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I Need Help Forcasting Extreme Weather! - Tips


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  • Location: West London - ASL 36.85m/120ft
  • Weather Preferences: Cold/stormy
  • Location: West London - ASL 36.85m/120ft


I do this as a hobby so im not the best at this. But i need help forcasting Storms ( not that we get any around here).

this is how i think you forcast it.

Extreme Snow I.e heavy snow.

528 dam line or below.

Low dew point around -3°C for the best flakes.

Temp around -1,2,3 and 0,1,2,3 °C

Cloud cover and precipitation.

So if that was the conditions that the GFS charts said Then there would most likely be snow?

Now for Thunder and lightning and tornados :D

Nice warm tempretures 20 - 35 °C

Slightly lower dew point.

CAPE, around 500+

Lifted indext 3 and lower.

Thats good conditions for a thunder storm. I just want to know If im right on that.

Now for the really big question.

I want to know what satalite images do to help. How can i use them to perdict how big a storm thats already occured will be?

I know i sound stupid but i want to know more


Cheers Liam,


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  • Location: West London - ASL 36.85m/120ft
  • Weather Preferences: Cold/stormy
  • Location: West London - ASL 36.85m/120ft

Perhaps a little too specific with your numbers regarding the ingredients needed for thunder and lightning - you don't necessarily need to meet the above for such activity. To simplify, a pool of cold air aloft associated with an upper trough (generally using the 500mb level as a guide) with only modest boundary layer moisture will provide the necessary ingredients for storm development. Cold air aloft is necessary for storm development during the colder seasons given the lack of solar input and moisture during this part of the year. Obviously the better the factors, e.g. higher CAPE, moisture, steep lapse rates, etc, the better the chance for good storm development.

However, the above factors are meaningless if there is no forcing mechanism in place, such as a front or post-frontal troughing, to act as the "trigger" for storm development. Concerning tornadoes and severe thunderstorm potential, you want to be looking at the vertical wind shear profile, either by looking at a Hodograph as part of a Skew-T diagram, or by looking at the relevant charts from the GFS. Backed surface winds and fairly strong veering of the wind profile with height (so a change in wind direction with height) will increase tornado potential, whereas only a considerable increase the winds with height, i.e. no change in direction with height, will increase the potential for organised, long-lived and/or severe storms. Also, with severe storm potential, an intrusion of dry air in the mid-levels, together with a good shear profile and decent instability, will be provide optimal conditions for such storms to develop.

As for satellite imagery, storms that are shown to flatten out (like a pancake) at their top is an indication that they have reached the maturity stage of a typical storm's lifecycle and, assuming they're in an environment of weak shear, will slowly dissipate as the downdraft dominates the storm. Storms in an environment of strong winds aloft but with little turning with height, will see their cloud tops blown ahead of the storm in relation to the storm's motion, as the downdraft is seperated from the inflow of warm, moist air "feeding" the storm, thus the storm will have increased longevity.

Thanks for that. The satalite imagery is now done for me i know it :)

How to i tell for a front or postal front troughting?

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