2019 Atlantic hurricane forecast

by Judith Curry and Jim Johnstone

CFAN predicts an active North Atlantic hurricane season season.

The Atlantic hurricane has begun.  We are off to an early start with one wimpy subtropical storm that lasted less than a day, and a small system that is trying to spin up in the Bay of Campeche.

Other forecast providers have begun issuing forecasts:

  • NOAA predicts a near normal season with 4-8 hurricanes.
  • Tropical Storm Risk predicts slightly below normal activity, with 6 hurricanes and ACE of 88.
  • Colorado State University predicts near normal season:  6 hurricanes and ACE of 100

Climate Forecast Applications Network (CFAN) is going bold, see below. [link] to forecast report.

CFAN’s seasonal forecast

Table 1. Current (May) 2019 hurricane forecasts of North Atlantic ACE, North Atlantic total hurricanes, U.S. landfalling hurricanes. 

Introduction

Indices of North Atlantic hurricane activity display substantial interannual variations (Fig. 1), in addition to prominent multidecadal changes that are positively associated with basin-scale sea surface temperature (SST) changes known as the Atlantic Multidecadal Oscillation (AMO). North Atlantic Accumulated Cyclone Energy (ACE), an integrative metric based on tropical cyclone wind speeds, approximately doubled with an abrupt 1995 shift toward warmer North Atlantic surface conditions.

Figure 1. North Atlantic hurricane indices, 1970-2018. Top: North Atlantic hurricane totals (red) and U.S. landfalls (blue). Center: Major hurricanes and U.S. landfalls. Bottom: North Atlantic Accumulated Cyclone Energy (ACE). Hurricanes, major hurricanes, and ACE increased abruptly in 1995 with a shift toward higher North Atlantic sea surface temperatures associated with the Atlantic Multidecadal Oscillation.

CFAN develops seasonal to annual climate forecasts using an innovative data mining approach guided by climate dynamics analysis. CFAN’s late-May seasonal forecast for the 2019 Atlantic hurricane season is based on climate conditions and tendencies observed in data from January 1 through May 17, 2019.

Recent climate anomalies and ENSO update

Overall, there is little change relative to CFAN’s ENSO forecast report in March 2019, although there is growing support for an El Niño Modoki in autumn. Expected summer sea surface temperature (SST) conditions in the tropical Pacific were assessed in CFAN’s March 2019 ENSO forecast. CFAN’s March ENSO forecast called for weakening eastern Pacific El Niño conditions during spring but a partial regrowth of central Pacific El Niño Modoki warmth during July-August-September (JAS), overlapping with the early part of the hurricane season. Forecasts suggest largely neutral anomalies of North Atlantic Arc SSTs.

CFAN’s ENSO forecast plumes from ECMWF (initialized March 1) are shown in Figure 2, for Niño1.2, Niño 3, Niño4, and the Modoki Index. ECMWF shows a continued decline of Niño 3 and Niño 1.2 through fall. Niño 4 and Modoki values increase through mid-summer, with moderate Modoki conditions through fall.  NOTE:  ECMWF’s June seasonal forecast will be available June 5 (tomorrow evening).

Figure 3: CFAN’s analysis of ENSO forecasts from ECMWF seasonal forecast system (SEAS5), initialized 5/1/19.

Hurricane Predictors

CFAN’s forecast method identifies precursors of Atlantic hurricane activity from seasonal patterns of anomalies and tendencies in globally-gridded sea surface temperatures (SSTs) and numerous dynamical and thermodynamic variables based on NCEP-NCAR Reanalysis data at 17 tropospheric and stratospheric levels. While simple patterns of spring-summer climate anomalies offer direct indications of expected hurricane activity, predictions at longer leads involve interactions of slow seasonal to interannual climate processes, including those related to ENSO and the Quasi-biennial Oscillation (QBO) of equatorial stratospheric winds, which tend to undergo rapid phase transitions during spring.

The actual predictors used are not described in the publicly-issued forecast report; more details are provided to our clients.

Forecast models

Figure 5 illustrates the historical leave-one-out forecasts by the most skillful models (gray lines), and overall annual forecast values (blue lines) based on the ensemble means. Forecast model results are shown in Table 1 and Figure 5. In Table 1, forecast uncertainty is reflected in the range of model predictions, and the mean absolute error (MAE) in leave-one-out tests.

 Figure 5. Model hindcast hurricane estimates (blue) and observed historical metrics (red). Fine gray lines depict individual model estimates and blue lines reflect model means. A. North Atlantic ACE. B. North Atlantic hurricane totals. C. US hurricane landfalls. D. Florida hurricane landfalls. Values in the lower right of each panel reflect the expected 2019 index value based on the mean of individual model estimates and the ±1 standard deviation spread.   Lower left values display index means over the 1995-2018 period.

Potential 2017 analogue

Our forecast issued in November 2018 suggested above-average hurricane activity in 2019, reflected by ACE forecast of 163 (1995-2018 mean: 132). High activity in 2019 was further suggested by Atlantic-sector atmospheric patterns in August-October (ASO) 2018 that closely matched those of ASO 2016, which preceded by one year the high-activity season of 2017 (ACE 226).

Currently, we find additional indications of atmospheric behavior that suggest a potential replay of 2017 conditions in 2019. Figure 6 compares 2019 (left) and 2017 (right) anomalies of global sea level pressure (SLP) (1st row, spatial correlation r = 0.5), NH SLP (2nd row, r = 0.5) and zonal-mean geopotential heights (3rd row, r = 0.7) and zonal (westerly) winds (4th row, r = 0.4).

Figure 6. Comparison of April-May atmospheric anomalies during 2019 (left) and 2017 (right), based on data from April 1-May 17. Top row: Global sea level pressure (SLP). 2nd row: NH SLP. 3rd row: Zonal-mean geopotential heights, by latitude (x-axis) and height (y-axis). 4th row: Zonal-mean U (westerly) winds.

Global April-May SLP anomalies during both years (Fig.6, 1st row) feature a wide zone of high pressure over the tropical Indo-Pacific and an Arctic high centered over Iceland-Greenland, while negative SLP anomalies prevail over a midlatitude band stretching from western Asia to the North Atlantic. In the Southern Hemisphere, similarly-structured zones of negative SLP anomalies cover most of the Antarctic and South America.

A polar perspective (Fig. 6, 2nd row) also highlights the similar NH SLP anomaly structures during 2017 and 2019, including a Greenland high that extends southward over Europe and the Indian Ocean. Zonal-mean (east-west) anomalies of geopotential heights (Fig. 6, 3rd row) share coherent positive anomalies from the surface to the 20 hPa pressure level in the tropical-subtropical lower stratosphere, in contrast to negative height anomalies over the NH midlatitudes and Antarctica. Zonal wind anomalies (Fig. 6, 4th row) display coherent positive (westerly) anomalies involving all vertical levels from 1000 to 10 hPa around 30°N and 50°S, while anomalous easterly flow is seen at tropospheric levels (1000 to 200 hPa) in the Southern Hemisphere around 15°S. Similar states of the stratospheric Quasi-biennial Oscillation (QBO) are indicated by positive zonal wind anomalies from 20 to 70 hPa during April-May 2017 and 2019. April-May patterns generally indicate strong vertical coupling of tropospheric and stratospheric pressure and circulation anomalies in spring 2017 and 2019.

Disparities between 2017 and 2019 conditions include a recent zone of low pressure in the tropical NE Pacific during April-May 2019 (not present in 2017) that is associated with the stronger April 2019 El Niño conditions relative to 2017. Strong hurricane activity in 2017 followed an unusually rapid early-summer transition toward La Niña conditions. Our retrospective analysis of the 2017 hurricane season identified additional factors as well, including pronounced southerly flows of low-level winds and moisture toward the Gulf of Mexico from south of the equator, part of a ‘meridional mode’ (north-south) pattern involving tropical ocean-atmosphere anomalies in both hemispheres. 

Discussion

Relative to average Atlantic tropical cyclone activity since 1995, our current forecasts call for above normal North Atlantic ACE and near normal North Atlantic hurricane frequency in 2019. These estimates are similar to our November forecasts, but somewhat higher than our March forecasts that were largely neutral relative to the mean activity since 1995 due to a prevalence of conflicting positive and negative indicators.

Recent indicators of high activity feature many related Arctic circulation anomalies related to positive SLP and geopotential height anomalies over the North Pole from April 1 to May 17. Arctic hurricane precursors are generally most robust during the yet-completed April-June window, and warrant close ongoing attention.

Forecast estimates of U.S.  landfalls are close to 1995-2018 averages and have greater forecast uncertainties than North Atlantic ACE and hurricane totals. We will issue a late-June follow-up report on developing conditions relevant to all hurricane metrics discussed here, with a particular emphasis on those relevant to U.S. and Florida hurricane landfalls.

JC remarks

Forecasts in late May are driven by the needs of the reinsurance industry.  Circulation patterns of relevance to Atlantic hurricanes generally are in place by the end of June.  In a few months, we will know which forecasting group has read the tea leaves correctly.

This is one forecast where I hope we are wrong; we really don’t need another active hurricane season. The key issue of importance is landfalls; we won’t have a good reading on that until the end of June.

45 responses to “2019 Atlantic hurricane forecast

  1. Great to see a forecast based on Science!

    Plus it is testable. Thanks Dr. Curry.

    Scott

    • “Plus it is testable.”

      Very true. If their forecast is highly inaccurate the marketplace will devalue future predictions.

      What happens when GCM’s are highly inaccurate? Average their outputs with a bunch of other inaccurate GCM’s and claim that will provide a better forecast.

      Can anyone provide any reliable evidence that the overall climate is worsening?

    • double sixsixman

      What is the purpose of predicting hurricanes, unless you can predict when and where they will make landfall ?

      Is this some kind of scientific game to waste taxpayers’ dollars?

      With a large range of 4 to 8 used for a prediction, it should be easy to
      be “right”.

      I’m going outside to take 10 basketball foul shots, and I predict I will make 4 to 8 of them, does anyone want to bet me $100 that my “prediction” will be right?

      Let’s say NOAA predicted 8 hurricanes in 2019, and there were actually 8 hurricanes — who would benefit from that knowledge, if anyone, and why are they not paying for the forecasts?

      The coming climate change catastrophe consists of 30+ years of repeated forecasts of a coming climate change catastrophe … that never comes.

      The last thing we need are more wrong climate forecasts, and more valueless climate forecasts.

      I’ve been reading climate science as one of my hobbies since 1997, and every time I hear the phrase “Scientists predict”, I burst out laughing like I’m watching a Three Stooges film.

      Modern climate “science” consists of too much predicting, that ends up wrong, and too much certainty about the future climate, backed up by too little knowledge.

      • afonzarelli

        Ah, poor Dr C
        (didn’t like my three stooges joke… ☹️)

      • afonzarelli

        Mike Flynn says:
        June 11, 2019 at 6:21 PM
        KG,

        I agree. Humans should stop emitting CO2 immediately. Force may have to be used to ensure compliance. The last human left can leap off a high cliff.

        Fixed.

        Cheers.

        Reply
        Roy W. Spencer says:
        June 11, 2019 at 6:52 PM
        Mike, before jumping off the cliff, though, that person should be responsible and turn off the lights.

        It’s all Spencer’s fault, Dr C (his bad company ruined my good character)…

  2. We iive on a barrier island in sw Florida. The home has been owned by the family since 1972. The worst hurricane to hit it, high water, was Donna in 1960. Until we inherited it, 2002, there had not been a storm problem. A few very high tides. Since we have hade it , Charlie, Wilma, and Irma. Have not noticed any significant sea ;level change. The wind from the west at high tide is the main water problem.
    I have given my theory of the Ice Age and hope I live long enough to see the water level begin going down

  3. Ireneusz Palmowski

    “Should the worst-case scenario of rainfall from a budding tropical feature in the western Gulf of Mexico become involved, levels on the lower Mississippi could approach that of the Great Flood of 1927.”
    High pressure in the Eastern Pacific may increase the amount of tropical storms in the Gulf of Mexico.
    http://tropic.ssec.wisc.edu/real-time/mtpw2/product.php?color_type=tpw_nrl_colors&prod=conus&timespan=24hrs&anim=html5

  4. News of ‘near normal’ seems, disillusioningly disquieting.

  5. Ireneusz Palmowski

    Bad forecast for Louisiana.

  6. Ireneusz Palmowski

    Tropical downpours reached Texas and Louisiana.

  7. Ireneusz Palmowski

    Clouds over Texas reach for the stratosphere.

  8. From the people who really watch these forecasts here is a nice collection of all the major organizations making 2019 hurricane forecasts:
    https://www.artemis.bm/2019-atlantic-hurricane-season/
    Artemis provides catastrophe bonds, insurance linked securities, reinsurance capital & investment, risk transfer intelligence.

  9. Ireneusz Palmowski
  10. Ireneusz Palmowski

    The downpours over Louisiana will last several days.

  11. Pingback: 2019 Atlantic hurricane forecast | Watts Up With That?

  12. Pingback: 2019 Atlantic storm forecast | Watts Up With That? – Daily News

  13. Ireneusz Palmowski

    The flow of ozone shows the circulation in the upper troposphere.

    You can see high in the eastern tropical Pacific.

  14. Ireneusz Palmowski

    Three lows will now cooperate in the south-central US.

    • Ireneusz Palmowski

      The formation of tropical storms in the Gulf of Mexico is affected by high pressure in the region of Nino 1.2.

    • Ireneusz Palmowski

      Within two days, the convection in the south-central US will once again reach a height of 16400 m.

  15. Ireneusz Palmowski

    In the period of low solar activity, the circulation is inhibited. That’s why a small tropical depression can be a big rain.

  16. Reading tea leaves is fraught with uncertainties. But apparently you have some help here.

  17. Ireneusz Palmowski

    Big thunderstorm over Oklahoma City.

  18. Ireneusz Palmowski

    Little Rock in Arkansas is in danger of flooding. Thunderstorms are shifting to Arkansas.
    https://www.tropicaltidbits.com/sat/satlooper.php?region=us&product=ir

  19. Says here fewer Hurricanes:

    Scientists are predicting a near-normal Atlantic hurricane season this year, with two to four major hurricanes reaching at least Category 3 status, with winds of 111 mph (178 km/h) or higher, the National Oceanic and Atmospheric Administration (NOAA) announced today (May 23)

    But here more:

    19 Atlantic hurricane season — which lasts from June 1 to Nov. 30 — is expected to have between nine and 15 named storms, which means they pack winds of 39 mph (62 kilometers/hour) or higher, NOAA reported. Of those, between four and eight could become hurricanes, meaning their winds reach speeds of 74 mph (119 km/h) or higher.

    https://www.livescience.com/65551-2019-atlantic-hurricane-season.html

    • Ireneusz Palmowski

      Atlantic circulation is not currently beneficial for hurricanes in the eastern North Atlantic.

  20. Ireneusz Palmowski

    Tropical depression has now spread to Florida.

  21. Ireneusz Palmowski

    Mexico still remains a region of formation of tropical depression.

  22. Ireneusz Palmowski

    The temperature in the Central Pacific drops again. A strong jetstream in the south will not allow the development of El Niño.

    • Is the running average enough to forgo a hurricane season?

      • Ireneusz Palmowski

        Tropical storms can strengthen in the western tropical Atlantic and in the Gulf of Mexico. Circulation in the eastern Atlantic is not conducive to hurricanes.

  23. As of 12.6.2019 there is no Tropical Cyclone activity in the Western Pacific, Central Pacific, Eastern Pacific and Atlantic basins. The only activity is TC Vayu in the Arabian Sea north of the Maldives – currently Cat 2 TC.

    The reason for the lack of activity in the WP to Atlantic basins is that atmospheric transport capacity away from the low latitudes remains greater than the volume of convection at the sea / air interface. Sea surface temperatures may be lower this year so far but convection will progressively surpass the carrying capacity away as the sun reaches Solstice and returns.

    This is the controlling mechanism that dictates the start of the TC season. Therefore the key driver from this point is how fast convection increases and accumulates. As a comparison in 2005 convection saturation occurred on the 18th May with accumulated convection (humidity) rising at a near linear rate from that point. A year of high and early ocean energy release.

    This rising rate reaches a second annual obstacle (resistance to pole-ward transport) between mid to late July which further increases TC activity.

    In the excellent series on tropical cyclones by Judith recently, which rightly questioned the attribution of CO2, (nil), I promoted the question “why do TC exist”, which is different to what they do.

    Why TC exist is identified above. They exist because convection exceeds the natural atmospheric carrying capacity away from the high convection zones toward the poles. This is the sole reason why tropical humidity increases.

    What do TC do, they transport equatorial energy/heat to the poles vertically, completely bypassing the 2 meter surface record.
    With regards
    Martin Cropp

  24. ZONEBUST above is saying we are in the Ice Making stage of the new Ice Age.

    • No, he is not. Climate and all its manifestations are completely determined by the need to transport a huge amount of heat from the tropics to the poles. This transport is carried out by mass (not radiation), in the atmosphere and oceans, that has to return to the tropics to close the loop.

      The idea that the climate of the Earth depends on its radiative balance at the TOA is pernicious for our understanding of climate. It depends on the amount of heat transported to the poles and what happens to it once there. The most important climate determinant has been known for 100 years, it is the latitudinal gradient of insolation (LIG) and the latitudinal gradient of temperature (LTG) that strongly depends on it. When the amount of heat that needs to be transported to the poles exceeds threshold values determined by the Bjerkness compensation capacity, the result is powerful energy arcs that short the normal transport mechanisms manifesting as El Niño, Monsoon, tropical cyclones, or deep convection. All of them increase the amount of heat transported, cooling the planet.

      • “Bjerknes (1964) first suggested that, if the net radiation forcing at the top of the atmosphere (TOA) and the ocean heat storage did not vary too much, the total energy transport by the climate system would not vary too much either; so any large variations in AHT and OHT should be equal in magnitude and opposite in signs. This simple scenario has become known as the Bjerknes compensation (BJC), suggesting a strong negative relationship between the changes in AHT and OHT.” https://www.researchgate.net/publication/282776980_Understanding_Bjerknes_Compensation_in_Atmosphere_and_Ocean_Heat_Transports_Using_a_Coupled_Box_Model/download

        An idea that falls at the first hurdle of large changes in TOA radiative flux and ocean heat due to dynamic changes in ocean and atmospheric circulation.

        In the tropics the planet gains more heat than it loses. In higher latitudes the reverse is true. But change in absolute heat content of the planet depends strictly on the instantaneous imbalance of power flux at TOA. The planet has multiple responses – including Planck feedback and less cloud over warmer oceans. A warmer planet will tend to restore flux balance as all energy gained is ultimately lost in maximum entropy.

        But with greenhouse gases the atmosphere and oceans will stay warmer raising the risk of small variability causing step changes in the global coupled system of ice, cloud, biology, ocean and atmospheric circulation and dust.

      • The tropical Pacific Ocean is known to act as a capacitor, accumulating and discharging heat in what is known as ENSO. On strong discharging years the climate system needs to transport a lot more heat poleward than on strong recharging years. So it is clear that ocean heat storage does not remain constant. Thus Bjerkness compensation is bypassed when the amount of heat to be transported reaches the threshold of what normal mechanisms can handle. The extra heat is shoot to the atmosphere by El Niño, deep convection, monsoons, and tropical cyclones and the ocean does not compensate.

        We know from proxies that there were no El Niños during the Holocene Climatic Optimum (Moy et al., 2002). El Niño is a feature of a cooling planet when the temperature gradient between the equator and the poles becomes steeper and more heat needs to be transported to the poles and lost there.

        The problem is in assuming that TOA radiative flux changes are governed by planet-wide phenomena like GHG content. Radiative flux at the poles is far from constant and on winter months depends solely on heat transport from lower latitudes. On dark winter months the ice at the poles acts as an insulator (think igloo), and all the heat transported there is lost to space regardless of GHG content. It radiates out regardless of CO2 as it has plenty of time to do it. The more heat transported there the more the planet cools, and vice versa.

        So looking at Arctic temperature by season that is what we see.

        http://ocean.dmi.dk/arctic/meant80n_anomaly.uk.php

        During warming periods Arctic winter temperature does not increase, and even decreases slightly. During non-warming periods (pauses) Arctic winter temperature increases so more heat is lost at the pole and the planet does not warm. This on the face of CO2.

        The coupling of energy transport to the poles during winter, that is strongly regulated, is what determines the temperature of the planet. Climate scientists are lost because they are observing the window insulation, when it is the door to the cold outside at the poles what determines the temperature of the house.

        And we should know because what characterizes climate over the past half billion years is the temperature gradient between the equator and the poles, as Christopher Scotese has shown:

  25. Ireneusz Palmowski

    Lows, along the jetstream, are moving over Mexico.

  26. Ireneusz Palmowski

    The sea surface temperature in the Gulf of Mexico is now high.

  27. Pingback: German Prof. Writes Activists Have Warped Climate Perception, Why Does Climate Agenda “Lie So Much”?

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