Hurricane Bud Forecast to weaken

Satellite image Hurricane Bud

Hurricane Bud reached peak intensity around 0600 UTC with a max wind of about 110 knots as it moved towards the northwest at about 5 knots. Hurricane Bud is forecast move in a north-northwestward direction for the next 36 hours then turn more towards the north.  Bud will be moving over cooler water and will gradually weaken and move across Baja California Sur as a tropical storm on Thursday.

NHC Forecast Track Hurricane Bud

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North Atlantic Cooling will affect the Hurricane Season

Bermuda High

Bermuda High and Tropical Cyclone tracks

The main tropical development area for the North Atlantic continues to cool relative to recent averages suggesting a stronger than normal Bermuda-Azores ridge. When this high pressure ridge is stronger or displaced west, as it appears to be now, tropical storm formation is less likely due to

NCEP Reanalysis mean surface pressure April 2018. Image credit https://www.tropicaltidbits.com

stronger wind shear and cooler SST temperatures caused by stronger trade winds, however, when tropical cyclones do form, a strong Bermuda-Azores high will tend to cause storms to track farther to the west increasing landfall risks.

 

Sea Surface Temperature Anomaly May 2018

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Subtropical Storm Alberto forms

NOAA Satellite Image

The National Hurricane Center has upgraded the disturbance over the northwestern Caribbean to Subtropical Storm Alberto.

The initial intensity has been set at 35 knots with movement towards the north-northeast at 5 knots. Alberto is forecast to slowly deepen reaching max winds of 50-60 knots over the next 72 hours as well as turning more towards the north then north-northwest.

TS Alberto forecast track from NOAA NHC

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New Tropical Cyclone forms over Arabian Sea

Satellite image of developing tropical cyclone

Tropical Cyclone 02A has formed over the Arabian Sea about 610 nm soth of Masirah Island and was moving towards the NNW at about 7 knots.

Max winds were 35 knots, however, conditions favor deepening and is forecast to reach hurricane intensity in 24-36 hours. The forecast track takes the center inland over Salaha, Oman on the 26th around 0600 UTC.

JTWC forecast track

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Tropical Cyclone Sagar moving over Gulf of Aden

Tropical Cyclone Sagar located today over the Gulf of Aden

Tropical Cyclone Sagar was located today over the Gulf of Aden about 181 nm east of Aden, Yeman and was moving towards the west-southwest at 7 knots. Max winds are estimated to be 45 knots with gale force winds extending outward 75 nm to the northwest and 40 nm to the southeast. Some gradually strengthening is forecast over the next 24 hours.

Forecast suggest that Sagar will begin to weaken after 24 hours as it continues to move west-southwest.

JTWC forecast track

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NOAA’s New Marine Forecast Product Improves Weather Forecasts and Safety at Sea

NOAA color satellite image

National Oceanic and Atmospheric Administration (NOAA) GOES-16 satellite image captures the rapidly-deepening storm off the East coast of the United States on Jan. 4, 2018, at 16:22 UTC. Image credit: NASA

 

The following post was published on March 8, 2018 on gCaptain.com

By Tom Cuff, Director, NOAA’s Ocean Prediction Center

NOAA’s Ocean Prediction Center (OPC) rolled out a new forecast product suite this week to provide mariners with comprehensive weather forecasts every 24 hours out to day four. Our goal is to deliver the very best impact-based decision support services and products possible to our users. These 72 hour surface weather and wind/wave forecast charts, and model generated 500 mb charts, will allow mariners to better prepare for severe weather at sea.

72 hr forecast

NOAA OPC New 72 hour Surface Forecast Chart

Complementing OPC’s 24, 48, and 96 hour products, the new 72 hour forecast charts fill a gap to ensure an even more robust forecast timeline, while identifying areas of maritime weather hazards. Elements include:

  • Winds and waves
  • Surface fronts and isobars
  • High and low pressure systems
  • 500 millibar heights
  • Wave period and direction

In order to implement these new charts, OPC reviewed existing products and services to ensure quality, consistency, and user needs given the ever-changing landscape of models and other forecast tools. Following a public comment period, minor changes were made to legacy products to allow our team to deliver this critically important new forecast tool to improve safety of life and property at sea. We began socializing this new approach with the maritime community in November 2016, and since then have received support from users across the industry.

These products do not lessen the quality of other legacy products disseminated via HFFAX. We are working hard to take the best possible advantage of 21st century forecasting skill and make it available to our users.

As the maritime weather enterprise continues to evolve, it is our goal to continually deliver the very best products, so we must be nimble enough to evolve too. We take seriously our mission to provide the world’s best marine weather forecasts, while preventing loss of life and property at sea.

Visit NOAA’s Ocean Prediction Center website for additional forecasts and information. 

See also:
URGENT “Notice to Mariners” – Changes to NOAA marine products effective March 7th, 2018

 

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URGENT “Notice to Mariners” – Changes to NOAA marine products effective March 7th, 2018

By Lee Chesneau

Lee is a senior marine meteorologist, lecturer, & a graduate from the University of Wisconsin (Madison).   Lee has had a distinguished career with NOAA’s National Weather Service (NWS), NOAA Satellite Service (NESDIS), U.S. Navy Ship Routing Officer (SRO) and  a Route Analyst for Ocean Routes, Inc.

Surface analysis

NOAA OPC Surface Analyis

Changes to NOAA marine products made last November and additional changes scheduled for March 7, 2018 will  likely make route planning and heavy weather avoidance more difficult for the mariner.

Changes to the 500 Mb Chart since last November
Prior to November 13th, 2017, NOAA depicted TROF axes on its 500 Mb charts, enabling a mariner to relate the upper levels of the atmosphere to the development & movement of surface weather systems, sometimes before they are even noticeable on the charts! See actual 500 Mb & associated Surface Pressure Charts below:

Old 500Mb Chart

500 Mb forecast chart prior to Nov 2017

 

 

NOAA OPC 500 Mb chart after Nov. 2017

 

 

 

 

 

 

 

 

 

After November 13th, 2017, the 500 Mb charts now look like what you see depicted to the left, forcing the mariner to figure out for themselves where the TROF axes are likely to be. This change was made mostly without soliciting comments via normal maritime communications channels (e.g., “Notice to Mariners), thus denying the mariner an opportunity to have their voices heard before theses changes were implemented!

For those professional mariners who have been formally trained in NOAA products & services through continuing  maritime education & training institutions such as the Maritime Institute of Technology & Graduate Studies (MITAGS), in Linthicum Heights, MD or Simulation Training and Research(STAR Center), Dania Beach, Fl & other recognized schools, be advised of new  further changes to NOAA products scheduled to go into effect on Wednesday, March 7, 2018.

Changes in tracking surface systems
The current system for tracking all low and high-pressure systems use movement arrows showing 24-hours before & 24-hours forward from the “Valid Date and Time” for each of the 24, 48, and 96-Hour Surface Pressure Forecast charts. This gives the mariner the ability to not only track each low & high-pressure system through 5-days, but also to see the intensity trends as well.  The new tracking system for the 4 times daily Surface Pressure Analyses charts and the 24-48 & 96 Hour Forecast charts will only show the +24-hour forecast position only for those low pressure systems of gale force winds and above.

NOAA OPC Surface tracking

 

To the right is an explanation of how the surface  charts are depicted today plus, below is an actual example of a NOAA 96-hour forecast chart.

 

This real time example of a 96-hour surface forecast chart provides tracking of all low & high-pressure systems: 24-hours before and 24-hours ahead of each systems “Valid Date & Time. The incremental 24-hour positions are depicted as an “X” for low pressure and a “X” inside a circle for high pressure.  Thus, the combination of the 500 Mb charts prior to 13 November 2017 and surface pressure analyses and forecast charts up until 07 March 2018 have been described as a “Standard of Excellence”, by the Director of Training, at the Maritime Institute of Training and Graduate Studies (MITAGS).

NOAA OPC  pre-March 7, 2018 surface map track depiction

Impact of Changes to NOAA Marine Products
The 500 Mb products have been routinely utilized in weather forecasting & vessel route planning. They are now less effective with the removal of the “TROF Axes”.  Now, in addition, NOAA will be removing the tracking of all migratory surface low & high-pressure systems…except for those systems that NOAA  deems as “hazardous”. This change will include all Surface Pressure Analyses & Forecast charts, effective on Wednesday, March 7th, 2018. Hereafter, only a forecast position arrow, signifying a low-pressure system moving ahead on the charts “Valid Date & Time” (+24-hours) will be depicted on the charts, provided they are (or forecast) to produce at least gale force surface winds (34 knots and higher). This will, in my opinion, increase the risk for a mariner to miscalculate the total weather picture when creating a route plan or when considering route changes.  To quote a former Director of Training at MITAGS regarding these changes: Imagine reading a book with every third page missing and trying to piece everything together”

NOAA also wants to increase the oceanic coverage of their colored digital graphic plots of wind information as depicted below (National Digital Forecast Database (NDFD) forecasts). They want to populate more coverage of the north Atlantic and Pacific Oceans within their area of responsibility (SOLAS mandated alpha-numeric text forecasts area of coverage). Once again, this is in lieu of the changes made to the 500 Mb charts & changes to the Surface Pressure Forecasts charts.

NOAA National Digital Forecast Database (NDFD) forecasts graphic 

 

Reasoning and Rebuttal
NOAA’s reasoning behind these changes appears not to  be based on staffing shortfalls, nor stakeholder demands, but in their stated position to maintain their relevancy. NOAA wants to add a 72-Hour Surface Forecast product which would then be inserted between the current 48 & 96 Hours Surface Forecast charts. This may indeed sound logical, however, the downside is the significance of eliminating the tracking system currently in place for ALL MIGATORY SURFACE LOW & HIGH-PRESSURE SYSTEMS! This then would leave surface pressure analyses and forecasts charts uneven when it comes to low and high-pressure system movements (or lack thereof).

Today’s NOAA surface pressure analyses and forecasts go out to 168-hours (7-days) via the Weather Prediction Center (WPC).  Thus adding, for example, a 144-Hour Surface Pressure Forecast (6-day) might be more useful than the planned 72-Hour  Surface Pressure Forecast (3 day).  A 144-Hour forecast would also be a game changer for vessel route planning and underway route diversions!  This would be a substantial upgrade to the current NOAA product suite, as well as enhance training of mariners on using these products via institutions such as MITAGS & STAR Center.

The depicted colored digital NDFD graphics are not mandated by any IMO or STCW edict, let alone any stakeholder demand. Most importantly, they are also not universally accessible on the high seas (outside of high speed Internet range)! Once again, NOAA adding the new products jut discussed would be in lieu of the changes made to the 500 Mb charts & the imminent changes to the current Surface Pressure Analysis and Forecasts charts.

Changes like this can occur without notification, in large part, due to a lack of a process of direct communication and feedback between maritime stakeholder and with NOAA.  There may also be a lack of understanding of the needs of the maritime industry stakeholders that are engaged in 90 percent of international commerce.

Lessons learned from the El Faro sinking
Some of the recommendations made by the National Transportation Safety Board (NTSB) after the sinking of the El Faro include better optimization of NOAA services to maritime stakeholders   and a review of the effectiveness of Coast Guard exams and third party provided training. They also tasked the Coast Guard to provide guidance to approved maritime training schools offering operational level training in meteorology to ensure it includes training on the characteristics of weather systems, weather charting and reporting, importance of sending weather observations, sources of weather information, and interpreting weather forecast products.

In consideration of lessons learned from El Faro, the changes to NOAA’s analysis and forecast charts will, in effect, make training tasks much more difficult and unnecessary!

Action Needed

For those mariners who have been trained well enough to understand and rely on NOAA’s products, the time to let your viewpoints known is NOW, by contacting Benjamin Friedman, Deputy Under Secretary of Commerce for Oceans and Atmosphere ASAP!

Email:  benjamin.friedman@noaa.gov
Phone: 202-482-4569

Notifying congress (e.g., congressmen/women) & senators as well can have an important effect as well. This is all about accountability from tax foundered service provider(s), in this case NOAA, and the impact on stakeholders (mariners at all levels). This issue must be addressed and acted upon, as to enhance logical decision making in support of SOLAS & IMO objectives & beyond, to minimize weather related incidences & disasters at sea!      

Ask for a restoration of 500 Mb TROF Axes and moratorium on planned changes to NOAA marine products on March 7th, 2018 that is urgently needed to allow for constructive dialogue, feedback & consensus solutions!

Lee S. Chesneau
Lee Chesneau’s Marine Weather
http://www.marineweatherbylee.com

email: lee@weatherbylee.com

 

If  you  are interested in in learning more about marine meteorology, weather forecasting, route planning and heavy weather avoidance through marine weather training  please let  us know here:

 

 

 

 

 

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High Wind and Wave Events Crossing the Gulf Stream

The Gulf Stream as per Ben Franklin

Benjamin Franklin provides a crude, but amazingly accurate rendition of the Gulf Stream for its time.

Crossing the Gulf Stream where ocean currents can exceed 2 knots takes some skill and if you try in under certain weather conditions, could be dangerous for any size vessel.  High wind and wave events can occur under certain conditions along the northern edge of warm, fast western boundary currents like the Gulf Stream off the US East Coast.  Other areas with similar conditions include the Kuroshio Current near Japan and Taiwan, near the Agulhas Current along the east coast of South Africa and the East Australian Current off east coast of Australia.

Boundary Currents Image

The figure above illustrates we global depiction of western boundary currents

There is also the Brazil Current, however, this major warm ocean current has not been a major part of commercial shipping traffic compared to the other currents which may explain why there have been no known major weather impacts reported.

The Gulf Stream

Benjamin Franklin, in 1786 noted that “vessels were “sometimes retarded and sometimes forwarded in their voyages by currents at sea”. He knew that ships coming from Falmouth to New York took a fortnight longer than those coming from London to Rhode Island. Franklin consulted a Nantucket sea captain regarding this and was told that the cause was the Gulf Stream. (Nantucket captains knew of the Gulf Stream because of the whaling trade.) That same captain marked the stream on a chart along with directions for avoiding it.

Temperature, Wind, and Waves: Its interaction with the Gulf Stream

During the winter months, when extremely cold air moves off the US East Coast and flows over the very warm waters of the Gulf Stream, unusually large waves can develop along the northern and western boundary of the stream. These events produce waves that are larger than one would expect for a given wind force and fetch. These conditions can present severe hazards to marine operations, especially to smaller vessels. In fact, there is documentation of waves being up to five (5) times the expected significant wave height values, as driven by higher winds. For example, gale force winds (34-47 knots) and higher, will generate, at a minimum, waves higher than 20 feet, and in addition, rogue waves have also been reported on occasion due to wave-current interactions.

The high winds associated with these cold air outbreaks arise from two factors:

  1. A decrease in friction as the wind moves offshore.
  2. Destabilization of the marine boundary layer (MBL) as cold air moves over warm water (especially, if there is a 20-degree difference in temperature (Fahrenheit) between air and the Gulf Stream surface.

During the winter, as arctic air moves offshore, the shallow cold air becomes unstable, especially over warm currents such as the Kuroshio of the Western North Pacific or the Gulf Stream of the Western North Atlantic.   The resulting strong vertical transfer of heat destabilizes and deepens the atmospheric boundary layer and the resulting de-stabilization allows high wind momentum to mix down to the surface. Ocean waves build quickly in response.

heat flux image

The COAMPS image above highlights the sensible temperature differential of Sensible Heat Flux with the ocean temperatures which becomes exacerbated with the infusion of cold air above.

Cold Air Over Warm Water

The illustration above depicts the stylized circulation in a shallow vertical scenario when cold air interacts with warmer ocean surface.

The synoptic situation for this scenario would be strong low pressure to the east of the Gulf Stream and high pressure to the west, setting up a NW wind flow which would cross the stream at a 90-degree angle to the NE set of the Gulf Stream (current’s direction of movement).  Another scenario is when wind opposes the current, especially in fall, winter and spring when we have strong temperature differences between the air above and the Gulf Stream below. Recent cruise ships have reported encountering winds of  up to 127 knots which was doubled what was forecast.

Satellite image showing cloud streets

The GOES-12 visible picture above at 26/1915z shows a pronounced area of cloud free skies along the coast of VA-NC-SC associated with cold / dry air moving offshore from the NW. As the air moves further offshore, “clouds streets” begin to form, oriented parallel to the wind flow. Note the closeness of the clouds streets indicates the strength of the winds.

QuickSCAT image showing winds blowing counter to the Gulf Stream during September

To the right is a QuikSCAT image in  a September scenario that depicts enhancement of higher winds blowing counter to the Gulf Stream (from the NE) that is 15-20 knots outside of the Gulf Stream compared to 30-35 knots inside the stream).

The temperature differences are not as great as perhaps in the November through March months, when wind speeds can be significantly higher.

QuickScat image Jan

QuikSCAT image in January showing winds blowing across the Gulf Stream

To the left is a composite QuikSCAT imagery taken in January showing an area of strong winds exceeding 35 knots over and south of the North Wall of the Gulf Stream. (The highest reported wind was 55 knots.) The black barbs indicate areas of possible rain contamination. However, very little rain was noted in this area, but banded street clouds were observed.  It should be noted again in this scenario; the winds are blowing from the NW or at a perpendicular of 90-degree direction to the “set” of the Gulf Stream.

Waves Moving Against the Current

When ocean wind or swell waves encounter a current moving in the opposite direction, the response will be for wave speed and length to decrease, wave period will not change, but wave heights will increase, resulting in taller, steeper waves. In some cases, this can even lead to waves breaking, resulting in greater energy against hulls. This type of event can occur in all seasons and may or may not be associated with the cold air outbreaks mentioned above. The region around the Agulhas Current is particularly prone to high waves resulting from this type of wind opposing wave-current interaction.

When swell that originates elsewhere encounters a current, its wavelength and height change. When the current is flowing in the same direction as wave travel, wavelength increases while wave height decreases. Where currents oppose waves, wavelengths decrease, and wave heights increase. Ocean current eddies can cause large variations in the wave height and period, because they contain both counter currents and following currents with respect to the waves over relatively short distances.

Agulhas Current running against prevailing waves

 

The illustration to the left, is typical of the influence of the southern hemisphere’s roaring 40s and screaming  50s impact on the Agulhas Current.

 

 

 

NOAA thermal satellite image

The thermal satellite image to the right is a depiction of the Gulf Stream and its eddies allowing one to see the dramatic temperature contrasts in temperature between the continental shelf waters to the north and the adjoining Sargasso Sea to the south.  

Rogue Waves

Because waves slow when they encounter an opposing current, they also refract. Just as bends in the coastline concentrate or diffuse wave energy, bends and meanders in ocean currents similarly concentrate and diffuse wave energy. Wave refraction is one possible origin for rogue waves. Wave-current interactions increase exponentially as the current speed increases.  This effect becomes significant when currents reach speeds of 1-1.5 knots.

The figure below depicts two North Wall scenarios; wind against current and wind flow perpendicular to the axis of the Gulf Stream.

Two North Wall Scenarios

 

 

 

 

 

 

 

 

 

Mariner’s Weather Wisdom

When crossing a boundary current like the Gulf Stream mariners must be aware of the wind and sea forecast before departure and while underway.  If wind waves or swell are opposing the set of the current or if arctic air is streaming offshore at right angles to the current a mariner should anticipate a risk for encountering wave heights from 40% to 100% higher than the general forecast values near the north wall of the current and also crossing eddies.

Learn more about Ocean Waves here

Fred Pickhardt, chief meteorologist,
Ocean Weather Services
http://www.oceanweatherservices.com

Lee S. Chesneau
Lee Chesneau’s Marine Weather
http://www.marineweatherbylee.com

If  you  are interested in in learning more about marine meteorology, weather forecasting, route planning and heavy weather avoidance through marine weather training  please let  us know here:

 

 

 

 

 

 

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Second Major Storm in a Week to Affect Atlantic Shipping

NOAA OPC Surface Analysis 1800 UTC 24 Feb 2018

A rapidly deepening major storm low is forecast to move southeastward from just south of Newfoundland Saturday to west-northwest of the Azores over the next 48 hours.  Winds are forecast to increase to 50-65 knots with seas building to 13 meters (42 feet) southwest of the center during the next 24 hours and 55-75 knots with seas to 15  meters (50 feet) west of the center within 48 hours.

NOAA OPC Surface Forcecast 1200UTC 26 Feb 2018

NOAA OPC Significant Wave Forecast for 1200UTC 26 Feb 2018

This will be a dangerous hurricane-force storm as it will  be moving through some of the main trans-Atlantic shipping lanes.

It  was less than  a week ago when another major  storm moved  through this part of the North Atlantic producing winds to 75 knots and seas to 19 meters (62 feet).    See  http://oceanweatherservices.com/blog/2018/02/20/north-atlantic-hurricane-force-storm-affecting-main-shipping-lanes/

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North Atlantic Hurricane-Force Storm Affecting Main Shipping Lanes

NOAA OPC Surface Analysis 1200UTC 20 Feb 2018

An intense hurricane-force storm low over the central North Atlantic was producing significant wave heights of an incredible 19 meters (62 feet) today, according to the National Weather Service Ocean Prediction Center.

After dumping some moderate to heavy snow in the US Northeast, this low rapidly intensified overnight on Saturday, developing hurricane force winds in excess of 64 knots by Sunday morning.

A satellite pass showing a max significant wave height of 61.23 feet (18.7 meters) in the North Atlantic on Tuesday, February 20, 2018. Credit: NOAA

Extreme Wave Heights

The latest NOAA Ocean Prediction Center (OPC) analysis for 20th 12 00 UTC shows and extreme max significant wave height of nearly 19 meters. This storm could set a new record for this part of the Atlantic.

Note: Significant wave height is the average height of the tallest one-third of waves (from trough to crest), so individual waves are likely to be much, much bigger.

Danger to Shipping

This storm poses an extreme danger to maritime shipping as it has tracked eastward at a fairly low latitude over some of the main shipping channels connecting North Europe and Mediterranean ports and US East Coast and Gulf ports.

The good news, however, is this monster is forecast to weaken rapidly over the next 24 hours.

Learn more about these wintertime hurricane-force storms

Learn more about ocean waves

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