# Presentation: 423155

## North American Drought Briefing:For August and JJA 2008

- Climate Prediction Center/NCEP/NOAA
- September 10, 2008
- _[http://](http://www.cpc.ncep.noaa.gov/products/Drought)__[www.cpc.ncep.noaa.gov](http://www.cpc.ncep.noaa.gov/products/Drought)__[/products/Drought](http://www.cpc.ncep.noaa.gov/products/Drought)_

## Partners & Contributors

**CPC:** Kingtse Mo, Wanru Wu, Muthuvel Chelliah, Wesley Ebisuzaki, Yun Fan, Huug van den Dool, Wei Shi
**EMC:** NLDAS Team: Ken Mitchell, Youlong Xia, Jesse Meng, Helin Wei
**EMC:** NAEFS Team: Zoltan Toth, Yuejian Zhu
**NASA/GSFC:** Randy Koster, Gregory Walker
**Princeton Univ.:** Eric Wood, Lifeng Luo, Justin Scheffield
**Univ. of Washington:** Dennis Lettenmaier
**Web Masters:** Viviane Silva, Joe Harrison
**Project Funded by NOAA  CPO/CPPA** **& NASA**

## Outline

- 1. Drought Monitoring:
-     i)  P (Accumulation & Anomaly)
-     ii) Objective Drought Indices
-     iii) Means/Anomalies (GVF,Ts)
-     iv) North American Monsoon
- 2. Drought Forecasts:
-     GFS, ESP, CFS Downscaling, ENSO Condition
- 3. Summary

## 1. Drought Monitoring

- _Highlights in Aug 2008:_
- Drought relief over Gulf coastal states, Southern Plains and the Southeast. Some were due to tropical storms. August was not a raining season in California, drought continued.

## Monthly Mean Precipitation Anomalies 

- Monthly Mean Precipitation Anomalies

- _For August 2008_
- _Wet: _Heavy rainfall over the Southern Plains, the Gulf coastal states and the Southeast, and the North American monsoon region.
- _Dry: _Negative P over the North Central and Northern Plains.
- _Notice__:_ The persistent pattern (from May-July) with dryness over the Southeast and the Gulf coasts and wetness over the Northern Plains and the North central reversed the phase in August 2008.

- mm/day

## P Daily Evolution

- _http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons/_

- Phase reversal between June-July & August

## Standardized Precipitation Index

- _[http://www.cpc.ncep.noaa.gov/products/Drought/Drought_index/Drought_index.shtml](http://www.cpc.ncep.noaa.gov/products/Drought/Drought_index/Drought_index.shtml)_

_**In JJA:**_
- Compared to previous season MAM:
- Drought improved over Californian & Nevada, SW monsoon region and Gulf coastal states;
- Drought developed over Oregon & Idaho;
- Wet Iowa-Missouri area became drier.

## Streamflow Percentile (USGS)  28-day Average obtained on 2008-09-02

- _[http://](http://waterdata.usgs.gov/waterwatch)__[waterdata.usgs.gov/waterwatch](http://waterdata.usgs.gov/waterwatch)_

- Below normal streamflow: California, TN, GA, the Atlantic Coast, West of North Dakota, WI
- Above normal: Gulf coast, central US, NW

## Multi-Model Standardized Runoff Index

- NLDAS-NCEP

- University of Washington

- Dry: The Atlantic coast, California
- Large differences over the North central and the upper Missouri Basin

## Multi-Model Soil Moisture Percentile

- (a) Soil Moisture Percentile for Aug 2008

- (b) University of Washington

- They all indicate:
- Dry: California, Nevada, TN, GA
- Wet: Central US, Southwest
- Category differs

## Keetch-Byram Drought Index (from WFAS)

- Keetch-Byram Drought Index (from WFAS)

- (KBDI = 600 - 800: Often associated with more severe drought with increased wildfire occurrence. Intense, deep burning fires with significant downwind spotting can be expected. Live fuels can also be expected to burn actively at these levels)

- Fire Danger Regions
- Correspond well with dry regions

## Green Vegetation Fraction

- Data source: ftp://ftp.orbit.nesdis.noaa.gov/pub/corp/scsb/wguo/data/GRIB/GVF_v4.0/Initial
- Figure plots: _http://www.cpc.ncep.noaa.gov/Drought/Satellite/GVF.shtml_

- GVF changes corresponding to land surface hydrological conditions such as preceding P & soil moisture. Further study is needed to identify their time lags.

**(e) SM in Aug (Leaky Bucket)**

**(c) 30-day P by 20080811**

**(d) 90-day P by 20080811**

## Surface Temperature Anomaly

- U.S. Temperature Analyses: _[http://](http://www.cpc.ncep.noaa.gov/products/tanal/accesspage.shtml)__[www.cpc.ncep.noaa.gov/products/tanal/accesspage.shtml](http://www.cpc.ncep.noaa.gov/products/tanal/accesspage.shtml)_

- _Aug 2008_

- _Jun-Jul-Aug 2008_

- Above normal Ts in most of the west (dry) region
- Below normal Ts in wet region

## North American Monsoon

- (c) From_ http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons/_

- (a) Jul-Aug P

- onset

## Moisture Surge & Rainfall

- Good correspondences between surges and rainfall.

- _Tropical storms in the eastern Pacific associated with moisture surges_
- Hurricane-1 Boris 27 Jun-4 Jul
- Hurricane-2 Fausto 16-22 Jul
- Hurricane-1 Genevieve 21-27 Jul
- Hurricane-3 Hernan 6-13 Aug
- TS Iselle 13-17 Aug
- Depression 11E 21-23 Aug

## 2. Drought Forecasts

- _(a) Drought Tendency during Sep-Nov 2008_

- _(b) Current Drought Condition_

_**Drought in the coming season:**_
- Impacts to ease: Southeast, Texas
- Drought to develop/persist: California, Nevada

## ENSO-neutral conditions are expected to continue through the Northern Hemisphere Fall 2008.

- During Aug 2008, SSTs remained slightly below average near the date line, while positive SST anomalies weakened in the eastern Pacific.

- With the ENSO-neutral conditions:
- Drought will improve over the Southern Plains;
- Over Texas & California, with no ENSO forcing, rain depends on intra-seasonal oscillations.

## GFS Week1/Week2 Forecasts

- (a) P & SM forecasts corrected with NARR

- (b) SM from Leaky bucket model

- ( b): http://www.cpc.ncep.noaa.gov/soilmst/mrf_jh.html

## ESP Prediction – SM & Runoff Percentile

- http://www.hydro.washington.edu/forecast/monitor/outlook

- Initialized 20080830

- (a) SM – 1 month lead

- (b) SM – 2 month lead

- (c) Accumulative Runoff – 1 month lead

- (d) Accumulative Runoff – 2 month lead

_**In Sep-Oct**_
- Wet central US and Florida;
- Dry : California, Nevada and Montana.

## CFS Downscaling Forecasts – SM Percentile

- _Initialized 200808_

- (a) Sep 2008

- http://hydrology.princeton.edu/~luo/research/FORECAST/fcstvrf.php

- (b) Oct 2008

- They started with dry soil conditions over the NW and they expect the dry conditions to persist through Sep 2008 and become less severe in Oct 2008 (and Nov 2008, not shown); Gulf coastal states stay dry?

## Summary

- Gulf coastal states made large drought improvement in August due to tropical storms.
- Drought over Southeast, Southern Plains and North Dakota also improved in August.
- In the following months, drought will persist in California/Nevada and further improve over Southeast and SW Texas.