Archive for February, 2011

24 Hour Rainfall Totals
February 28, 2011

Drew Michaels

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Earthquake Rattles Natural State
February 28, 2011

An earthquake occurred last night around 11pm with a second weaker quake taking place 17 minutes later. The first earthquake at 11pm was felt in most of Arkansas and other areas in Oklahoma, Missouri, Tennessee and Mississippi. The earthquake was felt over a zone that was 500 miles wide. At this time, there hasn’t been any reports of damage. The USGS says that the threshold of when damage takes place is normally between a 4.0 and a 5.0 magnitude, but can very significantly depending on many factors. As of 6am there were over 4,000 reports of the earthquake on the USGS site and hundreds of you have contacted us directly reporting the earthquake in our viewing area.

Ross Ellet

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New Tornado Watch Until 4 a.m.
February 27, 2011

EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1005 PM UNTIL
   400 AM CST.
  
   TORNADOES…HAIL TO 2 INCHES IN DIAMETER…THUNDERSTORM WIND
   GUSTS TO 70 MPH…AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
   AREAS.
  
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE
   MILES EAST AND WEST OF A LINE FROM 25 MILES WEST NORTHWEST OF
   HARRISON ARKANSAS TO 35 MILES SOUTH SOUTHWEST OF DE QUEEN
   ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).
  
   REMEMBER…A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS.
  
   OTHER WATCH INFORMATION…CONTINUE…WW 24WW 25
  
   DISCUSSION…TSTMS CONTINUE TO INCREASE IN VICINITY OF THE
   DRYLINE/PACIFIC COLD FRONT FROM ECNTRL OK INTO FAR NERN TX.  EXPECT
   A QLCS WILL EVOLVE THROUGH EARLY MORNING MONDAY AND MATURE OVER
   WRN/CNTRL AR.  ALTHOUGH THE STORM MODE MAY LARGELY BE LINEAR WITH
   EMBEDDED BOWS/LEWPS GIVING CORRIDORS OF HIGH WINDS…POTENTIAL
   EXISTS FOR A FEW TORNADOES AS 0-1KM SRH REMAINS QUITE HIGH.

Storms Getting Organized…9:30 Update
February 27, 2011

You know this night has a weird feel when you can walk outside at 9:00 p.m. without a coat.  We are still expecting showers and storms to develop across our area between 10 p.m. and 3 a.m.  I think the bulk of the storms will hold-off until closer to midnight in response to the best upper level dynamics.  We needed a trigger to ignite the storms, and that trigger is occurring as we speak across central Oklahoma.

Quarter hail, damaging winds over 60 mph, and isolated tornadoes are still possible tonight.  Right now the storms across northeast Oklahoma are starting to back-build south.  Those storms along the boundary in Kansas have rotated this evening. 

If a line of convection forms, the greatest threat will be strong gusty winds.  Isolated tornadoes can develop within lines of storms; however, the overall threat would be damaging winds.  Stay tuned.

Drew Michaels

Follow us on Twitter at “4029weather”

Tornado Watch to our North
February 27, 2011

EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 725 PM UNTIL
   300 AM CST.
  
   TORNADOES…HAIL TO 2 INCHES IN DIAMETER…THUNDERSTORM WIND
   GUSTS TO 70 MPH…AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
   AREAS.
  
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
   MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTHWEST OF JOPLIN
   MISSOURI TO 50 MILES SOUTHEAST OF VICHY MISSOURI.  FOR A COMPLETE
   DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
   (WOUS64 KWNS WOU4).
  
   REMEMBER…A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS.
  
   OTHER WATCH INFORMATION…CONTINUE…WW 20WW 21WW 23
  
   DISCUSSION…ISOLATED SEVERE/SUPERCELL STORMS ARE TRACKING EASTWARD
   ACROSS SOUTHEAST KS THIS EVENING…AND WILL MOVE INTO SOUTHWEST MO
   IN THE NEXT FEW HOURS.  OTHER STORMS ARE EXPECTED TO INTENSIFY
   ACROSS THE WATCH AREA AS THE UPPER TROUGH APPROACHES AND THE LOW
   LEVEL JET STRENGTHENS.  STRONG LOW LEVEL VERTICAL SHEAR WILL BE
   FAVORABLE FOR SUPERCELLS AND TORNADOES.  STRONG TORNADOES WILL ALSO
   BE A THREAT WITH ANY LONG-LIVED CIRCULATIONS.

Drew Michaels

Follow us on Twitter at “4029weather”

5:30 P.M. Update
February 27, 2011

Sorry for the infrequent posts today.  Ross and I are manning the shop as we remain short-staffed.  There are some timing differences from my earlier post.  I think the timing for the storms is going to be more from 10 p.m. till 3 a.m.

We haven’t been able to pop storms this afternoon, mainly because we don’t have the cold air aloft to act as a trigger.  That won’t come until closer till midnight.  Showers and storms are firing along the dryline as we speak, but they will stay out west during the evening.  The front will overtake the dryline and send the storms in our direction after midnight. 

While isolated tornadoes along the line are possible, the greatest threats will be damaging winds and small hail.

Drew Michaels

Follow us on Twitter at “4029weather”

1:30 p.m. Update
February 27, 2011

No real changes in the forecast at this time; now watches have been issued in our area at this point.  Breaks in the cloud deck along with strong southerly winds have pushed temperatures into the upper 60’s and lower 70’s.  Low level moisture continues to move in from the south as dewpoints have climbed into the upper 50’s and lower 60’s.

Storms over the next couple of hours will likely fire across Kansas and northern Oklahoma ahead of the cold front.  Our area should be quiet with just an isolated chance for storms.  6 p.m. through Midnight is still a good window for severe weather; although storms may continue after midnight along the cold front.

I’m concerned about central Oklahoma right now.  CAPE values have jumped between 2,000 and 2,500 J/KG ahead of the dryline.  If those storms in Kansas can build south down the dryline, they will most likely produce large hail and isolated tornadoes.  We will watch it closely.

Drew Michaels

Follow us on Twitter at “4029weather”

10am Severe Weather Update
February 27, 2011

The viewing area is on the edge of a slight versus moderate risk for later this evening and overnight tonight. The reason the moderate risk has shifted a little further east is because this region will have the best probability of thunderstorms during the most unstable time of the day. That does not mean our area is under any less of a threat. I think the severe weather threat for this evening and early overnight is very real considering the incredible dynamics that are coming into play here. Any thunderstorms that develop by late evening and overnight have the potential of going severe.

Timing

It now looks like there could be two windows of opportunity for severe thunderstorms. The computer models have a few thunderstorms breaking the cap in the warm sector after 6pm tonight to about 9 or 10pm. The best chance of this happening would be just to our east (hence the risk area shifting), but our eastern counties have the highest potential of seeing these thunderstorms develop. If this occurs, these thunderstorms could quickly become severe with supercells likely.

There is a second opportunity for thunderstorms as a strong cold front slices into northeast Oklahoma and western Arkansas. This is the main focus which will combine with the strong trigger, an upper-level wave, to ignite more widespread thunderstorms. Since the timing is later the instability will be lower. However, there is a good opportunity for these storms to become severe as well. The most likely time frame for these storms would be from 10pm to 2am.

Ross Ellet

Follow us on twitter “4029weather”

Severe Weather Outbreak Possible Sunday
February 26, 2011

The Storm Prediction Center has issued a moderate risk for severe weather for the entire viewing area on Sunday/Sunday night. Not only do I agree fully with this outlook, I wouldn’t be surprised if the SPC upgrades part of the moderate risk to a high risk sometime on Sunday. This is a classic loaded gun set up for Sunday evening. There is a moderate amount of instability with CAPE values near 1000 j/kg. Moisture values will be high with dewpoints in the low to mid 60s. Models have a weak cap in place, and this cap should erode in the warm sector by evening. Wind shear values are extremely high along with a very dry layer aloft and a low freezing level in the atmosphere. This will provide the region with a triple threat of large hail, damaging winds, and the potential for tornadoes. The most likely time for severe weather will be after dark from 6pm to midnight on Sunday night.

Ross Ellet

Follow us on twitter “4029weather”

Backyard Astronomy
February 25, 2011

Thanks to Dave Grosvold from the Arkansas Oklahoma Astronomical Society for this week’s post.  You can read more about their club by visiting www.aoas.org 

The Moon is just past Last Quarter this week, reaching New Moon at 1:47 PM CST on March 4th, so it’s rising later and later every morning. This means we will have nice, dark skies for evening viewing for the next 10 days or so as the Moon approaches First Quarter.

As the Moon rises later each day, Venus rises at the same time all this week, at about two hours before dawn. Shining at magnitude -4.2, Venus appears as the bright “Morning Star” in the east-southeast. On Monday morning look for the Moon to rise about an hour before dawn, with Venus following close behind. By Tuesday morning, Venus will rise 5.5° ahead of the Moon during that last hour of darkness.

At some point between Monday and Tuesday mornings, the Moon will pass very close to Venus. Unfortunately, the closest pass will occur when the Moon and Venus are both below our horizon. But, perhaps if you have a sharp eye, a clear daylight sky with no haze, and a pair of binoculars, you can spot Venus closer to the Moon in the middle of the day. Locate the Moon in your binoculars, and then “sweep” to the left and slightly down during the day on Monday, or to the right and slightly up on Tuesday.  With luck, you should find a very tiny pin-prick of brightness against the background sky.

After dinnertime at this time of year, four big predator constellations line up in a row across the eastern sky from the south to the north. Tracking their prey, they are lead by their noses high in the air as if walking on their hind legs (those that have legs, at any rate,) as they march across the sky toward the west. Canis Major (Greater Dog) leads the group in the south, followed by Hydra (Sea Serpent,) in the southeast, then Leo (the Lion) in the east, and finally Ursa Major (the Great Bear) bringing up the rear in the north-northeast.  


 

Jupiter shines brightly in the west at dusk all week, and sets roughly an hour after dark now. The best time to view it is in late twilight while it’s still high. Jupiter is now only 34 arcseconds wide, but you can still keep watch on its South Equatorial Belt and Great Red Spot as long as you can.

By 8:30 PM CST this week, the Big Dipper asterism in Ursa Major has risen to the same height in the northeast as Cassiopeia has descended to in the northwest. Their seasonal dominance is reversing; this is a sign of spring on the way, just as the opposite is a harbinger of autumn.

Uranus is now about 7° to the lower right of Jupiter and is disappearing into the still glowing evening twilight.

Saturn rises around 9 p.m., but it’s best seen in a telescope at its highest in the south around 2 or 3 a.m. Spica, slightly fainter, shines 9° below Saturn during evening, and left of it at dawn.

Drew Michaels

Follow us on Twitter at “4029weather”