Examination of Nesting Requirements
for CONUS and OCONUS in 2020+
Presented By: Geoff DiMego (NCEP/EMC)
Contributors:
Stan Benjamin, Curtis Alexander (ESRL/GSD)
Eric Rogers, Tom Black, Jacob Carley (NCEP/EMC)
Sam Trahan, Vijay Tallapragada (NCEP/EMC)
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Operational System Attribute(s)
System Name
Acronym
Areal
Coverage
Horz Res
Cycle
Freq
Fcst
Length
High Resolution Rapid Refresh
HRRR
CONUS
3 km
1 hr
15hr
North American Mesoscale Nest
NAMnest
O/CONUS
3-6 km
6 hr
60hr
[3km pending]
[1hr pending]
North American Mesoscale Fire Wx
NAMfrwx
Placeable
375x375
1.33 km
1.5 km
6 hr
36hr
High Resolution Window
[00z & 12z]
HiRESW
CONUS, HI
& Guam
3-4km
12 hr
48hr
High Resolution Window [6z & 18z]
HiRESW
Alaska, PR
3-4km
12 hr
48hr
HWRF
Nest
2 km
6 hr
120hr
Hurricane WRF
System Data Assimilation or Initialization Technique [LBC]
System
Attributes
HRRR
GSI 3DVAR (hybrid pending) w/15min radar data for 1 hour [RAP]
RAP/NAM
GSI EnKF-3DVAR hybrid, Diabatic Digital Filter w/radar data [GFS]
NAM nests
GSI EnKF-3DVAR hybrid (w/radar reflectivity pending) [NAM]
HiRESW
Init conditions from RAP for CONUS, from GFS for OCONUS [GFS]
HWRF
GSI 3DVAR hybrid w/tail Doppler radar [2-way large basin]
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Why System(s) are Operational
 Primary stakeholders and requirement drivers
• The Weather enterprise, NWS regions & WFOs, NCEP centers, Water Center
NIFC Boise & USFS, severe/hazardous wx, aviation/transportation, fire wx,
energy, hydrology, disaster recovery, NextGen etc
 What products are the models contributing to?
 NDFD forecasts, watches/warnings, outlooks, RTMA/URMA (RUA Rapidly
Updating Analysis - pending), AirQuality, WRF-hydro, WoF etc
 What product aspects are you trying to improve with your development
plans?
 QPF, sensible & severe wx via physics development
 Move away from deterministic to all ensemble based guidance suite
 Move from irregular to regular/reliable convection allowing scale HREF
with earlier delivery time, consolidates HRRR, NAM-nests & HiRESW.
 Top 3 System Performance Strengths
• Provides hi-res guidance to the whole nation albeit irregularly
• Provides both 1st look & outlook, highly efficient nesting in NMMB
• Hourly updates, aviation hazards, impactful storms/wx, aerosol capable
 Top 3 System Performance Challenges
• Convective initiation, QPF biases, stable PBL, cloud decks
• Advancing to 3km hourly/subhourly ensemble data assimilation
• Large/diverse enough membership of High-Res Ensemble Forecast (HREF)3
System Evolution
Over the Next 5 Years
 Major forcing factors
• Increasing obs – GOES-R, aircraft, renewable energy, ceilometers, ccpp
• Increase of high-impact wx events (flash floods, t-storms, wildfires, etc.)
• Increase in NCEP High Performance Computing (HPC)
 Science and development priorities
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Move to probabilistic guidance
Ensemble data assimilation
Improved physical parameterizations
Broader services e.g. atmospheric/land-surface forcing for WRF-Hydro
Hazardous event detection tool – collaboration with FACETs,
Provide initial/lateral boundary conditions for Warn-On-Forecast
 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,
•
more tropical storms & basins, NextGen terminal requirements
Leveraging selected NGGPS dynamic core and unifying regional efforts
around this core once the capability is in place
 Potential opportunities for simplification going forward
• Unify all regional modeling applications with HREF & SREF consolidation,
•
eventually including rapid refresh, 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.
Use same physics with scale-aware and aerosol-aware capability and inline
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aerosols for 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 (convection
allowing ensembles, ensemble DA, NGGPS dy-core, WOF, etc).
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