To John Fleck
BY Recent stories
by John Fleck
$$ NewsLibrary Archives search for
John Fleck '95-now
Thursday, July 03, 2008
Local Precipitation Patterns Cause Arguments Among Meteorologists
By John Fleck
Journal Staff Writer
You can feel that muggy air pushing out the dryness of June, and the perennial question returns: Has Albuquerque’s monsoon season begun?
Humidity is up, swamp coolers are laboring, and thunderstorms are forming around New Mexico every afternoon. After a withering spring, is the rainy season finally here?
There is no better way to trigger an argument among New Mexico meteorologists than to ask whether the monsoon has started. But a new by-the-numbers analysis suggests a way to answer it, and the answer as of earlier this week was a hesitant “yes.”
Every summer around this time, weather patterns shift and moisture streaming up from the south is converted into sometimes dramatic afternoon and evening thunderstorms. These rains bring Albuquerque as much as 40 percent of its annual precipitation.
But the arrival of summer rain here is an uncertain affair. It lacks the drama of India’s monsoon.
Winds in India can shift in a day, blowing in from the Indian Ocean and changing the weather from bone dry to a deluge. “They really do get a burst,” Deirdre Kann, lead scientist at the National Weather Service’s Albuquerque office, said.
Die-hards might complain about calling our summer rains a monsoon, pointing out that our version is far less significant than India’s. But Kann defends the term, noting that the predictable seasonal rains match the scientific meaning of the term.
Here, monsoon weather begins to the south as rainstorms creep up Mexico’s central mountains through June. By that measure, the monsoon is on our doorstep, weather service meteorologist Jesus Haro said.
“They have been getting cranked up pretty good in northern Mexico,” Haro said.
But Albuquerque typically does not experience a sudden wind shift or defining deluge. We’re more likely to slide gently into a rainier pattern — rain some afternoons; other days dry.
So Patrick Higgins, a University of New Mexico student, went data diving last year, digging through numbers from the National Weather Service archives looking for some sort of sign that might tell us when the rainy weather is here to stay.
The problem, according to Higgins, is that we can have “false starts,” days when it starts raining in late June or early July, only to turn dry again.
Higgins, working with UNM climate professor Dave Gutzler, looked at wind shifts to see whether there was an India-style signal in weather service data that might signal that the rains are here to stay. He found nothing.
But Higgins hit pay dirt when he looked at dew points, a measure of moisture in the air. When moisture stays high enough three days in a row, he found, you can be fairly confident the rains are here for good.
By Gutzler’s calculation, Tuesday was the third consecutive day that met Higgins’ test.
But it seems unlikely that Higgins’ analysis will settle the perennial argument among New Mexico meteorologists.
Haro said Tuesday that current conditions do not look like the monsoon to him. Most of the moisture now in the Albuquerque air is left over from weekend storms, which came from the east, not the south, he said.
Whatever you call it, the weather service is forecasting a chance of rain in Albuquerque every afternoon this week.