Pakistan Flood 2010: P. J. Webster R. A. Houze, Jr. P. J. Webster R. A. Houze, Jr. International...
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Transcript of Pakistan Flood 2010: P. J. Webster R. A. Houze, Jr. P. J. Webster R. A. Houze, Jr. International...
Pakistan Flood Pakistan Flood 2010:2010:
P. J. WebsterP. J. WebsterR. A. Houze, Jr.R. A. Houze, Jr.P. J. WebsterP. J. WebsterR. A. Houze, Jr.R. A. Houze, Jr.
International Weather & Climate Events of 2010, AMS Annual Meeting, Seattle, 25 January 2011International Weather & Climate Events of 2010, AMS Annual Meeting, Seattle, 25 January 2011
Could it have been predicted? Could it have been predicted?
withwith
V. Toma, H. Kim, K. Rasmussen, U. V. Toma, H. Kim, K. Rasmussen, U. Romatschke, S. Medina, S. Brodzik, D. Romatschke, S. Medina, S. Brodzik, D. Niyogi, and A. Kumar, Niyogi, and A. Kumar,
"Almost 20 million people need shelter, food and emergency care. That is more than the entire population hit by the Indian Ocean tsunami, the Kashmir earthquake, Cyclone Nargis, and the earthquake in Haiti—combined.”Secretary-General Ban Ki-moonAugust 2010
"Almost 20 million people need shelter, food and emergency care. That is more than the entire population hit by the Indian Ocean tsunami, the Kashmir earthquake, Cyclone Nargis, and the earthquake in Haiti—combined.”Secretary-General Ban Ki-moonAugust 2010
2000 lives lost, extensive livestock, household, infrastructure & agricultural ($20B)2000 lives lost, extensive livestock, household, infrastructure & agricultural ($20B)
Upcoming papers:
• Webster et al. (2011, GRL)• Houze et al. (2011, BAMS)
Monsoon Mean Rainfall Climatology
Webster et al. 2011
A COMPARISON OF RAINFALL IN 2008 AND 2010:
• 2010 produced devastating floods but was not an outlier meteorologically
• The hydrological uniqueness came because of the number of prior extreme events over the mountainous north, run-off due to drought in 2009, deforestation, and the TYPE OF STORM
Webster et al. 2011
ECMWF Ensemble Forecast analyzed by Webster et al. (2011)
• 51 Ensemble members• 50/80 km resolution• Compared to CMORPH
precipitation product
Webster et al. 2011
4-Day ensemble mean forecast
Webster et al. 2011
Summary of predictions of major July rain events in Pakistan
Does the type of storm matter?
• TRMM climatology shows different kind of rainstorms in eastern vs western Himalayan region
Deep Convective
Cores
Wide Convective
Cores
BroadStratiform
Regions
Climatology of extreme convective features shown by TRMM for 10 years of data
Normal
Normal 500 mb anomaly patterns for South Asian rainstorms
Nor
mal
Normal 500 mb anomaly patterns for South Asian rainstorms
Normal
500 mb pattern 28 July 2010: very abnormal
Nor
mal
Normal
Time sequence…
700 mb wind (~3 km)700 mb wind (~3 km)
LL LL LLLL
HH
Water vapor anomaly500 mb windWater vapor anomaly500 mb wind
Rain
Broad stratiform precipitation occurred over the mountains of Pakistan
Broad stratiform!
Floods!
Houze et al., BAMS 2011
ConclusionsWhat was predictable about the Pakistan floods?
•2010 was not an abnormally rainy year in Pakistan•The probability of major rain periods over Pakistan was predicable ~7-10 days in events
Could floods have been anticipated?
•Not every predicted major rain event produced floods•The July 28 storms occurred over deforested mountains•And they had mesoscale stratiform characteristics normally seen only in storms far to the east•The possibility of such cloud systems occurring in the west could be seen in the forecast wind pattern
What can be done in the future?
Webster et al., BAMS November 2010
Proof of concept in Bangladesh
•Could be applied to other basins•Need downscaling for type of storm and topography
EndEndThis research was supported byThis research was supported by
NSF grants ATM-0820586 and ATM-0965610 and NASA grant NNX10AH70GNSF grants ATM-0820586 and ATM-0965610 and NASA grant NNX10AH70G