Hurricane Fernando update

fernanda3Hurricane Fernanda over the eastern North Pacific continues to deepen and track towards the west with max winds about 115 knots and with hurricane force winds outward only 15-25 NM. Maximum significant wave height estimated to be 48 feet (14.6 meters).  Fernanda is forecast to reach a peak wind of about 120-130 knots during the next 24 hours before slowly weakening.

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TS Fernanda to intensify

NOAA Satellite image TS Fernanda

NOAA Satellite image TS Fernanda

Tropical Storm Fernanda over the eastern North Pacific is moving over warm sea surface temperatures and is expected to deepen rapidly reaching hurricane strength in 6-12 hours with max winds of 100 knots or more in 36-48 hours.

fernanda1

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Hurricane Eugene nears peak winds

eugene1Hurricane Eugene, located about 1037 NM south fo San Diego has been moving towards the N-NW at about 9 knots.  Max winds are estimated to be about 95 knots with hurricane force winds extending outward 20-30 NM from the center.  Maximum significant wave height 35 feet (10.7 meters).  Forecast has max wind 100-110 knots during the next 12 hours then gradual weakening is likely as the center moves over cooler ocean water.eugene2

 

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What should we expect for the 2017 North Atlantic hurricane season?

blog3Given the unusual occurrence of 3 named tropical cyclones prior to the end of June, one might ask what should we expect for the remainder of the 2017 hurricane season?

A number of forecast centers have already made their predictions for the 2017 hurricane season with most sources predicting either a normal to somewhat above normal season.  There is, however, quite a range in the total number of expected named storms, ranging from as low as 10 to as much as 17.  The most likely number being 12-13 storms.   For hurricanes, the range is from 6-10 with the most likely number being about 6 hurricanes.  For major hurricanes, estimates range between 1 and 4, the most likely number being 2 or 3.

Various 2017 North Atlantic Hurricane Season Forcasts

Various 2017 North Atlantic Hurricane Season Forcasts

One factor most forecasters are looking at is that there will be either a weak El Nino or as neutral ENSO conditions will prevail during the peak of this year’s season as well as warmer than normal SST across the tropical Atlantic and Caribbean Sea.  If we have a weak El Niño, then the likelihood is for a normal to somewhat below normal season. If, however, as predicted by NOAA, the current neutral ENSO conditions prevail, then a somewhat more active season is possible.

NOAA ENSO Forecast

NOAA ENSO Forecast

For this up-coming season, I have been looking at the SST Anomalies over the North Atlantic which have been showing a trend for cooler than normal temperatures north of about 40N latitude while mostly warmer than normal SST prevail to the south.  If this continues, there should be a tendency for high pressure areas that move off New England or Canada to be enhanced which will tend to block or delay tropical cyclones from turning northeastward.  This, in turn, would suggest a higher risk for storms moving northward over the western North Atlantic to threaten the US East Coast.

Current SST Anomalies

Current SST Anomalies

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What is the risk of encountering a tropical storm or hurricane during your Caribbean cruise?

 

All Tropical Cyclone Tracks

All Tropical Cyclone Tracks

 

 

 

 

 

 

 

 

 

 

Tropical cyclones are storms that originate over tropical and subtropical waters during the summer and fall seasons and are classified as follows:

  • Tropical Depression:A tropical cyclone with maximum sustained winds of 38 mph (33 knots) or less.
  • Tropical Storm:A tropical cyclone with maximum sustained winds of 39 to 73 mph (34 to 63 knots).
  • Hurricane:A tropical cyclone with maximum sustained winds of 74 mph (64 knots) or higher. In the western North Pacific, hurricanes are called typhoons; similar storms in the Indian Ocean and South Pacific Ocean are called cyclones.
  • Major Hurricane:A tropical cyclone with maximum sustained winds of 111 mph (96 knots) or higher, corresponding to a Category 3, 4 or 5 on the Saffir-Simpson Hurricane Wind Scale.

The official hurricane season for the Atlantic Basin (the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico) is from 1 June to 30 November.  As seen in the graph below, the peak of the season is from mid-August to late October, however, deadly hurricanes can occur anytime in the hurricane season.

Number of storms per 100 years

Number of storms per 100 years

 

 

 

 

 

 

 

 

 

Tropical cyclones have occurred during every month, however, the vast majority of them occur between June 1st and November 30th.  Below are monthly charts showing the most likely areas and tracks for tropical cyclones. These figures only depict “average conditions” and Hurricanes can originate in different locations and travel much different paths from the average.

Most likely tropical cyclone tracks during June

Most likely tropical cyclone tracks during June

 

 

 

 

 

 

Most likely tropical cyclone tracks during July

Most likely tropical cyclone tracks during July

 

 

 

 

 

 

Most likely tropical cyclone tracks during August.

Most likely tropical cyclone tracks during August.

 

 

 

 

 

 

Most likely tropical cyclone tracks during September

Most likely tropical cyclone tracks during September

 

 

 

 

 

 

Most likely tropical cyclone tracks during October

Most likely tropical cyclone tracks during October

 

 

 

 

 

 

 

Most likely tropical cyclone tracks during November

Most likely tropical cyclone tracks during November

 

 

 

 

 

 

 

The risk for a tropical cyclone moving through a particular 5X5 degree square of latitude and longitude during September (the peak of the season) ranges from about 25% to about 45% across the Gulf of Mexico, Southwestern North Atlantic and Caribbean Sea. This means that the risk for being near a tropical cyclone at the height of the hurricane season is less than 2% for any given day.

Cruise ships today are very hi-tech and are equipped with the latest communications and navigation systems and often also employ a professional weather routing service. If a tropical storm or hurricane is moving through or forecast to move through their area of operations, they will reroute the ship to avoid the storm or direct the vessel to a different port of call.  This doesn’t mean that you will not experience some rough weather, however.

During the summer and early fall, the risk of encountering rough seas (8 feet or more) is generally low (10 percent or less).  This does not mean you won’t encounter some rough weather if a cruise ship navigates around a particular storm. During the winter months, however, wind conditions tend to be higher so it can be a bit rougher. The risk for rough seas (8ft or higher) increases in winter up to 40 percent.  Fortunately, modern cruise ships use stabilizers to minimize the rocking and rolling motion of the vessel greatly diminishing the chances of passengers being adversely affected.

Useful Links

NOAA National Hurricane Center current Tropical Activity  http://www.nhc.noaa.gov/
Tropical Cyclone Climatology http://www.nhc.noaa.gov/climo/
Saffir-Simpson Hurricane wind scale  http://www.nhc.noaa.gov/aboutsshws.php
Tropical Cylclone names  http://www.nhc.noaa.gov/aboutnames.shtml

Fred Pickhardt
Ocean Weather Services

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NOAA NHC: “Above-normal Atlantic hurricane season is most likely this year”

NHC 2017 Hurricane Season Outlook

NHC 2017 Hurricane Season Outlook

“Forecasters predict a 70 percent likelihood of 11 to 17 named storms (winds of 39 mph or higher), of which 5 to 9 could become hurricanes (winds of 74 mph or higher), including 2 to 4 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher). An average season produces 12 named storms of which six become hurricanes, including three major hurricanes.”

Read more here

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Slowing Sea Level Rise Projections

NOAA Sea Level New York City

NOAA Sea Level New York City

In recent years there have been several projections regarding sea level rise, including claims that the oceans could rise up to 10 feet by 2100.  It is time to consider just how much weight we should give these projections as they would suggest that vast areas of the world’s coastline could be flooded before there was time to fully react.

What we know

Global warming
As per the National Oceanic and Atmospheric Administration (NOAA), the global temperatures are rising at a rate of about .07C per decade (0.7C per century) and currently are about 0.8C higher than around 1900. The warming has not been continuous; however, as there was a cooling trend between 1880 and 1910 followed by a moderate warming of about 0.25C from about 1910 to 1945.  Temperatures remained stable or possible cooled slightly between 1945 until about 1978 followed by another period of stronger warming of about 0.6C from 1978 to present.

NOAA Global Surface Temperature Anomaly

NOAA Global Surface Temperature Anomaly

 

 

 

 

 

 

 

 

Sea Levels
During the 20th Century, sea level rose at a rate of about 1.8 mm/yr based on actual tide gauges.  More recent data based on satellite observations suggests, however, that since 1993 the rate was between 2.9 mm/yr and 3.4 mm/yr.

The accuracy of direct sea level measurements via satellites is about +/- 2 cm (20 mm) so we may need more time to judge the accuracy of the trends calculated from these measurements vs. those made from long-term tide gage observations.  See: Sea Level Trends – NOAA Tide and Currents page 

Studies of sea level rise rates during the past century suggest that short-term (18-yr trends) of sea level rise rates have ranged between 0 and 4 mm/yr, even prior to 1950 (before most of   CO2 was added to the atmosphere). This suggests that the current higher rates may not be solely driven by greenhouse gas emissions and adds uncertainty to the various sea level projections.

18 year sea level rates

18 year sea level rates

Source:  Is sea level rise accelerating? Judith Curry Blog post February 23, 2016

The Future

Bottom line, sea level is rising and the rate has increased but there is significant uncertainty regarding predicting future rates and thus sea level estimates for the next 50-100 years are  problematic.  If the rate of sea level rise would double, for example, over the next century from the current satellite estimates, we would expect a total sea level rise of about 1.2-1.4 ft. by 2100

By contrast, global sea level rose by a total of about 120 meters over a period of about 8,000-9,000 years as the vast ice sheets of the last glaciation melted away. This equates to an average rate of sea-level rise during this period of roughly 1 meter (3.3 feet) per century or about 10mm per year (Some studies suggest the rate was up to 13 mm per year). Even if somehow we could get to the rates encountered after the last glaciation of 10-13 mm/yr over the next century then by 2100, the total rise will be about 1.8-2.2 feet.

So then the question is how could we get to a 6 to10 foot sea level rise so quickly?  A recent study suggests that a rapid collapse of the Western Antarctic Ice Sheet is possible. The western half of the Antarctic has its base lying below sea level so as global temperatures rise; warmer ocean water will melt the underside of the ice sheets.

The modeling suggests significant sea level rise is possible from Antarctica ice melt alone by 2100.  The key assumption here is that greenhouse gas emissions will boost the planet’s temperature by about 4 degrees C (7 degrees F) which is considerably more than the present 0.8C of observed warming.  The paper admits that under the model the timing and pace of Antarctica’s ice loss is “really uncertain”.

Without the vast continental ice sheets of the last glaciation, it is doubtful that we will reach the extreme prediction of  up to 10 feet. In order to see a sea level rise of 10 ft by 2100, the average annual rise would have to be about 37 mm/yr, more than 10 times the  current rate!.   In addition, these new estimates are also far above the estimates by the Fifth Assessment Report from the United Nations’ Intergovernmental Panel on Climate Change.  Here, they claim that the most likely amount of global sea level rise would be about 1 foot to slightly more than 3 feet by 2100.

Fred Pickhardt
Ocean Weather Services.

 

 

 

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TC Donna Update

TC Donna Satellite Image

TC Donna Satellite Image

TC Donna located over the South Pacific about 337 NM northwest of Port Vila, Vanuatu currently has maximum winds of about 85 knots with hurricane force winds extending outward about 25 NM from the center. Maximum significant wave height is estimated to be about 24 feet (7.3 meters).  Forecast track takes Donna south then southeast with maximum winds peaking  at about 100-110 knots during the next 18-24 hours before a weakening trend begins.

 

Updated Forecast Track

 

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Tropical Cyclone Donna strengthens over South Pacific

Satellite image TC Donna

Satellite image TC Donna

Tropical Cyclone Donna over the South Pacific was located about 298 NM N-NE of Port Vila, Vanuatu and was moving towards the west at about 9 knots. Conditions are favorable for development as Donna is currently over warm 30C sea temperatures with low atmospheric shear.  Forecasts suggest Donna will reach a peak of wind speed of 105-115 knots during the next 72 hours. A turn towards the southwest then south is expected during the next 48 hours then more towards the southeast.  Donna is a threat to the islands of Vanuatu.

Updated Forecast Track 

 

 

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TC 17S develops N-NW of Darwin

Satellite image via JTWC

Satellite image via JTWC

TC 17S  has developed about 179 NM NNW of Darwin Australia and was moving towards the SW at about 8 knots with max winds of about 35 knots.

Conditions favor some slow deepening over the next 24-36 hours then unfavorable conditions will cause the system to weaken and then dissipate in about 4 days.

 

Forecast Track:

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