TROPICAL PACIFIC CLIMATE GUIDANCE for 89

TROPICAL PACIFIC CLIMATE
GUIDANCE
for
89th ISLAND CLIMATE UPDATE
Climate Developments
January 2008
Seasonal mean circulation
http://www.cdc.noaa.gov/map/images/rnl/sfcwnd_90a.rnl.html
Monthly mean circulation
http://www.cdc.noaa.gov/map/images/rnl/sfcwnd_30a.rnl.html
BMRC SST anomalies
http://www.bom.gov.au/climate/current/anomsst.shtml
CDC SST Anomalies
http://www.cdc.noaa.gov/map/images/sst/sst.anom.month.gif
BoM OLR and anomalies
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/m.lm.html
BMRC MJO monitoring
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/mapro
om/RMM/phase.Last40days.html
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/h
ov.recon+anom.olr.gif
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/index.htm
Madden- Julian Oscillation at 26/01/2008
Current BMRC MJO: Phase 1
MSLP anomalies for
MJO-phase 1 (Blue: negative → rainy)
http://www.apsru.gov.au/mjo/current.asp
Statistical OLR MJO Forecast
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/fcsts/m.anom.OLR.uv850.gif
http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/fcsts/m.anom.OLR.uv850.gif
TRMM Rainfall
The ENSO Precipitation Index (ESPI) for the last 30 days is -0.4 (mod-strong La Nina below -1)
http://trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html
http://trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html
TAO/TRITON subsurface temperatures
NOAA subsurface temperatures
http://www.cpc.noaa.gov/products/analysis_monitoring/enso_update/sstxz.gif
NOAA Sea Level Anomalies
http://www.cpc.noaa.gov/products/analysis_monitoring/enso_update/sealev.gif
TAO array equatorial SSTs and zonal winds
http://www.pmel.noaa.gov/tao/jsdisplay/
NIWA SOI 1- and 3-month means
January 2008 SOI: 1m 1.5, 3m 1.3 (estimated)
ENSO Forecasts
EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION
issued by CLIMATE PREDICTION
10 January 2008
Synopsis: La Niña is expected to continue into Northern Hemisphere spring 2008.
La Niña remained at moderate strength during December 2007, with below-average sea surface temperatures
(SSTs) extending from 160ºE to the South American coast (Fig. 1). All of the Niño region indices remained cooler
than −1.0°C (Fig. 2), with the Niño-3.4 and Niño-3 indices persisting near −1.5°C. The upper-ocean heat content
(average temperatures in the upper 300 m of the ocean) in the central and east-central equatorial Pacific remained
below average (Fig. 3), with temperatures ranging from 2°C to 5°C below average at thermocline depth (Fig. 4).
Consistent with these oceanic conditions, stronger-than-average low-level easterly winds and upper-level westerly
winds continued across the central equatorial Pacific, convection remained suppressed throughout the central
equatorial Pacific, and slightly enhanced convection covered the far western Pacific. Collectively, these oceanic and
atmospheric conditions reflect a mature La Niña.
The recent SST forecasts (dynamical and statistical models) for the Niño 3.4 region indicate a continuation of La
Niña conditions into Northern Hemisphere spring 2008 (Fig. 5). Over half of the models predict a moderate strength La
Niña to continue through February-April, followed by weaker La Niña conditions. Current atmospheric and oceanic
conditions and recent trends are consistent with a likely continuation of La Niña into the Northern Hemisphere spring
2008.
Expected La Niña impacts during January-March include a continuation of above-average precipitation over
Indonesia and below-average precipitation over the central and eastern equatorial Pacific. For the contiguous United
States, potential impacts include above-average precipitation in the Northern Rockies, the Pacific Northwest, the Ohio
and Tennessee Valleys, and parts of the Great Lakes region. Below-average precipitation is expected across the
South, particularly in the southeastern states. Recent Madden-Julian Oscillation (MJO) activity has contributed to
short-term fluctuations in low-level winds and convection over the equatorial Pacific, which has acted to modify some
of the typical La Niña impacts on a sub-seasonal timescale.
http://www.noaanews.noaa.gov/stories2007/s2805.htm
Weekly Tropical Climate Note
Tuesday 22 January 2008
El Nino-Southern Oscillation Update
The 30-day Southern Oscillation Index [SOI] to 19 January was +18, with contributing pressure anomalies of -2.9hPa at
Darwin and +0.7 at Tahiti. The official monthly SOI for December was +14, and its 5-month running mean centred on
October was +7.
El Nino - Southern Oscillation [ENSO] indicators continue to show that La Nina characteristics are well established. Over
the past several months, cloudiness around the near-equatorial dateline and further east in the Pacific has mostly been
less than normal, corresponding to cooler than average sea-surface temperatures [SST] of that region. Cool anomalies in
subsurface water of the near-equatorial eastern and central Pacific have existed for much of the year and persist. Tradewinds in the near-equatorial Pacific have generally been stronger than normal and the Maritime Continent region
[including tropical north-Australia] has seen above average cloudiness. Over recent months the SOI has generally been
on a rising trend and has been positive since August and around one standard deviation or more above the long-term
mean since middle November. The SST about waters to the north and northwest of Australia's coast rose to be warmer
than normal for much of December, though the recent vigorous monsoon event has been followed by [probably
temporary] cooling.
See the Bureau's "ENSO Wrap-Up" at www.bom.gov.au/climate/enso/ which includes a compilation of ENSO dynamic
model predictions. Most model guidance is consistent in suggesting continuation of La Nina conditions throughout the
southern hemisphere summer months.
Intra-Seasonal Patterns
From early June to mid-October four active phases of the Madden-Julian Oscillation [MJO] were observed to develop
over the tropical Indian Ocean. The two most recent of these both progressed rapidly across the Indian Ocean, then
lingered over the longitudes of the Maritime Continent and western Pacific.
Convective activity increased over the central Indian Ocean around early December, associated with a renewed active
MJO phase in that region, continuing the apparent periodicity displayed in recent months of about 40-50 days. The
previous two events propagated relatively quickly across the Indian Ocean, however during the recent event broadscale
active convection persisted over the Indian Ocean longer. Nonetheless, active convection was a feature of the maritime
continent region through the final week of December. Deep monsoon westerlies were first apparent at Darwin from 27
December as the monsoon trough moved onshore there and intensified.
For the past two weeks or so, tropical convection has been predominately focussed around the western Pacific, in a
similar manner to the previous two MJO events that saw the active MJO phase linger over this region for an extended
period, perhaps consistent with existing La Nina conditions. This activity is likely to wane in this part of the globe as the
focus of tropical weather activity shifts to the western and central Indian Ocean over the next week or so, before shifting
further towards northern Australia later. As a consequence, tropical weather activity over much of northern Australia is
likely to be less than the season average until it is reinvigorated by this renewed active phase of the MJO about one to
two weeks into February.
http://www.bom.gov.au/climate/tropnote/tropnote.shtml
Summary of main seasonal ENSO model results
Statistical
Dynamical
Climate Model or Group
FMA 2008
MJJ 2008
ASO 2008
POAMA (Australia)
Cold
Cold
Unavailable
ECMWF (EU)
Cold
Neutral
Unavailable
NCEP CFS (USA)
Cold
Cold
Cold
Met Office (UK)
Cold
Cold
Unavailable
SCRIPPS/MPI (USA/FRG)
Cold
Cold
Neutral
NASA-NSIPP (USA)
Cold
Cold/Neutral
Neutral
JMA (Japan)
Cold
Neutral
Unavailable
FRCGC SINTEX (Japan)
Cold
Cold
Neutral
CPC CCA (USA)
Cold
Neutral
Warm
Neutral
Neutral
Neutral
NOAA Linear Inverse (USA)
Cold
Cold
Neutral
SSES (Ohio, USA)
Cold
Cold
Unavailable
CLIPER (USA)
Cold
Neutral
Neutral
Florida State University (USA)
Cold
Neutral
Neutral
LDEO5 (USA)
Individual forecasts on following pages, in the above order
Loosely Adapted from http://www.bom.gov.au/climate/ahead/ENSO-summary.shtml
IRI ENSO Forecast Summary
ENSO Update: 16 January 2008
Summary
La Niña conditions continue in the central and eastern
equatorial Pacific. Below-average sea surface temperatures
(SSTs) exist from the west coast of South America to west of
the dateline. Based on the latest observations and forecasts,
there is a 96% probability of maintaining La Niña conditions
over the coming season.
Average Niño3.4 SST anomaly forecast
FMA
MJJ
ASO
Dynamic
models
-1.3
-0.7
-0.4
Stats Models
-1.0
-0.5
-0.3
All
-1.2
-0.6
-0.3
http://iri.columbia.edu/climate/ENSO/currentinfo/SST_table.html
General Discussion
The state of the tropical Pacific remains largely unchanged
over the past month. La Niña conditions, which have been in
place since August 2007, are indicated by substantially
below-average sea surface temperatures in the central and
eastern equatorial Pacific, enhanced Trade Winds, and
reduced equatorial heat content. The sea surface
temperature anomalies are below -2 C throughout much of
the eastern-central equatorial Pacific. Strong and very
persistent easterly anomalies of the low-level winds extend
across most of the equatorial Pacific. Persistence of La Niña
conditions is highly likely through at least the next couple
months given the current magnitude and spatial extent of the
oceanic temperature anomalies.
Out of a large set of dynamical and statistical forecast
models, most models indicate continuation, but gradual
weakening, of the moderately strong La Niña conditions
through early 2008. Overall, based on model forecasts and
current observations of the ocean surface and subsurface,
the probability of a La Niña is estimated at 96% for the JanFeb-Mar season in progress. The probability of returning to
ENSO-neutral conditions increases to the climatological
value of 50%, by mid-2008.
Selected ENSO (NINO 3.4 region) forecasts
BMRC
Red=latest runs
Blue=previous runs
NCEP
UKMO
NASA
ECMWF