Gridded Cloud Layer Guidance to Support the TAF

_{GRIDDED CLOUD LAYER GUIDANCE TO SUPPORT THE TAF}

_by

_{Bob Glahn and Adam D. Schnapp}

_{Meteorological Development Laboratory}

_{National Weather Service, NOAA}

_{Silver Spring, Maryland}

_{Gridded MOS and LAMP guidance has been provided for many years to assist in the preparation of weather forecasts by National Weather Service forecasters and for use by private companies and the academic community. However, less emphasis has been placed on the production of guidance for aviation forecasts than for public and related forecasts. In particular, the TAF (Terminal Aerodrome Forecast) includes information about cloud amounts and heights, but the only cloud guidance provided by LAMP is ceiling height and total cloud cover. There is no guidance on whether the ceiling height is broken or overcast or on other possible cloud layers. The Meteorological Development Laboratory is developing a statistical postprocessing system to provide much more information than in the past. The system will augment the operational LAMP/HRRR Meld currently providing ceiling height and visibility guidance.}

_{The new system will provide forecasts of heights and amounts of up to three layers of clouds. Ceiling height will be the cornerstone, and will be provided as either broken or overcast. Forecasts of few and/or scattered decks will be provided, either with or without a ceiling. When there is a broken ceiling, broken or overcast layers above will also be forecast.}

_{These statistical forecasts will have been themselves postprocessed to provide consistent forecasts in space and time across other elements important for aviation forecasts. These results will lead the way for the National Blend of Models to provide more aviation-related guidance. In relation to the overall theme of the meeting, the guidance is a way of communicating to forecasters critical aviation-related information that is embodied in NWP models and observations.}

_{In this paper, we will report on the status of the work and show example forecasts and verification.}