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Results from Winter Storm Reconnaissance Program 2008

Yucheng Song IMSG/EMC/NCEPZoltan Toth EMC/NCEP/NWSSharan Majumdar Univ. of MiamiMark Shirley NCO/NCEP/NWS

http://www.emc.ncep.noaa.gov/gmb/targobs

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Acknowledgments

• NWS field offices, HPC/NCEP and SDMs• NOAA P-3 and the USAFR C-130 flight crews• CARCAH (John Pavone)• Jack Woollen - EMC• Russ Treadon - EMC• Mark Iredell - EMC• Istvan Szunyogh – Univ. of Maryland• Craig Bishop - NRL• + others who have contributed!

Winter Storm Reconnaissance Program

Objective:

Improve Forecasts of Significant Winter Weather Events Through Targeted Observations in Data Sparse Northeast Pacific Ocean

Adaptive approach to collection of observational data:1) Only Prior to Significant Winter Weather Events of Interest2) Only in Areas that Influence high impact event Forecasts

Past Results: 70+% of Targeted Numerical Weather Predictions Improve

10-20% error reduction for high impact event forecasts12-hour gain in predicting high impact events – earlier warnings possible

Operational since January 2001

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Valentine’s day Storm

• Weather event with a large societal impact• Each GFS run verified against its own analysis – 60 hr forecast• Impact on surface pressure verification• RMS error improvement: 19.7% (2.48mb vs. 2.97mb)Targeted in high impact weather area marked by the circle

Surface pressure from analysis (hPa; solid contours)Forecast Improvement (hPa; shown in red)Forecast Degradation (hPa; blue)

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The ETKF spotted the target area

Expected error reduction propagation

Targeting methods – ETKF (application example)

Storm

Dropsondes to be made by An Aircraft

How NCEP WSR program works

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About the Winter Storm Reconnaissance (WSR 2008) Program

• Took place 17 Jan – 15 March 2008• Dropwinsonde observations taken over the NE

Pacific by aircraft operated by NOAA’s Aircraft Operations Center (P-3) and the US Air Force Reserve (C-130s).

• Observations are adaptive – – collected only prior to significant winter weather events of

interest – in areas that might influence forecast the most.

• 35 good flights, around 629 dropsondes this winter due to the joint interests from HMT

• G-IV was not available due to installation

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WSR 2008 – New Tracks for P-3

• More ensemble members, efficient ET KF codes• No G-IV due to new instrument installation• New tracks for NOAA P-3 flying out of Portland,

OR

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Winter Storm Reconnaissance (WSR 2008) Program – Verification

• Experiment Design - Global parallel NCEP GFS experiments

– NCEP Global Forecast System running on T126L64 resolution hybrid-sigma with GSI vs. T12628 in the past

– Three sets of experiments• A. GFS run with WSR dropsondes being assimilated• B. GFS run with WSR dropsondes data rejected on all days

• Evaluation methods– Impact: compare differences between the paired runs– Forecast improvement: compare forecast fit to its own

analysis– Fit to observations: spatially averaged over the verification

regions

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VERIFICATION

• A Special HMT/WSR case

• Verification statistics

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A special HMT mission Feb 24 00Z, 2008

Large forecast uncertainties (blue regions) on Feb 22 andFeb 23, 2008

Relative measure of predictability

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A special HMT/WSR mission (Atmospheric River, Feb 24, 00Z, 2008)

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A HMT/WSR Mission(Surface PWAT)

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Impact of the Dropsondes

Signal Propagation

(250mb Height)

Forecast improvement

(Surface pressure)

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Comparison of ETKF signal and NCEP signal(Remarkable resemblance)

The ETKF signal The NCEP signal

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Comparison of ETKF signal and NCEP signal(Flight track 54, Feb 24 00Z 2008)

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A special HMT/WSR mission(Observed Precipitation)

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Forecast Verification for Surface pressure (2008)

RMS error reduction vs. forecast lead time

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Forecast Verification for Wind (2008)

RMS error reduction vs. forecast lead time

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Forecast Verification for Temperature (2008)

RMS error reduction vs. forecast lead time

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Overall results for Temperature(2007 vs. 2008)

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Overall results for Vector wind

The RMS error reduction could reach as high as 30% in certain verification areas in 2007

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Overall results for Surface pressure(2007 vs. 2008)

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Overall results for Humidity(2007 vs. 2008)

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• Due to the lack of G-IV, 2008 is not an impressive year from verification results

• P-3 tracks are close to inland (Portland, OR) - less likely the data would have a big impact

• C-130 flying lower compared to G-IV• Upper level wind may be important, especially in the Jet

regions – bode well for DWL measurement?

Summary

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WSR Summary statistics (2004-2007)

Variable# cases

improved# cases neutral

#cases degraded

Surface pressure 21+20+13+25=79 0+1+0+0=1 14+9+14+12=49

Temperature 24+22+17+24=87 1+1+0+0=2 10+7+10+13=40

Vector Wind 23+19+21+27=90 1+0+0+0=1 11+11+6+10=38

Humidity 22+19+13+24=78 0+0+0+0=0 13+11+14+13=51

25+22+19+26 = 92 OVERALL POSITIVE CASES.

0+1+0 +0 = 1 OVERALL NEUTRAL CASES.

10+7+8 +11 = 36 OVERALL NEGATIVE CASES. 71.3% improved 27.9% degraded

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Winter Storm Damages can’t be underestimated

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Composite summary maps

139.6W 59.8N 36hrs (7 cases) - 1422km 92W 38.6N 60hrs (5 cases)- 4064km

122W 37.5N 49.5hrs (8 cases) - 2034km 80W 38.6N 63.5hrs (8 cases) - 5143km

Verification Region

Verification Region

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3 649.5

60

63.5

0

1000

2000

3000

4000

5000

6000

0 20 40 60 80F o r e c a s t H o u r s

D i s t a n c e ( k m )

ETKF predicted signal propagation

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Precipitation verification

• Precipitation verification is still in a testing stage due to the lack of station observation data in some regions.

20.4416.50OPR

18.5616.35CTL

3:14:1Positive vs. negative cases

10mm 5mm ETS