The Weekly Global Climate Highlights
(WGCH) provides a quick, but not necessarily comprehensive, look
at current climate anomalies and episodic events. The product is designed
to alert the user to significant situations that warrant further examination
or study.
Typically, wet and dry anomalies
are characterized by 4-week precipitation totals which fall in the highest
or lowest 10% of a gamma distribution, which is bounded by zero. The 4-week
period was selected because of the high variability of precipitation totals
over space and time.
In contrast, mean temperatures, which
are more continuous (or smooth), are calculated for 2-week periods (to
eliminate large-scale synoptic features) and then compared against the
highest and lowest 10% of a normal distribution.
Episodic events are severe weather
conditions (tornadoes, hurricanes, flash floods, blizzards, etc.) that
have a significant impact on human activities.
Weekly
www.nws.noaa.gov 
