justin arnott – soo, nws gaylord, mi andrew m olthan – nasa sport

Seasonal Evaluation of Lake Effect Snow Forecasts from High Resolution WRF Simulations

Sensitivity to Microphysics, Lake Surface Temperatures and Ice Concentration

Justin Arnott – SOO, NWS Gaylord, MI

Andrew Molthan – NASA SPoRT

Jonathan Case – NASA SPoRT

Ongoing NWS/NASA SPoRT Collaboration

Operational Goal: Improve forecasts of Lake Effect Snow

Increase accuracy/detail of band timing/placement

Study Goal: Optimize Local WRF for LES Forecasts

Methods:

1. Seasonal verification of “bulk variables”

2. Case studies of particular events

Symbiotic Resource Exchange:

NASA provides additional computational resources

NWS provides platform to examine SPoRT Products

2010-2011 Results - Summary

Seasonal ComparisonNASA SPoRT vs. NCEP SSTs/Ice Coverage

Seasonal VerificationMaxT/MinT/Liquid Precipitation

vs NWS COOPs

2010-2011 Results - Summary

SPoRT data indicated greater ice coverage, warmer SSTs Local WRF simulations w/SPoRT data showed larger QPF

Precipitation climatology reasonably forecast

Minimum Temperature high bias

Over-prediction of precipitation amounts during intense LES bands

Further studies by NASA SPoRT for 20-21 January 2011 case study suggest Morrison microphysics may provide improved precipitation forecasts

2011-2012 Study Overview

Continue examination of NASA SPoRT SST/Ice vs legacy NCEP data

Update Operational Local WRF run at WFO Gaylord to Morrison Microphysics

Perform sensitivity of legacy WFO Gaylord simulation (2010-2011) with updated simulation for 2011-2012

Examination Period: 12/08/2011-2/26/2012 Only examine days with LES within WFO Gaylord forecast area

26 days included

2011-2012 Study Setup00Z Simulations (all other options identical)

1.Produced by APX NCEP SST/Ice

Morrison Microphysics

2.Produced by NASA SPoRT NASA SPoRT SST/Ice

Morrison Microphysics

Examine 12-36 Hour Forecasts (to match COOP obs time)

12Z Simulations (all other options identical)

1.Produced by APX NCEP SST/Ice

Lin et al. Microphysics

2.Produced by NASA SPoRT NCEP SST/Ice

Morrison Microphysics

Examine 00-24 Hour Forecasts (to match COOP obs time)

Microphysics Sensitivity Runs

SST Sensitivity Runs

APX Local WRF – Basic Setup

Two Nests 12km Outer

4km Inner

Run at 00/12Z Length: 36 hour

IC/BCs: Previous GFS

CP Scheme Outer: Kain-Fritsch

Inner: None

PBL: Yonsei

Operational Availability: T+3hr (~03/15Z)

SST Comparison – Lake Michigan

Average Difference: +0.7oC

SST Comparison – Lake Superior

Average Difference: +0.1oC

Ice Comparison –Average Lake Coverage

Average Difference: -0.3%

MaxT Comparison – Gaylord, MISST Sensitivity – 00Z Simulations

MinT Comparison – Gaylord, MISST Sensitivity – 00Z Simulations

QPF Comparison – Gaylord, MISST Sensitivity – 00Z Simulations

QPF Comparison – Gaylord, MISST Sensitivity – 00Z Simulations

NASA SST – 0.1”POD: 0.33 FAR: 0.67CSI: 0.20

NCEP SST – 0.1”POD: 0.33 FAR: 0.75CSI: 0.17

NASA SST – Total Liquid Precip: 1.58”

NCEP SST – Total Liquid Precip: 1.53”

Gaylord – Total Liquid Precip: 1.08”

3 out of 26 days with 0.1” liquid observed

QPF Comparison – Gaylord, MIMicrophysics Sensitivity – 12Z Simulations

QPF Comparison – Gaylord, MIMicrophysics Sensitivity – 12Z Simulations

Lin et al. – 0.1”POD: 0.00 FAR: 1.00CSI: 0.00

Morrison – 0.1”POD: 0.33 FAR: 0.50CSI: 0.25

Lin et al. – Total Liquid Precip: 1.01”

Morrison – Total Liquid Precip: 0.71”

Gaylord – Total Liquid Precip: 1.08”

3 out of 26 days with 0.1” liquid observed

QPF Comparison – Sault Sainte Marie, MISST Sensitivity – 00Z Simulations

QPF Comparison – Sault Sainte Marie, MISST Sensitivity – 00Z Simulations

NASA SST – 0.1”POD: 0.50 FAR: 0.40CSI: 0.38

NCEP SST – 0.1”POD: 0.50 FAR: 0.40CSI: 0.38

NASA SST – Total Liquid Precip: 1.68”

NCEP SST – Total Liquid Precip: 1.63”

SSM – Total Liquid Precip: 1.38”

6 out of 26 days with 0.1” liquid observed

QPF Comparison – Sault Sainte Marie, MIMicrophysics Sensitivity – 12Z Simulations

QPF Comparison – Sault Sainte Marie, MIMicrophysics Sensitivity – 12Z Simulations

Lin et al. – 0.1”POD: 0.50 FAR: 0.40CSI: 0.33

Morrison – 0.1”POD: 0.67 FAR: 0.33CSI: 0.44

Lin et al. – Total Liquid Precip: 1.70”

Morrison – Total Liquid Precip: 1.08”

SSM – Total Liquid Precip: 1.38”

6 out of 26 days with 0.1” liquid observed

Side by Side Comparison – Example18 Jan 2012Morrison

Lin et al.

Summary

Temperature Climatology reasonably simulatedMax T forecasts more skillful than Min T

Strong warm bias under radiational cooling

Similar performance regardless of SST/Microphysics

SPoRT SST Trends Similar to 2010-2011

SPoRT SST > NCEP

Inconclusive trends on Ice coverage

Summary - Continued

Morrison Microphysics Scheme provides improvement on high QPF bias seen with Lin et al. Higher CSI for 0.1” events at Gaylord and Sault Sainte Marie

Result may be obscured some by “model spin up”

Differences in QPF > Differences in band position between different microphysics schemes

Suggests that switching microphysics scheme provides an overall improvement to “usability” of model data

Little difference in overall performance using differing SST/Ice initialization

Acknowledgements

Rob RozumalskiWRF EMS Developer

NCDC Radar Data ArchiveNAM ArchiveWeather and Climate Toolkit

GrADSPlots