Tuesday, October 6, 2009

Taste Of Winter For Some

Parts of southwest North Dakota received the first accumulating snow of the season Monday with 1 to as much as 4 inches in a few locations.

More snow could be in store this weekend as a chilly storm system moves into the northern Rockies and high plains.

Perhaps chilly is an understatement -- maybe I should have said very cold! Temperatures across portions of North Dakota could drop as low as 15 degrees with the new storm system.

In fact, the Climate Prediction Center is outlining a huge portion of the middle US for below normal temperatures this coming weekend, along with some wet weather.

So let's wait and see just how this weekend weather system unfolds!

Here is another installment from our Hawaiian blogger....Ben Black.

Take a look at NOAA’s Northern Pacific weather maps at http://www.prh.noaa.gov/hnl/graphics/npac.gif and you’ll see that for much of the year, one or more high pressure areas align in a “convoy” near the 40th parallel north of Hawaii and glide slowly in succession toward North America.

The rotation around these “highs” reinforce the trade wind flow toward Hawaii to the south, and add impetus to the movement of storms in the north Pacific and Alaska. When a low is introduced to the tropics south of these high pressure areas or slips into traffic between the highs, interesting dynamics develop that can stop or reverse the trade wind flow around Hawaii. Depending on the location of the low, Hawaii might see a localized reversal of the direction of prevailing winds that we call “Kona” winds. These can draw up even warmer, more humid air from the equator. When a Kona storm or Kona winds move in, they can make the westerly sides of the islands rainier and leave the eastern sides dry and sunny.

Here’s a weather map from 9/29/09 that shows a low that’s worked into the line of high pressure areas. Compare the with this detail from the GOES-11 satellite photo to see the gorgeous pinwheel effect that spins out of this low pressure area.

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