediate beaches Wed and Thursday with brief late afternoon pulses. Higher numbers showed inland over warmer land to low 20’s and gusts to around upper 20’s with turbulent quality. Friday showed the highest in the period with inland troughing interacting with Atlantic High to increase the gradient along the coast.  Also to note that there was less decoupling each night, eventually giving way to short periods of stronger flow to beaches during the inversions in the early AM hours- mainly between 2:00am – 5:00am…with longer periods of elevations in the harbor.

We called it well in our Daily Briefings by having less confidence than the computer models were showing, thus increasing our own forecast confidence with discussion of marine layering effects and making manual adjustment to tables.

Patterns to think about: SST’s, inland daytime humidity readings/inland winds from NWS North Charleston daily climate summaries, nighttime inversion elevations with higher humidity, tidal factors, drops in pressure and air temps falling after peak heating.

 –> Climate Summary and Tide Table for other influences…. keep in mind the relative humidity and timing of the ebbing tide.  The Marine Boundary Layer (MBL) increasing its own humidity level is not shown since the NWS local summaries come from well inland over drier land. We can assume that levels were higher shore-side as thin layering was visible to the eye. Low tide suggests a possible pattern with higher numbers showing during roughly near those times…due to possible tidal flushing with warm water plumage providing a warmer top layer to increase sea surface temps for a slightly better mixing profile each day.

 

Quick look at Wednesday, April 2:

 

Daily Briefing -  good job Tim! 

 

METS FC 4-2-14

 

METS FC(2) 4-2-14

 

Fort Sumter graph in the Chas Harbor…notice the afternoon build on the Southerly turn.

Harbor graph 4-2-14

 

Here is the graph from Folly Pier…notice the pressure drops by 3mb’s with Seabreeze circs.

WED APRIL 2 FOLLY GRAPH

 

Climate Summary and Tide Table:

 CLIMATE SUMMARY 4-2-14

 

TIDE WED APRIL 2

 

Thursday, April 3:

Surface Analysis forecast ( my edited version from WSI )

4-3-14

 

 Daily Briefing:

METS FC 4-3-14

METS FC(2) 4-3-14

 

 

Charleston Harbor (Fort Sumter sensor)

Notice the early AM elevations, the late morning/midday flatline and then the steady afternoon increase. 

Could be associated with the late inversion land breezing finally giving way to the Seabreeze?

Chas Harbor

Isle of Palms Pier   – same thing here around 10:30am with Seabreeze picking up the flow again.

IOP

 

Climate Summary and Tide Table:

CLIMATE SUMMARY 4-3-14

TIDE THURS APRIL 3

 

 

 A look at Friday, April 4:

Inland toughing produced a moderate gradient build to the area, with mid-level strata and some lower level debris fanning out towards the ocean and dissipating as it reach out over the waters. Isle of Palms to the north saw first beach elevations as clouding approached there first. Folly Beach came later as troughing pressed southwards.  Notice during early AM hours how the inversion showed less decoupling issues even with higher humidity at 90% inland with a probability of being somewhat lower at ~80-90% along beaches.

Daily Briefing:

METS FC 4-4-14

 

METS FC(2) 4-4-14

 

Fort Sumter showing steady builds to low 20′s then UP’s and DOWN’s after 4:00p:

CHAS HARBOR 4-4-14

 

Isle of Palms – total pressure drop of 4mb’s

FRI APRIL 4 IOP GRAPH

 

 

Folly Pier – total pressure drop of 4mb’s with  a later build

FRI APRIL 4 FOLLY GRAPH

 

Picture taken at 11:30AM of mid level strata from inland trough encroachment (you can see winds laying down marsh grasses in the water along the SW inland builds)…location Cosgrove Bridge, ~10.5 miles inland.

TROUGHING 4-4-14

 

Climate Summary and Tide Table:

CLIMATE SUMMARY 4-4-14 TIDE FRI APRIL 4

 

 

 

 

 

END NOTE:

With water temps slowly coming up and beginning signs of the Bermuda High blocking pattern, we should see marine layering effects start to wear off – especially as SST’s surpass the 80° mark.  Subtropical ridging could still show weakening of the Seabreeze pattern with axis placements over the SE coast causing hazy conditions with more stable air, higher humidities, and greater chance for fogging inland/along beaches during early morning hours. 

 

 

 

 

Posted in Coastal South Carolina

San Diego Surprise

Tourmaline04082014San Diego say surprisingly strong winds, especially for Tourmaline (as pictured) thanks to unusually hot temperatures and very dry conditions.  This resulted in an early onset of the sea breezes, but rather than fading gradually, they lasted for several hours. This was largely thanks to the dry air mass and the absence of a marine inversion.  The local Venturi effect around Mt. Soledad only further aided Tourmaline’s winds.  Lesson learned!

-Benjamin Miller

WeatherFlow Meteorologist

Posted in Los Angeles, San Diego