|
<br />INTERMOUNTAIN WEST CLIMATE SUMMARY, JANUARY 2006
<br />
<br />EI Nino Status and Forecast Source: NOAA Climate Prediction Center, International Research Institute
<br />For Climate and Society
<br />
<br />According to the NOAA CPC ENSO Diagnostic
<br />Discussion issued January 12, 2006, La Nina
<br />conditions have been developing, and are expected
<br />to continue during the next 3-6 months. During the
<br />last two months, SSTs and subsurface temperatures
<br />have decreased in the eastern tropical Pacific and
<br />in the Nino 3.4 region, which is the basis of the
<br />official forecasts (Figure 13a). Collectively, these
<br />oceanic and atmospheric observations are consis-
<br />tent with the development of La Nina conditions.
<br />The most recent statistical and coupled model
<br />forecasts from NOAA and other sources indicate
<br />either ENSO-neutral conditions or the development
<br />of a weak La Nina (Figure 13b). To officially call
<br />these anomalies a La Nina, NOAA's definition re-
<br />quires a negative sea surface temperature anomaly,
<br />averaged over three months, greater than or equal
<br />in magnitude to 0.5oC in the Nino 3.4 region of
<br />the eastern equatorial Pacific region. A La Nina is
<br />generally accompanied by a northward shift of the
<br />jet stream in the eastern Pacific, and this is usually
<br />accompanied by drier-than-normal conditions over
<br />southern California and Arizona and wetter condi-
<br />tions in the Pacific North\:vest. NOAA cautions that
<br />given the late onset of this event there is consider-
<br />able uncertainty as to whether or not typical La
<br />Nina conditions will manifest themselves in the
<br />western United States. However, the persistent dry
<br />conditions in the Southwest -- including southern
<br />Utah and Arizona -- and the persistent wet condi-
<br />tions in the northwest, are typical of a La Nina.
<br />
<br />
<br />20N
<br />
<br />10N
<br />
<br />EQ
<br />
<br />108
<br />
<br />208
<br />
<br />Observed Sea Surface Temperature (CO)
<br />
<br />9-
<br />
<br />
<br /> 160W 140W 120W 100W 80W
<br /> I I I I I I I I I
<br /> 18 19 21 23 24 25 26 27 28 29 30
<br /> Observed Sea Surface Temperature Anomalies (CO)
<br />20N
<br />EQ
<br />108
<br />208
<br /> 140E 160E 180 160W 140W 120W 100W 80W
<br /> I I I I I I I I I I_I
<br /> -5 -4 -3 -2 -1 -0.5 0.5 1 2 3 4
<br />
<br />
<br />Figure 13a. Two graphics showing the observed SST (upper) and the
<br />observed SST anomalies (lower) in the Pacific Ocean. The Nino 3.4 region
<br />encompasses the area between 1200 W-1700 Wand 50 N-50 S. The graph-
<br />ics represent the 7 -day average centered on January 4, 2006.
<br />
<br />Model Forecasts of ENSO from September 2005
<br />
<br />3 IRILH:___
<br />, , ,
<br />, , ,
<br />. . .
<br />
<br />Dynamical
<br />· NASA
<br />· NCEP/CFS
<br />· JMA
<br />· SCRIPPS
<br />· LDEO
<br />· AUS/Poama
<br />· ECMWF
<br />, UKMO
<br />· KOREA SNU
<br />. · ZHANGICM
<br />-~~.~ .~. ECHAM/MOM
<br />· COLA ANOM
<br />
<br />Notes
<br />Two graphics in Figure 13a produced by NOAA show the
<br />observed SST (upper) and the observed SST anomalies
<br />(lower) in the Pacific Ocean. This data is from the TOGAfTAO
<br />Array of 70 moored buoys spread out over the Pacific Ocean,
<br />centered on the equator. These buoys measure temperature,
<br />currents and winds in the Pacific equatorial band and transmit
<br />data in real-time. NOAA uses these observations to predict
<br />short-term (a few months to one year) climate variations.
<br />Figure 13b shows multiple forecasts for SST in the Nino
<br />3.4 region for nine overlapping 3-month periods from Sep-
<br />tember 2005 to July 2006. "Nino 3.4" refers to the region of
<br />the equatorial Pacific from 1200 W to 1700 Wand 50 N to 50 S,
<br />which is one basis for defining ENSO sea surface tempera-
<br />ture anomalies. Initials at the bottom of the graph represent
<br />groups of three months (e.g. SON = Sept-Nov). The expected
<br />skills of the models, based on historical performance, are not
<br />equal to one another. The skills also generally decrease as
<br />the lead-time increases. Forecasts made at some times of the
<br />year generally have higher skill than forecasts made at other
<br />times of the year. They are better when made between June
<br />and December than between February and May. Differences
<br />among the forecasts of the models reflect both differences in
<br />model design and actual uncertainty in the forecast of the pos-
<br />sible future SST scenario.
<br />
<br />On the Web
<br />- For a technical discussion of current EI Nino conditions, visit: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/
<br />enso_advisory/.
<br />- For updated graphics of SST and SST anomalies, visit this site and click on "Weekly SST Anomalies": http://www.cpc.ncep.
<br />noaa. gov /prod ucts/preci piC WI i n k/MJ 0/ enso. shtm I#cu rrent.
<br />- For more information about EI Nino, including the most recent forecasts, visit: http://iri.columbia.edu/climate/ENSO/.
<br />
<br />2.5
<br />
<br />; ; ;
<br />, , ,
<br />. . .
<br />.-.. ... .......--.... ... ....--....
<br />2 ; ; ;
<br />
<br />....-.... ;;;
<br />
<br />~ 1.5 .--. -<.--.--._~._..... .~----.--.
<br />
<br />>.
<br />ro
<br />E
<br />o
<br />C
<br /><(
<br />t; 0.5
<br />en
<br />"""
<br />c0
<br />o
<br />IC
<br />Z
<br />
<br />. - -. . - ... - - . - - . - -. - - . . - . . - -. - - . - - .
<br />, , ,
<br />. . .
<br />
<br />; ; ;
<br />, , ,
<br />. - - . . - .;. - - . - - . - -:. - - . . - . . ~ - . - - . - - .
<br />, , ,
<br />. . .
<br />
<br />
<br />o
<br />
<br />--"':1 Statistical
<br />
<br />o CPC MRKOV
<br />Q CDC L1M
<br />o CPC CA
<br />D CPC CCA
<br />IJ CSU CLlPR
<br />CJ USC NNET
<br />Q FSU REGR
<br />o UCLA- TCD
<br />JAS
<br />
<br />-0.5
<br />
<br />. . . . .
<br />I I . I I I I
<br />-1-: - H:_ - H,U _,__H I' -- - -- --, ---- - ---!- --- - - -,----- - -, --- --- --, ---- - --, - ----
<br />..-. '-':"""'-b~s~J~~-"" ~~re-J~~t'-'T ... ... r'--""!""-- '-r""'-- 'r' .....
<br />-2
<br />ASO Oct OND NDJ DJF JFM FMA MAM AMJ MJJ JJA
<br />2005 2006
<br />
<br />Figure 13b. Forecasts made by dynamical and statistical models for sea
<br />surface temperatures (SST) in the Nino 3.4 region for nine overlapping 3-
<br />month periods from December 2005 to October 2006 (released December
<br />15, 2005). Forecasts are courtesy of the International Research Institute
<br />(IRI) for Climate Prediction.
<br />
<br />FORECASTS 11 6
<br />
<br />
|