CPC latest update on ENSO=Neutral by late spring

[cycloneye]

EL NIÑO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP
February 10, 2005
Synopsis: A transition from weak warm-episode (El Niño) conditions to ENSO-neutral conditions is expected during the next three months.

Sea surface temperature (SST) anomalies decreased in the equatorial Pacific everywhere east of the date line during January 2005, resulting in decreases in all of the Niño indices with the exception of Niño 4 (Fig. 1). However, positive sea surface temperature (SST) anomalies greater than +1°C (~1.8°F) persisted in portions of the central and western equatorial Pacific (Fig. 2). By early February 2005, positive equatorial SST anomalies greater than +0.5°C (~0.9°F) were found from 140°E eastward to 155°W (Fig. 3). The pattern of anomalous warmth in the equatorial Pacific in recent months and the most recent 5-month running mean value of the Southern Oscillation Index (-0.5) indicate that a weak warm (mid-Pacific El Niño episode is in progress. However, through December there was a lack of persistent enhanced convection over the anomalously warm waters of the central equatorial Pacific, which limited El Niño-related impacts.

Since late 2003 MJO activity has resulted in week-to-week and month-to-month variability in many atmospheric and oceanic indices. The MJO activity weakened considerably during early November 2004 and remained weak through mid-December. During the last half of December the MJO strengthened, as enhanced convection and precipitation over the Indian Ocean shifted eastward across Indonesia into the western tropical Pacific. Since early January enhanced convection has persisted in the western equatorial Pacific and expanded eastward into the central equatorial Pacific (Fig. 4), accompanied by a weakening of the low-level easterly winds over the region. At this time it is not clear whether the recent enhanced convection and weakening of the easterly winds in the central equatorial Pacific are transient features (related to the MJO) or perhaps evidence of a coupling between the anomalously warm waters and the overlying atmospheric circulation.

Based on the recent evolution of oceanic and atmospheric conditions and on a majority of the statistical and coupled model forecasts, it seems most likely that weak warm episode (El Niño) conditions will gradually weaken during the next three months and that ENSO-neutral conditions will prevail during the last half of 2005




No surprise about the transition from weak el nino to neutral as the data in recent weeks has shown just that.So without el nino around we can expect another above average season in 2005 continuing the string of active seasons since the 1995 season.

[cycloneye]

It went dow rapidly so I am bumping this important information about ENSO.

[MWatkins]

Yep...the atmosphere hasn't really been behaving as if there's a warm episode in place anyway...

Here's the latest forecast spread from NCEP (note the ensemble mean is now slightly cool for the key months of Aug-Sep-Oct for Nino 3):

http://www.cpc.ncep.noaa.gov/products/p ... SSTMon.gif

And from NASA/Goddard:

Nino 3:

http://nsipp.gsfc.nasa.gov/exptlpreds/l ... e=forecast

Nino 3-4:

http://nsipp.gsfc.nasa.gov/exptlpreds/l ... e=forecast

Nino 4:

http://nsipp.gsfc.nasa.gov/exptlpreds/l ... e=forecast

Unless something completely unexpected pops up...the issue of Nino negatively impacting this 2005 season can probably be put to rest. That means all US and Caribbean residents should get ready for yet another busy season...

MW

[weatherwindow]

it will be interesting to see if we achieve a neutral trending to cool position and whether it will be in place by late may/early jun. does anyone have any thoughts on the prospects of early season activity based on the current enso trends?.......................rich

[MWatkins]

it will be interesting to see if we achieve a neutral trending to cool position and whether it will be in place by late may/early jun. does anyone have any thoughts on the prospects of early season activity based on the current enso trends?.......................rich

Usually there's a relationship between warm ENSO and early season starts. So if we trend neutral to cool once things get underway...the probability of something developing on the tail-end of a front would be reduced (a lot of early season activity is related to old frontal boundaries hanging around in the tropics...which is not as prevelant during normal/cool enso years...look at 1997...early-season frontal activity but little from the Main Development Region).

And if the Bermuda high pattern continues like it has...the biggest concern for early season activity would shift to the western Gulf of Mexico but would not be a concern for most of the basin...unless an early developing Africian wave gets "lucky"...but that's hard to predict this far out.

To me this looks like yet another Africian-wave MDR season...and these types of years can get off to late starts.

Given the choice between early and late start, my $ is on late.

MW

[donsutherland1]

In general, seasons with an early high TNA are also less likely to start early:

TNA: +0.300 or Above:
• First storm before July 1: 4/13 (31%) seasons
• First storm July 1 or later: 9/13 (69%) seasons

TNA: .Below +0.300:
• First storm before July 1: 27/44 (61%) seasons
• First storm July 1 or later: 17/44 (39%) seasons

[cycloneye]

it will be interesting to see if we achieve a neutral trending to cool position and whether it will be in place by late may/early jun. does anyone have any thoughts on the prospects of early season activity based on the current enso trends?.......................rich

Usually there's a relationship between warm ENSO and early season starts. So if we trend neutral to cool once things get underway...the probability of something developing on the tail-end of a front would be reduced (a lot of early season activity is related to old frontal boundaries hanging around in the tropics...which is not as prevelant during normal/cool enso years...look at 1997...early-season frontal activity but little from the Main Development Region).

And if the Bermuda high pattern continues like it has...the biggest concern for early season activity would shift to the western Gulf of Mexico but would not be a concern for most of the basin...unless an early developing Africian wave gets "lucky"...but that's hard to predict this far out.

To me this looks like yet another Africian-wave MDR season...and these types of years can get off to late starts.

Given the choice between early and late start, my $ is on late.

MW

Yeah MW it looks like we who live in the islands will have to deal with some threats this 2005 season.

[Derek Ortt]

how is the recovery coming along in the Lesser Antilles, the VI and Puerto Rico after the trifecta of Earl, Ivan, and Jeanne last year

[cycloneye]

how is the recovery coming along in the Lesser Antilles, the VI and Puerto Rico after the trifecta of Earl, Ivan, and Jeanne last year

In terms of Puerto Rico after Jeanne it has recovered but no major damage was caused by it.The worse thing that happened here was the power blackout that was caused not by the storm but by a supervisor who turned off the switches for all the island.The result was that he was fired.

I dont have information about what is going on in Grenada.