#PRECIPITATION TOTALS MAP SERIES#

Also, in just the past two years (20), eight of the sites-or more than 10%-experienced their wettest single year on record. All of those sites that observed their driest year on record were in the west, with the exception of Birmingham, Alabama (its driest year on record was 2007). Since 2001, 23 of the 70 sites have experienced their single wettest year on record versus 11 their driest. It’s interesting to note that, along the West Coast, this decade has so far been Seattle’s wettest on record whereas it has been Los Angeles’s record driest decade. Maps by climatologist Brian Brettschneider also show an increasing precipitation trend for many U.S.

We will likely see this reflected in increases at many sites when the 30-year standard climatology shifts from 1981-2010 to 1991-2010. The trend toward increasing precipitation is notable especially for the period of 1991-2019 with 44 sites (well more than half of all 70 sites) observing their wettest decades since the 1990s compared to only 5 observing their driest such. As is evident in the table, the central portion of the country was most affected. This, of course, is not surprising given the famous drought during the Dust Bowl era of the Great Depression. The driest decade was that of 1931-1940, with 19 sites observing such and only two sites observing their wettest. By this measure, the wettest decade has been (so far) the current decade of 2011-2019, with 26 of the 70 sites observing their wettest decade since 1901 and only one site (Los Angeles) observing its driest such. The most pronounced increases have been in the Northeast, Ohio Valley, and Upper Midwest. Northern Rockies and Plains: + 0.11” per decadeĪs can be seen, all regions of the country have seen an average decadal increase in precipitation since 1901, aside from the Southwest region, which has seen a slight decrease. From the Climate at a Glance website, the average per-decade regional change in precipitation for the period of 1901-2019 has been as follows: into nine different climate regions as shown above. The book contains month-by-month precipitation totals for Death Valley since the site became operational in October 1911 (hence there is no data for the first decade in my table below for this site). In addition, for Death Valley, California, I used the monograph The Death Valley Climate Book, compiled by Chris Stachelski and published in July 2013 by the National Weather Service office in Las Vegas. Much of this early data is not available in NOWData.

from the beginning of their PORs through 1922. These reports (which I have in my weather library) contain month-by-month precipitation totals for every site in the U.S.

#PRECIPITATION TOTALS MAP SERIES#

Weather Bureau’s three-volume series “Summaries of Climatological Data by Sections, Bulletin W” (U.S. In some cases the older data had to be retrieved from the pages of the U.S. The data is 90% sourced from the NOWData files from NOAA’s National Centers for Environmental Information (NCEI). The list is arranged in a general progression from north to south and east to west in order to make it easier to compare how cities fared in the same region relative to one another. These sites were chosen for their continuous POR (periods of record) dating back to 1901, and also in an attempt to give equal weight to each region of the United States. I will also comment briefly on how the decadal snowfall totals compared to the decadal precipitation records for the 40 sites that I covered in my snow survey.īelow is a table of decade-by-decade precipitation annual averages for 70 select sites in the contiguous U.S., as shown above. In this blog I do the same for overall precipitation, but for 70 sites instead of 40, since I now include all of the climate regions of the contiguous U.S., not just those that receive regular winter snowfall.

snowfall decade by decade for 40 significant sites across the contiguous U.S. In a Category 6 entry I posted this past January, I took a look at U.S. (Missouri Highway and Transportation Department) The largest total has been in the current decade (2011-2019, but still one year to go), with 26 of the 70 sites measuring their wettest decade since 1901 in the 2010s. Fourteen of the 70 sites investigated in this post had their wettest decade on record in the 1990s, which is the second largest total for any decade.

Above: The Missouri River floods Missouri’s state capitol, Jefferson City, during the great spring flood of 1993.

Precipitation totals map