# Presentation: 197234

## Improving the Validation and Prediction of Tropical Cyclone Rainfall

- Robert Rogers
-  NOAA/AOML/HRD
- Tim Marchok
-  NOAA/GFDL
- Bob Tuleya
- NCEP/EMC/SAIC

- Funded by NOAA Joint Hurricane Testbed

## Rainfall forecasts from landfalling TC’s

- _standard forecasting tools_

-  Kraft rule of thumb
-  numerical model guidance
-  R-CLIPER

- _standard validation tools_

-  bias score
-  equitable threat score
-  pattern correlation

## Factors impacting rainfall distributions in landfalling TC’s

- topography
- interaction with synoptic-scale features
- storm intensity
- land-surface boundary

## Track errors for all Atlantic and U.S. landfalling cases

## U.S. Landfalling Cases for Model Evaluation

- Matthew

- 40

- Jeanne

- 105

- Ivan

- 110

- Gaston

- 65

- Frances

- 95

- Charley

- 125

- Bonnie

- 45

***2004***

- Kyle

- 35

- Hermine

- 35

- Isabel

- 90

- Isidore

- 55

- Irene

- 70

- Georges

- 90

- Henri

- 30

- Hanna

- 45

- Harvey

- 50

- Frances

- 45

- Grace

- 35

- Fay

- 50

- Gabrielle 60

- Floyd

- 90

- Earl

- 70

- Claudette

- 75

- Edouard

- 35

- Barry

- 60

- Helene

- 65

- Dennis

- 60

- Charley 40

- Lili

- 85

***2003***

***2002***

***2001***

***2000***

***1999***

***1998***

- Bill

- 50

- Bertha

- 35

- Allison

- 45

- Gordon 55

- Bret

- 100

- Bonnie

- 95

- Matthew

- 40

- Jeanne

- 105

- Ivan

- 110

- Gaston

- 65

- Frances

- 95

- Charley

- 125

- Bonnie

- 45

***2004***

- Kyle

- 35

- Hermine

- 35

- Isabel

- 90

- Isidore

- 55

- Irene

- 70

- Georges

- 90

- Henri

- 30

- Hanna

- 45

- Harvey

- 50

- Frances

- 45

- Grace

- 35

- Fay

- 50

- Gabrielle
- 60

- Floyd

- 90

- Earl

- 70

- Claudette

- 75

- Edouard

- 35

- Barry

- 60

- Helene

- 65

- Dennis

- 60

- Charley
- 40

- Lili

- 85

***2003***

***2002***

***2001***

***2000***

***1999***

***1998***

- Bill

- 50

- Bertha

- 35

- Allison

- 45

- Gordon
- 55

- Bret

- 100

- Bonnie

- 95

## Storms Included in this study

## Models included in this study

- GFDL

- Regional
- 1/2o, 1/6o

- (2-nest)
- 42 levels

- 2003 version

## Isabel 24-hr rain from 12 UTC 18 to 12 UTC 19 September 2003 (12 UTC 17 forecasts)

**Stage IV**

- Isabel 24-hr rain from 12 UTC 18 to 12 UTC 19 September 2003 (12 UTC 17 forecasts)

## Parameters describing skill of TC QPF forecasts

-  Volume
-  Extreme amounts
-  Sensitivity to track errors

## Matrix of TC QPF Metrics

## Pattern

## Pattern comparisons for U.S. landfalling storms

- Equitable Threat Score

## Volume

## Distributions of rain flux in bands surrounding storm track

## Distributions of model rain flux in bands surrounding forecasted storm track

## Extreme amounts

## Top 5% of rain flux comparisons

## Sensitivity to track error

## Example of grid-shifting of rain field 

- Example of grid-shifting of rain field

- Lili Stage IV

- r increased from 0.36 (unshifted) to 0.85 (shifted)

## ETS improvements due to grid shifting

## Summary comparison for all models

## Summary comparison for all models (cont.)

## Future work

- finish development of a set of metrics that synthesizes various aspects of TC QPF
- determine way of picking out other contributors to rainfall variability other than track (e.g., topography) in validation scheme
- develop parametric rainfall model that accounts for vertical shear; validate this model using same metrics
- add other sources of variability to new parametric model (e.g., topography, synoptic environment)

## New forecasting tools for TC rainfall

## Example of footprint: Hurricane Ivan

**06 UTC 09/23/2004**

_**a) Wavenumber 0**_

_**b) Wavenumber 1,2**_

**The Footprint is “stamped” on a lon/lat grid every 15 minutes, providing a storm total accumulation**

***mm h******-1***

***mm h******-1***

## Impact of shear on accumulated rain

***(inches)***

_**Only Wave numbers 1,2 included**_

## Impact of shear on total accumulated rain

_**Ivan – R-CLIPER run including shear**_

_**Ivan – R-CLIPER control run**_

***(inches)***

***(inches)***

## QPF Equitable Threat Score