An Investigation of the Mesoscale Predictability An Investigation of the Mesoscale Predictability over the Northeast U.S.over the Northeast U.S.

Brian A. Colle, Matthew Jones, and Joseph OlsonBrian A. Colle, Matthew Jones, and Joseph Olson

Institute for Terrestrial and Planetary SciencesInstitute for Terrestrial and Planetary Sciences

Stony Brook University / SUNYStony Brook University / SUNY

andand

Jeffrey S. TongueJeffrey S. Tongue

NOAA/NWS Upton, NYNOAA/NWS Upton, NY

Deterministic Runs since 1999 using Eta init/bdy: 00/12Z (60 h – 36/12 km domains, 12-36 h 4-km nest). Grell (36/12 km), Simple ice, MRF PBL.

Problem: Sea breezes move inland too fast

(At ISP, 50% early, 38% on time, and 16% late)

SNE Sea breeze verification (~ 40 events): MM5 wind direction mean absolute errors (36 – 12 km)

Data sampling over Long Island Sound using the Port Jefferson to Bridgeport Ferry: http://www.stonybrook.edu/soundscience/

ObservedWinds

ModelWinds

17:00 GMT June 23rd, 2003

Port Jefferson 17 GMT departure

Bridgeport 18:10 GMT arrival N

360 0

= 1 m/s

Port Jefferson Bridgeport

Warm season cool bias over water

Cool season warm bias over water

Floyd (1999) Storm Total Precipitation (in mm)

L

MM5 storm total precipitation(a) 36-km

(b) 12-km

(c) 1.33 km

36-km MM5 6-36 h Precip total for physics ensemble

Member Convective Scheme PBL scheme1 Kain-Fritsch 2 MRF 2 Kain-Fritsch 2 Blackadar3 Kain-Fritsch 2 ETA4 Grell MRF5 Grell Blackadar6 Grell ETA7 Betts-Miller MRF8 Betts-Miller Blackadar9 Betts-Miller ETA10 Kain-Fritsch MRF11 Kain-Fritsch Blackadar12 Kain-Fritsch ETA

Member FO / Perturbation set1 ETA -1 (21z)2 ETA -2 (21z)3 ETA +1 (21z)4 ETA +2 (21z)5 ETA ctrl (21z)6 GFS (00z)7 ETA (00z)

INITIAL CONDITION ENSEMBLE MATRIX (each uses Grell-MRF physical combination)

PHYSICS ENSEMBLE MATRIX

18-Member MM5 Ensemble (00 UTC cycle, 36/12 km domains)

Nor-easter

6 DEC 2003

21Z 6 DECL

12-km Refl, 700 mb fronto (21 h)

0 oC isotherm (21 h)

Most Prob cat pcp 21-24 h

1 = .01- 0.1 in

2 = .1 - .25 in

2-m Temperature Mean Errors (12 km domain, warm season 2003)

dayNight DayDay Night

2-m Temperature Mean Absolute Errors (12-km domain)

Night Day Night Day

2-m Temperature Mean Absolute Errors (Islip, NY)

Night Day DayNight

2-m Temperature Mean Absolute Errors (12-km domain)

Night Day DayNight

Summary and Future Work

Stony Brook University has been running the MM5 in real-time and completing verification during the past 4 years. We are currently testing the WRF model.

Mesoscale predictions of the sea breeze are hindered by parameterization problems (excessive surface fluxes) as suggested by cross-Sound ferry data and standard verification. For Floyd (1999), there were large precipitation sensitivities with the convective and PBL physics.

An 18-member ensemble forecast system down to 12-km grid spacing has been developed to better quantify uncertainty over the Northeast at moderately high resolution.

The physics members were more useful than the IC members for temperature and windspeed due to large model biases. 14-day bias correction and MOS can provide additional significant improvements.

Warm season precipitation will soon be verified from the 18 members.

REAL-TIME WEB PAGEhttp://atmos.msrc.sunysb.edu/mm5rt

REAL-TIME REFERENCES (2003)

Colle, B. A., Olson, J. B., Tongue, J. S. 2003: Multiseason Verification of the MM5. Part I: Comparison with the Eta Model over the Central and Eastern United States and Impact of MM5 Resolution. Weather and Forecasting, 18, 431–457.

Colle, B. A., Olson, J. B., Tongue, J. S. 2003: Multiseason Verification of the MM5. Part II: Evaluation of High-Resolution Precipitation Forecasts over the Northeastern United States. Weather and Forecasting: 18, 458–480.

Colle, B. A. 2003: Numerical Simulations of the Extratropical Transition of Floyd (1999): Responsible Mechanisms for the Heavy Precipitation. Mon. Wea. Rev., 131, 2905=2926.

Roebber, P, D. Schultz, B. Colle, and D. Stensrud, 2003: The Risks and Rewards of High Resolution and Ensemble Forecasting. Submitted to Weather and Forecasting.

12-km MM5 30-day average cool season precipitation

Summary and Future Plans

Stony Brook University has been running the MM5 in real-time and completing verification for the past 4 years. We are currently testing parallel runs of WRF in real-time.

Develop case studies to demonstrate how to use ensemble and high resolution data in the forecast process.

Add more ensemble members (NOGAPS and CMC grids, warm start runs using observations).

Use ensembles in various applications (energy load, wave modeling, storm surge, etc…)

Add more data sets for verification (e.g., ferry data, scatterometer) and test new verification approaches.