Archive for August, 2010

Beyond The Cone of Uncertainty
August 31, 2010

Every time a storm forms, The National Hurricane Center issues a storm track that contains a “cone of uncertainty”. But, why is there such a thing ? It’s quite simple, because of situations that we are getting ready to deal with. For Oklahomans, it’s just your typical cold front, but for those along The East Coast, it’s more than just a blue line with barbs on the weather map.Why? Because the speed of this front will make a world of difference in whether Earl makes landfall, or if it never touches US soil. I’ll explain:

Let’s say that this cold front decides to slow down some, this would likely be a worst case scenario as it would play out something like this:

A landfalling hurricane in the U.S.. Again, this would be if the cold front slowed down some. Now, let’s assume that the front speeds up, then what? Well, good news!

If the front speeds up, the hurricane never makes landfall in The United States (perhaps somewhere farther north in Canada) saving millions of dollars in tourism money for Labor Day and damage. Either or, many people along The East Coast will be paying just as much attention to a dangerous hurricane as they will to a cold front moving across The Central Plains.



Rainy Season Returns?
August 31, 2010

Who could forget August? As much as we would like, we’ll remember it for the heat, the lack of rain and the onset of a drought.

But, all hope is not lost if  our goal is to get rid of this drought before we go into the dry winter season. Because while August gave us very little rainfall at Will Rogers Airport (not even .10″), September is a fairly wet month for us as we usually average almost 4.00″ of rain, making it the 3rd wettest month of the entire year!. It’s much needed too because after September, our average monthly rainfall begins to drop sharply and won’t be this high again until next May. Fortunately, September may start off rather wet (no complaints here).

A cold front (don’t worry, it’ll be gone by Labor Day Weekend) is expected to bring us a fair amount of rain late Thursday night/Friday morning. The NAM model this morning was squeezing out as much as 2 inches of rain, while the GFS model was indicating about 1.5 inches of rain.


We’re Done with the 90s!
August 30, 2010

That’s not a typo, after today, we’ll be done with the 90s. Err..I mean, done saying that our average high temperature is in the 90s. lie…check it out:

Today marks the very last day where our average high is in the 90s. Starting tomorrow, it drops into the 80s. Our average highs won’t return into the 90s until next June. But, does this mean we won’t see any more 90s? I wish..sadly.. they’ll still stick around for a while .


Do You Believe in the Farmers Almanac?
August 30, 2010

The Farmers Almanac just issued their winter outlook and while some may scoff at what The Almanac says, this year, I don’t find myself disagreeing with it all that much. Here is what it’s saying:

A ‘kinder, gentler winter on tap”. It seems rather easy to understand from a meteorologist’s point of view. The main reason..2 words “LA NINA”. As La Nina shows signs of returning, thei mpacts it has on The United States are huge. For some, the news is welcome, for others, it’s rather upsetting. I’ll let you pick what you like about this graphic:

La Nina is typically most pronounced during the winter months, and thus, the outlook is that we’re likely to see a warm and dry weather pattern. Some may enjoy the warmth, however, this pattern usually comes with the increased threat for a high fire danger during the driest time of the entire year. So, why do I believe the Farmer’s Almanac this year? With La Nina in place, we’re bound to see less snowstorms and cold this winter compared to last, that is, if past history is any indicator of future performance. But, am I to say that we won’t get any snow this winter? I wouldn’t say that. We’ll still see our chance of snow and ice, but the likelihood will be some what less.


Farewell to Summer?
August 30, 2010

Are we saying farewell to summer? Well, kinda..depending on who you ask. In the meteorological calendar, summer ends on Wednesday. (Not sure why, it’s just what I was told in my weather classes). So, as we head into the first week of September, where should we be with our temperatures?

Average highs for the first week of the month are in the upper 80s and by the end of the month, upper 70s. So, when the 80s come knocking next month, don’t be surprised…that’s normal.


The End Of Sumer…Kinda, Sorta
August 29, 2010

Summer offically lasts until September 21st, the date of the autumnal equinox, when the sun’s rays are directly over the equator.  However, in meteorology the seasons are simplified into three month blocks.  The months of June, July and August are meteorological summer.  So starting September 1st, Wednesday, meteorological autumn begins.

Whether you start your autumn on Wednesday, or you wait until the third week of September, you can’t deny that summer is losing it’s grip on our weather.  It still may be hot and humid, and your air conditioner is still going to get a workout for awhile, but the seasons are transitioning.  Look at the number of minutes of daylight we now have as compared to just two weeks ago.  There is nearly 30 minutes less daylight today than there was back in mid-August.  We’re losing daylight at a rate of 2 to 3 minutes a day.

As that is happening, the sun angle is decreasing as well, meaning less of the sun’s energy is reaching the earth. The highest point above the horizon the sun reaches is 78 degrees on June 21st, the first day of summer.  That is when the sun is the strongest.  By July 4th, the sun angle has decreased to 73 degrees.  Today, at it’s highest point in the sky, the sun angle was 63 degrees.  By Halloween it will be down to 40 degrees, and on December 21st, the first day of winter, and the shortest day of the year, the sun angle will be a measly 31 degrees.  Remember, the smaller the sun angle, the less energy is reaching the earth.  Less energy from the sun means less warming of our atmosphere.

Our atmosphere cools first most dramatically in the northern latitudes where the sun angle is lower even in the summer compared to those of us in the south.  This leads to pools of cooler air that move south into the United States behind the first cold fronts of the season.  At first the fronts are fairly weak (although last week’s was a nice doozy), but they get colder and colder as we move deeper into autumn.

So even though the calandar says we still have three weeks of summer, know that autumn is lurking just around the corner, even if you can’t quite feel it yet.


Earl Will Make The East Coast Squirm
August 29, 2010

Hurricane Earl is still out in the Atlantic, moving west-northwest at 12 mph with winds of 85 mph.  The storm will strengthen in the next few days with winds increasing to 115 mph by mid-week.  Earl’s projected path takes it awfully close to the East Coast, especially from North Carolina northward to New England.  Right now a direct hit does not seem likely, but a glancing blow to places like the Carolina Outer Banks, and New England’s Martha’s Vineyard is possible.  It would not take much of a westward shift in the path to put places like Washington D.C. and New York City in harm’s way.  This will be an interesting storm to watch in the coming week.  Here’s the current path (which will likely change a bit over the next few days):


Earl Continues to Strengthen
August 28, 2010

Tropical Storm Earl fought some shear earlier today, but conditions look favorable for rapid strengthening over the next 48 hours Earl’s maximum winds are now 65mph, and it should become a hurricane on Sunday. The minimal central pressure has also dropped to 989mb.

Earl is headed towards the Leeward Islands, where Tropical Storm Warnings will probably have to be upgraded to Hurricane Warnings soon. The British Virgin Islands, U.S. Virgin Islands and Puerto Rico also look to feel some impact from Earl.

Looking forward, Earl’s path make take it closer to the East Coast of the U.S. than we have seen from any other tropical system this year. The official forecast has Earl becoming a Category 3 (major hurricane) with winds of 115mph by late Tuesday, and maintaining that strength through Thursday.

Noticed the far left side of the “Cone of Uncertainly” would have Earl close to making landfall near Cape Hatteras, North Carolina.


Understanding The Drought
August 27, 2010

As Rick mentioned last night, the drought conditions continue to worsen across most of Oklahoma despite the fact that some areas did receive a healthy amount of rain this past week. However, the heaviest of the rain was isolated to only tens of miles and did not affect everyone. However, while we are now seeing the drought approach Oklahoma City, it’s a “special” kind of drought that we’re dealing with. I’ll explain..

There are 3 types of droughts. A meteorological drought, an agricultural drought and a hydrological drought. A meteorological drought is a drought where below average precipitation is experienced for a prolonged amount of time. An agricultural drought is one that affects crop production ( usually due to prolonged periods of below normal rain). And third, a hydrological drought where th lakes are impacted by having low water levels.

This particular drought that we’re dealing with is mainly an agricultural drought that is mainly impacting the farmers. (As well as locals who relay on Mother Nature to supply water to their lawns). Here is why things may be looking a bit brown lately:

Of course, this reading is from Will Rogers, but you get the point. That amount of dryness will certainly lead to a drought. Remember, it’s not how much rain you see, it’s when you get it. So, even if we’re still above normal for the year (2.75″), the recent dry spell is what’s hurting us. Reports suggest that the soybean crop is really the only crop that has been impacted, which even so has been very little. But, things could get worse if rain doesn’t come in soon!


Remember When…
August 27, 2010

Do you remember when we last got into the 50s here in Oklahoma City? This morning we did it, barely, at 59 degrees. So, when did we last hit the 50s? Yesterday? Nope. Two days ago? No…

You have to go back to May 21st when we last hit the 50s here in OKC. That was shortly after we had our last HIGH RISK severe weather day here in Oklahoma.