nowcasting and short-term weather prediction: a high priority for the forecasting community cliff...

Nowcasting and Short-Term Nowcasting and Short-Term Weather Prediction: A High Weather Prediction: A High Priority for the Forecasting Priority for the Forecasting

CommunityCommunity

Cliff MassUniversity of Washington

Minutes to HoursAlthough weather prediction on the scale of days and climate prediction over decades and longer are undoubtedly important, only modest emphasis, outside of severe convective forecasting, has been given to the periods of minutes to hours.

The Premise

• Understanding and predicting weather features on times scales of minutes to hours has the potential for huge societal benefits—saving lives, protecting economic assets, improving the quality of life.

• Recent technological and scientific advances have opened the door to huge improvements in short-term diagnosis and prediction as well as the communication of this information to the public.

Bottom Line: We need more emphasis on

NOWCASTING

AMS Nowcasting Definition

A description of current weather and a short-term forecast varying from minutes to a few hours; typically shorter than most operational short-range forecasts.

American Meteorological Society’s Glossary of Weather and Climate

Some Examples of Why We Need It

Nowcasting and Auto Accidents

More People are Killed or Injured by Auto Accidents Associated with Roadway Icing,

Fog, and Heavy Rain Than Any Other Traditional Weather Threat (Floods,

Hurricane, Thunderstorms)

Consider the statistics of accidents occurring in the presence of rain, sleet, snow and fog, and on wet, snowy, slushy or icy pavement.

U.S. Weather-Related Accidents

Accidents: 1,561,430 police-reported weather-related accidents per yearInjuries: 673,000 per year on averageFatalities: 7400 per year on averageBottom Line: A quarter of all reported crashes are weather-related, and the National Highway Traffic Safety Administration estimates 57 percent of all weather-related accidents go unreported.

State-of-the-art Nowcasting Coupled

With New Data Delivery Approaches

(smartphones, electronic message boards) Could

Reduce the Toll of Death, Injury, and Loss

Heavy Rain Crossing Roadways

• Many examples of multi-vehicle crashes when convective cells cross roadways.

• Leaving the heavy precipitation in daylight often blinds drivers…and major accidents occur, sometimes involving tens of cars/trucks.

Nowcasting Solution• Use time extrapolation of intense radar echoes—

perhaps providing 10-15 minutes warning lead time.• Use electronic message boards to slow down the

traffic and instruct drivers to leave more room for cars in front of them.

Multi-vehicle Accidents in Fog and Dust

Interstate 10 Dust Storm in ArizonaThree died, 22 vehicles

Oct 22, 2009

Nowcasting Approaches

• Dust-lofting algorithms coupled with real-time observations could predict visibility loss.

• Satellite-based observations of dust and fog.• Fog diagnosis from highway observations.• Use of electronic message boards, flow

control, and smartphone warning systems to get the message out.

Guiding Road Maintenance Crews

• Road maintenance crews need real-time information to pre-position trucks with deicer and plows.

• This information is often lacking with bad results.• Example: November 22, 2010—Seattle was thrown

into gridlock when maintenance crews did not realize severe icing conditions were imminent.

• Obvious from weather observations—cold air was surging southward and elevated roadways were covered in slush.

Once the traffic locked up, it was too late—some people abandoned cars, others took 12 hr to get home. Probably could have been avoided if real-time weather

data was effectively used.

Construction• Unexpected weather events cost the

construction industry many millions of dollars per year (if not billions).

• Some of these losses could be prevented if a short-term warnings of adverse weather were readily available.

Local Example: UW Molecular Engineering Bldg.

Waterproofing goes on one day

Washes off a few hours later

Reapplied the Next DayHow Much Did This Cost?

Wind Energy

The Ramp-Up, Ramp-Down Problem Costs Millions

• Current automated forecasts have been poor at predicting steep energy ramps in the short-term• More effective nowcasting would greatly enhanced wind energy’s potential.

December 13, 2006: The Madison Valley Storm

December 14, 2006Nearly 1 inch in an hour

Predicting Heavy Precipitation Events an Hour in Advance—Perhaps By Temporally Extrapolating Radar-- Could Save Lives and Property

One-hourtotals

Do We Expect Such Events to Increase

in Frequency or Intensity Under

Global Warming?

A woman drowned in her basement

and dozens of cars lost.

Recreation and Commuting

• Should I head out on my bicycle?

NO!!!

Short-Term Warning For Severe Convection

• Obvious and profound benefit.• The one area in which nowcasting is well-

developed and often effective.

Current Status of Nowcasting• U.S. National Weather Service: not much

emphasis except for convective storms– 6-hr basic forecast cycle– Bias towards forecast consistency even when there

is a suggestion that reality is going elsewhere.– For significant weather NWS sometimes releases

special statements.– Not unusual for short-term forecast and observed

weather to be inconsistent.

Forecast Released at 8:41 AM Sept 18, 2010

Reality: Sunny Warm Morning

Infrequently, a short-term forecast is provided

Gridded Forecasts Every Three Hours,Updated Every 6 hr, Modified If Necessary

The Weather Channel

WeatherChannel’s TruPoint (0-6 hr)• TruPoint uses weather radar, satellite, a

lightning detection network, weather prediction models, surface sensors and observations to derive the current weather conditions.

• Temperature, wind, humidity, precipitation, visibility, and cloud cover are updated several times each hour for points every 1.5 miles across the country.

Short-Term Objective Forecast• Start with NWS model output (RUC) as a "first

guess."• Statistically combines with geographical data,

conventional surface observations, satellite data, Doppler radar, and lightning data to produce the forecast.

• Apples quality-control procedures to ensure a sensible weather report/forecast

Local TV StationsMorning, noon, dinnertime, and

late night updates

Radar Temporal Extrapolation: The Predominant Automated

Nowcasting Technology

NCAR (RAL) AutoNowcaster

The Key Ingredients For Next-Generation Nowcasting Are Now

Available

Ingredients

• The Communication Revolution• The Weather Data Revolution• New Generation of Data Assimilation and

Modeling Systems• Nowcasting Testbeds

The Communication Revolution• Until recently, a major problem for

nowcasting was the inability to get weather information rapidly to users…quickly enough for decision making.

• But that has all changed now.

First, PCs Connected to the InternetHardwired, WIFI, or 3G

Today Smartphones Offer a Powerful, Portable Platform for Viewing

Weather Information, Forecasts, and Warnings

Smartphones are Ideal!

• Lots of bandwidth• They know where they are, so forecast

information can be tailored to the user• Substantial computational capacity.

And other real-time delivery approaches now exist

The Weather Data Revolution

• Exponential increase in surface and upper air data has given us a highly detailed view of the conditions at the surface over land.

• Extraordinary number of new surface networks, from highway departments and air quality agencies, to utility companies and local governments.

• Plus amateurs with good weather stations on the internet.

Example:The Pacific Northwest

Based on 72 different networks

3000-4000 observations per hour over WA and OR

And much more..• ACARS and TAMDAR data from aircraft flying

in and out of airports.

Remote Sensing Mesoscale Revolution

• U.S. Doppler radars soon to include dual-polarization. Provides precipitation-type information.

• Global hyperspectral soundings—radiosonde vertical resolution every 15 km globally.

• Global COSMIC soundings using GPS delay information.

• And many, many more.

New Generation of Data Assimilation and Modeling Systems• Can we effectively combine observations with high-

resolution models?• Can we produce a physically consistent description of

the atmosphere with short-term predictions every hour?

• Can we do this, considering the uncertainties in the observations and imperfections in the modeling systems?

National Weather Service Rapid Update Cycle (RUC) System

•Hourly•13 km grid spacing•Includes virtually all mesoscale data sources.•18 h forecasts•MAP model•3DVAR assimilation

Replacement This Year: Rapid Refresh (RR)

•Uses WRF ARW Model•Larger domain•Also 13-km•3DVAR

High-Resolution Rapid Refresh (HRRR)

•3-km•3DVAR

But can we do high-resolution data assimilation more effectively?

Can we get beyond deterministic data assimilation?

Ensemble Kalman Filter (EnKF) Effort at the UW (Greg Hakim and

C. Mass)• High-resolution WRF ensembles (36 and 4-km)• 60 members• Three-hour cycle• Multiple Data Sources

– Multi-networks at the surface– ACARS and satellite winds– Radiosondes

Mesoscale Covariances: A Big EnKF Benefit over 3DVAR

Camano Island Radar |V950|-qr covariance

12 Z January 24, 2004

Currently Under Rapid Development and Real-Time

Testing at the UW

Nowcasting Testbeds

Olympic Nowcasting:The Last Few Olympic Games Have

Been Used to Test Prototype Nowcasting Systems

• Major, multi-national nowcasting efforts at the Sydney, Vancouver, and Beijing Olympics.

• Tested radar temporal extrapolation, radar-model hybrid extrapolation, ultra-high resolution prediction initialized with massive observation data enhancement, and other approaches.

The Beijing 2008 Forecast Demonstration Project

• Systems from China, Australia, Canada, and the United States.

• Mix of radar echo extrapolation methods, numerical models, techniques that blended numerical model and extrapolation methods, and systems incorporating forecaster input.

• Focus on the skill of convective forecasts.

University of Washington Department of Atmospheric

Sciences Has Been Developing a Range of Nowcasting Tools

I90 Route View

Sends emails to appropriate officials!

Also sends out emails!

A Nowcasting Test Using My Blog

People Want This!Nowcasting Done on 11 January

The Vision

Component I: Complete the Nowcasting Engine

MesoscaleData from

Heterogeneous Networks

MesoscaleData from

Heterogeneous Networks

Hybrid EnKF/Variation

al Data

Assimilation/Short-term

High-ResolutionForecasting

System

Hybrid EnKF/Variation

al Data

Assimilation/Short-term

High-ResolutionForecasting

System

Mesoscale Analyses

Mesoscale Analyses

Short-Term (1-6 hr)

Forecasts

Short-Term (1-6 hr)

Forecasts

BiasRemoval

BiasRemoval

4D “Datacube”0-6 hr

Component II: A Revised National Weather Service Forecast Office

• Less emphasis on human forecast intervention beyond 24-h

• At least one forecaster dedicated to nowcasting in each office. Hourly gridded updates of all basic fields (hourly time resolution) out to 6 hr.

• Starts with Component 1 and perfects it.• Hourly nowcasting discussion.

Component III: New Generation of Nowcasting Applications for

Specific Needs• Drawing on the real-time gridded information of

component I and raw observations, produce real-time, nowcasting guidance for a wide range of societal needs.

• Develop range of Smartphone-based nowcasting apps. – Provides weather information relevant to your location:

Some Examples

WeatherProtector

WEATHERPROTECTOR

Tells you whether heavy precipitation, winds, or other weather issue are approaching your position.

BikeWeatherGuard

BikeWeatherGuard

•Using a map interface, input your planned route and when you want to travel.•Tells you whether you should delay your trip, or perhaps leave a few minutes early, to stay dry.

GardenKeeper• Using calibrated radar-

based precipitation data, tells you when watering is necessary at your location (considering water demands of your plants and evapotranspiration based on recent weather)

• Warns when freezing conditions are imminent during the winter.

GardenKeeper

There has never been as big a gap between what weather forecasters know and what they communicate

to the public.

And society has never had so powerful an ability to adapt and avoid dangerous weather.

The END