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University of Washington: "Improvement of mesoscale forecasting in the Pacific Northwest"

Final Report

1. Project Accomplishments

During the period of this project there has been significant progress in a number of areas:

A. A highly successful two-day Pacific Northwest Weather Workshop was jointly organized by the Seattle WSFO and the UW during 21-22 February with approximately 140 attendees from the throughout the Northwest as well as California (Naval Postgraduate School), COMET, and others. Real-time mesoscale modeling was one of the major themes of this meeting.

B. Major advances have been made in the area of regional mesoscale modeling and particularly in real-time regional numerical weather prediction. During the first two-thirds of 1996 the MM5 was run twice-daily at 27 km resolution for the Northwest and distributed the output over the net to the NWS and other users. During the middle of the year funding was acquired from local, state, and federal agencies for a powerful multiprocessor server (SUN ES-4000), which allowed the inception of high resolution (12 km resolution) real-time forecasting for the Northwest. The UW and Seattle NWS are major participants in this regional mesoscale modeling consortium. Together MM5 output was converted to gempak format to allow the generation of MM5 meta files to viewed using ntrans at both NWS offices and at the university. The Seattle NWS office is working on verifying the MM5 output at coastal and offshore buoy locations.

C. A successful student volunteer intern program has continued in which undergraduate students spent 3-10 hours per week at the Seattle forecast office. These students both learned about the forecast process and NWS operations and assisted with a variety of tasks.

D. Together, the Seattle NWS office and the UW put on a mesoscale modeling workshop for the Western Region on 25-26 September 1996. Over two-dozen NWS forecasters participated in a review of regional mesoscale modeling and its application in the Northwest. Total workshop attendance was 80 participants.

E. We continue to work with the Seattle WSFO to manage the 915 MHz profiler with RASS installed at Sand Point. The data stream is being managed by the NWS/UW, with the data being archived at the UW. There has been a continuous and active interactive between the UW and NWS regarding the operation and interpretation of the data from this unit. Software has been constructed that allows the UW/NWS to view the Sand Point profiler data on UNIX workstations. The profiler data have also been placed on the department Web server and NWS SEA home page.

F. The regional mesoscale data base has been further enhanced. The Seattle WSFO has made available the hydromet and RAWS data which are now being ingested, decoded, and archived at the UW. Mesoscale maps produced at the UW are now being shipped to the Seattle WSFO and printed every three hours. They are also provided to the NWS in a format that allows animation of a time sequence of hourly mesoscale maps.

G. Research on the importance in diabatic effects on rain/snow forecasting has continued by Garth Ferber (NWS/NW Avalanche Center) and Cliff Mass. A paper based on this research is almost complete and was submitted to Wea. and Forecasting.

H. The data base of papers on Northwest weather is being updated.

I. The COMET graduate fellow, Ken Westrick, has continued his studies at the UW, working on the integration of the MM5 output into a regional distributed hydrological model. Mr. Westrick also participated in the Alaskan Region Mesoscale Modeling Conference held in Fairbanks on 10-13 June 1996.

J. The UW and Seattle NWS have worked to complete a real-time feed of the Level II WSR-88D data to the UW for research and archival. This data feed is now being used with an analysis program named ZEB that will also be used at the Seattle WSFO

K. The Seattle NWS and the UW put on a downslope windstorm workshop that included NWS participants from throughout the country.

L. Numerous discussions have taken place on major forecast events, including the major snowstorms/ice storms of late December 1996.

M. Brad Colman provided a lecture to the senior forecasting class and has been an active member of several graduate student committees.

N. The Seattle NWS office and UW have worked cooperatively on their WEB home pages, exchanging data and graphics.

2. Benefits to the University resulting from the collaboration.

Some examples include:

A. The close relationship with the Seattle WSFO has provided students with considerable exposure to operational forecasting. For example, several students are serving as volunteer interns at the Seattle WSFO and Brad Colman has lectured on operational problems to the senior forecasting class.

B. The cooperative relationship has made several data sets available to the university (e.g., 1 km visible satellite data, hydro data).

C. The cooperative effort has made possible the acquisition and operational transfer of the 915 MHz profiler data and Level II radar data.

D. The close association between the NWS and the UW has facilitated the employment of many UW students in the National Weather Service.

3. Benefits to the NWS office resulting thus far from the collaboration

A. The NWS continues to utilize Harry Edmon as a systems analyst resource. This has led to rendering the HP workstations and N-AWIPS more useful, which in turn has resulted in more accurate forecasts on a number of occasions.

B. Once student volunteers become proficient in certain duties, time is freed up for NWS personnel to work on projects, etc.

C. Daily access to output from the MM5 mesoscale model by NWS forecasters has led to better understanding of terrain-induced circulations, and hence better forecasts. The MM5 forecasts have become more and more reliable and forecasters routinely use the model guidance for marine forecasts.

D. The Amtospheric. Science department maintains the mesoscale network observations archives. This gives NWS more time for studies, etc., since we do not have to devote resources to the archiving function.

E. Free access to University's data archive. The data include microfilm of upper air and surface, all local surface observations including the non-standard set cooperatively collected, and many full resolution model grids. Several of this past years forecaster studies relied upon this data archive.

F. Through the university sponsored mesoscale modeling committee, the NWS developed closer ties with the Puget Sound Air Pollution Control Agency.

4. Outreach Program related references (publications and presentations)

Bond, N. A., C. F. Mass, B. F. Smull, R. A. Houze, M.-J. Yang, B. A. Colle, S. A Braun, M. A. Shapiro, B. C. Colman, P. J. Neiman, J. E. Oveland, W. D. Neff, and J. D. Doyle, 1997: The coastal observation and simulation with topography
(COAST) experiment. Accepted in the Bull. Amer. Meteor. Soc.

Colle, B. A. and C. F. Mass, 1997: Windstorms along the western side of the Washington Cascade Mountains, Part I: a high resolution observational and modeling study of the 12 February 1995 event. Accepted in Mon. Wea. Rev.

Colle, B. A. and C. F. Mass, 1997: Windstorms along the western side of the Washington Cascade Mountains, Part II: characteristics of past events and three-dimensional idealized simulations. Accepted in Mon. Wea. Rev.

Steenburgh, J., C. F. Mass, and S. A. Ferguson, 1997: The influence of gaps in a coastal mountain barrier on temperature and snow level. Accepted in Weather, and Forecasting,

Chien, F. C. and C. F. Mass, 1996: A numerical study of the interaction between a warm-season frontal system and the coastal mountains of the western U.S., Part I: prefrontal pressure ridge, onshore push, and alongshore southerlies. Accepted in Mon. Wea. Rev.

Chien, F. C. and C. F. Mass, 1996: A numerical study of the interaction between a warm-season frontal system and the coastal mountains of the western U.S., Part II: Evolution of a Puget Sound Convergence Zone. Accepted in Mon. Wea. Rev.

Bond, N. A., C. F. Mass, and J. Overland, 1996: Coastally-trapped southerly flow along the U.S. West Coast: Part I, climatology and temporal evolution.

Mass, C. F. and N. A. Bond, 1996: Coastally-trapped southerly flow along the U.S. West Coast: Part II, synoptic evolution. Mon. Wea. Rev., 124, 446-461

Colle, B. and C. F. Mass, 1996: An observational and modeling study of the interaction of low-level southwesterly flow with the Olympic Mountains during COAST IOP4. Mon. Wea. Rev., 124, 2152-2175

Steenburgh, J. and C. F. Mass, 1996: The interaction of an intense midlatitude cyclone with coastal orography. Mon. Wea. Rev., 124, 1329-1352

Several presentations by both NWS and UW personnel based on the COMET work were given at the Northwest Weather Workshop during February 1996. A description of the UW/Seattle NWS work was also presented at the COMET workshop at the Weather Analysis and Forecasting Conference in Norfolk.