Tracking the sputtering monsoon of 2009

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By Scot Johnson

The on-again, off-again monsoon continued in August. Rainfall from Aug. 12-14 and Aug. 23 -24 was clearly associated with monsoon conditions; moisture flow from the south and heat-triggered convection.

The rest of August was generally dry, although some mountain showers cropped up during the last few days of the month.

Even with the last-minute boost, however, the rainfall total for the month was about half of normal in both Los Alamos and White Rock.

Los Alamos received 1.66 inches of precipitation during August, 50 percent of the normal 3.33 inches. White Rock’s 0.95 inches was 45 percent of the normal 2.12 inches. Nearly all of New Mexico has had below normal precipitation during the monsoon this year.

The precipitation total for 2009 in Los Alamos is 13.25 inches of liquid equivalent so far. This is right on target, but the official Los Alamos rain bucket at TA-6 has been at the right place at the right time all year. More representative of the county’s overall precipitation total this year is White Rock’s 7.66 inches which is 85 percent of normal there.

The mean high and low temperatures in Los Alamos were 80 and 54 degrees, respectively. Both are about 2 degrees higher than normal, so it is no surprise that the average temperature of 67.2 degrees was almost two degrees higher than the normal 65.4. No temperature records were set in Los Alamos during August.

In White Rock, the average temperature of 68.6 degrees was right on normal, but temperatures fluctuated more than usual there. The average high of 85.7 degrees was 3 degrees higher than normal. The average low of 51.5 degrees, on the other hand, was about 3 degrees lower than normal. The relatively extreme range in daily temperatures generally occurred on dry days. This suggests a drier than normal atmosphere on those days, leading to greater heating by day and greater cooling at night.

White Rock set several temperature records in August. On Aug. 5, the temperature reached 95 degrees. The previous record for that date was 94 degrees, set in 1981. The minimum temperature of 45 degrees on Aug. 9 bested the previous record for that day of 47 degrees set in 1974. Finally, the low of 43 degrees on August 26 bested the 1966 mark of 44 degrees by one degree.

Average wind speed and maximum daily gust speeds were about normal in Los Alamos during August at 6 and 22 miles per hour, respectively. White Rock’s averages were 7.5 and 29 miles per hour, respectively, around 20 percent above normal there.

El Niño conditions have appeared in the tropical Pacific and are expected to grow into a moderate-to-strong event this winter, which increases chances of snow here. The El Niño predictions have apparently not yet affected the NCEP seasonal forecasts, which predict warm conditions and normal precipitation in our area through winter.