The Hurricane Weather Research & Forecasting (HWRF) Prediction System

• Next generation non-hydrostatic weather research and hurricane prediction system

• Movable, 2- way nested grid (9km; 27km/42L; ~68X68)• Coupled with Princeton Ocean Model

• POM utilized for Atlantic systems, no ocean coupling in N Pacific systems• Vortex initialized through use of modified 6h HWRF first guess• 3-D VAR data assimilation scheme

• But with more advanced data assimilation for hurricane core • Plans for use of airborne and land based Doppler radar data

• Became operational in 2007• Under development since 2002

• Runs in parallel with the GFDL

2010 HWRF Upgrades

• Fixing known bugs in HWRF model (mostly related to radiation)– Led to definition of new baseline configuration for

HWRF• Improved initialization (Additional data in GSI

near the storm environment) • Surface Physics Changes (Cd/Ch coefficients

calculated based on observations)• Gravity Wave Drag Parameterization

*HWRF *GFDL Grid configuration 2-nests 3-nests

Nesting Force-feedback Interaction thru intra-nest fluxes

Ocean coupling POM (Atlantic only) POM

Convective parameterization

SAS mom.mix. SAS mom.mix.

Explicit condensation Ferrier Ferrier

Boundary layer GFS non-local GFS non-local

Surface layer GFDL ..(Moon et. al.) GFDL ..(Moon et. al.)

Land surface model GFDL slab GFDL slab

Dissipative heating Based on D-L Zhang Based on M-Y tke 2.5

Gravity wave drag YES NO

Radiation GFDL (cloud differences) GFDL

*Configurations for 2010 season

2011-2013 HWRF UPGRADE PLAN• Data assimilation:

– Advanced initialization for hurricane core – assimilate airborne Doppler radar observations to define storm strength and storm structure

– Continuous upgrades to HWRF hurricane core initialization through advanced 4-D data assimilation for winds and reflectivity

• Model resolution upgrades:– Increase resolution: Horizontal resolution 1-6km, Vertical resolution ~100 levels (dependent

on results of current studies). • Hurricane ensembles: High-resolution hurricane model ensembles.

– Development of HWRF ensembles in progress • Model Physics:

– Continuous upgrades to gravity wave drag parameterizations, sea spray parameterization, atmospheric/ocean boundary layer (fluxes), microphysics, deep convection (cloud-resolving scales), radiation

• Ocean coupling– Replacement of POM with the HYCOM ocean model for 2011

• Other upgrades:– Coupling to land surface model with advanced surface physics for improved rainfall forecasts

at landfall. Important input to hydrology and stream flow models which will address inland flooding.

– Advanced Wave Model (WAVEWATCH III) to forecast waves up to the beach, i.e. improve non-linear interactions, surf-zone shallow water physics, wave interactions with currents.