McGill University: "Cold season quantitative precipitation forecasting for the Burlington, VT region"

Final Report

SECTION 1: PROJECT OBJECTIVES AND ACCOMPLISHMENTS

The objectives of the project include:
Scientific goals:

1. To understand the necessary and sufficient conditions associated with significant cold-season precipitation events in the Burlington, Vermont region.

2. To understand the role of topography in northern Vermont, northern New York and southern Quebec in modulating wind and precipitation fields.

3. To understand the relationship between the synoptic scale and mesoscale processes in precipitation events.

4. To examine the predictability of the extreme cold-season precipitation event.

These goals were met with the following completed work (accomplishments are numbered to correspond to each of the above goals:

1. Dorothy Durnford has successfully completed Master's thesis entitled "An analysis of Montreal's record-breaking heavy rainfall event of 8-9 November 1996, and a comparison with its best analogue", 2001 (115 pages). This study distinguishes the significant event from its less-significant counterpart by identifying mesoscale cyclogenesis and frontogenesis as occurring in the record-breaking November 1996. These processes were absent in the analogue case of 1977.
   
   We have followed up on Dorothy Durnford's Master's thesis entitled "An analysis of Montreal's record-breaking heavy rainfall event of 8-9 November 1996, and a comparison with its best analogue", 2001 (115 pages), with a successful mesoscale simulation of this case with the Mesoscale Compressible community model. These results were presented to the community at the AMS Conference on Weather Analysis and Forecasting this past August 2002 in San Antonio, TX. This study distinguishes the significant event from its less-significant counterpart by identifying mesoscale cyclogenesis and frontogenesis as occurring in the record-breaking November 1996. These processes were absent in the analogue case of 1977. We have followed up this work with new simulations using the MC2 model to test the role of orography on the dynamics of this case. Currently, we are preparing this work for submission to the Monthly Weather Review.
   
   A manuscript, entitled "Synoptic and planetary-scale precursors to significant cold-season precipitation events in Burlington, Vermont (Sisson and Gyakum 2003), has been submitted to the American Meteorological Society and is in final review for the Weather and Forecasting journal. We are currently working on the revisions requested by the Editor, and expect the manuscript to be published in 2004.

2. The role of orography was investigated through testing of mesoscale models at grid-spacings ranging down to 3 km.

3. As for #1 above.

4. The predictability issue is the topic of Dorothy Durnford's Ph. D. dissertation work on the role of upper-level precursors in the predictions of quantitative precipitation for the Saint Lawrence and Champlain Valleys.

Operational forecasting goals:

• To improve the predictions and warning times of extreme cold-season precipitation events in the Burlington, VT region.
• To provide the forecaster with a focused set of tools that assist in this prediction improvement.
• To determine the differences between extreme and benign events.
• To improve the forecasts of the mesoscale details of precipitation in the Burlington forecast region.
• To be able to communicate to NWS customers the likelihood of a heavy precipitation event, and the topographic variability of wind and precipitation

Educational goals:

1. further the understanding of NWS forecasters on the extreme cold-season precipitation events in the region through local workshops and local web based training modules.

2. To further the understanding of NWS forecasters in the topographic variability of wind and precipitation

Accomplishments:

1. A joint NWS-BTV/ McGill workshop on winter weather was held at the Burlington Forecast office on Wednesday, December 5, 2001. Ron McTaggart-Cowan produced a lecture on potential vorticity concepts. John Gyakum discussed the March 1993 Superstorm, and also gave a laboratory on forecasting heavy wintertime precipitation events.

2. Availability of testing results of mesoscale modeling is being made to the forecasters.

3. Planning meetings were held at McGill on 3 July 2001, 24 October 2001, and 23 January 2002, 10 April 2002, 13 Jun 2002, 3 July 2002, 17 July 2002, 16 October 2002, 24 Jan 2003, 7 March 2003, 15 April 2003, 21 June 2003, 23 June 2003. Meetings were held at Burlington WFO on 11 June 2001, 22 August 2001, 5 December 2001.

4. Jason Neilson, Meteorological Intern, WFO Burlington, completed precipitation type analysis of the moderate and light precipitation cases used in the composite analysis.

5. Workstation Eta 5-km Mesoscale model was upgraded to Version 2.0 and moved to a dual 1.5GHz Linux workstation. Forecast length increased to 60-h and made available in AWIPS for operational forecasters in real-time.

6. Paul Sisson developed Advanced Weather Interactive Processing System (AWIPS) procedures developed for use by operational forecasters to view output from the workstation Eta.

7. Paul Sisson presented an overview of the 7 January 2002 heavy mesoscale banded snowstorm at the 9 January 2002 WFO Burlington Station meeting.

8. The McGill team has implemented the most recent version (4.9.3) of the Mesoscale Compressible Community Model (MC2) at 3-km resolution for approximately the same domain as being used for the workstation Eta 5-km mesoscale model. The model has been running continuously in real-time since May 21, 2002, each day with a 0000 UTC initialization time, for a 48-h forecast range.

9. To support the above real-time modeling effort at McGill, we have hired a senior undergraduate student, Sebastien Chouinard, to produce forecast products, and to distribute these to the BTV forecast office.

10. John Gyakum, Professor Isztar Zawadzki, and McGill graduate student Florence Bocquet, participated in the Warm-season severe weather workshop in Burlington on 15 May 2002. Prof. Zawadzki presented a summary of the operational and research products offered by the Stewart Marshall McGill University Radar Observatory. Florence Bocquet presented her Master’s Thesis research on the relationship between synoptic-scale precursors and the development of mesoscale vortices in the Montreal region.

11. The combination of real-time modeling efforts that are occurring at both the BTV forecast office and the McGill University are helping to accomplish the scientific, operational forecasting, and educational objectives goals listed above.

12. A new initiative has begun to enhance our understanding of heavy precipitation with two case studies. The abstract of this work, involving operational forecasters from the National Weather Service and the Meteorological Service of Canada, follows:
    
    This research focuses on the physical processes relating to two recent events of precipitation in which at least 25 mm of liquid equivalent precipitation occurred within a 12–h period. The first event was that of the heavy snow in Albany, New York of 7 January 2002, and the second event was that of a heavy snow in Halifax, Nova Scotia of 4-5 February 2002. Each event was evidently unrelated to topographic forcing. Each case was also mostly unforecasted by the operational models with horizontal resolutions ranging to 6 km. Although each case occurred in a large-scale flow that was favorable for cyclogenesis, several crucial details relating to the extreme mesoscale development are identified and studied. Additionally, cyclogenetic mechanisms are studied.
    
    The mesoscale environment is studied in the context of both upright and slantwise convection. The processes that were responsible for this destabilization include upper-level cooling associated with the advance of an upper-level short-wave trough, and the development of conditional symmetric instability.
    
    Frontogenetic forcing was especially large in the middle troposphere in each case. The fact that ascent maxima of –20 to –50 microbars per second occurred in the vicinity of these zones of frontogenesis suggest the importance of this forcing contributing to these events’ strength.
    
    Considering that the upper-level frontogenesis was associated with a sloping dynamic tropopause, we investigate the role of the diabatically-induced effects of the observed moist convection in each case. To do this, we use a high-resolution version of the Mesoscale Compressible Community Model (MC2) with an accurate microphysical parameterization and explicit representation of cumulus effects. We investigate the hypothesis that moist upright convection produces a positive feedback on surface cyclogenesis through the mechanism of diabatically-induced ridging. This ridging shortens the wavelength, and increases the cyclonic vorticity advection over the developing cyclone.

We have also produced a credible MC2 simulation of the 7 January 2002 case for Albany, NY. Diagnostic analysis of this case has begun using the MC2 forecast data. The collaborative research on these cases continues. We have followed up on this work by quantitatively assessing the role of water vapour initialization in the MC2 following the technique of McTaggart-Cowan et al. (2003), and have begun to write up this work for publication in the Monthly Weather Review. Presentations of this work are summarized in section 3.

SECTION 2: SUMMARY OF RESEARCH AND EDUCATIONAL EXCHANGES:

Seminars or training workshops conducted by either the university or NWS:

1. 4 December 2001: Meteorological Service of Canada workshop on extreme winter weather, hosted by McGill University. Presentation listed in section 3.

2. 5 December 2001: Joint NWS-BTV/McGill workshop on winter weather was held at the BTV forecast office. Presentations by both McGill and BTV personnel are listed in section 3 below.

3. 17 February through 1 March 2002: John Gyakum was the lead academic instructor for the Winter Weather Course at COMET in Boulder, Colorado for the Meteorological Service of Canada. The enrollment was 20 students, including six from the US National Weather Service.

4. 13 May 2002: Invited presentation to the COMET course in Boulder, Colorado, entitled "East coast cyclogenesis". Duration of 2 hours.

5. 15 May 2002: Joint NWS-BTV/McGill workshop on summer severe weather was held at the BTV forecast office. Presentations by both McGill and BTV personnel are listed in section 3 below.

6. A joint NWS-BTV/ McGill workshop on winter weather was held at the Burlington Forecast office on Wednesday, November 13, 2002. Ron McTaggart-Cowan produced a lecture on real-time modeling with the MC2 at McGill University. John Gyakum presented a lecture, entitled "Potential vorticity and the dynamic tropopause."

7. Ron McTaggart-Cowan participated in a forecast shift at WFO BTV on Nov 16, 2002.

8. 29 May 2003: Operational Weather Workshop at the BTV Forecast Office. Both Dr. Gyakum and Mr. McTaggart-Cowan participated in this workshop.

Joint preparation of publications:

1. Sisson, P. A., and J. R. Gyakum, 2003: Synoptic and planetary-scale precursors to significant cold-season precipitation events in Burlington, Vermont. Wea. Forecasting, submitted.

2. Sisson, P. A., P. J. Roebber, J. R. Gyakum, 2002: Forecasting for the 1998 Ice Storm. Work in progress.

Participation of students at the forecast office:

McGill graduate students Dorothy Durnford, Florence Bocquet, and Ron McTaggart-Cowan have visited the BTV forecast office several times during the past year for meetings and workshops. Specific formal presentations are listed in the next section.

SECTION 3: PRESENTATIONS AND PUBLICATIONS

John Gyakum:

• Gyakum, J. R., and P. J. Roebber, 2001: The 1998 Ice Storm - analysis of a planetary-scale event. Mon. Wea. Rev., 129, 2983-2997.
  
• Ouranos Meeting, Montreal, QC (McGill University) - November 15, 2001: "Severe Weather and Natural variability: Ice Storms and Extratropical Transformations"
  
• MSC meeting on "Extreme Weather" (McGill University) - December 4, 2001: "The extratropical transition."
  
• Winter weather workshop (Burlington Weather Forecast Office) - December 5, 2001: Laboratory on "A wintertime heavy precipitation exercise"
  
• Winter weather workshop (Burlington Weather Forecast Office) - December 5, 2001: Lecture on "The 1993 Superstorm."
  
• CWRP-CFCAS workshop on quantitative precipitation forecasting (Rimouski, QC):--May 20, 2002: “A study of heavy precipitation occurring in continental and marine environments”
  
• CWRP-CFCAS workshop on quantitative precipitation forecasting (Rimouski, QC):--May 21, 2002: “Orographic influences on the mesoscale structure of the 1998 ice storm”.
  
• 36th Congress of the Canadian Meteorological and Oceanographic Society (Rimouski, QC) – May 23, 2002: “Orographic influences on the mesoscale structure of the 1998 ice storm”.
  
• 36th Congress of the Canadian Meteorological and Oceanographic Society (Rimouski, QC) – May 23, 2002: “Synthesis of water and energy fluxes over the Mackenzie River Basin during the 1998-99 water year”.
  
• 36th Congress of the Canadian Meteorological and Oceanographic Society (Rimouski, QC) – May 25, 2002: : “A study of heavy precipitation occurring in continental and marine environments”.
  
• Roebber, P. J., and J. R. Gyakum, 2003: Orographic influences on the mesoscale structure of the 1998 Ice Storm. Mon. Wea. Rev., 131, 27-50.
  
• Seminar at the State University of New York/Albany: "The Ice Storm of January 1998: Planetary and mesoscale analyses". 28 October 2002.
  
• Seminar at the Meteorological Service of Canada, St. Laurent, QC: "Real-time forecasting at McGill University using the MC2 model". 30 October 2002.
  
• Lecture, entitled "Potential vorticity and the dynamic tropopause." (Winter weather workshop at BTV: 13 November 2002.
  
• Lead academic instructor during the two-week December 2002 Winter Weather Course at COMET in Boulder, Colorado for the Meteorological Service of Canada. The enrollment was 20 students, including six from the US National Weather Service.

Ron McTaggart-Cowan:

• Winter weather workshop (Burlington Weather Forecast Office) - December 5, 2001: Lecture on Potential vorticity concepts
  
• Winter weather workshop (Gray, Maine Weather Forecast Office) - November 16, 2001: Lecture on Potential vorticity concepts
  
• The Fourth Northeast Regional Operational Workshop SUNY-Albany - 6 November 2002: "Real-time forecasting at McGill University using the MC2 model".
  
• Winter weather workshop (Burlington Weather Forecast Office) - 13 November 2002: Lecture on Real-time mesoscale modeling at McGill University.
  
• McTaggart-Cowan, R., J. R. Gyakum, and M. K. Yau, 2003: Moist component potential vorticity. J. Atmos. Sci., 60, 166-177.

Dorothy Durnford:

• Dorothy Durnford: Master's thesis entitled "An analysis of Montreal's record-breaking heavy rainfall event of 8-9 November 1996, and a comparison with its best analogue", 2001. 115 pp.
  
• Presentation at the C-star workshop on winter weather, entitled "An analysis of Montreal's record-breaking heavy rainfall event of 8-9 November 1996, and a comparison with its best analogue". Albany, NY, November 7, 2001.

Florence Bocquet:

• Summer severe weather workshop (Burlington Weather Forecast Office) -- May 15, 2002: Synoptic-scale signatures of warm-season heavy precipitation events associated with mesoscale vortices in the Montreal region.

Paul Sisson (BTV):

• 19th AMS Conference on Weather Analysis and Forecasting - 14 August 2002: A Study of Heavy Precipitation Occurring in Continental Environment and Marine Environments - John R. Gyakum, , R. McTaggart-Cowan, P.A. Sisson, G. Toth, P. Lewis, and J.K. Parker
  
• The Fourth Northeast Regional Operational Workshop SUNY-Albany - 5 November 2002: A Case Study of Heavy Precipitation Occurring in a Continental Environment - John R. Gyakum, , R. McTaggart-Cowan, P.A. Sisson, G. Toth, P. Lewis, and J.K. Parker
• Winter weather workshop (Burlington Weather Forecast Office) - 13 November 2002:
  1) Review of Cool Season Heavy Precipitation Signatures
  2) A look back at Thanksgiving 1996 Lake Champlain Effect Event
  
• Sisson, P. A., and J. R. Gyakum, 2003: Synoptic and planetary-scale precursors to significant cold-season precipitation events in Burlington, Vermont. Wea. Forecasting, submitted.

Dan St. Jean ( BTV CSTAR participant):

• 19th AMS Conference on Weather Analysis and Forecasting – 12 August 2002: Characteristics of Upslope Snowfall Events in Northern New York State and Northern Vermont: Diagnostics and Model Simulations of Several Northwest-flow Cases Daniel St. Jean and P. A. Sisson
  
• The Fourth Northeast Regional Operational Workshop SUNY-Albany - 5 November 2002: Characteristics of Upslope Snowfall Events in Northern New York State and Northern Vermont: Diagnostics and Model Simulations of Several Northwest-flow Cases. Daniel St. Jean and P. A. Sisson
  
• Winter weather workshop (Burlington Weather Forecast Office) - 13 November 2002: Characteristics of Upslope Snow Events

SECTION 4: SUMMARY OF BENEFITS AND PROBLEMS ENCOUNTERED

University Benefits:

• McGill University group continues to benefit from interactions with the BTV Forecast office. John Gyakum and his graduate students (Dorothy Durnford, Florence Bouquet, and Ron McTaggart-Cowan) have each visited the BTV Forecast office for discussions and presentations. In turn, Paul Sisson has visited McGill bimonthly since July 2001. These meetings have been consistently productive and have involved interactions with both students and faculty (in addition to John Gyakum).
  
  
• The identification of a challenging forecast problem, that of a cold-season precipitation forecast evidently unrelated to orography has been identified the forecasters. A collaborative effort designed to study the case of January 7, 2002, will be presented at the forthcoming Weather Analysis and Forecasting Conference this coming August in San Antonio, Texas.
  
  
• The Burlington Forecast office has provided data that were crucial in Dorothy Durnford's completion of her Master's Thesis concerning the record-breaking November 1996 rainstorm.
  
  
• The summer severe weather workshop (May 15, 2002) has provided McGill graduate student Florence Bocquet and opportunity to present here Master’s Thesis work.
  
  
  •As a result of the new initiative that has been created in collaboration with Dr. Isztar Zawadzki of McGill, concerning the relationship between synoptic-planetary scale forcing and mesoscale cyclones in the Saint Lawrence/Champlain Valleys, Professor Zawadzki has become more actively involved in real-time observing and forecasting. He presented his work at the Warm-season weather workshop at the Burlington, Vermont Forecast office on May 15, 2002.

NWS Benefits:

• NWS Burlington has benefited from the collaboration from knowledge of Potential Vorticity (PV) uses as presented in the 5 December workshop.
  
  
• Several forecasters continue to employ PV analysis/diagnostics in there forecast procedures.
  
  
• Dialog between McGill and WFO Burlington on the use of PV during and immediately after precipitation events by telephone and email with exchange of graphical depictions of PV as helped to solidify points made during the 5 December 2001 workshop.
  
  
• Addition of the new forecast tool, vertical integral of water vapor transport to AWIPS, is being developed.
  
  
• The McGill group continues to provide valuable collaborations with NWS BTV and has continued to stimulate interest in operational research.
  
  
• Dr. John Gyakum and Ron McTaggart-Cowan assisted in the development of a NWS BTV Warning Event Simulator(WES) training module for BTV forecasters of the 7 January 2002 Snowstorm for operational forecasters for the cool season training for 2002-2003. Results from this meeting, model simulations, and presentations at the 19th AMS Conference on Weather Analysis and Forecasting were directly applied to the WES training in addition to teletraining from the CSTAR project on mesoscale banding.
  
  
• A new forecast tool in the form of an AWIPS 4 panel plan view procedure was developed on the WES to complement the CSTAR 4 panel cross section procedure to pinpoint areas ripe for heavy mesoscale precipitation band development within an area of synoptic scale forcing. These procedures were then moved from the simulator to the AWIPS for use in operations for the cold season.
  
  
• These procedures were demonstrated to the operational forecasters during the WES simulations. They were used successfully during BTV warning and forecast operations for the 25 December 2002 and 4 January 2003 snowstorms. Probability of detection(POD) for BTV winter storm warnings for these two event were approximately 0.92. The Nov 2002 – Jan 4 2003 POD is .96 for BTV winter storm warnings.
  
  
• The above illustrated the value of integrating the results of both the COMET and CSTAR projects, in which BTV participated.
  
  
• The use of the project results directly into the one-on-one WES training at BTV also shows the value of operational research to the operational forecasters who can directly apply the results to their warning and forecast duties.
  
  
• Figure 1 shows Dr. John Gyakum and Ron McTaggart-Cowan using the WES machine.
  
  
• Figure 2 shows the AWIPS 4 Panel Plan View Procedure for identifying heavy mesoscale precipitation banding for winter storms.

Figure 1. Dr. John Gyakum and Ron McTaggart-Cowan in the
NWS BTV conference room reviewing the 7 January 2002
Storm on the BTV Warning Event Simulator (WES).

Figure 2. AWIPS Plan view 4 panel display from 4 January 2003 integrating the results of the COMET and CSTAR projects into a usable tool for warning and forecast operations at BTV. Upper left panel shows MSL pressure(solid white), 500-hpa heights(solid gray), 850-500 hPa Q-vectors(green arrows), and divergence(negative shaded). The upper right shows 700-hPa heights, winds, temperatures, and 2-d frontogenesis (positive values shaded). The lower left shows 850-500 hPa lapse-rate (positive shaded) and lower right shows 850-500 hPa mean relative humidity(shaded greater than 70 percent), precipitable water(solid black), and 700-500 hPa omega(cyan dashed negative).

References:

Durnford, D., 2001: Master's thesis entitled "An analysis of Montreal's record-breaking heavy rainfall event of 8-9 November 1996, and a comparison with its best analogue". 115 pp.

Gyakum, J. R., and P. J. Roebber, 2001: The 1998 Ice Storm - analysis of a planetary-scale event. Mon. Wea. Rev., 129, 2983-2997.

Gyakum, J. R., P. A. Sisson, R. McTaggart-Cowan, J. Parker, P. Lewis, and G. Toth, 2003: A study of heavy precipitation occurring in continental and marine environments. Work in progress.

McTaggart-Cowan, R., J. R. Gyakum, and M. K. Yau, 2003: Moist component potential vorticity. J. Atmos. Sci., 60, 166-177.

Sisson, P. A., and J. R. Gyakum, 2003: Synoptic and planetary-scale precursors to significant cold-season precipitation events in Burlington, Vermont. Wea. Forecasting, submitted.