San Diego Southerly Smash

So, San Diego isn’t exactly known for its wealth of wind.  This is especially true in the summer.  But today is an exception!Winds_SoCal_23Jul2016

 

Just how has this happened?

  1. We’re seeing strong NW flow across the far outer waters of the bight.
  2. There is high heat in the inland areas as offshore flow prevails.
  3. A well-formed Catalina eddy has centered itself in just the right spot, south of San Clemente Island.
  4. There is mid-level and upper-level support, enabling the eddy to endure.

WRF_SoCal23Jul2016

Posted in Los Angeles, San Diego

Anatomy of a tough Gorge forecast

aWCWBGorgeVid

Timing is everything!

by Mike Godsey, mike AT iwindsurf.com

I avoid forecasting for the Gorge for a number of reasons. The two biggest reasons are that it takes about 2-4 years of forecasting in a new

area to learn how to interpret all the model output and empirical data to do decent forecasts. The second is that by personality and by training I am an educator. So if I forecast for the Gorge it would be like the Bay Area where I would arrive at a launch site and have a choice of either getting hung up explaining what was happening or not happening with the wind or being an impolite jerk. Except it would be worse in the Gorge since the first few years would be spent explaining why I blew the forecast again. So have taken the easy way out and just follow other people’s forecasts.

But I know enough about Gorge forecasting to recognize a tough forecast situation like today. Looking out the window at 9AM I am seeingZZ0B607341
glassy calm conditions in the corridor.
Yet the forecasts suggest LATE strong winds especially way out East today. Why?

Looking at the first image above at 9AM note the compression of isobars (lines of equal pressure) stacked up along the coast. Higher pressure is to the west and lower pressure is to the east over the coast range. But without any venturi effect in that region the winds are very light.

Now looking at the same image note that there are almost no isobars over the Gorge. Hence the weak winds this morning.5PM Gorge Gradient

Now look at the second image for 5 PM today. Notice how tight the isobars are one the Gorge from about Stevenson to about The Wall. This means that there is a strong W. to E. pressure gradient in this region. But the pressure gradient tapers off as you get past The Dalles. But this concentration of isobars would by itself only produce low 20’s wind and the wind would taper off past Dougs. Yet the forecast is for strong  LATE winds all the wayGorgeSurfaceLATE winds to Rufus.

So there has to be some missing factor to make the winds reach towards the mid 20’s and to reach to The Wall.

So let’s first examine how the surface winds  develop, in theory, during today. This first animation shows how the isobar dance we saw above plays out wind wise at the SURFACE.

Notice how weak the AM SURFACE winds are in the Gorge. Then note how the winds pick up in the late afternoon as the isobars tighten. Also note the focus of the winds in the Corridor to just past The Dalles. But still this is only low 20’s wind. So where does the stronger juice come from?GorgeLATEwinds2000ft

The next animation give the answer. Now we are looking at the modeled winds at the 950 hectopascal level at about 2000 feet of elevation. Notice not much action at that level until about 5 PM.

Then as a short wave upper trough passes over the Gorge momentum from 50 knot winds at that level stir up a blast of  winds at 2000 feet which in turn transfers momentum to the surface winds. Typically this would mean gusty winds at the surface since the pressure gradient is mild.

Of course all of the above is derived from a couple of models and personally I am hoping the winds arrive much earlier!

Posted in Columbia River Gorge

Wet Microburst in Chandler, AZ shows 116mph winds.

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By WeatherFlow Meteorologist Shea Gibson

Ever been in a thunderstorm and a sudden burst of strong winds and rain comes down at the same time? This is called a “wet microburst”, which packs quite a punch when it comes to the strong winds associated with them. They can be particularly dangerous for airplanes and can level trees in forest areas. Not to be confused with tornadoes, winds can reach up to 100mph or higher (equal to an EF-1 tornado) as the moisture core of the storm cell drops all at once (due to updraft weakening) and slams to the ground.

By the NOAA definition, a microburst is a localized column of sinking air (downdraft) within a thunderstorm and is usually less than or equal to 2.5 miles in diameter. Microbursts can cause extensive damage at the surface, and in some instances, can be life-threatening. There are two primary types of microbursts: 1) wet microbursts and 2) dry microbursts. Wet microbursts are accompanied by significant precipitation and are common in the Southeast during the summer months.  (Anything larger than 2.5 miles in diameter is called a “macroburst”.) 

microburst

Microburstnasa

Just recently in Phoenix, AZ on July 18, 2016, an incredible picture was captured of a wet microburst dropping from a storm cell. It was taken by Bruce Haffner using a drone. He is a television helicopter pilot/reporter in Phoenix, Arizona. Check out their aerial HD videos at

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Here is a report we got from the Chandler Airport, AZ (southeast Phoenix) with 116mph winds at 6:50PM.

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My first thought when I saw the pics were of atomic blasts, so I just had to something together. Below is that same wet microburst picture from Phoenix, AZ on July 18, 2016 placed under the “Operation Crossroads” pics of atomic testing in 1946 near Bikini Island Atoll in the Pacific Ocean. That yield was 23 kilotons (and you can see the ships steaming from flash burns!). Of course they are two totally different forces (man made explosion going up and nature-generated microburst going down), but what a striking resemblance in photos!

Operation_Crossroads_Baker_Edit

Operation Crossroads 2

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Nature surely is impressive isn’t it? Stay safe and please take Severe Thunderstorm Warnings seriously.

Cheers!

Shea Gibson
WeatherFlow Meterologist
SE Region/ EC / Tropics
Outreach/ New Station Projects
Twitter: @WeatherFlowCHAS

 

 

Posted in Cape Cod, Chesapeake Bay, Coastal Georgia, Coastal South Carolina, Columbia River Gorge, Connecticut, Delmarva, Long Island/SE New York, Long Island/SE NY, Los Angeles, Massachusetts North Coast, New Jersey, Ontario- Simcoe, Ontario: Lake Erie, Ontario: Lake Ontario, Outer Banks of North Carolina, Rhode Island, San Diego, San Francisco, SouthEastern North Carolina, Tidewater Virginia

Quiet in the Atlantic Basin? Don’t Get too Complacent.

20160718_0600_sport_nhemis_sstcomp

By WeatherFlow meteorologist Shea Gibson
Written on 7/18/2016:

Tropics Update:

We started the late spring somewhat active along the SE United States and western Caribbean for the Atlantic Hurricane Season 2016. Don’t forget – we had an early storm in the eastern north Atlantic in January, which was Hurricane Alex (and still our strongest so far at 85mph winds).  We began the pre-regular season with Tropical Storm Bonnie (top winds 45mph) and went to Colin (top winds 50mph) just at the start of the hurricane season on June 3. Soon thereafter, we had a briefly lived Tropical Storm Danielle (top winds 45mph) that developed in the Bay of Campeche and quickly pushed into Mexico on June 20. Since then, it has been very quiet over the Atlantic basin.

01278ef342af105b4f72b6ffcdb98ca1

A very large Bermuda-Azores High has encompassed much of the northern Atlantic to keep drier air and a consistent Easterly trade wind pattern going for weeks now.  Along for the ride is the “Dusty Tongue of the Sahara” – or the SAL (better known as the Saharan Air Layer) that is continuing to eject African desert dust into the mid levels of the atmosphere.  This keeps tropical cyclone activity down as areas of Low pressure emerge off of the African coast along the Intertropical Convergence Zone (ITCZ) and move west while blending with this drier dust. As far as the Caribbean and Gulf of Mexico are concerned: Dissipating tropical waves, lack of consistent troughing or cold front tail-ends… and upper level shear have been keeping development down.

Saharan Air Layer showing the dust in red mixing in with the tropical feed just north of the equator.

Recording #190

With absence of any significant tropical waves pulling across from the east or cold fronts being able to drop down and become stationary through Florida to help create more precipitable water environments over the Caribbean, western Atlantic and Gulf of Mexico, the sea surface temperatures (SST’s) have been steadily rising to very high numbers.  We are now seeing 30°C or 86°+ temperatures with a few low 90’s around the waters of Florida. Early last week on July 12, we recorded 94.1° from the Old Port Tampa Bay sensor and 91-93° elsewhere in various spots around the state waters from as far back as July 8.

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13581916_10210514674366963_7172415391740439543_o

Here are the current Atlantic basin and northern Pacific SST’s through NASA’s Sport SST product.

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Capture3

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Needless to say, there are quite a few factors that go into the allowable development of tropical cyclones such as a relaxed upper shear environment and surface Low pressure development; however all of this surface heat is apt to provide plenty of fuel to storms once the pattern shifts and we see favorable conditions begin to emerge from our tropics. It has been just over 10 years since we have seen a major Hurricane make United States landfall (last one was Category 3 Hurricane Wilma that made landfall at Cape Romano, FL with 120mph winds on October 24, 2015 – this was after Cat 5 Katrina that same year).  Don’t let your guard down. We haven’t begun heading towards our peak time of the year just yet.

peakofseason

There are some signs that the ITZC will start becoming more active towards the last half of this month as it slowly lifts north and the monsoonal trough makes a better connection with Low pressures coming off of Africa.  We will begin watching the regular swath of tropical waves traveling westwards across equatorial Atlantic and northwards up into the Caribbean.  The Gulf of Mexico could be a hot bed of activity in time, especially with the SST’s so high.

Capture6

Here is the list for the next few years through 2021 – next up for us this year “Earl” in the Atlantic basin. This snippet is from the NHC website:

Capture2

And here is the list of predictions by entity – notice NOAA going with a near normal season prediction base of 10-16 names storms…and NC State University going aggressive with 15-18 names storms.

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Tricky year with the transition from El Niño towards La Niña (expected by fall 2016 /winter 2017). Right now, we are in a neutral or what is called “ENSO Neutral” phase.

Cheers and stay safe!

Shea Gibson
WeatherFlow Meteorologist
SE Region/ EC/ Tropics
Twitter: @WeatherFlowCHAS

Posted in Cape Cod, Chesapeake Bay, Coastal Georgia, Coastal South Carolina, Connecticut, Delmarva, Long Island/SE New York, Long Island/SE NY, Massachusetts North Coast, New Jersey, Rhode Island, SouthEastern North Carolina, Tidewater Virginia

Bay Area weather: Why the long run of the Mutt & Jeff Eddy show?

WC103fall

Blame it on the winds aloft!EddyRoundW850 above

by Mike Godsey, mike AT iwindsurf.com

For old timers the strong WSW winds of recent weeks north of the Bay Bridge see like a blast from the past. And if you have been a kiter or windsurfer for less than 15 years on the coast or Peninsula it probably seems like the wind machine is broken.

The reality is more complex. Yes the WSW winds and marine layer clouds have come on strong in recent weeks yet the cause is very different than in past decades. Most of the WSW flow has been the product of very local and very persistent counter-clockwise spinning eddies just west of the Bay Area.

And… no the coast and Peninsula wind machine is not broken but rather we have had about 15 years of unusually common strong NW ocean winds and those winds have often been absent this year.

So what is the cause of the sustained eddy action? In recent years it has become common for tiny eddies to form just west of the Golden Gate. Lacking a formal name for these eddies I have taken the liberty of calling them the Golden Gate Eddy since they are typically confined to the waters from about Stinson Beach in Marin to about Pacifica.

Most of the time the southerly flow along the coast from these Golden Gate Eddies fades away mid day as the eddy dies. This allows the North Pacific High’s surface NW winds to curve into the coast and reach the Peninsula and Waddell. This also means weaker wind for the East Bay  and Sherman Island.

But the recent eddies have been far larger than the Golden Gate Eddy and EddySliver850have been lasting for days. Moreover they have been very variable in shape ranging from the very rotund to the extremely slender.

In the top satellite animation you can see such a “Jeff” type long lasting eddy which is round and mostly seen in the early days of an eddy pattern.

In the second animation you can see a “Mutt” type of eddy that is long and slender and runs parallel to the coast. Note that in this case it extends from Big Sur to way past Bodega.

Why the varying shapes and the very long life spans?

Well the typical Golden Gate Eddy forms when the North Pacific High’s NW winds turn more NNW. This tends to create low pressure in Marin, Sonoma and Napa. At the same time the NNW winds hit  Pt. Reyes at an angle favorable for eddy formation.

And once this happens the southerly flow from the eddy is sucked towards the Golden Gate and towards the low pressure in the North Bay. Later in the day the low pressure goes up in the Central Valley and the NW wind reaches the coast and this Golden Gate Eddy is blown apart.

But in recent days we have upper trough at ≈ 18,000 ft. near the Bay Area and this has induced counter-clockwise circulation in the air EddySurface850above us from near the surface up to the 850 mb level at ≈ 5000 ft. This flow above us goes on for days and it causes the surface eddy to enlarge and continue day and night. This means non stop southerly flow along the coast. And for the Peninsula it means W to SW flow at many launch sites.

You can see the impact of the winds at 5000 feet in the 3rd. animation. See how the winds at 5000 feet would act to reinforce and expand the surface eddy.

When the upper counter-clockwise spinning circulation is directly over the waters just west to the Bay Area we get a “Jeff” type long lasting eddy which is round in shape. This means it really only impacts the coast from about Half Moon Bay to Bodgea.

As the upper trough at ≈ 18,000 ft. moves eastward the counter-clockwise circulation above us also moves westward so the surface eddy becomes compacted near the coast and we see a “Mutt” type of eddy that is long and slender and runs parallel to the coast.

Once you see a “Mutt” type of eddy you know that the eddy pattern will end in a day or so. And it also means the the North Pacific High’s surface NW winds will return to the coast as we will see today July 17, 2016.

Posted in San Francisco

To Mix or not to Mix? WF-WRF and the Typical summertime forecast issue for the New Jersey Coast.

Our newest WF-WRF model has been unleashed on the New York/New Jersey domain and we have been seeing some amazing results!

During the summer months, the NJ coast often gets a series of cold fronts but these aren’t exactly ‘fronts’ because in summer they weaken and often die before they get over the NJ coast.   Models tend to over-estimate their potency and it’s quite common to see a model predict for days out a strong West, SW, or NW flow only to get to that day and see light winds when the front dies out.    And… don’t forget the sea breeze explosiveness of the NJ coast.   All we need is a weak offshore flow to provide the circulation and the sea breeze could get quite healthy.

So… this day was lining up to see a typical model predicted Westerly which I suspected would weaken and could give an undercut of an accelerated sea breeze.

Setup:

nam2.24hrnam2.36hr724070.cloud

WF-WRF predictions:  (this is cool!)

wrf 12z 3pm valid wrf 12z 4pm valid wrf 12z 5pm valid wrf 12z 6pm valid

Morning Soundings (kinda):

rap sounding

And… here’s what happened:

2pm

Long Beach Island:

LBI arch

Trixie’s Landing:

Trixies arch

 

 

Sandy Hook:

Sandyhook arch

Meanwhile… an interesting day on Cape Cod too!  Check out the 20+ mph southern beaches and the nearly calm northern beaches.

 

cape coming on

Summary:

So did I get it right?   Well not really.  I went with the WF-WRF solution but moderated it a bit keeping the sea breezes in.    Morning update I pulled the numbers back even further.   Ultimately, no sea breeze happened that day.   The mixing was deep and the winds aloft were able to reach the surface with gusty winds through the afternoon.   Note that Sandy Hook was spot on with the NW flow all day long.

Can’t blame the WF-WRF and in fact it was simply responding to the initial conditions from the “parent model”.   It showed behavior that we have observed often using real time obs in these very similar setups.   It’s a great sign that with some further tweaks this model can get it right in the future.

 

 

Posted in New Jersey

The big picture of the eastern pacific on a strange day

CWB Golden Gate

The video for today July 10 shows what a major North Pacific High looks like on a typical April and July and September day.NPH&Storms2N&S

by Mike Godsey, mike AT iwindsurf.com

In April the NPH is often huge and is often interacting with storm systems in the Gulf of Alaska and along the coast of the Pacific Northwest. This tends to kill the Gorge winds and enhance the Southern California and Bay Area winds. As you can see in the video such will be the case today in July.

In July wintry storm are a memory and the NPH anchors west of the Gorge keeping the winds strong and the skies blue. In reality this July day brings showers, clouds and weak winds. Meanwhile in July the NW ocean winds are weakening in for Southern California and the Bay Area as fog and milder thermal winds rule. In reality NW winds will rip the Bay Area to Southern California coast today.

In September the North Pacific High is shrinking fast and has departed the Gorge is heading to the SW while being buffeted by passing tropical storms and hurricanes way to the south. In reality today the NPH is spring time huge but its trade winds are encountering a parade of tropical storms.

After getting paid to forecast the North Pacific High 3X daily for 25 years you get a sense of what is within the normal range of variation. It is increasingly common to see patterns that are not within that range. Today is such an example.

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

Part 1: When Big Eddie comes calling the doors closes on Coast, Coyote and 3rd. Ave.

WCWB3rdconvergenceZone

 Combo of late season storms and early season tropical storms favors NNW ocean winds & southerly eddy flow.ZZ697B9709

by Mike Godsey, mike@iwindsurf.com

Take a look at the wind graph to the right for June 13.  The channel sensor is blowing 24 knots at 4:56 PM so you would expect hoards of kiters and windsurfers on the waters and rigging in the parking lot. But the cam image below the wind graph shows both the lot and the waters are calm.

This is a pattern we  have seen over and over this June and early July. I think most would agree that this is the worse season, so far,  in decades for the Coast and Coyote and 3rd. Ave. Yet paradoxically the waters north of the Bay Bridge have had one of the best seasons in years.

We always expect there to be brief periods when the  wind is  crappy for some part of the greater Bay Area but this long period of worst and best winds is unprecedented.

And as Coyote and 3rd. Ave. regulars know our forecasts for inside have also often been crappy as we and the models struggle to figure out this abnormal pattern.

In Part One of this 2 part blog I will give you the big synoptic picture of why we have seen almost endless southerly eddy flow on the coast and in the Coyote and 3rd. Ave. area.EddyNstormSstormNNWflow

Then in Part Two, later in the week, will cover the super micro scale of the 3rd. Convergence Zone and the Palo Alto eddy. This should give you some insight as to why the winds inside at Coyote and 3rd. Ave. have been so weird and why they are so hard to forecast.

Looking at the next image first find the North Pacific High. Then notice the extension or ridge from the NPH that extends towards the Pacific Northwest and Canada. These ridges commonly form as storm systems pass by to the north. Most of June there was an unending parade of such storms so the NPH frequently had such a ridge.

Notice how the winds in the ridge area are N to NNW as they reach California. As you know the Northern California coast mostly has NW wind in the early summer but this June NNW winds prevailed due to the common appearance of the ridge.

This NNW flow encourages eddies to form in both the Bay Area and in Southern California. In the Bay Area the eddy can range from a tiny Golden Gate Eddy in the waters between Pt. Reyes and Pacifica or it can huge and span the waters from Bodega  to past Half Moon Bay. Either way the eddies create southerly flow along the coast  despite the strong NNW wind west of our ocean buoys.

While such eddies form several times a month in the summer they typically die about mid day as does the southerly ocean wind. But this June the eddies were often jazzed up by southerly upper level winds or low pressure towards Redding or by increases NNW flow due to the unusual early season of tropical storms to the far south.

This southerly flow is good news for sites north of the Bay Bridge since the wind coming through the Muir Gap in Marin and the Golden Gate is less inclined to curve to the south so more of it makes a turn northward at the Golden Gate and Point Blunt heading into the North and East Bay.

But on the Peninsula the Hwy. 92 gap, which faces to the SW, funnels those eddy winds towards the Coyote and 3rd. Ave. launches. At the same time southerly eddy wind hits the San Bruno Gap where it curves towards the low pressure in the Central Valley via the Altamont and Hwy. 84 passes and San Jose plains as NNW to NW wind. And, as we will see in Part Two later this week, that causes problems for Coyote and 3rd. Ave. near shore.

The next animation shows the NPH ridge and the NNW flow and the eddies from June 30 to today July 6. Notice each day how the ridge creates NNW flow and how eddies form near the Bay Area and Southern California.

Then today, July 6, the wind goes more NW as the ridge fades. As I type this at 12:22PM on July 6 there is still faint signs of an eddy and Half Moon Bay and Coyote and 3rd. Ave. have SW wind. But we have a much better chance than recent days of having WNW wind at or near the launch site.
BayNPHridgeEddyKillC3coast

Posted in Los Angeles, San Diego, San Francisco

What happens when Eddy calls in support from aloft?

bay5WCWBmovie

Day and night southerly ocean winds rule!BayAllDayEddy

 

by Mike Godsey, mike@iwindsurf.com

Update at 5PM Saturday June 2: Here is a satellite animation of the huge eddy I forecast when I did the blog below Thursday evening.

Thursday May 30: See the sensor in my banner image above? That is our San Pablo Bay Nav. Aid sensor and it has seen strong southerly winds the last 3 days and it will see more of them this weekend along with the coast and much of the bay.

Why?BayGGeddyWindAloft

Because the typical (at least in recent years? Golden Gate Eddy that fades in the early to mid afternoon receives support from aloft so it keeps blowing for days.

Looking at first image when SURFACE is highlighted you can see the counter-clockwise spinning eddy spinning from Pt. Reyes to past Half Moon Bay. This keeps southerly flow along the coast and though the Hwy. 92 gap, Muir gap and the Golden Gate gap. Note that the North Pacific High’s surface NW winds are far from shore.

Now watch as 300 meter is highlighted notice that there is also an counter-clockwise spinning at this level just above the surface Golden Gate Eddy. This circulation tends to reinforce the surface eddy.

Now check out the image as 600 meters is highlighted. As you can see this counter-clockwise spinning flow is much stronger and spans the entire area from Big Sur to Bodega.

Now let’s jump to 750 meters and the spin area has gone off the map.

All of this counter-clockwise spinning flow comes from an upper level low pressure at about ≈ 18,000 ft. above Central California and Southern California.

All of counter-clockwise spinning flow will keep the surface eddy going at least Saturday and Sunday. This will kill the coast winds expect for some southerly winds near Pacifica and the S.F. Zoo. It will also spoil the winds inside at Coyote and 3rd. Ave. But you can expect strong winds from the north tower past Point Blunt through the Olympic Circle to near Pt. Isabel on into San Pablo Bay past Davis Pt. then through Benica and finally to Sherman Island.

Posted in San Francisco

Why are Sherman dawn winds weak today?

shermanTurbineWCWBToo much of a good thing!

by Mike Godsey, mike AT iwindsurf.com

Doesn’t it drive you crazy when the evening forecast is for low 20’s dawn wind at Sherman Island and then the 7AM forecast and theEddy2 southerly wind graphs shows weaker winds?

Last night Kerry forecast low 20’s morning winds for Sherman Island and then I made the change to mid teens. Why?

There is a tendency for Sherman Island and East Bay customers to think that the Golden Gate Eddy is always a good thing for wind in their regions.

But as we see today for Sherman Island in the AM and probably the East Bay this PM it all depends upon where the eddy is located.

Notice how strong the winds were yesterday at Sherman Island at 7AM.

But note how much weaker they are today. So what happened?

Looking at the 2nd image notice how the North Pacific High’s winds are a bit NNW. That often helps create a eddy just west of the Golden Gate. If this eddy is tiny and just west of the Golden Gate it sends WSW flow into the Bay which helps Sherman Island.

But if the eddy is larger and spans the waters towards Pacifica then the southerly flow is more SSW. And SSW flow tends to sweep up into San Pablo Bay.

As this SSW wind passes in the Richmond San Rafael Bridge area it rises over the points on either side of the bridge. This cools the air so water vapor condenses forming fog. The satellite imagery shows the resulting 2 jets of fog shooting up San Pablo Bay into Napa. This flow diverts the wind that otherwise would head towards Sherman Island. Hence the modest winds there in the AM.

Many days the eddy fades mid day and as this happens the normal WSW flow returns and Sherman Island sees strong PM wind.

This pattern is easy for us to see when there are lots of marine layer clouds. But if the clouds are sparse it takes more detective work to forecast the pattern. And doing this 24 hours in advance is very tricky unless the eddy is really powerful.

Posted in San Francisco