Exploitation of Ensemble Output(and other operationally cool stuff)

at NCEP HPC

Peter C. Manousos

NCEP HPC Science & Operations Officer

(peter.manousos@noaa.gov)

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

Questions ???

peter.manousos@noaa.gov

301 763 8000 x 7307

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