Paul Knight - Winter Outlook '08 / '09

Pennsylvania State Climatologist and senior lecturer of synoptic meteorology at Penn State University...Paul Knight latches onto what may be this winter/s sleeper leading indicator...the apparent development of a relatively weak la Nina...as suggested strongly by the MEI...which has been below the -0.5°C threshold for the two most recent reporting periods (AS & SO).

"The two oceanic influences that will have some effect on this winter’s weather in northeast North America will be the developing weak La Nina and the continuing cool phase of the Pacific Decadal Oscillation (now in its 8th year). These two favor below normal temps in the northern tier of the nation, above normal in the southern states and an active storm track in between.

"Another index that is likely to be negative for the majority of the winter is the North Atlantic Oscillation - NAO - and this also favors cooler than normal conditions in eastern North America.

"Finally, the fact that the majority of this season’s tropical storms occurred prior to Sept 10 favors cooler than normal weather in the eastern US. Add to this, the CFS forecast from NCEP that shows colder than average temps likely in Nov-Dec and part of Jan - this leads me to the following estimate for southwest Pa and the Laurel Highlands:

"Above average snowfall (most coming in Dec)
Colder than average beginning, but then warmer than normal end
Generally more snow than last year
Colder than last winter in the mean, especially from mid-Nov until mid-Jan.

"Who knows when big storms will come along, though we’ve had a major snowfall between Dec 2-6 on 3 of the last 4 years."

Knight/s outlook was issued in response to an inquiry by TV station WJAC of PA universities with meteorology programs.