WMO

Anticipated advances in Numerical Weather Prediction,

and the growing technology gap in weather forecasting

 Ken Mylne

Chair DPFS (Data-processing and Forecasting Systems) & Chair SWFDP SG

WMO; WDS

du = ∂p – fvdt ∂xdv = ∂p + fu dt ∂yp = RTρ

Interpretation, Risk Analysis & CommunicationKnowledge

70 levels25km

80km high

The Role of the GDPFS in creating weather services –

Forecast Model

Observations

GDPFS = Global Data Processing and Forecasting System

Core Foundation Systems of the GDPFS

Nowcasting – up to ~6h forecasting Global NWP (numerical weather prediction)

Deterministic – single best guess forecast Ensemble – probabilistic forecast for risk estimation Resolution now ~16-45km

Limited area NWP Convection-permitting – high resolution, local area Deterministic & Ensemble

Coupled Seasonal and climate models Numerical ocean wave and storm surge prediction

UKV and MOGREPS-UK1.5km 70L (40km model top)3DVAR (3 hourly)36hr forecast 4 times per day12-member EPS - 2.2km 4x/day 36h

2013 NWP Models in Suite

Global and MOGREPS-G 25km 70L (80km model top) (17km from PS34) Hybrid 4DVAR – 60km 66hr forecast twice/day 144hr forecast twice/day 12-member EPS - 33km 4x/day 72hr 24-member EPS - 60km 2x/day 15d

Ocean coupled up to 6 months© Crown copyright Met Office

Euro4 4km 70L (40km model top) Global downscaler 66hr forecast twice/day 144hr forecast twice/day

Specialized Activities of the GDPFS

Forecasting hydrometeorological hazards Seasonal to sub-seasonal Climate prediction Tropical cyclone forecasting Volcanic ash advisory services Response to environmental emergencies

Nuclear & non-nuclear incidents Marine pollution incidents

Sand and dust storm forecasting Non-real-time verification and testing

GDPFS Centres

Network of Global, Regional and Specialised Centres

See paper for full list of centres

Status of Global Models

Deterministic global models now running at c. 16-45km grid-lengths

Ensembles at c. 40-100km Global coverage Up to 15 days range (EPS) Approaching resolutions of

recent regional models Capable of capturing

much severe weather Ensembles provide the

probability part of “risk”

Global Ocean Wave Ensemble products

Probability of significant wave height over 4m

Wave EPS Meteogram

Met Office 15-day Global ensemble forecast evolutionGusts > 60kt – damaging strong winds in EuropeFrom 8 days to 2 days ahead

Low probability early warning

Consistent guide to most likely location from at least 5 days ahead

Higher resolution models even better

Tropical Cyclone Products

Storm tracks and strike probabilities Experimental TC intensity forecasts

Global Hazard Map

Summary map to track features through days of forecast

Daily map to overlay different hazards and

vulnerability layers

Biggest Weakness – (Tropical) Convection

Useful guidance, especially when calibrated

SWFDP feedback is positive even in the Tropics, but…

Convection-Permitting Models Rapidly replacing the old regional models

© Crown copyright Met Office Frames at 10min intervals

With grid-lengths of 4km or less modern regional models partially resolve convection and give far better forecasts for convective severe weather … which dominates Tropical severe weather

Convection-permitting Ensembles

Probabilities for localised heavy rain

But …computationally very expensive small domains

Prob of Torrential Rain

>16mm/h

Not affordable for Tropics yet, but…

UK Floods 24th November 2012

RadarMOGREPS-UK 2.2km

Chance of Heavy Rain in the HourUKV 1.5km

Meteo-France 2.5km Ensemble

Radar rainfallDeterministic >20mm (Dark)Prob(20mm)>10% (Light)

Lake Victoria Model

4km deterministic models are becoming affordable over a limited number of additional domains …with funding

Met Office 4km UM

Run at Global Centre

Products supplied to Regional Centre and NMHSs

East Africa WRF model Tanzania Meteorological Agency

5km model run by Tanzania

Boundary conditions provided by DWD (German Met Service)

Global Remote Sensing

Observation systems provide basis for nowcasting

Satellite ImageryATD Lightning Detection

Rapid refresh models for nowcasting

Models are starting to be used with assimilation of radar data for nowcasting

Expected to replace extrapolation nowcasting over next few years in advanced centres

National Met Centres and the GDPFS

Each WMO Member (country) is required to have a National Meteorological Centre

A key NMC Function is preparation of National Severe Weather Warnings for protection of lives and property, as required by the Member.

To achieve this, NMCs should: Be staffed and equipped to participate in the WWW

(World Weather Watch) be linked to the WIS (WMO Information System) have capacity to exploit GDPFS products

Some NMCs have difficulty in this…

NMCs and the technology gap

Typical Advanced NMC Co-located with Global/

Regional GDPFS centre NWP Post-processing to

produce automated routine forecasts

Forecasters freed to focus on High Impact Weather

Established procedures: warnings PWS communication

for civil protection action

Typical Developing/LDC NMC

Little or no NWP capability Experimental Remote from NMC Low resolution – similar

to today’s global No ingestion in products

Forecasters occupied with routine production

Limited or no procedures for warning dissemination and action

Why not provide NMHSs with Regional Models?

As noted above, a number of NMHSs have (or have had) regional NWP systems generously supplied by donors, mainly experimental

This is NOT generally an effective method of capacity building in an NMHS with limited resources: Very complex to support effectively (see next slide) Distracts scarce resources from core function of issuing

warnings and communicating with civil protection decision-makers

Technical Requirements for operational NWP

Running effective regional NWP requires: Large (expensive and power-hungry) supercomputer

Convection-permitting resolution (~4km or better) required to add benefit to today’s global models

Complex, reliable and high-bandwidth telecoms import boundary conditions and observations

Advanced data assimilation Hi-resolution observations Large team of expert scientists and computer scientists for

implementation, maintenance and upgrades Expensive to recruit and difficult to retain once experienced

Best Concentrated in few Global/Regional Centres NMCs then focus resources on Local Interpretation,

Forecasting and Service Delivery

Global NWP centres to provide available NWP/EPS and sat-based products, including in the form of probabilities, cut to the project window frame;

Regional centres to interpret information received from global centres, prepare daily guidance products (out to day-5) for NMCs, run limited-area model to refine products, maintain RSMC Web site, liaise with the participating NMCs;

NMCs to issue alerts, advisories, severe weather warnings; to liaise with user communities, and to contribute feedback and evaluation of the project;

NMCs have access to all products, and maintained responsibility and authority over national warnings and services.

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Global Centres

User communities, including Disaster

Management authorities

NMCsRSMC Pretoria

SWFDP Cascading Forecasting Process – efficient delivery of GDPFS

Technical Requirements for SWFDP Benefit

Cascading of SWFDP products and guidance uses: Simple web pages Products as Images including

animation

Requirements to benefit: Web-browser Low band-width connection

Forecaster and PWS training Highly efficient and cost-

effective Capacity Building

www.wmo.int

Thank you for your attention

DISCUSSION