Archive for November, 2011

Drought Update
November 17, 2011

The latest drought monitor was just issued for the week and it continues to show improving conditions across the region. For the 1st time in a long time, the weakest of the drought (ABNORMALLY DRY) conditions are now appearing in Eastern Oklahoma. Oklahoma City, which last week had EXTREME DROUGHT conditions is now showing a drop in the drought to SEVERE DROUGHT status. Western Oklahoma continues to show the worst of the drought, EXCEPTIONAL DROUGHT. From where we were a few months ago, this drought monitor is looking very nice despite the fact that it still has a lot of red on it.

The short term outlook does look nice, especially for early next week as the models continue to show another storm system moving into The Southern Plains.

The potential for heavy rainfall does exist, but the models have been inconsistent in showing where the heaviest of the rain will set-up. This far out a lot can and will change. But, with November traditionally known as a dry month for us, the fact that we’re getting many shots of rain is awesome. ! Should I wash my car… I mean, for Oklahoma I will. Usually when I do…it rains. Signs of a true meteorologist!

-Damon

Shaking in Oklahoma
November 16, 2011

Oklahoma Struck by Series of Quakes
Number of earthquakes increasing in area
                                Posted on November 9, 2011 at 7:02 pm by Tania Larson
Map showing the shaking intensity from Oklahoma's M5.6 quake reported to the USGS website, Did You Feel It?
Shaking from Oklahoma’s M5.6 main shock, the largest quake in the State’s history, was clearly felt from St. Louis, Missouri, to Lubbock, Texas.

Over the past few days, Oklahoma has been hit by a sequence of significant earthquakes, including a magnitude 5.6, the largest quake to hit Oklahoma in modern times:

  • A magnitude-4.7 foreshock struck 20 miles northeast of Shawnee and 46 miles east of Oklahoma City on Saturday, November 5, at 2:12 a.m. local time at the epicenter.
  • The magnitude-5.6 main shock struck 21 miles north northeast of Shawnee and 44 miles east northeast of Oklahoma City on Saturday, November 5, at 10:53 p.m.
  • A magnitude-4.7 aftershock struck 17 miles north northeast of Shawnee and 43 miles east of Oklahoma City on Monday, November 07, at 08:46 p.m.

The previous record for the largest Oklahoma quake is a magnitude-5.5 earthquake that occurred near El Reno on April 9, 1952.

During Saturday night’s magnitude-5.6 quake, about 8,000 people were exposed to very strong or severe shaking with the possibility of moderate to heavy damage to some structures, according to the USGS PAGER (Prompt Assessment of Global Earthquakes for Response) system.

Shaking from this quake was clearly felt from St. Louis, Missouri, to Lubbock, Texas — indicating that ground shaking reached distances of 300 miles from the earthquake’s epicenter.

Aftershocks will likely continue, but decrease in frequency

There have also been dozens of smaller aftershocks. These aftershocks will continue for weeks and potentially months, but they will likely decrease in frequency.

This amount of aftershock activity is not unusual for an earthquake sequence with a main shock magnitude of 5.6.

Earthquakes have been increasing in this area

Earthquakes are not unusual in Oklahoma; they are often simply too small to be felt. However, earthquake activity in this area has increased over the past 4 years.

From 1972 through 2007, the USGS recorded about two to six earthquakes a year in Oklahoma. But in 2008, earthquake activity began to increase, with more than a dozen earthquakes recorded that year. In 2009, the rate continued to climb, with nearly 50 quakes recorded — many big enough to be felt. In 2010, the trend continued.

There has also been a change in the distribution of the earthquakes.

From 1973 to 2007, the earthquakes were scattered broadly across the east-central part of the State. The events since 2008, however, have been more clustered in the vicinity northeast and east of Oklahoma City and generally southwest of Tulsa. This sequence of earthquakes was in this area.

Map showing history of seismic events in OklahomaFrom 1973 to 2007, earthquakes in Oklahoma were scattered broadly across the east-central part of the State. Since 2008, there has been a dramatic increase in the number of earthquakes, and the events have been more clustered in the vicinity northeast and east of Oklahoma City and generally southwest of Tulsa. (Illustration by Richard Dart, USGS, click on image to see full size.)

Is an even larger quake on its way?

There is always a small possibility of an earthquake of larger magnitude following any earthquake, but the occurrence of the magnitude-5.6 earthquake and the increase in activity in recent years do not necessarily indicate that a larger more damaging earthquake will occur.

To monitor and locate aftershock activity in more detail, the Oklahoma Geological Survey deployed portable seismograph stations after the magnitude-4.7 on November 5, and they are in the process of deploying more stations. The USGS deployed additional seismographs in the region in 2010 to help monitor the ongoing earthquake activity and will be deploying about 12 more stations over the next few days.

Faults in Oklahoma

In general, it is very difficult to correlate earthquakes to specific faults in the region. However, the earthquake sequence that started Saturday occurred close to where a magnitude-4.1 earthquake occurred on February 27, 2010. From the location of the earthquake and the focal mechanism, it is possible that these earthquakes are occurring on the Wilzetta fault.

The Wilzetta fault is one of a series of small faults formed in the Pennsylvanian Epoch (approximately 300 million years ago) during the intraplate deformation known as the Ancestral Rocky Mountains mountain-building episode (orogeny).

The relationship between the recent earthquakes and this older structure is still unknown and requires further investigation.

The Meers fault is also located in Oklahoma, in the south-central area about 60 miles southwest of Oklahoma City. It is the only fault identified in the State with evidence of surface-rupturing earthquakes in the last 3000 years (prior to historical settlement of the region). Paleoseismology studies have identified a temporal clustering of a least three earthquakes on this fault, two of which are dated (1200 – 2900 Before Present) and the third is believed to be older in age.

Earthquakes in the eastern United States

These earthquakes are typical of the larger areas of North America east of the Rocky Mountains that have infrequent earthquakes large enough to cause minor to major damage.

Some smaller areas of eastern North America are more active, including

  • the New Madrid seismic zone centered in the region where Missouri, Kentucky, Tennessee, and Arkansas come together;
  • the Charlevoix-Kamouraska seismic zone of eastern Quebec;
  • the Wabash Valley seismic zone along the border region of southeast Illinois and southwestern Indiana;
  • the Central Virginia seismic zone (which had the magnitude-5.8 earthquake on August 23, 2011);
  • the Eastern Tennessee seismic zone;
  • a broad zone in New England, and
  • a zone in the New York-Philadelphia-Wilmington urban corridor.

For example, December 16, 2011, is the bicentennial anniversary of a sequence of large earthquakes in the New Madrid region. There were three main earthquakes with magnitudes of about 7 – 8 and hundreds of aftershocks from December 16, 1811, to February 7, 1812.

However, much of the region from the Rocky Mountains to the Atlantic Seaboard can go years without an earthquake, and several States have never reported a damaging earthquake.

Earthquakes of magnitude-5.6, like the one that occurred Saturday, are believed to be capable of striking anywhere in eastern North America at irregular intervals.

Shaking spreads farther in the East

Earthquakes east of the Rocky Mountains, although less frequent than in the West, are typically felt over a much broader region.

East of the Rockies, an earthquake can be felt over an area as much as 10 times larger than a similar magnitude earthquake on the West Coast.

For example, the magnitude-5.8 earthquake that hit Virginia on August 23, 2011, caused damage as far away as Delaware, southeastern Pennsylvania, and southern New Jersey and was felt throughout the eastern United States (from central Georgia to central Maine and west to Detroit, Michigan, and Chicago, Illinois) as well as in many parts of southeastern Canada (from Montreal to Windsor).

Be prepared

Farewell Warmth..
November 15, 2011

Sheesh, where were these cold fronts in the summer? I waited months and months and months it feels like to get one of those blue lines with pointy edges on them into Oklahoma and now, they’re rolling in every couple hours. Our next front is just hours away.

Our next front is hauling in from the north and will likely pass through the OKC Metro during the mid-afternoon hours. A sudden drop in temperatures will likely occur as we gof rom the upper 60s to the upper 50s by 5pm. But, the coldest air is still about 36 hours behind the front. Running one of our in-house models, we came up with these numbers for Thursday Morning (NOT WEDNESDAY)

If your plants weren’t killed by the last freeze, this one outta do it. And any green blades of grass left on your lawn will likely begin to disappear a little faster.

-Damon

Get Ready for the Winds!
November 15, 2011

Get ready for the winds to return across the state later this week. Winds strong enough to make it feel like your roof may blow off from time to time. Right now the weather models are thinking that Friday and Saturday could see some of the strongest winds where sustained, could reach as high as 40 mph and even stronger gusts.

Why aren’t there more kite stores in the state? Sounds like a potential business opportunity…

-Damon

What Were You Doing 100 Years Ago?
November 11, 2011

OK, chances are many of you weren’t around. But, let’s pretend that we have television then and you’re watching your favorite weather team (KOCO of course). Here is how the weathercast would have gone that week. ‘It’s warm out, but there’s seems to be some cooler air up north..a weather observer just told us that the air got real cold in Colorado.” (Remember, this is before fancy weather models, computers and our only method of communication from afar was via telegraph). The weather map would have looked like this:

By the early afternoon, we expect it to be warm. The actual high that day was 83 degrees. A record for the date and a record that still holds true to this day. But, all of a sudden, the winds kicked up from the north, the dust blows in and temperatures start to drop…and drop….and drop. By midnight… holy cow…

It’s 17 degrees at the Oklahoma City weather observation that night. A record low! That’s right, we went from setting a record high to a record low in just a matter of hours.

Could this “Blue Norther” have been the strongest front to ever roll through Oklahoma? Chances are yes as we have never had a day where both a record high and a record low occured on the same calendar day. The front moved quickly and most likely caught many Oklahomans by surprise. It’s events like this that make me appreciate all the technology invested in the weather today. If you think it’s hard to dress your kids right now for school, imagine how it must have been on November 11, 1911.

-Damon

Drought Update!
November 10, 2011

It was a week that started off with some much needed rain, and as we end the week, the impacts the rain had on our drought are officially tabulated. Here is the latest drought monitor that was just issued. It shows that there was drought improvement north of OKC where anywhere from 3-5 inches of rain fell.

Western Oklahoma is still struggling with the worst of the drought, though it is nice to see the EXCEPTIONAL DROUGHT conditions, which is the worst you can have getting scaled back some. For Oklahoma City, we did see some improvement in the drought, but not enough to drop us out of the EXTREME DROUGHT level.

So, how much rain do we still need to see in order to return the soil to 100% moisture capacity? Remember this number can change with winds, etc, but today, it looks like this:

According to The Oklahoma Mesonet, most of the state still needs another 1-3 inches of rain to return the soil to full moisture. Western OKlahoma… not pretty, over half a foot at least. Remember, this is just the soil we’re talking about. The lakes will need a lot more than this.

-Damon

Oklahoma November Tornadoes
November 8, 2011

Were you surprised by yesterday’s tornado outbreak? You probably were, and it’s OK. Why? Because when it comes to tornadoes in November, it doesn’t happen all that often. Yes, I know, it’s Oklahoma and tornadoes can happen any time of the year, but November isn’t exactly a month that screams tornadoes at me the way April, May and June do.

So, how often do we see tornadoes in November? Well, the graphic above tells us that in the last 61 years, we’ve only seen 83 tornadoes. Which means, that averages to about 1.4 evert November. However, the last time we had a tornado in November was back in 2008.

-Damon

HUGE Alaskan Storm
November 8, 2011

This should make you appreciate those crab legs next time you sit down at the table.

A RAPIDLY DEVELOPING STORM LOCATED ABOUT 600 MILES SOUTHWEST
OF SHEMYA THIS AFTERNOON WILL INTENSIFY INTO ONE OF THE
MOST SEVERE BERING SEA STORMS ON RECORD AS IT MOVES NORTHWARD
ACROSS THE CHUKOTSK PENINSULA TUESDAY NIGHT. THIS STORM
HAS THE POTENTIAL TO PRODUCE WIDESPREAD DAMAGE.

THE STORM WILL PRODUCE WIDESPREAD WINDS OF 40 TO 55 MPH
WITH HIGHER GUSTS OVER THE WEST COAST TUESDAY NIGHT INTO
WEDNESDAY EVENING. STRONG WEST WINDS ARE EXPECTED TO CONTINUE 
OVER ST LAWRENCE ISLAND WEDNESDAY NIGHT. GUSTS TO 70 MPH CAN BE
EXPECTED ALONG THE CHUKOTSK PENINSULA AND IN AREAS NEAR KOTZEBUE.
WINDS OF 60 TO 75 MPH ARE EXPECTED OVER ST LAWRENCE ISLAND AND 
THE BERING STRAIT COAST. WINDS ARE EXPECTED TO APPROACH HURRICANE
FORCE OVER THE CHUKCHI SEA AND NORTHERN BERING SEA. THE STRONG
WINDS WILL GENERATE SEAS TO AS HIGH AS 20 FEET OVER THE CHUKCHI
SEA...AND TO 15 TO 25 FEET OVER THE NORTHERN BERING SEA.

THE STRONG WINDS WILL PUSH LARGE AMOUNTS OF WATER INTO NORTON
SOUND...RAISING SEA LEVELS TO AS HIGH AS 8 TO 9 FEET ABOVE NORMAL
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THE HIGH SEA LEVELS
COMBINED WITH HIGH WAVES WILL PRODUCE SEVERE BEACH EROSION AND
MAJOR COASTAL FLOODING ALONG THE NORTHERN AND EASTERN SHORES OF
NORTON SOUND AND ALONG THE BERING STRAIT COAST. HIGH WATER
LEVELS WILL PRODUCE COASTAL FLOODING ALONG THE SOUTHERN
SHORE OF NORTON SOUND. STRONG WINDS AND WAVE ACTION MAY PUSH 
ICE IN NORTON BAY ON SHORE.

MODERATELY ELEVATED SEA LEVELS AND HIGH WAVES WILL CAUSE
SEVERE BEACH EROSION AND MAJOR COASTAL FLOODING ALONG THE
SOUTH AND WEST FACING COASTS OF ST LAWRENCE ISLAND TUESDAY 
THROUGH WEDNESDAY NIGHT.

ALONG THE CHUKCHI SEA COAST FROM CAPE KRUSENSTERN NORTHWEST...
SOUTHEAST WINDS GUSTING TO A HIGH AS 70 MPH WILL PRODUCE HIGH
WAVES AND SOME ELEVATION OF SEA LEVELS...RESULTING IN SEVERE 
BEACH EROSION AND MAJOR COASTAL FLOODING. THE VILLAGE OF
KIVALINA WILL BE HIGHLY VULNERABLE TO DAMAGE CAUSED BY
BEACH EROSION AND COASTAL FLOODING.

THE STORM WILL ALSO PRODUCE SIGNIFICANT SNOWFALL AND BLIZZARD
CONDITIONS OVER ALMOST ALL OF THE WEST COAST TUESDAY NIGHT
AND WEDNESDAY. SNOWFALL AMOUNTS OF AS MUCH AS 14 INCHES
ARE EXPECTED ALONG THE SOUTHERN SEWARD PENINSULA COAST AND
IN PARTS OF THE INTERIOR SEWARD PENINSULA.

 

Today’s Tornado Risk
November 7, 2011

Real quick blog post today before we get into the severe weather meeting this morning. Chance for severe storms, with SW Oklahoma having the best chance for seeing tornadic storms. Today will become sloppy at some point with lots of storms all over the place, so the window of tornadic storms appears to be early in the day before the tornado threat diminishes.

Once the storms approach OKC, they should be more of a wind and hail threat and less of a tornado threat. The good news out of this…there’s rain, and lots of it.

This is the type of rain that fills the lakes. Enjoy!

-Damon

Earthquakes, Severe Thunderstorms, and Heavy Rain….Oh My!
November 6, 2011

Last evening’s 5.6 magnitude earthquake that was centered in Lincoln county was the strongest quake in Oklahoma history.  We were in the middle of our late news when  the studio began shaking and rumbling.  Despite all of the smaller quakes in Oklahoma over the years, this is the first one I’ve ever felt.  Thankfully injuries have been few, and damage has been mostly minor.  But this quake took place in a year that has been simply amazing in terms of record-breaking events in Oklahoma.  According to our friends at the National Weather Service in Norman, here’s a list of what we’ve endured in 2011 in Oklahoma:

Most Snow in a 24 Hour Period:

27 inches

Spavinaw, OK

Feb 9-10, 2011

 

Coldest Temperature:

-31 degrees

Nowata, OK

Feb 10, 2011

 

Largest Hailstone:

6.0 inches

2 miles north of Gotebo

May 23, 2011

 

Highest Wind Speed  highest official surface wind measurement (not radar-based)

150.8 mph

El Reno

May 24, 2011

 

Highest Summer Average Temperature:

86.8 degrees

This was also the hottest average summer temperature in history for any state

 

Warmest August Average Temperature:

87.7 degrees

The list could also include the incredible number of 100 degree days that the state endured this past summer.  The bottom line is that we’ve had an extreme year…and it’s not over yet.  In fact, a strong storm system will bring heavy rain and a threat for severe weather to Oklahoma tomorrow into Tuesday.  Here’s the severe risk for tomorrow:

The most likely time for severe thunderstorms will be later tomorrow afternoon into tomorrow evening.  Hail and wind will be the main threats, but a couple of tornadoes will be possible as well, especially across southwest Oklahoma.  Despite the severe threat, the storm system will bring in some much-needed rainfall.  Here is the rainfall potential for Monday into Tuesday morning:

Widespread 1-2 inch rain amounts look likely.  That moisture will go a long way to help the winter wheat crop, as well as our depleted soil moisture. By Tuesday, the storms shift into far eastern Oklahoma and points east.  The remainder of the week looks more tranquil.

Rick