The temperature-based turfgrass growth potential predicts how grass growth can respond to temperature. This growth potential (GP) was developed by PACE Turf and has been put to many uses such as predicting the time of overseeding, estimating turfgrass nitrogen requirements, assessing turfgrass stress, and evaluating growth and optimum times for various maintenance practices.
When the temperatures are not conducive to growth for cool-season (C3) or warm-season (C4) grasses, there isn't much one can do to force the growth. Extra nitrogen can be added, but it really doesn't have its full effect until the temperatures get into an optimum range for growth.
After reading that tweet, I looked up the temperature data for Tulsa. Sure enough, the growth potential for C3 grass has been pretty low for the past month. Growth potential of C3 and C4 grasses at Tulsa are plotted in this chart, with data included for the past 472 days, from 1 January 2013 until 17 April 2014.
I find the growth potential useful in a lot of ways. On golf courses with both cool and warm season grass, as at Bristol Hill Golf Club near Kisarazu, it can be useful to study the growth potential when planning maintenance activities.
Cool season (C3) and warm season (C4) grass at Bristol Hill Golf Club near Kisarazu, Japan
The GP at Kisarazu for the past 472 days is show below. Ideally, disruptive maintenance practices such as scarifying or core aerification will be done at times when the turf has a high growth potential. This allows for a rapid recovery time and minimizes disruption to play.
I looked up the data for a couple other cites. At Sydney (data from the Sydney Airport), the temperatures are milder.
At Dubai, the temperatures are more extreme.
With all the variation in temperature from place to place, there is also a big difference in the way grass will respond. The growth potential puts a numerical value to this. This can then be used in maintenance planning, in useful comparisons to other locations, or in explanations of why the turf is responding in a certain way.