West Coast Wind Blog: Far afield for a quick look at…

Super Cyclone Debbie

by Mike Godsey,

Pretty windy in much of the S. F. Bay Area today. But Kerry, one of the Weatherflow Bay Area meteorologist, has family near Airlee Beach Australia and it is really windy in that area today as super cyclone Debbie kept the nearest sensor above 100 knots. Here is some imagery from Debbie.

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, Ontario- Simcoe, Ontario: Lake Erie, Ontario: Lake Ontario, Outer Banks of North Carolina, Rhode Island, San Diego, San Francisco, SouthEastern North Carolina, Tidewater Virginia

Watching the Tropics in March Already.

By WeatherFlow meteorlogist Shea Gibson.

There is a bit of a pre-season area of disturbance to be watching for in the tropical Atlantic basin…

We are watching this area for Sunday through Tuesday in the western Atlantic as models are coming into more and more agreement for possible tropical activity. The area in question has a good chance at becoming a surface Low feature over warm waters, but looks to eventually move over cooler waters. This would give it a subtropical signature as the surface low develops and heads NE/ENE in time. Either way, the SE coastal region may get a small bump in swell heights and Bermuda should watch for moderate to fresh gales.

GFS forecast for Monday at 2AM.

ECMWF (Euro) forecast for Tues 8AM EDT (12PM UTC)

 Using NCEP, CMC (Canadian) and  ECMWF (EURO) ensembles for chance of tropical cyclone genesis, here is the latest:
And here are the current Sea Surface Temps with the area shown in the blue box. Notice the cooler waters towards the NE quadrant of the box.
This is a reminder that pre-season systems are possible as we head into our warmer season, so it’s time to shake off the dust and oil the tropical bookmarks. We aren’t expecting a named system out of this, but Subtropical Storm “Arlene” would be the most likely scenario if it does strengthen.


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

Sources: NASA Sport SST,  Tropical Tidbits, Hurricane Forecast Improvement Program- NOAA 

Posted in Coastal Georgia, Coastal South Carolina, Outer Banks of North Carolina, SouthEastern North Carolina

West Coast Wind Blog: Fast moving storm front…

Strong SE storm winds rake the Bay Area…briefly.

by Mike Godsey

Here some imagery of the rapidly developing and fast dying winds that are currently hitting much of the Bay Area. You can see why I am forecasting these winds to die fast both in the satellite imagery and in the model output.

Posted in San Francisco

Converging Winds push Leo into the 20s.

by Meteorologist, Kerry Anderson

The first day of forecasting in the Spring season feels like a bear coming out of hibernation. It is time to dust off the forecasting tools and see what patterns Mother Nature throws at you for the season.  After a long winter the hope is always that there won’t be any surprises. Yesterday at first glance seemed easy enough when looking at the typical parameters. A fast moving cold front had dumped cool air over the Los Angeles Basin, so there was little in the way of thermal gradients to push sea breezes into action.

Afternoon Temperatures March 7, 2017

In fact at first glance all signs were that offshore winds would squelch any wind development at the beaches.  High pressure moved inland behind the front leaving a  tight pressure gradient that pushed N/NorthEasterly winds down the canyons toward the beaches.

Surface pressure map March 6, 2017

But instead of gusty offshore winds Leo Carrillo reported WNWest winds in the 20s for much of the afternoon.  I wish I could say that I forecast this accurately but it caught me by surprise. ( Not the way I wanted to start the forecast season.)  But as I returned to reanalyze and figure out where the forecast went awry I found that the Wf-Wrf model had nailed the forecast.

Leo Carrillo graph March 7,2017.

    Weatherflow’s microscale forecast model – Wf-Wrf – accurately forecast the anomalous winds. Weatherflow offers a variety of forecast models to forecasters and consumers. A large part of the science of forecasting is knowing the strengths and weaknesses of each model and knowing which solution will be right for each circumstance.  The Wf-Wrf, which uses a fine 3km grid, was able to pick up on the convergence of the offshore winds with the coastal northwesterlies which then pushed back toward shore from bringing a zone of strong W/WNW winds from Leo Carrillo to Cabrillo.  As the High pressure moves further inland the offshore winds will continue to die down over the next 24 hours.

Posted in Los Angeles, Weather Blog

West Coast Wind Blog: Why no NW clearing winds after yesterday’s storm?

The North Pacific High’s surface NW winds are siphoned off towards the Pacific Northwest

by Mike Godsey

So it is beach meteorology folklore that after a spring storm that the skies clear and the S. F. Bay Area has strong to wild NW clearing winds? So why did Kerry and I forecast weak winds today after the weekend’s storm?

First take a look at the isobar map for this morning. Isobars are lines that represent areas that have the same atmospheric pressure.

Note the North Pacific High in the lower left corner. This is a dome of high pressure air from which wind spirals outward in a clockwise fashion. Notice the isobars that extend outward from the center of high pressure. The pressure is the strongest at the center of the NPH. Why? Well you can visualize the North Pacific High as a mountain or dome of air and since the atmosphere is thicker in this dome there is higher pressure.

Usually after the passage of a storm there is lower pressure air in the California Central Valley and/or in the Great Basin. This creates a pressure gradient between the North Pacific High and that low pressure. Hence NW clearing wind.

But looking at the map again notice that the North Pacific High dome of high pressure has an extension extending into California over the Bay Area, the Central Valley and Great Basin. Just like mountains have steep ridges extending from their crest the NPH sometimes has ridges of high pressure extending from its center. Since this NPH ridge is an area of high pressure it spoils the pressure gradient from the pressure gradient to the Central Valley and Great Basin. So we lose the NW clearing wind!

But where does all that post storm NW wind disappear to? Well today there is a huge low pressure from the recent storm in the Columbia River Basin and points east. You can see it in the upper right corner of the map. So now we have a pressure gradient from the North Pacific High towards this low pressure.

As you can see in the next animated image (annotated from earth.nullschool.net) most of our clearing winds is being diverted towards the far Columbia Basin and the Rockies.

So can you see why we are only forecasting weak SW winds for most sites?

Posted in San Francisco

Early Cannonball Run for Coastal SC in 2017

By WeatherFlow meteorologist Shea Gibson on February 22, 2017.

Here we are again with the annual Cannonball Jellyfish update – in February! This year has been quite the anomaly with warmer air temps than normal all the way into late February (4th warmest January on record). Basically, Spring has started to show early this year along coastal SC. And guess what? Our little lumpy friends have shown up early on our beaches as well.

Great article here from the National Phenology Network on the early spring anomaly using “first leaf outs” and accumulated air temps: https://www.usanpn.org/data/spring

Here are the past Cannonball Jellyfish arrival dates and blogs:
* 2014: Late April to early May as Sea Surface Temps rose to upper 60’s low 70’s. http://blog.weatherflow.com/cannonball-jellyfish-signify-the-end-of-marine-layering-along-sc-coast/

* 2015: April 11/12th first sightings during a quick surge of Sea Surface Temps to low 70’s. http://blog.weatherflow.com/gulf-stream-surge-brings-the-cannonballs-back-early-in-2015/

* 2016: Middle of March first sightings with Sea Surface Temps in the middle 60’s. http://blog.weatherflow.com/cannonballs-fire-the-first-warming-shot/

For the record, Sea Surface Temps from February 15th to present (Feb 22) have been roughly 57-60°, which is warmer than normal for this time of the year. This is also 5-6 degrees cooler than past years with their arrival.

Here is the current Sea Surface Temp loop from NASA Sport SST from Feb 1 to Feb 21 – notice the slight warm nudge of warmer Gulf Stream water into the coastal shelf waters along GA to our south.

Feb 15 SST:

This pic of Cannonball Jellyfish was taken on February 17, 2017 at Edisto Beach, SC by Kevin Verbrugge via Twitter: https://twitter.com/SurfFisher48/status/832699739590246400

Another pic of one at Isle of Palms on February 20, 2017 provided by Justin Gern via Twitter: https://twitter.com/justingern/status/833674489217032192

And a Mushroom jelly from Charleston local Cacky Rivers Vlcek via Instagram/ Facebook: https://www.instagram.com/p/BQQwrfHAUba/

So why did this happen early this year?

We have seen a succession of Bermuda and Bahamian High pressure setups create systematic moderate S/SW flows, which coupled with cooler shelf waters this time of the year brings the Cannonball jellies and Mushroom jellies up the coast.

Here is a Bahamian High setup from Feb 17, which helped to push the jellies northwards sooner.  Source: Levi Cowan of Tropical Tidbits.  

We typically see these Highs setup to the north along the mid Atlantic with moderate to strong NE/ENE winds which keep them suppressed to the south (a weak La Nina transitioning into a ENSO Neutral phase has quite a bit to with this pattern).

Also, we have seen our coastal Sea Breezes remaining moderate to the barrier island beaches due to high air temps remaining mild and allowing for beach coupling (land-sea interface coupling). Here is a good example from this past Friday, Feb 17, 2017 where Isle of Palms showed a solid moderate build in the afternoon.

“At the surface”, it certainly appears that the jellyfish have brought the Sea Breezes back to the beaches early this year. However, don’t be so quick to assume it will remain the norm. Once air temps surge into the 80’s again over the next few months, we’ll see the marine layering (much weaker speeds to beaches) show until the SST’s warm up to at least the mid to upper 70’s.

All in all…we are ~20 days ahead of schedule for spring with Sea Surface Temps holding just above normal. Looks like we will continue with a mild climate right through Meteorological Spring (March 1st) and into the Spring Equinox (March 20 at 6:29AM EST). Here is s quick glimpse of the 16 day air temperature forecast for inland Charleston via our friends at WeatherBell Analytics:

Until next year……


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

Sources: National Phenology NetworkNASA Sport SST, Justin Gern – Twitter: @justingern, Kevin Verbrugge – Twitter: @SurfFisher48, Cacky Rivers Vlcek via Instagram/ Facebook: https://www.instagram.com/p/BQQwrfHAUba/Tropical Tidbits, WeatherBell…and our own professional WeatherFlow DataScope viewer.

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

Crazy strong Gorge East winds and El Norte winds for Baja…


High pressure blankets mid USA creating strong pressure gradients.zz48cb69c1

by Mike Godsey, mike@iwindsurf.com

Tomorrow, Thursday Dec. 8, 2016 will see very strong east winds in the western Gorge to Portland while Baja’s East Cape sees significant El Norte winds. Surprisingly these winds, separated by thousands of miles of land, have the same cause.

But first let’s look at the NWS discussion for the Gorge tomorrow. While the models bicker a bit about the max strength of the Gorge winds it looks like we will see gusts in the 60-80 mph range at Rooster Rock. But what about that mention of 110 mph gusts? We will come back to that also.gorgeewinterwindsbaja

The cause of both the Gorge E. winds and the North winds in Baja is a enormous high pressure zone located in the middle of the USA. In the 2nd. image that high pressure zone is in red. Notice how the high pressure area is just east of the Gorge and north of Baja. Now notice the tightly wound low pressure storm system west of the Pacific Northwest. So the Gorge has strong low pressure to west and strong high pressure to the east. This means there is an extreme pressure gradient over the length of the Gorge. But the Cascades make a partial barrier to the winds created by this huge pressure gradient. So the main route for the east winds will be in the Stevenson to Troutdale corridor. So the venturi effect will be strongest there.

This pressure gradient is so massive that if all of the winds was near surface wind we would be seeing gusts to 110 mph range. But tomorrow there is strong wind from the surface to over 5000 feet. This means a good portion of the wind will be able to slip over low places in the Cascades rather than being focused just in the Gorge.

Now looking at Baja notice that the huge high pressure zone is partially over the Great Basin  and 4 corners zone. High pressure in that zone creates a pressure gradient to the frequent low pressure zones south of Baja. This pressure gradient should create solid El Norte winds tomorrow.

Now note the location of the North Pacific High. This is location is far to the south of the North Pacific High’s summer time residence off our west coast. In recent years the North Pacific High has been even further south so it is often sending NW to WNW winds over Baja pushing the El Norte N-NNE winds  away from the shore especially at El Sargento  and sometimes La Ventana. But tomorrow it looks like the North Pacific High is positioned so it will actually jazz up the El Norte winds.




Posted in Cape Cod, Los Angeles, San Diego, San Francisco

Another Short Wave Wind Killer for Charleston, SC.

by WeatherFlow meteorologist Shea Gibson

We have discussed short wave troughs (known as “short waves”) before in previous blogs, but here is a quick recap:
According to NOAA’s definition, this is, “A disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it. If other conditions are favorable, the upward motion can contribute to thunderstorm development ahead of a shortwave trough.”
Also see my focused blogs on past short wave events:

June 2, 2015: http://blog.weatherflow.com/what-is-a-short-wave-and-how-can-it-affect-winds/ 
April 19, 2016: http://blog.weatherflow.com/never-forget-the-short-wave/

On November 1, 2016, we saw High pressure to the north set up a fairly solid and moderate NE Wedge down the SE Coast. Specifically, Charleston, SC is know for accelerations of speeds due to Sea Breeze coupling as cool air dives down over warmer waters and intensifies along the barrier island beaches. This is known as “backdoor Sea Breezing” when a “backdoor” cold front has moved down the coast and High pressure wedges in down behind it. In this case, a weak cold front moved through and slowly fizzled out over SC/GA.

Here in the WPC NCEP surface map from 7:00am, a tail end of troughing still remained offshore.

At 7:47AM, the NE/ENE winds picked up to 16kts g20 (gusting to 20kts) due to the sun coming up, the gradient tightening and speeds elevating according to the onshore turn/acceleration process of initial Sea Breezing.

Quick note: Air Temps were already in the upper 60’s, so the radiational heating process in the atmosphere got things going earlier once the sun came up.

By midday to 12:55pm, the backdoor Sea Breeze process had winds up to 18kts g22, which we consider a moderate flow.

A little after 1pm, the drain got pulled on the winds and speeds plummeted. By 1:38pm-1:42pm speeds north of the Charleston Harbor had dropped to 10/11kts. Folly Beach kept its speeds to 18kts g21.

My first reaction was to check radar, but no precip showed up. Took a look at the sky and saw cloud layering with overcast-type skies. That was my first clue that short waving was occurring somewhere nearby. I brought up the SPC Mesoanalysis, which I have set to update every 1 minute – and caught a small atmospheric disturbance to the south:
The positive tilt (upwards bow) in the High pressure 1022 isobar (equal line of pressure) was representative of a short wave trough developing. Counter-clockwise rotation in the surface wind barbs are a classic signature of a short wave beginning to allow for weak surface low pressure development. You can see the showers showing up on the radar imaging. This was likely initiated by a bit of rotation intensifying over the warm waters of the Gulf Stream. 

So looking at our Datascope viewer, I was able to capture the short wave developing into a weak low (mesolow) and heading into northern Georgia. The outflow aloft showed that the gradient held up just south of the Charleston Harbor, but clouding aloft cut off the flow to the north. It was actually sunnier to the south within an open pocket in the clouding, which kept the Sea Breeze alive to Folly Beach a bit longer.

Here is a different perspective from WSV3:

Eventually, areas to the south including Folly Beach saw the drop in winds. Just took a little longer. Here is the graph of Folly Beach that day – you can see the downward trend around 1:45pm:

All-in-all, this is yet another way we can detect short waves by first analyzing our coastal mesonet and then using the sky as another reference point before even checking regional radar or the regional mesoanalysis.  Many times, just knowing the NE/ENE wind behavior and knowing that a sudden drop of onshore flow usually means either a) a short wave/area of low pressure weakens the gradient from nearby (common) or b) the overall gradient weakens just that fast (not very common).

Until next time – stay safe out there.

Shea Gibson
WeatherFlow Forecasting Team
East Coast/ SE Region
Outreach/New Station Projects
Twitter: @WeatherFlowCHAS


Sources: NOAA SPC, NOAA WPC NCEP archives, WSV3, and our own WeatherFlow Datascope Professional Viewer 

Posted in Coastal South Carolina

Beware the Witch of November!

by WeatherFlow meteorologist Shea Gibson

Get ready Great Lakes for a possible “November Witch” to broom into the area by Thursday/Friday with a cauldron of warm air, cold air and violent gales! The name comes from intensifying Low pressures with a clashing of warm air, rain and storms ahead drawn up from the Gulf of Mexico…and cold Canadian air with heavy snow wrapping down around it. At times in the past, we have seen hurricane category force 1 and 2 winds generated over the Great Lakes as the two air masses collide. This is typically a more frequent event to see this time of the year; however, the effects of a La Nina pattern have kept warmer air up across the upper midwest until this week as we see the pattern begin to act more like the fall season.

The old saying goes: “Beware the Witch of November!”

The Witch of November phrase was used in the famous song “The Wreck of the Edmund Fitzgerald” (happened in 1975) by Canadian singer-songwriter Gordon Lightfoot, which was a tribute to one of the most well-known Great Lakes shipwrecks known in that area.

Artistic rendition of an angry and cruel Lake Michigan.


And the “pointy hat” of a “cruel witch” from Photographer Dave Sandford.


S.S. Edmund Fitzgerald before it went down in Lake Superior on November 10, 1975. All 29 of its crew perished. Between 1878 and 1987, 6,000 ships have been lost on the Great Lakes…with upwards of 25,000 individuals losing their lives over the last 300 years.


Sadly, the National Weather Service Marquette, WI did issue fair warning ahead of their departure, but they went anyways.


GFS model surface run showing a possible 987mb Low (very strong winds are typically generated at this pressure)


GFS 500mb chart showing the strong mid level vorticity just west of the Great Lakes by Friday afternoon.
ECMWF (EURO model showing agreement with lower pressure at 982mb’s.
San Francisco State University 300mb (~30,000ft)  jet stream analysis showing an intense dip in the jet stream with strong Southerly flow aloft pushing over 100kts – with higher areas of streaking to the SW and the NW.

As we head into Saturday, we see winds pick up across the Great Lakes:

Here is the GFS wind forecast for (Lake) Superior West Buoy topping 30mph – the CMC Canadian model (yellow line) reaches into the 40’s.
And here is the forecast not too far away at Stannard Rock in Lake Superior as well:
Even though this is still 5-6 days out with much that could change, it does serve as plenty of heads up to mariners up that way to keep an eye on developing conditions this week.

UPDATE 11/18/16: Looks like this storm verified with wind in excess of 50mph over Lake Superior and other locales where the wrap-around winds are really cranking up. Here is a video of the system and the winds + gusts.  Snow and blizzard conditions are on the N/NW/W/SW side of the system where cold air is wrapping into it… with white-out conditions for many locales.

Stay safe everyone!
Shea Gibson
WeatherFlow Meteorologist/Wind Forecaster
SE Region/East Coast/Tropics

Outreach & New Station ProjectsHow to find me:
Twitter: @WeatherFlowCHAS
Wind Alert – https://www.facebook.com/windalert/ 
WeatherFlowCHAS – https://www.facebook.com/WeatherFlowCHAS/
Chucktown Wind Report – https://www.facebook.com/groups/ChucktownWindReport/

Sources for this blog: Our own Datascope viewer, Tropical Tidbits (Levi Cowan), WeatherBell Analytics, NWS Marquette, WI , SFSU.edu, Photographer Dave Sandford

Posted in Ontario- Simcoe, Ontario: Lake Erie, Ontario: Lake Ontario, Weather Blog

Winter arrives and the North Pacific High departs while…


Storms dominate northern pacific

by Mike Godsey, mike AT iwindsurf.com

Remember this summer when the North Pacific High dominated the waters between the west coast and Hawaii? Back then wind most days was a given. So where did the Southern California, Bay Area and Gorge winds go?

Part of  the answer is the decreased hours of sunshine to heat inland valleys. And then there is the lower winter angle of the sun which promotes less heating. Both of these factors mean the
pressure gradients from the coast to the Southern California deserts, Columbia Basin, Central Valley and the Great Basin are much weaker in the late fall and winter.

But a large part of the answer is the location and size of the North Pacific High. During the summer the upper troughs up at ≈ 18,000 ft. that pass over the west coast take a more northerly path. As they graze the Gorge the just act to indirectly jazz up the surface winds. While in the S. F. Bay Area and Southern California they deepen the marine layer and in so doing impact the strength and location of the wind.

But in winter the upper troughs take a more southerly track bringing storms and rain to the west coast as they guide surface storms towards us. And this more southerly track plays a role in moving the North Pacific High to a winter home often well south of the west coast.

In this animation I have removed the clouds so we can more clearly see the wind patterns as well and rainy storms and high and low pressure systems.winternph

First notice the relative small North Pacific High in the lower right corner of this image of pacific and west coast. Notice that its clockwise winds are creating weak NW winds along the coast of Baja. Back in the summer the NPH was much larger and located west of Northern California.

Now notice the huge pacific storm and its counter-clockwise spinning winds that is slowly plodding towards the Pacific Northwest. The bands of rain in this storm are in green. Also notice the cold front associated with this storm.

Next notice the developing high pressure in the 4 corners area of the USA. This high pressure moved in in the wake of the recent storm and should make for a mild El Norte wind event in Baja’s Sea of Cortez tomorrow and/or Tuesday.

Come spring the average path of the upper trough at ≈ 18,000 ft. will slowly move north and you will see the storm track move northward. And as spring progresses the average position of the North Pacific High will be in California waters and the stage will be set for NW clearing winds.

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