THE OUN WRF EXPERIMENT Gabe Garfield Introduction Highresolution

THE OUN WRF EXPERIMENT Gabe Garfield

Introduction � High-resolution modeling already used operationally in near-term (6 – 8 hr) forecasting. � Little to no use in short-term forecasting (due to latency).

Warn-on-Forecast � The goal of warn on forecast

Warn-on-Forecast � Currently using warn-on-detection paradigm (no modeling). � Need to create forecasting structure suitable for warn-on-forecast. � Trouble is, most models are operational, run at national centers. How to test?

Norman Weather Forecast Office Weather Research Forecast Model (OUN WRF) � Computational cluster with 10 nodes and 80 processor cores �Each core is an Intel E 5620 (2. 4 GHz) � Infini. Band communication link between nodes (20 Gbit/s) � WRF Version 3. 1. 1 � Runs every hour out to 8 hours

The OUN WRF � Advanced Research WRF (ARW) solver � 3 -km grid-spacing � Domain covers the Southern Plains, centered on OUN

The OUN WRF

The OUN WRF � Boundary conditions: � 12 Z, 00 Z WRF forecasts � Initial conditions: �Advanced Regional Prediction System’s 3 D -VAR data assimilation � “Hot starts” through ARPS 3 D-VAR

Model Specifications Parameterization Scheme Cumulus None Microphysics WRF Double-Moment 6 -species Planetary Boundary Layer Yonsei University Land-Surface Model NOAH Longwave Radiation Rapid Radiative Transfer Model Shortwave Radiation Dudhia Scheme

How does the OUN WRF fit into the Spring Experiment? • Use OUN WRF to move toward using high- resolution forecasts for warning decisions (Warn-on-Forecast) • Problem: explicit forecasts of individual storms (let alone tornadoes) aren’t good enough yet • What do we do in the mean time?

OUN WRF Experiment • Use severe storm “proxies” – products that imply the presence of a particular type of hazardous weather (e. g. , updraft-helicity, vertically-integrated graupel) • Use model output to forecast relevant largerscale processes. For example, • Convective initiation/demise (location and timing) • Storm mode

OUN WRF Experiment � Investigate the effect of hourly output (in 15 -min increments) on situational awareness during warning operations � Examine forecaster workload and determine how high-res output can be streamlined into warning operations

Research Questions � Do severe storm proxies add skill to a convective forecast? � Does the OUN WRF forecast of relevant, large-scale processes (e. g. , evolution of storm mode, timing of convective initiation, etc. ) increase situational awareness during warning operations?

Research Questions � Does the high frequency of OUN WRF output increase forecaster situational awareness? � How does the introduction of highresolution model data impact forecaster workload?

Research Questions � What new, high-resolution model products might increase forecaster SA? � How can high-resolution model data be streamlined into warning operations?

Data Collection � 2 area forecast discussions � Live blogging � In-house warnings � Survey � Daily post-mortem discussions

Day in the Life of the Experimental Warning Program Monday 10 am-3 pm ○ New participant orientation ○ Project introduction seminars 3 pm-6 pm ○ WES training / Informal IOP 1: 30 pm-2: 30 pm ○ EWP daily briefing 2: 30 pm-4 pm ○ CI monitoring and morning shift final AFD issued 4 pm-9 pm ○ Warning IOP or training/archive feedback Tues-Thurs 9 am-11 am ○ Work with EFP CI desk 11 am-noon ○ Issue initial AFD Noon-12: 30 pm ○ Lunch 12: 30 pm-1: 30 pm ○ EFP/EWP joint briefing Tues-Thurs Friday 10 am-12 pm ○ Weekly debrief 12 pm-1 pm ○ Optional brown bag lunch seminars Adapted from a presentation by Chris Siewert.

Products to be evaluated � Updraft-helicity – is the vertically integrated product of vertical velocity and vorticity. It may be useful as a proxy for supercells. � Simulated 1 -km reflectivity - is a derived product that serves as a proxy for storm intensity.

Products to be evaluated � 10 -meter wind speed - can be used as a proxy for severe wind gusts. � Updraft/downdraft velocities - have implications regarding the intensity of convective overturning.

Products to be evaluated � Layer storm-motion - can be used as guidance for storm motion. � Vertically-integrated graupel - may be useful for the prediction of severe hail.

Questions or comments? gabriel. garfield@noaa. gov