Skip Navigation Links 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center

HOME > Expert Assessments > Climate Diagnostics Bulletin


Extratropical Highlights - June 2001

1. Northern Hemisphere
The Northern Hemisphere 500-hPa circulation during June featured a wave-four pattern of anomalies within the latitude band 40-50N, and a dominance of positive anomalies in the lower mid-latitudes throughout the hemisphere (Fig. E10). In the subtropics and lower mid-latitudes, these height anomalies were accompanied by a large-scale pattern of 200-hPa anticyclonic circulation anomalies (Fig. T22, bottom), which were especially strong from the Caribbean Islands eastward to the northern flank of the Asian monsoon ridge. This entire region experienced surface temperatures in the upper 90th percentile during the month.

A corresponding region of anticyclonic circulation anomalies was also evident in the Southern Hemisphere from the western South Atlantic eastward to southeastern Australia. In both hemispheres, these anomalies were situated along the poleward flanks of the mean subtropical ridge axes, consistent with an overall poleward expansion of the subtropical ridges.

a. North America

The mean 500-hPa circulation over North America featured above-average heights across the southwestern United States and eastern Canada, and below-average heights over southwestern Canada (Fig. E10). These areas coincided with above-normal and below-normal mean surface temperatures, respectively (Fig. E1).

Above-average rainfall (Fig. E3) was recorded during the month across the Gulf Coast states, the Southeast, the Ohio Valley (Fig. E5) and along the eastern seaboard of the United States northward to eastern Canada. The Gulf Coast states and the Southeast region have experienced lower-than-average rainfall for the past two years. The Ohio Valley region has recorded generally below-average precipitation since October 2000 (Fig. E5).

b. China

Above-average rainfall covered eastern and east-central China during June (Fig. E3), with area-averaged totals reaching the 95th percentile (Fig. E4). Above-average rainfall was also observed during May over large portions China. Climatologically, June represents the onset of the peak in this area’s rainy season. Last year above-average precipitation prevailed throughout the entire June-August peak in the rainy season.

2. Southern Hemisphere

The Southern Hemispheric circulation during June featured anticyclonic streamfunction anomalies at 200-hPa from the western South Atlantic eastward to southeastern Australia (Fig. T22, bottom). These anomalies are located along the poleward flanks of the mean subtropical ridge axes, and are consistent with an overall poleward expansion of the subtropical ridges. As discussed above, similar anomalies were also evident along the poleward flanks of the mean subtropical ridge axes in the Northern Hemisphere.

In Australia, this overall anomaly pattern was accompanied by above-average 500-hPa heights across the southern part of the continent. (Fig. E9). The largest positive height anomalies were observed in the east and southwest, and were accompanied by below-average rainfall in both regions (Fig. E3). Extreme warmth was also observed across eastern Australia during the month, with surface temperatures exceeding the 90th percentile throughout the region (Fig. E1, bottom).

NOAA/ National Weather Service
NOAA Center for Weather and Climate Prediction
Climate Prediction Center
5830 University Research Court
College Park, Maryland 20740
Page Author: Climate Prediction Center Internet Team
Page last modified: August 24, 2007
Information Quality
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities