Let it pour: December more wet than dry

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By Scot Johnson

December began warm and wet, and ended cold and dry, with winds considerably stronger than normal.Overall, wet won over dry with December’s monthly precipitation totaling three times the norm in Los Alamos and White Rock. Also, cold prevailed as the average temperature was about two degrees below normal, the lowest in comparison to the normal climate since last January. December began with a soaking as a slow-moving storm moved in from Baja California. One-and-one-quarter inches of rain fell in Los Alamos on Dec. 1, as much as came down the day before.By Dec. 2, the monthly total precipitation count was well above the normal 0.92 inches (liquid equivalent) in Los Alamos and 0.69 inches in White Rock. Disappointingly, the southerly flow was too warm to produce snow, even on Pajarito Mountain.But snow came shortly after, with another set of storms that spanned Dec. 7-11. The moisture again came from the south, as it so commonly does during heavy snowfall events. Almost 1.5 inches of liquid equivalent were counted over the five-day span in Los Alamos along with 9 inches of snow.Again, the warmth took a toll on the snowfall, as the ratio of snow to liquid equivalent was about six-to-one, where it is typically more like 10- or 15-to-one in December.By Dec. 8, the unseasonable warmth had given way to colder-than-normal conditions that would remain for the rest of December, owing to storms and an endless barrage of cold fronts.December’s average temperature was about 28 degrees in Los Alamos and White Rock, two degrees below the norm of 30 in both towns.The average wind speed in Los Alamos and White Rock during December was more than six miles per hour, about 30 percent above normal for Los Alamos and 20 percent above White Rock’ normal wind speed.Average daily maximum gust speeds were 24 mph in Los Alamos and 22 mph in White Rock, about 20 percent above normal in both towns.The strongest gusts of the month came during the waning hours of the Nov.30-Dec. 1 storm. Gusts in Los Alamos reached 50 mph in the afternoon of Dec. 1, and 56 mph in the early morning hours of Dec. 2.In White Rock, a gust of 47 mph was recorded Dec. 1. The snowfall total so far this season is 15 inches, where 19 inches is normal for Los Alamos.The yearin weather

Total Los Alamos precipitation for 2007 is 20.3 inches of liquid equivalent (melted where the precipitation is snow or hail), 7 percent above the normal 19 inches. White Rock’s 2007 total is 15 inches, or 12 percent above the normal 13.5 inches there.The average temperature in Los Alamos during 2007 was 49.2 degrees, exceeding the 1971 through 2000 average of 47.9 degrees for the 10th year in a row.The moderate La Nia event in progress in the tropical Pacific is expected to remain moderate-to-strong through February and then gradually diminish. The expected impact on New Mexico includes warm and dry conditions through at least March.

Scot Johnson is a meteorologist with the Waste and Environmental Services Division, Geotechnical Services Group, Los Alamos National Laboratory.