2004 Regional Climate Highlights2004 Regional Climate Highlights

ByBy

Gerald BellGerald BellClimate Prediction CenterClimate Prediction Center

NOAA/NWS/NCEPNOAA/NWS/NCEP

Contributors: Vernon Kousky, Craig Long, Rich Tinker, Wasilla Thiaw, Song Yang

OutlineOutline

•Temperature and precipitation anomalies

•Indian and African monsoon seasons

•Active Atlantic, suppressed East Pacific hurricane seasons

•Evolution to early stages of El Niño, MJO influence

•Anomalous conditions over North America (Apr-Aug)

•Stratosphere: Antarctic ozone

•January stratospheric warming

Temperature and Precipitation AnomaliesTemperature and Precipitation Anomalies

Regional Temperature Anomalies during 2004Regional Temperature Anomalies during 2004

CoolSummer

Hot and Dry,Wildfires

Warm

Warm

Warm

El Niño Develops

Jan.-Sep. 2004 Temperature RankingsJan.-Sep. 2004 Temperature Rankings

1 is the coldest since 1950 55 is warmest since 1950

Regional Anomalies during 2004Regional Anomalies during 2004

5 landfallingTC’s (Jan-Mar)

CoolSummer

Hot and Dry,Wildfires

Warm

Warm

Warm

El Niño Develops

DroughtContinues

Suppressed rainfall

Inactive East Pac. hurricanes

Active Atlantic Hurricanes

7 U.S. landfallingTC’s

Monsoon RainsMonsoon Rains

•India•West Africa•Southern Africa

June-August India Monsoon Rainfall June-August India Monsoon Rainfall

Figure Courtesy: Song Yang See Yang and YooPoster 1.26

Total 2004 rainfall: 13% below average

Above average

Below average

West Africa and Southern Africa West Africa and Southern Africa Monsoon Rainfall Anomalies (mm)Monsoon Rainfall Anomalies (mm)

Posters:Thiaw and Mo, P. 1.2Nicholson, P. 1.19Thiaw, P. 1.28

Posters:Thiaw, P. 1.28

Anomalous 200-hPa VPOT andAnomalous 200-hPa VPOT andDivergent Wind VectorsDivergent Wind Vectors

Enhanced West African monsoon system and suppressed rainfall over Central America/ Amazon Basin predominant since 1995.

Anomalous 200-hPa STRM andAnomalous 200-hPa STRM andRotational Wind Vectors Rotational Wind Vectors

Inter-hemispheric symmetry to anticyclonic streamfunction anomalies•Stronger subtropical ridges reflect enhanced West African monsoon system and suppressed Amazonian rainfall system (Chelliah and Bell 2004),•Classic for above-normal Atlantic hurricane seasons (Bell and Chelliah 2005)

Anticyclonic

Atlantic and East Pacific Hurricane SeasonsAtlantic and East Pacific Hurricane Seasons

See poster:Chelliah, Bell and Mo, P. 1.24

Very Active Atlantic hurricane Season Very Active Atlantic hurricane Season

2004 NormalsTropical Storms 15 9-10Hurricanes 8 5-6Major Hurricanes 6 2

7 landfalling systems in 2004, 18 landfalls during 2002-2004.14 of these systems made landfall along the Gulf Coast

Suppressed East Pacific hurricane Season Suppressed East Pacific hurricane Season

2004 NormalsTropical Storms 11 15Hurricanes 6 9Major Hurricanes 3 4.4

East Pacific hurricane seasons generally below normal since 1995

2004 Atlantic Tropical Cyclone Tracks2004 Atlantic Tropical Cyclone Tracks

Figure Courtesy Unisys Weather.com

Above-normal seasons have large number of systems forming in Main Development Region (MDR). During 2004, 8 /14 TS, 7/8 H and 5/6 MH formed in MDR (9oN-21.5oN).

MDR

Aug-Sep 2004: Total Precipitation (mm) during the Aug-Sep 2004: Total Precipitation (mm) during the periods in which the six landfalling tropical systems were periods in which the six landfalling tropical systems were producing precipitation in U.S., and % of 2-month totalproducing precipitation in U.S., and % of 2-month total

Since 1995, 8 of 10 Atlantic hurricane seasons were above normal.On average 2-3 hurricanes hit the U.S. in above-normal seasons.

Warmer SSTs

Amplified subtropical ridge (200-hPa)

Stronger TropicalEasterly Jet

Favorable AEJ

Enhanced Cyclonic RELV

These conditions have prevailed since 1995-8 of 10 hurricane seasons have been above-normal.Also characterized the active decades of the 1950s-1960s

Primary Conditions associated with Primary Conditions associated with Active 2004 Atlantic Hurricane SeasonActive 2004 Atlantic Hurricane Season

Weaker easterly trades 850-hPa westerlies

Very low verticalwind shear(200 – 850 hPa)

Standardized SST Departures in Standardized SST Departures in Main Development RegionMain Development Region

19951970

Above normal 2004 Atlantic hurricane season associated with ongoing anomalous warmth across tropical Atlantic that began in 1995—reflects warm phase of Atlantic multi-decadal mode (Goldenberg et al. 2001)

Less cyclonic

More cyclonic

Stronger Easterlies

Weaker easterlies

Lower Shear

Higher Shear

Recent Decade of Favorable ConditionsRecent Decade of Favorable ConditionsAnomalies are relative to Inactive 1979-1994 PeriodAnomalies are relative to Inactive 1979-1994 Period

Averaging Regions

Vertical Wind Shear: 200-850 hPa

700-hPa Zonal Wind

700-hPa Relative Vorticity

Bell et al., BAMS, May 2004

Evolution to Early Stages of El Niño Evolution to Early Stages of El Niño

See poster:Kousky, P. 1.15

Latest SST Anomalies (Latest SST Anomalies (oC): 4-10 October 2004C): 4-10 October 2004

Evolution of SST Anomalies Averaged 5oN - 5oS

• Largest positive SST anomalies were west of date line until July

• Since July, anomalous warmth has persisted and expanded eastward.

•Negative anomalies in eastern Pac. disappearing

Strong MJO during 2004Strong MJO during 2004 200-hPa Velocity Potential Anomalies200-hPa Velocity Potential Anomalies

averaged 5N-5Saveraged 5N-5S

MJO has produced significant variability in the atmosphere MJO has produced significant variability in the atmosphere and in Pacific Ocean temperatures. No El Niño signature and in Pacific Ocean temperatures. No El Niño signature yet. See poster: Weickmann and Berry, P. 1.25yet. See poster: Weickmann and Berry, P. 1.25

AnomalousDivergence

AnomalousConvergence

Area-Averaged SST AnomaliesArea-Averaged SST Anomalies in Niño-4 and Niño 3 Regions in Niño-4 and Niño 3 Regions

Intraseasonal SST fluctuations are associated with oceanic Kelvin waves triggered by MJO

In September, the anomalous warmth expanded eastward to cover Niño-3 region

ExtratropicsExtratropics

Persistent April-July Circulation Persistent April-July Circulation over North Americaover North America

•Hot and Dry Alaska

•Cooler Canada, cooler summer in U.S.

•Below-average Southwest U.S. monsoon

April-July 2004April-July 2004

Precipitation Percentiles

300-hPa Heights and Temperatures

June-AugustJune-AugustMean Temperature RankingsMean Temperature Rankings

1 is the coldest since 195055 is warmest since 1950

June-August June-August Mean Maximum Temperature Anomalies (C) Mean Maximum Temperature Anomalies (C)

Some Summertime Cold-air OutbreaksSome Summertime Cold-air Outbreaks

StratosphereStratosphere

• Antarctic Ozone hole

• January N.H. Stratospheric Warming

Antarctic Ozone Hole (Concentrations <220 DU)Antarctic Ozone Hole (Concentrations <220 DU)NOAA SBUV/2 Satellite EstimateNOAA SBUV/2 Satellite Estimate

Figure Courtesy of Craig Long, poster P 1.23

January 2004 Stratospheric WarmingJanuary 2004 Stratospheric WarmingDaily Temperature Departures (C)Daily Temperature Departures (C)

Figure Courtesy of Craig Long, poster P 1.22

Height Anomalies (m) associated with Height Anomalies (m) associated with 2004 Stratospheric Warming2004 Stratospheric Warming

Stratospheric warming contributes to strong negative phase of the Arctic Oscillation

SummarySummary•Many temperature and precipitation anomalies associated with multi-decadal fluctuations: Chelliah and Bell 2004, Goldenberg et al. 2001)

Precipitation: Temperature Enhanced West African monsoon Warm N. Atl

Drier Amazon Basin Active Atl. hurricanes, summertime eastern U.S. rainfall,

•Evolution to early stages of El Niño •No single cause of N.A. circulation anoms. during Apr-Aug., hemispheric-scale pattern of anomalies, extended into middle strat.

•January negative AO also linked to stratosphere—warming event

•Antarctic ozone hole near 1994-2003 mean size