Evolution and Priorities for OCONUS and
CONUS Guidance Systems including a
convection permitting ensemble system
Presented By: Geoff DiMego (NCEP/EMC)
Contributors:
Stan Benjamin, Curtis Alexander (ESRL/GSD)
Jacob Carley, Brad Ferrier, Eric Rogers (NCEP/EMC)
Jack Kain, Lou Wicker (NSSL), Israel Jirak (NCEP/SPC)
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Operational System Attribute(s)
System Name
Acronym
Areal
Coverage
Horz Res
Cycle
Freq
Fcst
Length (hr)
Rapid Refresh
RAP
N. America
13 km
1 hr
18
High Resolution Rapid Refresh
HRRR
CONUS
3 km
1 hr
15
North American Mesoscale
NAM
N. America
12 km
6 hr
84
North American Mesoscale Nests
NAMnest
O/CONUS
6-1.33 km
6 hr
60/36
High Resolution Window
HiRESW
O/CONUS
3-4 km
12 hr
48
SREF
N. America
16 km
6 hr
87
Short Range Ensemble Forecast
System Data Assimilation or Initialization Technique
System
Attributes
RAP
GSI EnKF-3DVAR hybrid, Diabatic Digital Filter w/radar data
HRRR
GSI 3DVAR (hybrid pending) w/15min radar data for one hour
NAM and
NAM nests
GSI EnKF-3DVAR hybrid 12-h NAM Data Assim System w/3-h
updates w/radar data
HiRESW
RAP for CONUS and GDAS for OCONUS
SREF
Initial condition diversity via RAP, NAM and GFS
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Why System(s) are Operational
 Primary stakeholders and requirement drivers
• The weather enterprise, NWS regions & WFOs, NCEP centers, Water Center,
Air Quality, broadcasting, dispersion/transport, severe/hazardous wx
environment, agriculture, transportation, energy, NextGen etc
 What products are the models contributing to?
 NDFD forecasts, watches/warnings, outlooks, airmets/sigmets,

CMAQ/HYSPLIT, reg’l wave height, NLDAS, regional ic’s & lbc’s etc
What product aspects are you trying to improve with your development plans?
 QPF, sensible wx, severe wx environment via physics development
 Move deterministic guidance to all ensemble based guidance suite
 Consolidate old SREF, NAM, NAMRR & RAP into new SREF
 Eventually transition to single-core ens. & ensDA [NGGPS]
 Expansion?: domain for TCs, inline lake, aerosols, fire behavior; coupling
 Top 3 System Performance Strengths
• Provides reliable guidance to the whole nation multiple times per day
• Provides both 1st look [early slot] & outlook [to 3.5 days]
• Hourly updates, aviation hazards, storms & storm/pre-storm environment
 Top 3 System Performance Challenges
• Pre-convective environment, QPF biases, stable PBL, C&V, cloud decks
• Advancing ens. DA, scale aware physics [parent&nests]
• Large/diverse enough membership for new SREF to improve on GEFS
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System Evolution
Over the Next 5 Years
 Major forcing factors
• Digital Services, WxReadyNation, FACETS = need for probability guidance
• Increasing sat. obs GOES-R, JPSS while JCSDA solves sfc emissivity
• Mandate to simplify production suite while moving to ensemble guidance
 Science and development priorities
• Probabilistic guidance across the full spectrum of wx phenomena
• Provide initial/lateral boundary conditions for HREF
• Ensemble techniques, ens. data assimilation & improved physics
 What are your top challenges to evolving the system(s) to meet
stakeholder requirements?
• Resistance to ensembles & streamlining, must be able to drop legacy stuff
• HPC for ens DA and ens forecasts, observational data latency and QC
• Leveraging selected NGGPS dynamic core and unifying regional efforts
•
around this core once the capability is in place
Resistance to unification & to development based on best science with
focus on performance not “ownership”
 Potential opportunities for simplification going forward
• Unify all regional modeling applications with HREF & SREF consolidation,
•
•
eventually including rapid refesh, hurricane, fire weather, AQ etc using a
single-dycore [from NGGPS?]. Single ensemble DA including aerosols and
even land-surface. Retain GSI common regional/global DA extended to 4D
Unify physics with scale-aware and aerosol-aware capability
Inline aerosols, fire behavior and couple to ocean, lake, wave, ice & eco
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across both regional and global models.
Top 3+ Things You Need
From the UMAC
1. Start with the simplest possible future operational suite (single
regional model/ens/assim and single global model/ens/assim).
• Then, UMAC can help NOAA consider if all forecast
requirements can be met by them before adding complexity.
• Simplicity is more plausible with a 3km global model.
• Similarly, given a 1km regional ensemble
• Expanded CONUS including all area within 48h landfall
• Avoid all moving nests because fixed nests support
ensemble effectiveness.
2. Help with trade offs among delivery time, forecast range, update
frequency, number of nests, ensemble size & member
configuration choices etc
3. Guidance on how to focus/balance resources (computing &
manpower) based on multitude of requirements (continental vs
local, ensembles, ens. DA, NGGPS dy-core, HREF-SREF-GEFS,
WOF, FACETS, etc).
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