Lab IV: Operational NWP Models/Forecasting Statistics

Due: Wednesday 12 April


Problem 1:
Using Black (1994) and the following web pages that contain more recent information concerning operational NWP:

summarize the major characteristics (e.g., resolution, domain, physical parameterizations) of the NCEP ETA model. Discuss some of the strengths and weaknesses of the Eta model compared to the NGM and AVN when applied for operational weather prediction. Describe some of the Eta model biases that could be adjusted to produce improved forecasts.

Problem 2:

On 12 December 1995, a powerful extratropical cyclone struck the west coast of North America, producing damaging winds and floods from central California to Washington State. Discuss the relationship of the observed precipitation to the primary terrain features of California and the accuracy of the MRF, ETA, NGM and Meso-ETA model precipitation forecasts for this event (use the 0000/0300 UTC 12 December initializaiton runs). Which models best captured the observed distribution of precipitation? Discuss how differing model characteristics (e.g., vertical coordinate, horizontal resolution, precipitation parameterization, etc...) influenced the performance of these models during this event.

Problem 3:

Unlike many of us in the meteorological world, you have decided to venture out into the real world and start your own forecasting company. Your first client, "Saltair Orchards" is located in the Cache Valley and is the largest producer of fruit in Utah. Their primary weather concern is frost and have invested in sophisticated wind generation equipment to reduce near-surface nocturnal cooling. The system costs $1000/night to operate and, for the purposes of this excercise, always keeps the temperature above freezing. On the otherhand, if the equipment is not used and frost occurs, estimated crop losses are as follows:

Minimum Temperature Damage
Above 32 $0
30-32 $2,000
27-29 $20,000
23-26 $100,000
Below 23 $1,000,000

Using your knowledge of probabalistic meteorology and cost/benefit analysis, create a formula that, given probabilities of the minimum temperature being in each category above, will determine whether or not it is cost effective to operate the wind generating machinery. Assume the orchard grower has defined his acceptable cost/loss ratio as 50%. How might you use this formula to provide a better product for your customer? What are some of the major strengths and weaknesses of determining yes/no decisions (such as whether or not to operate this equipment) with this type of approach?