[Request] storm widge that show difference in pressure change during a period of time

I hope that someone can help me to create a storm widget that is similar to this app in movescount.com

This App shows you the difference between initial (read at App start) and current baro pressure. The result is updated every second. If baro pressure decreases lower than -2 hP , the watch beeps 5 times. For better view the result is shown without decimals and in Pa (not in hPa; 100 Pa = 1 hPa).