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2.
The uncontrollable excitement that extreme weather geeks get when signs of fun weather appear on the long-range forecasts. If the forecast becomes more boring as the time frame gets nearer, a forcasm can be followed by severe depression.

NOTE: The definition of "thrilling weather" is subjective and varies from person to person.
When a possible March blizzard showed up on the 10-day forecast, Dave began having an intense forcasm. But it was short-lived, as two days later the forecast showed nothing but the usual cold March rains. However, that caused Julia to then have a forcasm because she'd already taken off her snow tires and wasn't looking forward to another round of snow and ice. The disappearing blizzard was a huge relief!
by DJ Bonneromics February 26, 2012
 
1.
The time you're very exited about any kind of specific weather, mostly snow or rain etc.
usually the weather will cancel any sort of activity you would kill yourself to go to.Usually at a family picnic or a boring meeting. exitment
(1st guy): Dude, i'm about to have a major forcasm now!
(2nd guy): What for?
(1st guy): My friend told me the rain is gonna pour! Let's hope that the family picnic gets canceled! We can do whatever we want!
(2nd guy): Yeah!
by Spazbo 777 February 18, 2009