Wind errors in the GFS Tommy Gun's Valentine's Massacre Dinner Show - February 14 and 17 – Forget dat romantic Valentine's Day and celebrate it wit a bang! Join us in our annual re-enactment of the St. Valentine's Day Massacre after our dinner show, in honor of Valentine's Day - Chicago- style.

Fang-Lin Yang GFS.033 behind ECMWF,.006 behind Met Office GFS.019 ahead of ECMWF

Fang-Lin Yang GFS.051 behind ECMWF,.037 behind Met Office GFS.078 behind ECMWF

GFS slightly better than ECMWF; GFS 6-10 day forecasts explain 50% of variance CPC

GFS poor precip forecasts, large bias MMB

Jan T170 L42 May 2001 cloud liquid water, momentum mixing, stonger QC AMSU Oct T254 L64, analysis changes May 2005 T382 L64, increased mountain blocking, decreased vertical diffusion May 2007 GSI, hybrid vertical coordinate

Note increase in number Of observations

Improvement has leveled off Last 2 years

Little improvement last 5 years

GSI improved agreement with analyses, not with raobs

GFS analyses Closer to rawinsondes

ECMWF forecasts Closer to Rawinsondes

GFS Day 1 problem GFS day 1 and day2 problem

In NH extratropics, fall behind ECMWF first 24 hours In tropics fall behind ECMWF day 2 Wind errors not just a tropical problem.

Zonal mean RMS difference in wind analyses

Analyses most different at equator Above 700 hPa GFS most like ECMWF Most different from FNMOC EC more similar to Met Office Than GFS except above 150hPa at equator

RMS difference in wind analyses at equator

Biggest differences in analyses 200 hPa and above And in ePacific hPa

GFS stronger trades than other centers

GFS more variability in forecasts than other centers FNMOC less variability Transient eddy kinetic energy (1/2(u’ 2 +v’ 2 ))

GFS tends to have larger rms wind errors than ECMWF, Met Office Not just a tropical problem Analysis differences quite large near equator GFS stronger trade winds western hemisphere FNMOC less variability than other centers GFS more variability in forecasts Initially GFS error grows more slowly near equator than other centers, more rapidly than other centers in midlatitudes.