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A Very Typical La Nina Year

By Joe D'Aleo
Monday, September 15, 2008

Early this year in several stories we wrote about what La Ninas and a negative PDO mean for our weather. So far every one of the typical characteristics have been seen.

(1) With more La Ninas than El Ninos, declining global temperatures. This has been the case this year

(2) More cold and snow across the northern tier from the Pacific Northwest and Rockies into the northern plains to the Great Lakes and Northern New York and New England.

This past winter had heavy snows in Washington and Oregon and all-time record seasonal snows from parts of Colorado and Wyoming to Wisconsin, parts of Ohio, Vermont, New Hampshire and Maine and much of southern Canada


(3) More winters with below normal snow Mid-Atlantic south (with the exception years in the occasional usually weaker El Nino).


Below normal snows fell from southern New England and New York south.


(4) More late winter and early spring floods from late storms and snowmelt for the central and northern states.

Many central areas had more than 50% above normal rainfall coming after a wet/snowy winter with saturated ground. This led to the worst flooding since 1993 in places.


(5) Dry winters and early springs in the southeast including Florida with spring brush fires.


The case this winter and early spring, for the southeast states a continuation of a drought that began last summer as La Nina first developed.

(6) Dry winters in the western part of the southern and central Plains


See that also the case as shown above.


(7) More Atlantic hurricanes threatening the Gulf and east coast from Florida north, especially as long as the Atlantic stays warm (Atlantic usually lags up to a decade or so after the Pacific in its multidecadal cycles).


We have already seen landfalling storms in the Gulf, Florida and the east coast. Still well over 2 months left to the season.


(8) Greater chances of growing season drought in the major growing areas during onset years, especially when they occur after El Nino winters.  Second La Nina summers are often cooler and wetter.


Last year we came off an El Nino in the winter to a La Nina during the summer. Developing heat and drought in the southeast states during the summer gradually spread west and north during the late summer. This summer was cooler and wetter even in the southeast.