With the end of August, one of the climatic annual time frames has come to an end. Here is how precipitation record ending with the month of August:
000 CDUS45 KFGZ 010737 CLIFLG CLIMATE REPORT NATIONAL WEATHER SERVICE FLAGSTAFF, AZ 1235 AM MST WED SEP 1 2010 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LASTVALUE (LST) VALUE VALUE FROM YEAR NORMAL .................................................................. PRECIPITATION (IN)YESTERDAY 0.00 1.79 1963 0.08 -0.08 0.00
MONTH TO DATE 3.56 2.89 0.67 0.74 SINCE SEP 1 23.69 22.91 0.78 13.30 SINCE JAN 1 18.98 15.17 3.81 6.94 SNOWFALL (IN) YESTERDAY 0.0 0.0 MM 0.0 0.0 0.0 MONTH TO DATE 0.0 0.0 0.0 0.0 SINCE SEP 1 144.2 109.8 34.4 86.0 SINCE JUL 1 0.0 0.0 0.0 0.0 SNOW DEPTH 0
Wow! 144.2 inches of snow. 23.69 inches of total water. But wait! While the 144.2 inches of snow, excuse me, 12 feet of snow is well above normal, the total precipitation is only about 3/4 of an inch above average. But, hasn’t it been wet? Or, has it been dry?
Joth J. took the data from 1950 to 2008 and plotted this histogram.
Annual Flagstaff Precipitation, 1950 - 2008
We see that 50% of all years fall in the range of 17 to 24 inches. While this September to September annual precipitation of 23.69 inches is in the upper end of the middle section, it’s not outrageously high. This was due to last fall and spring being very dry by comparison. On the other hand, for September 2008- September 2009, the precipitation total was only 13.30 inches. Clearly, 2008-2009 was a dry year that was easily outside of the 17-24 inch band. Here is how the last few years have come in for the same time frame.
Year Precipitation
2000-2001 19.9 2001-2002 11.6 2002-2003 18.3 2003-2004 15.9 2004-2005 33.5 2005-2006 12.4 2006-2007 14.6 2007-2008 19.3 2008-2009 13.3 2009-2010 23.7 Average 18.2
The average is right where is should be during this 10 year time frame. But, look at the swing over that time.33.5 inches in 2004-2005 and 11.6 inches in 2001-2002. Seems like it matches the longer-term picture. Still, there were more dry years (5 years with less than 17 inches) in the last 10 years than wet years (1 year with greater than 24 inches).
I will try to finish up a winter forecast this weekend to publish next week. How will this recent trend effect it?
