Given web server and time concerns, I am posting a very short update today (11 April). The spatial distribution of global tropical and extratropical SSTs along with their anomalies are generally the same today as they were 2-4 weeks ago. There are weak positive SST anomalies from the eastern Indian Ocean into
http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)
Since the eastward propagation of tropical convective forcing into the west central
First, the tropical forcing did have a MJO component (#4 for this cold season). Nevertheless, understand that the MJO only explains ~20 percent of the tropical convective variability, on average. Whether or not the west Pacific Ocean signal was a MJO is irrelevant. The point is that meridionally directed Rossby wave energy was dispersed (RWDs) by the west Pacific convection that arced across the PNA sector and then dynamically forced the western
Secondly, and this possibility was discussed on my 15 March posting (and followed up last week), there has been large week-2 forecast errors of the NCEP GFS ensemble mean ending 11 April. In fact, per
week-2 North American ACC scores of 500mb Z anomalies are nearly zero (5-day averaged). I do attribute these errors to not only the west
Full disk satellite imagery and all my other tricks indicate the tropical forcing is slowly increasing across the
Global relative AAM remains low (~minus 1.5 sigma through 9 April per R1 climatology) and is probable to stay that way for at least the next few weeks. The global mountain torque is ~minus 10 Hadleys including contributions from both East Asia and the
Portions of the central and southern High Plains had some decent precipitation (rain and snow) this past week, particularly eastern
Severe weather internationally (including temperature extremes) appears to have increased a bit during the last week. I continue to leave it to the expertise of the appropriate weather centers internationally to alert the public of these risks.
As discussed above, tropical thunderstorm activity is probable to become quite intense/severe from the Indian Ocean into
An experimental quasi-phase space plot of the GSDM utilizing time series of normalized global relative AAM time tendency (Y-axis) and normalized global relative AAM anomaly (X-axis) can be found at
We call the behavior of this plot the Global Wind Oscillation (GWO). While the intent of the legacy GSDM is to extend current thinking beyond the MJO, the GWO quantifies variations used to derive the original GSDM in a manner that is “user friendly” analogous to the WH (2004) “convention”. In addition, the GWO plot does not have the ENSO signal removed.
Please see the revised description of the GSDM per above link. Also, I encourage the readers to study the annotated MJO and GWO phase space plots to help relate the global variations explained by those techniques to “weather”.
Links to CPC and PSD ENSO discussions:
The following is a link to information about the stratosphere:
These are probabilistic statements, and work is ongoing to quantify in future posts (for example, risk assessment maps, signal to noise ratio plots and shifts of probability). We hope that an opportunity will arise for us (soon) to have a dedicated web page effort to expedite more objectively, with rigor, thoroughness and verification. The WB (2007) paper on the GSDM has been published in the February issue of MWR. In addition, a two-part paper is in preparation by WB that will formally introduce the GWO along with subseasonal composites. Given shift work and upcoming travel, updates remain extremely difficult. I am planning on posting another discussion next weekend, 19-20 April.