Updraft: December 28, 2010 Archive

Driving force

Posted at 6:52 AM on December 28, 2010 by Craig Edwards
Filed under: Winter storms

Image of the GFS forecast position of the jet stream at 6PM CST on Wednesday. The strong wind maxima indicated by the red color, exceed 100KTS. One jet streak is about to sweep into northern Mexico, while another stronger jet is diving southeast off the Pacific Coast.

These jet streaks play a big role in spinning-up the weather at the surface. They work to distribute thremal energy in the atmosphere, plunging cold air south, or transporting warmer air north.

For the time being enjoy the rather quiet weather pattern the next thirty-six to forty hours. A push of milder air over the dense snowpack has the potential to initiate some freezing drizzle and fog on Wednesday night and Thursday.

Temperatures should climb above the thawing point on Thursday, thus precipitation should be in the form of just rain in southeast Minnesota during the afternoon.

Here's a graphical forecast from the Chanhassen NWS issued Tuesday morning. Note that they indicate even the second low pressure may be close enough to eastern Minnesota to produce a mixture of rain and snow in the Twin Cities on New Year's Eve.

CE

Tracking two low pressure centers

Posted at 4:59 PM on December 28, 2010 by Craig Edwards
Filed under: Winter storms

This forecast map from the GFS at about the five thousand foot level indicates that the dew point temperature of plus two to plus four degrees Celsius over a large part of eastern Minnesota suports rain at noon on Thursday. From about Brainerd to Duluth northward the surface temperatures will hoover close to thirty-two degrees.

Here is the latest concensus track for two surface low pressure systems. System one has the potential to dump four to seven inches of snow from Grand Forks to Roseau, including Thief River Falls on Thursday.

The second low tracking towards Kansas City on Thursday could turn north and produce a band of heavy snow close to the Twin Cities to Duluth on Friday into New Year's Eve.
CE