Archive for July, 2010

Largest Hail Stone Ever
July 30, 2010

Here’s a picture of the largest hail stone in terms of weight (1.94 pounds) and diameter (8.0 inches) to ever be preserved. It fell last Friday, July 23rd, in Vivian, South Dakota.

*Photo Courtesy of the University Corporation for Atmospheric Research

The stone is now at the cold lab at the National Center for Atmospheric Research in Boulder, Colorado.

A hail stone that fell in Aurora, NE a few years ago is still in the record books for greatest circumference, just slightly larger than this stone.

The plan is to make a casting of this stone so that replicas can be displayed in various museums and weather service offices.



The Jetstream
July 29, 2010

We don’t talk about the Jet stream that much in the summer, and there is a good reason for it.  It shifts north.  The Jet Stream is simply a tube of strong winds that is found in the upper levels of the atmosphere but it dictates our weather and weather patterns in many ways.  Most simply put, the colder air stays north of the Jet Stream and the warmer or milder air stays south of the Jet Stream.  In the winter, the Jet Stream can be right over us or even south of us at times.  When the Jet Stream shifts south it allows the cooler air to filter into the area.

When forecasting Severe Storms, we look for the Jet Stream to be right over us.  Severe storms are more likely when strong upper level winds are available to us.   In summer, the Jet stream shifts north, as seen below.

Very little cool air makes it into Oklahoma in the summer, because the Jet is so far north that we just stay hot.  As expected with this upper level pattern, no big cool downs in the near future, it just looks hot and humid through the beginning of August.


The Streak Ends!
July 28, 2010

Wow, yesterday was interesting, but no complaints here as our daily temperature fell 3 degrees below normal. Thus, our streak of 14 days with above normal temperatures ended. But, we may start a new streak soon, the heat will be returning!


The Hottest Day?
July 28, 2010

I posted about this earlier, but felt like pushing it back to the top of the page for today’s reading. Yesterday, we mentioned it was the hottest week of the year, but today marks the hottest day of the year. That’s right!

Today’s average high is about 94.4 degrees. After today, it will start to return back towards 94.0 degrees. It’s a shame though that even as our average high starts to cool, that our temperatures won’t! High pressure this weekend will likely bring in the 100s.


Rare Montana Tornado?
July 28, 2010

An EF-3 tornado struck a tiny community in Northwestern Montana on Monday. And while it’s not uncommon to see a tornado in Montana, seeing one of this magnitude is! Over the past 5 years, tornadoes in Montana may occur here and there from time to time.But this year seems to be the year gone crazy up there.

Already up to 24 tornadoes. And this is coming from a state that usually only sees about 4 a year. And, if you think it’s interesting to see a tornado in Montana, we may as well have considered this one in Canada!Check out the location..

So, are tornadoes in Canada even rarer? They do happen, but are usually weak and not long lasting…


Tuesday Afternoon Update
July 27, 2010

Well so far Temps are staying on the low side so our streak of above average temps may be broken.  We are holding in the 80s as of 12:30.  There are some storms firing in TX, but not much in OK so far, that is expected to change later today. Expect a few clouds from these storms later today but as High pressure builds over us Wednesday and into the weekend, more sunshine is expected.

The dew points are lower in parts of NW Oklahoma, this allows the temperature to heat up a bit more than it would otherwise, and on the flip side where dew-points are higher, temps are typically lower.  Here is an example.

Ofcourse there are other factors that affect the temperature such as sunshine vs. how much cloud cover, but this is one example of how the higher moisture content keeps temps down a bit.  These areas have higher heat index values than other places that have less moisture and therefore lower dew points.  NW Oklahoma has higher temps but the heat index is not too far off the temp, as you can see it is more significant in Eastern and Southeastern Oklahoma.


Could The Streak End Today?
July 27, 2010

The streak continues once again. 2 weeks now that we have seen above normal temperatures. Yesterday, we just barely went above normal with a high of 97 degrees. Factor in the low of 70 degrees and that made our daily temperature only 1 degree above normal. For the streak to reach 15 days in a row, we’ll need to hit a high of 97 degrees today. The waiting game begins….


Holy Hailstone Batman!
July 27, 2010

That hailstone you see above is no ordinary hailstone, it’s actually the largest hailstone ever recorded. This 8 inch wide (about as wide as a basketball) chunk of ice fell over Vivian,South Dakota last Friday. The updraft speed of this supercell had to be in excess of 150 mph to support this stone. The previous record for largest hailstone ever was 7 inches, that fell in SouthCentral Nebraska about 8 years ago. Incredible!


The Hottest Week!
July 27, 2010

Welcome to the hottest week of the entire year. Yep, that’s right… the hottest week. Now, if you look at the 7 day forecast, you may be thinking, ” hm, highs in the mid 90s, I can handle that if it’s the warmest we’re going to get”. But, not so fast. You see, just because climatology states this is the hottest week, doesn’t mean that we still can’t sneak in a heat wave during August. So, what makes this the hottest week? It’s because we’re in the middle of where our average high of 94 degrees maxes out.

After this week, our average high will slowly start to drop. By the end of August, our average high will be 90 degrees and 3 months from now, 69 degrees. So, if this is what climatology states is the hottest week of the year. What has the weather looked like during the final week of July?

We’ve seen a few 100 degree plus days during the last week of July. Last year, we had 1 during this week and in 2006, almost the entire week was over 100 degrees. Certainly makes our 97 degree high not sound quite as bad now huh?


The Streak Continues…
July 26, 2010

13 is the number for now. That is, number of days that have seen above normal temperatures in Oklahoma City. After today, it’ll likely reach 14. How long this streak goes is anyones guess. Right now, the forecast calls for the next week to see above normal temperatures. Even our low temperatures at night will be quite warm. To be honest, with the information I am seeing right now, I wouldn’t be surprised if we see this streal reach 25 days… lie.