Archive for February, 2007

Mid-Afternoon Update
February 28, 2007

The Oklahoma Mesonet is showing the dryline has pushed (mixed) through about the western half of the state.

SPC is monitoring north central and northeast Oklahoma for a possible weather watch.

While dewpoints have surged into the 50s across much of the state ahead of the dryline, we’ve not see the dewpoints in the 60s that was advertised by the NAM.

It still looks like eastern Oklahoma will have the best chance of storms, but we’re ready in case any try to fire here.

Rick

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Afternoon Update
February 28, 2007

My 1:00 pm surface analysis shows a deepening surface low over Beaver county in the Oklahoma panhandle. The dryline is setting up from the low, arcing to the southeast through the western quarter of Oklahoma.

Ahead of the dryline, dewpoints are in the 50s to low 60s in southern and southeastern Oklahoma, but only in the 20, 30s and 40s in the far northern part of the state.

Winds are southwest behind the dryline, and to a certain degree ahead of the dryline. There’s not much convergence right now. Of course, if the surface low continues to deepen, winds in the central and east could back to the southeast increasing dryline convergence.

The satellite animation shows cumulus clouds developing along and east of I-35 in central Oklahoma.

While the RUC does break out thunderstorms along I-35 by 3 pm, the NAM and the GFS have been consistent in keeping storms at bay until early evening, and then developing them farther east.

Our crews are already out in case we see storms popping around here.

Rick

Update: Moderate Risk For Northeast OK
February 28, 2007

The latest severe weather risk discussion is available from the Storm Prediction Center.

http://www.spc.noaa.gov/products/outlook/day1otlk.html

They have upgraded part of northeast Oklahoma into a moderate risk for severe weather this evening. The moderate risk area also includes northern Arkansas and southern Missouri.

I’ve had more time to look at the newest models and still feel that storm chances are low in central Oklahoma. Our convective temperature off of this morning’s Norman sounding is 93 degrees, which signifies a pretty strong cap that will likely hold throughout the afternoon.

It’s still a close call and our plan to have storm trackers ready in case storms can manage to fire remains unchanged. Again, if storms can fire they will be severe, but the chance of them firing is low in this part of the state.

Rick

A Close Call For Storms
February 28, 2007

Last year during storm season, it seemed like the magical point for storms to fire was the I-35 corridor. Many of our storm situations involved having to make a decision on whether storms would form along or east of I-35. Today we are in that same situation. Central Oklahoma is once again the cut-off point for severe weather ingredients, with more favorable storm conditions to our east, and little to no threat to the west.

Since my thunderstorm philosophy is to be prepared for any scenario, we will proceed with plans to have our storm trackers in place and ready for action by late afternoon in central Oklahoma.

If storms can manage to break the cap, they will have a good chance of becoming severe with large hail and damaging winds being the main threats. An isolated tornado or two cannot be ruled out. The storms will likely move northeast at 40 mph, and by late evening the threat will have moved into eastern Oklahoma. Severe weather conditions actually increase across northeast Oklahoma by late evening, so as the storms move into that part of the state, they could intensify.

It’s interesting that while the models do show many of the ingredients needed for storm formation in central Oklahoma, none of them that I have seen actually develop storms in central Oklahoma. They all show development in eastern Oklahoma. This is one of the reasons why our chances for actual storm formation along the I-35 corridor are low. In any case, we will be prepared.

After this evening, the forecast is pretty straight forward. We’ll cool down into the 50s for the next few days with a chilly wind. Saturday looks to be the coolest day, and after that temperatures start to rebound. We’ll have dry weather though much of next week.

I spoke with our newest meteorologist, Rusty McRainey last night. His first day at KOCO will be Monday. He’ll spend next week getting familiarized with our equipment, and he’ll make his Oklahoma on-air debut on Monday, March 12th on the morning show. We are looking forward to having him join our team.

My web project that I have been teasing you with has hit a bit of a snag so I’m not sure if I will be able to start it next Monday or not. I’ll keep you posted.

A reminder that I will be speaking at the Severe Weather Conference in Norman on Friday at 10:30 am. My topic is how KOCO prepares for severe weather. Chris Lee has been editing the video and so far it looks good. If you would like more information on the conference, here is a link: www.norman.noaa.gov/nsww2007/

Make sure you check back with Eyewitness News 5 throughout the day to see what is going to happen with the severe weather risk. Have a great day!

Rick

Another severe weather episode today
February 28, 2007

An active pattern continues with parameters set for another severe weather outbreak. Moisture is currently streaming north in a narrow corridor from central Texas into central Oklahoma. The dryline will mix and move east this afternoon and stop just west of the I-35 corridor. The dryline is a focus for severe storm initiation. Computer models are at odds with one another as to whether or not the cap will break. If the cap holds, no storms for us, if it breaks, then isolated tornadic storms are likely for the metro area. Only time will tell which models are correct, but with the way things are looking, I’m leaning towards the cap to break and storms to form. After the storms move through late this afternoon, they will move into eastern Oklahoma and Arkansas at night prompting the concern for more night tornadoes. Once again, another early spring storm…
AT

Today Bears Watching
February 28, 2007

Meteorologists are faced with an exceptionally difficult forecast for the day today, primarily with regards to severe weather potential.

A brief overview:

An intense upper-level trough is digging down the West Coast early this morning, much like the case last Friday. A very strong jet streak has formed at the base of this trough over the SW U.S.. At the surface, substantial pressure falls in the lee of the Rocky mountains have induced moderate SEerly winds that are beginning to advect moisture-laden air into the Southern Plains from the Gulf of Mexico, while a dryline is now forming across the High Plains of KS, OK and western TX. In addition, a low-level jet has begun to develop from the Gulf of Mexico northward into the Central Plains.

In the next 12-24 hours this trough will begin it’s eastward advance, taking aim on the Great Plains of the United States. As this happens the aforementioned jet streak is forecasted to intensify further as it shoots out across the Southern Plains of TX and OK. A rapidly strengthening surface low pressure system will be developing somewhere in the vicinity of SW KS, NW OK, or the TX panhandle. As this low deepens (intensifies) it will pull in even richer low-level moisture northward into the Southern Plains. Dewpoints are forecast to rise steadily during the day from central OK eastward, with warm temperatures making it feel a bit more muggy than is typical for the last day of February. As temperatures warm up and the dryline sharpens there will be an increasing chance of a thunderstorm to develop anywhere along or within 50 or so miles of the I-35 corridor. If a storm does manage to fire, all eyes will be on it, because the amount of instability and wind shear look to be quite sufficient to propel it to severe levels rather quickly late Wednesday afternoon.

The biggest question at this point in time is whether or not the layer of moisture drawn northward will be deep enough to set the stage for thunderstorm formation. At this point, it looks like a close call. This still looks like a slight chance of a storm, but a high chance of a severe storm, if a storm forms scenario. As such, folks may want to pay some attention to the forecasts this afternoon.

Regardless, it is really looking like portions of E OK, SE KS, most of MO and AR look to be in for a long night of potential severe weather, including large hail, high winds and tornadoes as this powerful storm system moves into the nation’s heartland and interacts with rich, warm and unstable Gulf of Mexico air.

Tune back in with Eyewitness News 5 during your day on Wednesday. Should severe weather threaten, we’ll keep you informed!

Ilya Neyman
Weather Intern

Late Afternoon Update
February 27, 2007

It’s been a windy and warm day across the state with temperatures well into the 60s and even low 70s with abundant sunshine. The warm weather definitely makes me feel better with my sickness.

Unfortunately, the winds have helped fuel a few fires across the state. Check out this satellite image from earlier this afternoon from the National Weather Service in Norman:

Most of the time we use infrared imagery from satellites to track clouds, but occasionally they are useful for other purposes. In the image, you can see that grass fires can be spotted on the infrared imagery by the heat they give off into space. The darker areas indicate the hot spots (areas of high temperature).

In terms of the forecast, tomorrow looks to be another warm and windy day. Winds will be gusty from the south around 20-35 mph. That will enhance the fire risk once again, especially across the western parts of the area behind the dryline. Relative humidity values there will be very low, and the winds will be from the dry southwest instead of the south. There are already red flag fire warnings across southwest Oklahoma for tomorrow. High temperatures will be well into the 70s across the state. I wouldn’t be surprised to even find some 80s in southwest Oklahoma.

As mentioned earlier, there are some questions with the chance of thunderstorms on Wednesday. The latest data still suggests the risk in central Oklahoma is minimal, but definitely not zero. The moisture looks to be very shallow, which is one reason the chance isn’t all too great. However, surface temperature and dewpoint values indicate a decent amount of instability. Thus, if any storms do develop ahead of the dryline, they could be severe. The primary area of development would be I-35 eastward. Chances increase the farther east you go across the state. Definitely stay-tuned on this.

After the thunderstorm chances Wednesday, a cold front will move through the state early Thursday. Once the front passes through, the weather looks to stay fairly cool for a while because of a northwest flow aloft. That should help bring another weak reinforcing shot of cool air through the state on Saturday. There won’t be any bitter cold air, but temperatures will be back below average for this time of year Thursday through Saturday.

Highs will generally stay in the 50s with lows dipping back into the 30s beginning Friday morning. Overall, the coolest days look to be Friday and Saturday (with Saturday possibly the coldest). Also, there will probably be more clouds across the state Friday and Saturday.

Highs should be close to 60 by Sunday, and should warm well into the 60s with gusty south-southwest winds on Monday. A weak front may move through late Monday, bringing in slightly cooler weather on Tuesday–but the front may never make it through because right now it looks pretty weak.

At this time it looks dry for a while after Wednesday’s chance of thunderstorms, but that can always change.

Now it’s time for me to get some homework done–hope you have an awesome rest of the week!

Vivek
Weather Intern

Windy, Mild, Slight Chance Of Storms
February 27, 2007

I’m running a bit late today as I slept in to help defeat this cold. The funny thing is that every one who was in the weather office Friday night is suffering some at least some cold symptoms. I have a head and chest cold, Aaron has a sinus infection, Steve’s throat is sore, and even Vivek the intern is under the weather. Somebody must have sneezed on the pizza we shared while waiting for storms to form.

At least the weather will be quiet today. We’ll continue with a good deal of sunshine as temperatures climb into the mid 60 this afternoon. Winds will increase to 15 to 25 mph out of the southeast.

The low level jet kicks in tonight helping to transport moisture into the eastern half of the state. There will be no rain, but humidity levels will increase. The combination of higher humidity and an active south wind will keep temperatures from falling below 50.

Wednesday will be an interesting day with concerns for fire danger and thunderstorms in different parts of the state. A dryline will set up across the western third of Oklahoma by afternoon. Behind this, the air will be very warm and dry, so the fire danger will be increasing west of a line from Buffalo, to Anadarko, to Lawton, south to the Red River.

Thunderstorm concerns for Wednesday will be mainly eastern Oklahoma. Although, I can’t rule out storms trying to form as far west as the OKC metro by late in the day along the dryline. The Storm Prediction Center has put the eastern quarter of Oklahoma in a slight risk area for tomorrow. Main threats will be wind and hail, with isolated tornadoes possible.

For OKC, I’m going to keep in a slight chance of a storm developing late in the day, or perhaps the evening. If storms can manage to fire, I would not be surprised to see some severe weather. However, the best chance will be east of Interstate 35.

By Thursday the storm system moves north and east of Oklahoma. This will produce another heavy snowstorm for folks in parts of the northern and central Plains as well as parts of the Midwest.

In Oklahoma, we’ll be cooler and mainly dry for Thursday and Friday. Highs will be back to normal in the 50s after hitting the 70s on Wednesday. The weekend will be dry with a cool day Saturday, but starting to warm up on Sunday.

Chris Lee and I (well, mostly Chris Lee) will be working on the video today that I am going to present at the Severe Storm Conference in Norman on Friday. Chris is a very talented photo-journalist and a superb editor, not to mention storm chaser extraordinaire. I am anxious to see how this is going to turn out, but I bet he’ll make it pretty special. I’ll be showing it on Friday at 10:30 am, and it deals with how we cover severe weather at KOCO.

I hope you’ll tune in to watch Eyewitness News 5 tonight at 5, 6 and 10 pm. Have a great day!

Rick

Slight Chance Of Sooner Storms On Wednesday
February 26, 2007

Absolutely beautiful weather is on tap for the next couple of days with afternoon temperatures warming into the 60s and even 70s with comfortable overnight lows starting out a bit on the chilly side tonight in the 30s before rebounding back to a mild 50ish on the heels of south-southeasterly winds come Wednesday morning.

Another thing to watch on Wednesday will be another potent late winter storm moving across the Rockies. There are subtle, yet significant differences in the computer forecast model projections as to what exactly will come out of this system for our area. Right now, it appears that moisture will have some time to rebound back into the southern Plains Tuesday night through Wednesday, with the exact trajectory of the winds in the lowest 5,000 feet being a huge factor to the sensible weather for Oklahoma.

For instance, the GFS model shows quite an unfavorable environment for thunderstorm development across most of the state Wednesday afternoon as it depicts lower level winds that are too veered (SW-W) in the low levels, keeping any substantial lower-level moisture across the eastern 1/3 to 1/2 of the state. Additionally, it forecasts winds at the 850mb level, or roughly 4,500 feet above sea level, to be coming in from the WSW during the afternoon on Wednesday. This trajectory would advect warm and dry air atop a rather shallow moist layer and would serve to “cap” the atmosphere, thus limiting storm chances.

However, as Rick Mitchell alluded to in the previous post, the NAM model paints a different picture for us. Unlike the GFS, this model forecasts a deeper surface low to develop over the northern panhandle of Texas. As a result the surface winds are projected to develop a more SSEerly component across the area, in turn drawing richer moisture north and west from the Gulf of Mexico. At the same time the NAM progs the 850mb winds to be more southerly across the state, a direction which is MUCH more conducive to moisture advection as well as a weaker atmospheric cap. In terms of forecasting the development of thunderstorms, the NAM looks significantly more impressive than the GFS.

Both models show very strong jet stream energy and powerful wind fields for Wednesday, so if thunderstorms would manage to form, the potential for them to become severe is quite high.

But the big mystery is whether or not thunderstorms will be able to form in the first place, so as of now I feel we have a slight chance of storms developing late Wednesday afternoon or evening, with the highest chances being across eastern Oklahoma and southwest Missouri/western Arkansas. Keep in mind this could change in either direction once the models and forecasters get a better feel of what exactly this system will do and how it evolves over the next couple of days.

Check back with us for more later!

Ilya Neyman
Weather Intern

Battling A Cold, But Enjoying The Weather
February 26, 2007

I felt it coming on over the weekend, and now I have my first cold of the season. Luckily, it’s not that bad. Although between me and other members of my family, we’ve gone through several boxes of Kleenex. I made it through most of the cold and flu season before obtaining this virus. Plenty of hand washing and healthy eating maybe bought me some time. In any case, it’s not bad enough for me to stay home, so on with the show.

My morning weather analysis shows a small area of low pressure located over central Oklahoma. This low will move east quickly today. Its only purpose will be to shift winds into the northwest (that means blowing from the northwest) across the state. While there may be a few gusts over 20 mph this morning, the winds will not be much of a factor today. In fact, the afternoon will be pleasant with lots of sunshine and highs in the 60s.

Tuesday will see low pressure develop to our west. That in turn will bring our afternoon wind speeds up to 15-25 mph out of the southeast. We’ll have a good deal of sunshine and temperatures will be mild in the mid to upper 60s.

The low pressure to our west is in response to an upper level storm system that will be moving into the Plains on Wednesday. This upper system is not as concentrated as the one that moved through over the weekend, but some ingredients will be in place for some thunderstorms to develop late Wednesday into Wednesday night. Severe weather can’t be ruled out.

This is the day three severe weather risk from the Storm Prediction Center valid on Wednesday:

It shows the best potential for severe weather to be well of the east of OKC. While I originally agreed with that position, a closer look into the 12 z run of the NAM shows that the potential for severe weather could be a bit farther west.

This image is valid at 6 pm Wednesday:

It shows the NAM is predicting dewpoint temperatures of near 60 degrees into central Oklahoma, with a lifted index of -8. The lifted index is a measure of the stability of the atmosphere. The lower the number, the more unstable the atmosphere is. Values less than zero are usually required for severe thunderstorms.

Here is the same model, only for midnight Thursday morning:

Again, it shows decent surface moisture and instability right along I-35. So does mean severe weather for central Oklahoma? Well, I have to wonder if the NAM isn’t a bit optimistic with the moisture return. And if that is the case, it may also be overplaying the instability. What is interesting is that the NAM does not break out thunderstorms over central Oklahoma, but rather in eastern parts of the state.

The bottom line is that we already have thunderstorm chances in the forecast for late Wednesday, and they will likely stay there. Of course we’ll adjust the forecast as it becomes clearer what will actually happen.

Thursday through Sunday look quiet and cooler with highs mostly in the low to mid 50s, although a return to 60s is likely by Sunday.

A reminder to those of you attending the severe weather conference this weekend in Norman. I will be speaking at 10:30 Friday morning on how KOCO prepares for severe weather. I’m working on a presentation that will hopefully be informative and entertaining. If you don’t get a chance to see it at the conference, I going to try and have it posted on the website so all can have a look.

I am also working out the last details of my latest web project that I will debut next Monday morning. Stay tuned for more information.

I hope you have a great Monday. Don’t forget to check in on Eyewitness News 5 at 5, 6 and 10 pm.

Rick