EGOWS 2008

The Beijing 2008 Nowcasting Forecast Demonstration Project

John BallyCAWCR

Beijing ‘08

• WMO >> WWRP >> FDP

• Implement nowcasting science and systems for the Olympics

• Provide an enhanced weather service

• Technology transfer and training

• Quantify the benefits

Beijing ‘08 Daily probability of rainfall in Beijing from August 1 to September 30

Olympics Paralympics

Beijing ‘08 Vulnerabilities

Beijing ‘08 Enhanced data collection.....

Beijing ‘08 Many systems will be in Beijing...

BJANC (BMB&NCAR)

CARDS (MSC)

GRAPES-SWIFT (CMA)

MAPLE (McGill & WDT),

NIWOT (NCAR)

STEPS (CAWCR)

SWIRLS (HKO)

TIFS (CAWCR)

Real Time Verification (CAWCR)

Socio Economic Impacts Assessment

(BMB)

Beijing ‘08 Many Systems will be in Beijing.....

Beijing ‘08 How will we use so many systems?

Beijing ‘08Which system is best ?

Real Time Forecast Verification

every 6 minutes

Beijing ‘08 Web Page display for forecasters

Beijing ‘08 Concentrate on some big risks….

High Impact Weather

Observed Frequency

Precipitation 35 %

Thunderstorm 25 %

Heavy Rain 6.5 %

Beijing ‘08To make probability of flash floods

start with the rain already on the ground...

Beijing ‘08 Look at the STEPS forecast...

Beijing ‘08 And any other good forecasts you can get ... this one’s from the Hong Kong “SWIRLS” system

Beijing ‘08 And do the stats on the ensemble to get the probability of hitting a threshold, given the obs rain..

..... Export the threat polygons to VIPS..

Beijing ‘08 Rainstorm Warning Products issued by Chinese forecasters using realtime FDP information

Beijing ‘08 Start with the TIFS interface…. single radar, single track-set TS Warning generation.....

Thunderstorm strike probability

Histogram of storm detections wrt forecast (normalizedspeed and direction). after Dance, Ebert, Scurrah

Mathematics

where (x, θ is a point in polar coordinates, t is forecast time, V is speed, σv is speed standard deviation, σ θ direction standard deviation. after Dance, Ebert, Scurrah

=

PDF that thunderstorm centre is over a point, based on Gaussian distribution in polar coordinates.

Strike probability field (with contours) for storm over 1 hour (black = 1, white = 0)

Beijing ‘08 Ensemble strike probability calculated in TIFS... Automated and Manual versions.....

..... Export the threat polygons to VIPS..

Beijing ‘08 But not before the expert forecaster adjusts the nowcast....

Beijing ‘08 During the adjustment ....

Beijing ‘08 After adjustment ....

Beijing ‘08 Thunderstorm and lightning threat products issued by Chinese forecasters using realtime FDP information