Monday, December 27, 2010

End of week warmth could lead to flooding problems

While much of December has seen below average temperatures, it looks like for the last couple of days of 2010 we'll actually rise above...well above average!  A pretty big pattern change in the jetstream is about to take place and replace the trough we've had in place with a ridge of high pressure starting Wednesday night.  As this change takes place an area of low pressure will begin to develop along the Rockies and move eastward into the Plains by Wednesday night.  Gusty southerly winds ahead of this system will help transport warm, moist air from the Gulf in the Great Lakes.  With temperatures expected to remain just below freezing Wednesday night areas of freezing drizzle/rain could be possible before temperatures rise above freezing Thursday afternoon.  This will change any frozen precipitation over to light rain showers.  Along with the rain will come the potential for locally dense fog to persist through the end of the week.

As the low moves closer Friday afternoon, heavy rain and maybe even a few thunderstorms could be possible during the afternoon and evening hours.  Temperatures will likely rise into the middle and maybe upper 40s.  I'm a little hesitant on going any warmer just because if we stay foggy through much of Friday we'll have a hard time reaching the 50s.

With the transport of moisture from the Gulf heavy rainfall could be possible Friday which would likely lead to some flooding concerns as the ground is frozen and the current snow cover is over a foot deep in some spots.  Latest trends of the weather models has been to back off on total rainfall amounts.  If this trend does continue then the current snow might be able to absorb some of the rainfall.

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