Lessons in predictability part 2 the march 2009 megastorm
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Lessons in Predictability: Part 2 The March 2009 “Megastorm”. Michael J. Bodner, NCEP/HPC Camp Springs, MD Richard H. Grumm, NWS WFO State College, PA Neil A. Stuart, NWS WFO Albany, NY. NROW 2009.

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Lessons in Predictability: Part 2 The March 2009 “Megastorm”

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Lessons in predictability part 2 the march 2009 megastorm

Lessons in Predictability: Part 2 The March 2009 “Megastorm”

Michael J. Bodner, NCEP/HPC

Camp Springs, MD

Richard H. Grumm, NWS

WFO State College, PA

Neil A. Stuart, NWS

WFO Albany, NY

NROW 2009


Lessons in predictability part 2 the march 2009 megastorm

The storm was well predicted predicited at days 4-7 by the major meteorological centers deterministic models and ensemble packages


Lessons in predictability part 2 the march 2009 megastorm

Deterministic

GFS

Deterministic

ECMWF HR

Verifying

84 HR FCST


Lessons in predictability part 2 the march 2009 megastorm

GEFS

mean

8 member Poor Man’s Ensemble (GFS and EC)

Verifying

84 HR FCST


Lessons in predictability part 2 the march 2009 megastorm

Deterministic

GFS

Deterministic

ECMWF HR

Verifying

96 HR FCST


Lessons in predictability part 2 the march 2009 megastorm

GEFS

mean

8 member Poor Man’s Ensemble (GFS and EC)

Verifying

96 HR FCST


Lessons in predictability part 2 the march 2009 megastorm

Deterministic

GFS

Deterministic

ECMWF HR

Verifying

108 HR FCST


Lessons in predictability part 2 the march 2009 megastorm

GEFS

mean

8 member Poor Man’s Ensemble (GFS and EC)

Verifying

108 HR FCST


Calculation for 500 hpa flip flop tool results in units of decameters

Calculation for 500 hPa Flip Flop tool – results in units of decameters

________________________________

√(cycle-12hr-cycle-24hr)x(cyclecurrent-cycle-12hr)


Lessons in predictability part 2 the march 2009 megastorm

500 hPa D-Prog/Dt Flip Flop Tool

GFS and ECMWF

84 HR

FCST


Lessons in predictability part 2 the march 2009 megastorm

500 hPa D-Prog/Dt Flip Flop Tool

GFS and ECMWF

96 HR

FCST


Lessons in predictability part 2 the march 2009 megastorm

500 hPa D-Prog/Dt Flip Flop Tool

GFS and ECMWF

108 HR

FCST


Lessons in predictability part 2 the march 2009 megastorm

This is what happened – Is this a “Megastorm?


Lessons in predictability part 2 the march 2009 megastorm

This was the first event of 2008-09 to effect all of the major eastern cities. The storm received a NESIS classification of “1”


Conclusions introducing the lagged average forecast and flip flop tool

Conclusions - Introducing the Lagged Average Forecast and “Flip Flop” Tool

  • Lagged average forecast or “poor man’s ensemble” - average the 4 most recent deterministic runs of both the GFS and ECMWF.

  • Advantage of the LAF

    • Uses a multi model approach to ensemble forecasting

    • Does not lose resolution because multiple deterministic forecasts are being used instead of ensemble means and members

    • Less smoothing of key features

  • The “flip flop” tool algorithmically combines the 3 most recent deterministic model runs

  • Displays the magnitude of reverting trends (flip flops) when contrasting previous model runs.

  • Positive values indicate that the model “flip flopped.”

  • Both tools provide the forecaster a quantitative way to evaluate model trend and uncertainty for specific features

  • Both geographical and temporal evaluation of uncertainty, thereby increasing or decreasing forecast confidence.

  • Future work includes formal verification and looking at other model output parameters.

Thank you for your time – Any questions?


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