Crafting a forecast with the tools at hand

Posted at 3:34 PM on December 1, 2011 by Craig Edwards (1 Comments)
Filed under: Cold, Forecast models

It's times like these where a meteorologist gets pumped about the profession. Sorting through the computer models, matching the satellite data with previous computer model output and tracking surface weather make the job challenging and sometimes even rewarding.

Here's the infrared satellite imagery at mid afternoon. The large scale circulation over the southwest corner of the US appears to be more tame than the weather reported from southern California to Colorado. Winds have gusted from 60 to 80 miles an hour from near Los Angeles to Las Vegas in the past eighteen hours. The national news networks are delivering the details of this savage weather.

Meanwhile another surge of cold air is sweeping through Albert, tracking toward the Dakotas and Minnesota as indicated in the enhanced (red) cloud tops.

These two separate systems are likely to meet up from Minnesota to Missouri on Saturday.

Here's an image of the mid level jet stream from noon today. The wind field is approximately 18k feet.

The closed circulation of the upper low stands out over southern California and Arizona. Wicked winds have been induced at the surface as a result of the topography and the atmospheric dynamics of this system.

By noon on Saturday, as shown by the NAM, the low in the southwest has weakened and continues to track east, but no longer a closed circulation. At the same time a trough has been craved out in North Dakota. These two forces of nature will combine to create the problematic weather in southeast Minnesota.

The reflection of weather on the surface is what television weathercasters typically deliver to the viewers to keep the meteorology simple. But significant precipitation is induced by factors at cloud level of 5K and greater.

Here's the consensus track of the surface low from NOAA for the next couple of days. Indeed a favorable track for snow in our neck of the woods, but not a particularly deep center of low pressure.

Put this altogether and it still targets the best chance for accumulating snow over southeast Minnesota. NOAA's Environmental Prediction center indicates the most likely area for four or more inches of accumulation on Saturday.

Want the condensed version of this story? See this snapshot from the Chanhassen NWS Office.

Tune in tomorrow morning for details of your weekend weather forecast.
CE

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Comments (1)

Such a beautiful cut off low. Enjoyed the explanation of the strong Santa Ana winds. Hope we get snow. Sandy

Posted by Sandra Anderson | December 1, 2011 7:59 PM

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