MDL's June 2001 Progress Report

METEOROLOGICAL DEVELOPMENT LABORATORY

MONTHLY PROGRESS REPORT

June 2001

Statistical Forecast Development (P. Dallavalle): Development of AVN-based MOS equations to predict the probability of precipita tion amount during the warm season (April - September) was completed. As part of this development, we also updated the probability of precipitation (PoP) forecast equations by adding another year of data to the dependent sample. Categorical precipitation amount guidance will become available in the AVN MOS guidance package in July. Probability thresholds needed to obtain categorical visibility and obstruction to vision guidance were redeveloped and will also be implemented in July. Develop ment of AVN-based MOS equations to predict wind speed and direc tion during the warm season from the 0600 and 1800 UTC runs of the AVN model was completed. We're now testing these equations on an independent sample taken from April 2001.

Testing of an Eta-based MOS system to predict PoP for sites in the contiguous U.S. is underway. Initial results on the October 2000 to March 2001 period indicate that the Eta-based PoPs for 12-h periods are 5% more skillful than the NGM-based MOS PoPs. Differences in skill between the Eta and AVN MOS PoP guidance for the 24- and 36-h projections vary by region of the country; for all stations combined, the skill of the two systems is approxi mately the same. For the 48- and 60-h projection, the AVN MOS PoP system provides the most skillful guidance.

Operations and Software Support (M. Erickson): Preparations to implement the new AVN MOS precipitation amount guidance system have been completed. The precipitation amount guidance will be available in the AVN MOS alphanumeric messages. We've also modified the visibility and obstruction to vision system to incorporate the new threshold probabilities required to produce categorical guidance. Finally, changes in the operational MOS system were made to produce probabilistic and categorical guid ance for precipitation characteristics (drizzle, steady precipi tation, or showers). The implementation of AVN MOS precipitation characteristics is required to support the Interactive Forecast Preparation System (IFPS). Both the precipitation amount and characteristics guidance will be available in the digital (BUFR) MOS guidance messages. All of these changes to the MOS system are scheduled for implementation in the NCEP job suite during mid-July.

National Digital Forecast Development (D. Ruth): At the invita tion of the Australian Bureau of Meteorology, Dave Ruth partici pated in a "Forecast Streamlining and Enhancement Project work shop" in Australia. A wide range of issues concerning IFPS was discussed such as the best techniques for editing the forecast database, how to use computer model guidance in creating fore casts, and "people issues" associated with the introduction of forecast preparation systems at weather offices. Mr. Ruth provided briefings each day and answered many questions on the NWS implementation both at the workshop in Brisbane and the Head Office in Melbourne. The Australians are still in the early stages of implementing IFP technology. Their interest was intense.

Forecast Verification Analysis (V. Dagostaro): We provided verification statistics for May, 2001, to OCWWS for max/min temperature, PoP, ceiling height, visibility, and cloud amount. In addition, we provided sample data files containing local and NGM MOS precipitation type verification scores for January-April, 2001. We also helped error check OCWWS's prototype system to compare AVN MOS verification scores with those of either NGM MOS or with local forecasters.

We're developing a prototype web page for disseminating MOS verification information for approximately 330 sites. This test system allows the user to view scatter plots of max/min tempera ture data, PoP reliability graphs, and several verification scores for monthly samples of NGM-, AVN-, and MRF-based MOS guidance. We're continuing to investigate the utility of various types of verification diagrams and scores for addition to this web page. Our goal is to assist the forecaster in improving forecasts by examining recent MOS behavior.

We reviewed a draft of NWSOM Chapter 75, provided PoP verifica tion data to Central Region Headquarters, investigated some unusual PoP verification scores within the Eastern Region, and coordinated with the AVP software developer to add 4th period PoP data to the existing verification bulletin transmitted from field offices.

Storm Surge and Wave Forecasting (W. Shaffer): We coupled several deep-water parametric wave models to the SLOSH wind field for predicting waves generated by tropical cyclones. Tests with hurricanes Bonnie and Georges in 1998 show that the highest waves computed compare favorably with observations. We anticipate that the computations of maximum waves will be useful to marine forecasters, as well as for our use in developing coastal wave impacts.

Although tropical storm Allison will be remembered for its rainfall, it also generated storm surges along the Texas coast line and along Galveston Bay. The highest storm tides noted from the NOS tides online web site were 6 feet at Manchester, along the upper part of the Houston ship channel. Outer coast water levels were in the 2-3 foot range.

Dr. See-Whan Kang from the Korean Ocean Research and Development Institute visited our storm surge group and discussed the appli cation of SLOSH-type surge modeling to the South Korean coast.

WFO Application Development and Support (E. Mandel): A little over a year ago, Jack Kelly created an Integrated Work Team (IWT) led by Bob Glahn for Data Encoder/Decoder Development and Mainte nance. The Team established an Encoder and Decoder Software web site (www.nws.noaa.gov/tdl/iwt) to provide easy access to the NWS "official" encoders and decoders. As of mid May, 18 of the 24 decoders/encoders originally identified by the IWT in January 2000 are now available from the web site. These encoders and decoders have been supplied by NCEP (12), OHD (2), OST/MDL (3) and OOS (1).

The web site includes the new GRIB2 (General Regularly-distrib uted Information in Binary, Edition 2) encoder and decoder developed by OST/MDL. This new edition of GRIB can achieve greater data compression than the current version. MDL contrib uted much to the actual coding algorithm. The World Meteorologi cal Organization (WMO) intends to approved GRIB2 for operational use after November 7, 2001. Until then, GRIB2 can be used experimentally to distribute products within the US and will be used in the NDFD work.