Dynamic Hurricane Season Prediction Experiment with the

NCEP CFS CGCM

Lindsey Long and Jae Schemm

Climate Prediction Center / Wyle IS

NOAA/NWS/NCEP

October 27, 2009

The 34th Climate Diagnostics and Prediction Workshop,

Monterey, CA

Outline

• Description of the CFS Experiments• Datasets Used• Analysis of storm activity statistics• Focus on the Atlantic and Western North Pacific

basins– Statistics and performance evaluation

• Future plan

CFS T382 Hurricane Season Experiments

• One of the FY07/08 CTB internal projects

• Model Components:– AGCM: 2007 operational NCEP GFS in T382/L64 resolution– LSM: Noah LSM– OGCM: GFDL MOM3

• All runs initialized with NCEP/DOE R2 and NCEP GODAS. – 00Z Initial Conditions from April 19-23– Runs through December 1st

• Tropical cyclone detection and tracking method based on Camargo and Zebiak (2002)– Vorticity max, pressure min, wind max, warm-core system

Datasets

• CFS Hindcasts at T382 (~33km)– 5-Member Ensemble

• April 19th-23rd Initial Conditions

• Output every 6 hours

• 1981-2008, 28 years

• Appropriate ICs for CPC Operational Hurricane Season Outlook

• Observations from the HURDAT and JTWC Best Track Dataset– Tropical depressions and subtropical storms are not

included in storm counts.

Western North Pacific North Indian

Atlantic Eastern North Pacific

Examples of Storm Tracks for 4 NH Basins

Composite of 20 Atlantic Storms With SLP < 990hPa

Max winds, 27 m/s Min Pressure, 984 hPa

Frequency of Minimum Pressure – ATL

AtlanticBasin

Atlantic Tropical StormsMay-Nov, 1981-2008, T382

Obs Clim – 11.4CFS Clim – 10.9

EasternPacific

Eastern Pacific Tropical StormsMay-Nov, 1981-2008, T382

Obs Clim – 16.3CFS Clim – 13.0

WesternPacific

Western Pacific Tropical StormsMay-Nov, 1981-2008, T382

Obs Clim – 24.2CFS Clim – 18.1

JJA Nino 3.4 SST Index

Red = Statistically Significant at 0.95

T382 Correlations

IC=0419 0.72

IC=0420 0.67

IC=0421 0.68

IC=0422 0.57

IC=0423 0.64

April Ensm 5 0.68

T382 Correlations

IC=0419 0.63

IC=0420 0.64

IC=0421 0.73

IC=0422 0.67

IC=0423 0.67

April Ensm 5 0.71 Red = Statistically Significant at 0.95

JJA Atlantic MDR SST Index

T382 Correlations

IC=0419 0.43

IC=0420 0.54

IC=0421 0.66

IC=0422 0.68

IC=0423 0.69

April Ensm 5 0.70 Red = Statistically Significant at 0.95

JJA Atlantic MDR Shear Index

Cool Water Wake - SLP and SSTs Aug 29 - Sep 12, 1981

Correlations Total

IC=0419 0.44

IC=0420 0.33

IC=0421 0.35

IC=0422 0.43

IC=0423 0.54

April Ensm 5 0.61

Anomalous Number of TC: Atlantic Basin

Red = Statistically Significant at 0.95

Correlations Total

IC=0419 0.47

IC=0420 0.58

IC=0421 0.28

IC=0422 0.49

IC=0423 0.59

April Ensm 5 0.62

Atlantic Basin ACE Index

Red = Statistically Significant at 0.95

% o

f Nor

mal

Correlations Total

IC=0419 0.40

IC=0420 0.47

IC=0421 0.01

IC=0422 0.53

IC=0423 0.14

April Ensm 5 0.46

Anomalous Number of TC: Western N. Pacific

Red = Statistically Significant at 0.95

Correlations Total

IC=0419 0.43

IC=0420 0.51

IC=0421 0.33

IC=0422 0.47

IC=0423 0.34

April Ensm 5 0.50

WNP Basin ACE Index

Red = Statistically Significant at 0.95

% o

f N

orm

al

CFS April 2009 ForecastAtlantic Basin

Storm Count and ACE Index

ATL – Below Average Year Predicted

CFS predicted 7.5 storms versus a 10.9 storm climatology.With an ACE Index of only 75% of Normal

Courtesy of Unisys

8 Named Storms for 2009: 6 TSs and 2 Hurricanes28-Yr Climatology = 11.6 Storms

CFS April 2009 ForecastWestern N. Pacific BasinStorm Count and ACE Index

WNP – Above Average Year Predicted

CFS predicted 21.5 storms versus a 18.1 storm climatology.With an ACE Index of 144% of Normal

As of Oct 22, Courtesy of Unisys

24 Named Storms for 2009: 12 TSs and 8 Typhoons, 4 Super Typhoons28-Yr Climatology = 27.3 Storms

Summary

• CFS in T382 resolution exhibits robust climatological seasonal cycle of tropical cyclones over three NH basins.

• Warming trend and intensification of hurricane activity in the Atlantic basin captured in the CFS hindcasts.

• Fair level of skill in predicting interannual variability of seasonal storm activities for the Atlantic and West. N. Pacific basins.

• Provided input for the 2009 CPC Hurricane Season Outlook with real time prediction runs. Plans for an operational implementation in 2010.