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Exploitation of Ensemble Output(and other operationally cool stuff)
at NCEP HPC
Peter C. Manousos
NCEP HPC Science & Operations Officer
Goals of Presentation
• Show how ensemble output is exploited at HPC
• Briefly – Sneak in an intro on NCEP and HPC
– Provide a short term roadmap for the NCEP modeling system
– Introduce downscaling techniques employed at HPC
• Answer questions
NWS CONSTRUCT
OF OPERATIONAL
OFFICES
CWSUs and Regional Headquarters not depicted
WFOs
RFCs
HPC PRODUCTS AND SERVICES
• QPF– 5 Day QPF– Excessive Rainfall– Probabilistic Snow/Ice– Compile National Flood Outlook
• Fronts/pressures– Surface Analysis & Daily Wx Map– 12h - Day 7 Forecasts– General Weather through 48h– Day 3-7 Max/Min/24h PoP (gridded)– Tropical guidance (to Day 7)
• Model diagnostics
• International Desk
• Experimental products
HPC also provides Emergency & Special
Products and Services
http://www.hpc.ncep.noaa.gov
Ensemble Exploitation
Static Reference• Nominally derived ensemble parameters (means,
spreads, clusters, etc.)
• Serve as reference to quantify pattern evolution uncertainty and assist in pattern evolution preference
http://www.hpc.ncep.noaa.gov/mdd
http://www.hpc.ncep.noaa.gov/wwd
Automated Guidance
Automated ensemble products highlighting areas most likely to
exceed critical thresholds
http://www.hpc.ncep.noaa.gov/wwd/impactgraphics
Starting Point Forecaster selected blends to
generate starting point grids
Targeted PDF ApplicationGeneration of probabilities by applying (centering) ensemble spread on manually
generated deterministic forecast
http://www.hpc.ncep.noaa.gov/ (winter weather, QPF, Medium Range)
QPF Confidence Interval
Max/Min QPF derived from HPC
QPF
and
Characteristic
uncertainty of
current pattern
http://www.hpc.ncep.noaa.gov/qpfci/qpfci.shtml
Model Info
NWS Modeling System - Short Term Road Map
• CCS – Central Computing System– New System being installed/tested– Slated to be operational Jan 07 – all CPU resources already earmarked for use
• GFS – Global Forecast System– T384/64L resolution, T190 after 180 hrs– No planned increases in resolution – conversion to hybrid sigma/p coordinate system, tweaks to
init schemes and physics packages planned after CCS upgrade
• NAM – North American Mesoscale Model– WRF core run at 12km/60L res, non hydrostatic, sigma/p coordinate system– No short term planned increases to model res, tweaks to init schemes and physics packages
intended after CCS upgrade
• GEFS – Global Ensemble Forecast System– 14 members run at T126/L28 4x/day– Increase to 20 members and L64 after CCS upgrade– NAEFS will also increase to 16 CMC + 20 GEFS = 36 members after CCS upgrade
• SREF – Short Range Ensemble Forecast System– 21 members run at approx 34km horiz res 4 cycles per day (posted to 40km res grib files)
» 10 Eta members, 5 RSM, 6 WRF– Intention to convert all members to WRF after CCS upgrade
Monthly Synergy Meetings• Informal meeting with
– EMC, NCO, MMB, NCEP Service Centers, WFOs
• Near term model development and super computer/comm systems plans provided
• Users can anticipate and accommodate changes
• Highlights posted to web and emailed to “allsoos list”
http://www.hpc.ncep.noaa.gov/html/model2.shtml#synergy
Downscaling to 5km
5km PRISM data is applied to 380
point forecasts to generate 5km forecast grid
5km Gridded MOS is being tested to
replace PRISM data
NDFD D5 Max T HPChttp://www.hpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
QPF related grids can be downscaled via
PRISM as well
Impact of downscaling on
QPF related grids only occurs where
significant gradients in terrain exist
http://www.hpc.ncep.noaa.gov/wwd/internal
How do we get 5km detail from just 380 points ???
• 5km PRISM data is used as a starting point
• Difference between HPC and PRISM data taken at all HPC forecast points (380)
• A “difference grid” (HPC – PRISM) is generated
– Results in a 5km grid with little detail
• “Difference grid” is then added on top of the PRISM data
Gotcha’s with mean/spread for QPF
QPF “mean” can be misleading if output from individual members do not overlap each other
