donsutherland1
11-18-2004, 10:51 AM
Has anyone in Texas noticed how wet November has been? For those who have not, some hints from Houston:
∙ November 1-2: 2.84" rainfall
∙ November 17: 3.37" rainfall
Month-to-Date: 6.23"; Normal: 2.43"
What has happened?
If one examines the global indices, one finds two key developments that could have implications for the winter.
ENSO Region 1+2: The Disappearance of the Cool Anomaly:
In recent weeks, Region 1+2's cool anomaly has disappeared and at last word, its anomaly was moving into weak El Niņo territory:
Region 1+2
Week..........Anomaly
22-Sep-04..-0.2
29-Sep-04..-0.2
6-Oct-04......0.0
13-Oct-04...-0.4
20-Oct-04.....0.3
27-Oct-04.....0.1
3-Nov-04......0.2
10-Nov-04....0.5
If one figures in a roughly two week lag between the disappearance of the cool anomaly in this region, one would have reasonably expected that a more active subtropical jet would see Houston's rainfall begin to increase starting around October 20. A look at Houston's data finds that Houston's rainfall picked up dramatically starting October 23.
Houston's Rainfall (30 Day Totals):
Total Rainfall (September 23-October 22): 0.90"
Total Rainfall (October 23-November 17): 7.38"
During September and October, the Southern Oscillation Index average slightly negative (-2.8 and -3.7 respectively). At last word, its 30-day average was at -4.41. A closer look also finds several bursts where it fell below -10 this month. Combined with the warming of Region 1+2, the active subtropical jet is delivering abundant rainfall to Texas.
What lies ahead?
Whether or not the ENSO criteria is sustained for a basin-wide ENSO to become official remains to be seen. However, given a broader look at the Pacific, I tend to doubt that this criteria will be maintained as the normal water temperatures continue rise. If I'm correct, as November ends and December begins, the warm anomalies in Region 1+2 should begin to shrink.
However, before that happens, November should remain wetter than normal and at least the first 10-15 days of December should also see above-to-much above normal precipitation.
The PDO Goes Negative:
For the first time in 27 months, the PDO dropped below zero in October. Typically, winters in which the PDO averages < 0 and there is a weak El Niņo wind up normal to wetter than normal in the precipitation department in Texas. 1990-91 and 1991-92 are two classic examples.
However, as the winter evolves, and assuming that Region 1+2's warm anomaly fades, one might look for more normal precipitation, particularly during January-February. 1963-64 would be a representative winter given reasonably similar ENSO regional anomalies and QBO.
For now, Texas' march toward the Winter solstice should prove a soggy one.
∙ November 1-2: 2.84" rainfall
∙ November 17: 3.37" rainfall
Month-to-Date: 6.23"; Normal: 2.43"
What has happened?
If one examines the global indices, one finds two key developments that could have implications for the winter.
ENSO Region 1+2: The Disappearance of the Cool Anomaly:
In recent weeks, Region 1+2's cool anomaly has disappeared and at last word, its anomaly was moving into weak El Niņo territory:
Region 1+2
Week..........Anomaly
22-Sep-04..-0.2
29-Sep-04..-0.2
6-Oct-04......0.0
13-Oct-04...-0.4
20-Oct-04.....0.3
27-Oct-04.....0.1
3-Nov-04......0.2
10-Nov-04....0.5
If one figures in a roughly two week lag between the disappearance of the cool anomaly in this region, one would have reasonably expected that a more active subtropical jet would see Houston's rainfall begin to increase starting around October 20. A look at Houston's data finds that Houston's rainfall picked up dramatically starting October 23.
Houston's Rainfall (30 Day Totals):
Total Rainfall (September 23-October 22): 0.90"
Total Rainfall (October 23-November 17): 7.38"
During September and October, the Southern Oscillation Index average slightly negative (-2.8 and -3.7 respectively). At last word, its 30-day average was at -4.41. A closer look also finds several bursts where it fell below -10 this month. Combined with the warming of Region 1+2, the active subtropical jet is delivering abundant rainfall to Texas.
What lies ahead?
Whether or not the ENSO criteria is sustained for a basin-wide ENSO to become official remains to be seen. However, given a broader look at the Pacific, I tend to doubt that this criteria will be maintained as the normal water temperatures continue rise. If I'm correct, as November ends and December begins, the warm anomalies in Region 1+2 should begin to shrink.
However, before that happens, November should remain wetter than normal and at least the first 10-15 days of December should also see above-to-much above normal precipitation.
The PDO Goes Negative:
For the first time in 27 months, the PDO dropped below zero in October. Typically, winters in which the PDO averages < 0 and there is a weak El Niņo wind up normal to wetter than normal in the precipitation department in Texas. 1990-91 and 1991-92 are two classic examples.
However, as the winter evolves, and assuming that Region 1+2's warm anomaly fades, one might look for more normal precipitation, particularly during January-February. 1963-64 would be a representative winter given reasonably similar ENSO regional anomalies and QBO.
For now, Texas' march toward the Winter solstice should prove a soggy one.