Thursday, April 10, 2008

Vicky Slows Down & Tracks Farther West

This is what it will look like here at home tonight. Paul Hadfield did a great job of capturing this lightning for us in Decatur, Illinois.

Here is the big update on the weather: It looks like our call of late night thunderstorms is still on target with most of our shower and thunderstorm activity reaching Tippecanoe County after 10 p.m. We have had heavy rain in the area so far today and this will give way to thunderstorms by later this evening once the warm front moves through the area. Here is the breakdown of our severe weather potential:

We have a 25% chance of 58 mph wind gusts or higher late tonight and Friday morning within 25 miles of your backyard. I have a high wind gust potential at 60 to 65 mph as our 5,000 foot winds increase tonight to near 70 mph. This can sometimes be forced or pushed to the ground during strong thunderstorms.

There is a 20% chance of large hail of nickel size or greater. I think the higher threat of hail would be across north and northwest portions of our viewing area.

There is a 5% chance of a tornado, but right now the greatest threat for that happening looks to be in southern Indiana, especially south of Bloomington.

The storm track is a bit farther west which we saw so many times during the instead of missing out on snow, we could very well miss out on the brunt of the severe weather. But remember it only takes one isolated storm to cause big trouble around here.

Update on the Meteorological Soundings:

CAPE will rise to near 1,000 j/kg late tonight and early Friday morning.

The LIFTED INDEX will be near -3 by morning.


I will have the charts on these numbers and what they mean here this evening and post the changes to get some trends. It is all about NOWCASTING in these situations and that is why Live Doppler 18 is so important. I will keep you posted. A special thanks to our Purdue intern Pat Wright for putting this together for us while I did some weather maps this afternoon!

Lifted Index:

+3 to +1: Slightly Unstable, chance of showers

+1 to -1: Unstable, expect showers and possibly an isolated thunderstorm

-1 to -3: Moderately Unstable, supports widespread thunderstorms

-3 to -6: Very unstable, widespread thunderstorms that may be severe

< -6: Extremely unstable, widespread severe weather

Total Totals:

44-46: Spotty weak thunderstorms

46-48: Isolated moderate thunderstorms

48-50: Heavy thunderstorms

50-52: Heavy thunderstorms with hail possible

52-56: Heavy thunderstorms with hail and possibly tornadoes

56 or greater: Heavy thunderstorms with tornadoes likely


500-1000 J/kg: Thunderstorms are possible

1000-2500 J/kg: Moderate thunderstorms, possibly severe

>2500 J/kg: Severe Thunderstorms likely

These numbers are only guides and should not be taken literally, just like our weather models.


Anonymous said...

Mike...thanks for that scale you shared with us as well as the explanation. I am keeping that one in my wx files. You did not mention the flooding prospects on here. Got any update on that? And, my baro is starting to level out. I had a low reading of 29.57 with the arrow leveling out at 29.63. I am up to .85 inch rain with the creek filling up. Benton County seems to have had more rain which is not good news for us.

Mary Anne in Remington

Anonymous said...

That was interesting to read the numbers, and what it means in terms of weather.

I never heard of these numbers/terms before - so it is nice to learn something new about the weather.

I enjoy your blogs, when you are able to put in information, such as the info you shared on this blog.

Mary Anne in Remington was asking about the River Levels and the prediction. There is a web site that I always refer to - it is a part of NOAA and called the "Advanced Hydrology Prediction Service". It is fairly accurate, and hs been in invaluable resource for me. I was elated to see that the expected crest at the Wabash, in Lafayette, went down from 17.5 ft to 14.2 ft (whew).

Again - thanks for the blog and the great information you share with us.

River Lover
West Lafayette