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The latest GFS has a sizable amount of instability forecast for the area covered in Day 5, amounting to up to 2000 j/kg, considered substantial for severe storms. In addition, wind shearing from the surface to mid levels will be fairly high, at 60 knots, enhancing the potential for tornadoes.
I don't have much time, so this is all I can give you, but I do consistently update my Facebook Page at www.facebook.com/TheWeatherCentre
9 comments:
Wait, wait, wait. Last year I thought that you said that 2000 was the least needed for severe thunderstorms, and now your saying that 2000 is substantial.
I have seen severe thunderstorms develop in cape levels of only 250 j/kg. It is not ideal but it can happen. If I want severe thunderstorms I want cape values in the 1500+ range. Once things get over 3500 j/kg conditions can become very dangerous.
Please note the higher the values the higher the severe weather threat. But convective available potential energy is not the only factor when it comes to severe weather. To name a few you also need strong wind shear, steep lapse rates, and moist air.
Anonymous: Last year, that was the guideline I strictly abided by. However, after seeing the wild year of weather last year and this year, it has come to my attention that 2000 is actually pretty substantial for thunderstorms.
Eastern WX: Your last comment is absolutely correct.
Actually ERN WX's last comment isn't correct. In general yes but once things get above 3500 j/kg you also need a substantial amount of shear. Otherwise, you get a situation with random pulse thunderstorms that destroy themselves if they get too strong. If you can get shear though, high instability like that usually leads to damaging winds/hail, not really tornadoes unless the shear gets crazy (100 kts+)
Anonymous, I clearly understand you need strong wind shear in excess of 40 knots to keep supercells alive. I have seen tornadoes develop in an environment where there is very little shear. All of the shear in the world won't help if you have no cape. I said, "... you also need strong wind shear..." I have been doing meteorology for several years now.
Not wanting to be rude, but it is rare for shear to exceed 100 knots. I am a co-worker with ERN WX.
All of the cape, shear, and moisture in the world will go nowhere without a trigger. IE cold front or dry line.
Anonymous: ERN WX's comment was indeed correct.
MTG: Welcome! Yes, shearing must be very high for the strongest tornadoes. I believe April 27, 2011 tornado outbreak had a 140 mph jet stream, if I remember correctly.
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