300 likes | 482 Views
Hydrometeorological Analysis and Support Function Overview. Mike Ekern, Sr. HAS Forecaster NOAA, National Weather Service California Nevada River Forecast Center. Hydrologist. hydrologic expertise & judgment. model guidance. Forecast Inputs. H A S. Flood Forecast Guidance.
E N D
HydrometeorologicalAnalysis and Support Function Overview Mike Ekern, Sr. HAS Forecaster NOAA, National Weather Service California Nevada River Forecast Center
Hydrologist hydrologic expertise & judgment model guidance Forecast Inputs H A S Flood Forecast Guidance Precip (QPF) Snow Levels Temperature • Bulletins • Graphics parameters data Model Calibration Observing Systems www.cnrfc.noaa.gov Operational Flood Forecasting NWSRFS SAC-SMA SNOW-17
HydrometeorologicalAnalysis and SupportBasic Functions H A S • assimilation and quality assurance of observed and forecast data sets for use in the hydrologic modeling process • production of hydrometeorological discussions • coordination • interact with other offices on hydrometeorological inputs to hydrologic operations • serve as a liaison with WFOs and HPC to ensure full utilization of hydrometeorological data in the hydrologic modeling process
HydrometeorologicalAnalysis and Support H A S • Apply meteorological expertise to specialized activities above and beyond the basic HAS functions, such as… • QPF verification analysis • Development and improvement of hydrometeorological procedures
Forecast Inputs NWSRFS Forecast Inputs H A S Precip (QPF) Snow Levels Temperature
Mountain Mapper Software • Specify (QPF) - uses PRISM monthly precipitation climatology to distribute point QPF data to a 4km grid using inverse distance squared weighting • DailyQC (QPE) – uses PRISM monthly climatology to quality control observed precipitation. Compares gage data to its own estimate (based on surrounding gages) • Verify (QPF – QPE)
QPF Process Sequence National QPF – Hydrometeorological Prediction Center HPC
QPF Process Sequence National QPF – Hydrometeorological Prediction Center • QPF data are converted from HPC contours to grid • Grid RFC QPF point data using bilinear interpolation and sent to RFCs as ASCII SHEF-encoded text file
Challenges . . . • Time constraints • QPF due in the hands of the hydrologists by 7:30 AM to get a hydrologic forecast out by 8:00 AM • 12 6-hour periods X 66 QPF points = 792 possible points to edit! • 5 Minutes per 6-hour period (4.5 secs/point) • limited time for WFO/HPC coordination
…more Challenges… • Disparity between model guidance and between model guidance and HPC • which model do you choose? • false alarms – when do you trust guidance?
…more Challenges… • Experience vs. Guidance • forecaster experience crucial in extreme events • requires coordination • Scrutiny of 10 WFOs using your QPF • Can impact watch/warning criteria
…and more challenges… • Information overload • WRF-NAM / GFS / UKMET / ECMWF / RUC / SREF / GFS Ensembles / CANSAC / Bufkit / CMC • Model continuity (06UTC vs. 00UTC) • more data and 12UTC WRF-NAM arriving during the forecast process • Limitations of the MM software • non-climatological distribution of precipitation • Credibility – if QPF/snow levels are wrong??? (NWSRFS Garbage In – Garbage Out)
…and still more challenges • Freezing Levels • based on GFS model guidance (from HPC) • difficult to observe/verify • HMT vertical radars help in short term • time intensive • competes for time with QPF • 12 periods X 66 points
Forecast Area Challenges… • Upper Sacramento • Balance between releases and runoff below dam • Russian/Napa • poor radar coverage • challenging QPF • East-side Sierra Nevada • lee-side “spillover” • San Diego • Reacts like “flash flood” • sensitive to low QPF
daily_qc (PRISM) • gage only • 676 Points • qc’d by hydrologists QPE