Forecast predicts below-average hurricane activity

Posted: June 22, 2018 by oldbrew in Natural Variation, predictions, research, weather

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US researchers who accurately forecast last year’s busy Atlantic hurricane season are not expecting a similar level of activity this year, partly due to lower sea surface temperatures as El Niño effects fade away.

Hurricane season didn’t officially start until June 1, but Subtropical Storm Alberto made an appearance early, causing more than $50 million in damage as it made its way inland and up the coast in late May, reports

Twelve people—seven in Cuba and five in the U.S.—died as Alberto’s fallout included flooding, landslides, tornados and mudslides.

Is Alberto’s early-season appearance an indicator of another active Atlantic hurricane season? Not necessarily, according to predictions by researchers at the University of Arizona.

The UA forecasting model predicted a below-average number of hurricanes for the 2018 hurricane season, which runs through November 30. UA researchers are predicting four hurricanes, two of which will be major hurricanes, defined as those reaching Category 3, 4 or 5. That forecast falls below the median of seven hurricanes with two majors.

The UA prediction is among the lowest of all published forecasts, which include predictions by the National Oceanic and Atmospheric Administration, the London, United Kingdom-based consortium Tropical Storm Risk and other universities.

Last year, the UA’s forecast was among the highest—11 hurricanes with six majors—and came closest to hitting the mark. The 2017 hurricane season ended with 10 hurricanes and six majors, making it the most active since 2005 and the seventh-most active in the NOAA’s historical records dating back to 1851. Last year, Irma (Florida) and Maria (Puerto Rico) were 5s, and Harvey (Texas) and Jose (offshore Caribbean) were 4s.

Xubin Zeng, his former graduate student Kyle Davis, and former UA professor Elizabeth Ritchie developed the UA’s hurricane forecasting model, which has proven to be extremely accurate over the last four years.

“Since we began issuing our annual hurricane prediction in 2014, our average error is 1.5 hurricanes,” said Zeng, director of the UA’s Climate Dynamics and Hydrometeorology Center, a professor of atmospheric sciences and the Agnes N. Haury Endowed Chair in Environment in the Department of Hydrology and Atmospheric Sciences at the UA.

A main factor in this year’s prediction is the low sea surface temperatures over the Atlantic, where little warming occurred from April to May. The sea surface temperatures are the lowest Zeng and his team have seen since 2014, but similar to long-term average temperatures.

The Atlantic Multidecadal Oscillation index in May, which describes multidecadal climate variability in the North Atlantic, is zero, which is below the threshold at which El Niño would affect hurricane activity in the UA model.

Continued here.

  1. craigm350 says:

    Reblogged this on WeatherAction News and commented:

    Although Joe B has warned of possible in close season in Gulf of Mexico.

  2. oldbrew says:

    Slim pickings for climate ambulance chasers this season if the forecast is sound.

    May have to find some other spurious excuses to sound the fake alarm.

  3. angech says:

    “Last year, the UA’s forecast was among the highest—11 hurricanes with six majors—and came closest to hitting the mark.”
    I guess when there are any number of predicting outlets there will be a range of choices and any one of them in retrospect has to turn out right.
    Credence? none.
    Either we know, in which case prediction is not needed, or we don’t know, so we have to guess, i.e. predict.
    Show us the 3 years before, show us the next 3 years then I predict we can have a cup of coffee, or tea and a laugh
    Cup of tea would be better of course.

  4. oldbrew says:

    Sea surface temperature may well have an effect on the intensity of a hurricane, but…
    …the complex nature of hurricane formation makes predicting with a high degree of accuracy very difficult.
    – – –
    Whether the number of hurricanes is related to SSTs is another question…

    Sea surface temperatures must be 82 degrees Fahrenheit (F) or warmer for tropical cyclone formation and sustenance.
    . . .
    Another necessary ingredient is rotating winds over the ocean’s surface.
    . . .
    Air temperature and humidity are also important factors.
    . . .
    Rainfall intensity is the final ingredient.
    – – –
    General info: Hurricane Science

    Hurricane life cycle

  5. ren says:

    Both the temperature of the northern and tropical Atlantic is now very low.

  6. ren says:

    In the full Atlantic there are no conditions for the formation of hurricanes.

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