Thursday, May 31, 2007
Friday Morning Storms...12:00 a.m. Update
Please read my blog entry below for more discussion on nocturnal thunderstorm complexes. I have explained in detail how they typically form during these types of weather patterns. We're looking at a complex to move out of Kansas and into Oklahoma and Arkansas after 3 a.m.
Storms to our north continue to develop a cold pool that will accelerate their movement over the next couple of hours. I have included a graphic that shows the mean movement of these complexes. Strong damaging winds of 60 to 70 mph are possible along the leading edge of the storms, along with heavy rainfall and small hail. It could be a rough start to June! We'll watch them closely.
Posted by Drew Michaels at 9:38 PM
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Wednesday, May 30, 2007
The Low Level Jet and Nocturnal Storms.......
You will often hear us mention on television the formation of a low level jet that feeds into thunderstorms; moreover, LLJ's serve as a great initiator for overnight thunderstorm complex development, and locating them can be a key to pinpoint thunderstorm formation. Last night we saw a complex of storms called a Mesoscale Convective Complex (MCC) initiate across western Oklahoma and move southeast all the way into Louisiana. This organized complex of storms was responsible for 20 severe wind reports. Could we see these types of storms in our area?
Our current weather pattern has a broad upper level low spinning around the upper Midwest. Low level moist air is surging into this low from the south, creating a favorable environment for these complexes to develop. Let's take a look at some of the latest model data that suggests a possible scenario for nocturnal storms by Friday morning.
This 850 mb forecast chart above let's us know where to start looking. Notice the winds are moving north toward our low pressure area across the upper Midwest. This ribbon of strong air around 5,000 ft is responsible for transporting rich moist air from the Gulf of Mexico. We call this ribbon of air the "low level jet (LLJ). It's typically a wind at 850 mb that's stronger than 35 knts that can provide moisture and lift for storms to form.
The maximum wind speed appears to be close to 50 knts across west Texas into western Oklahoma around midnight. The LLJ becomes stronger at night due to less friction in the lower part of the atmosphere we call the boundary layer. Radiation from the sun stops, so the ground begins to cool rapidly. Air aloft remains warmer, so the boundary layer becomes stable. Since friction drops off on top of the boundary layer, the winds become faster, and transport more moisture north. LLJ's are almost always apart of MCC development, so this is our first clue, but now we need to find a disturbance aloft to kick all of this off.
This is a 500 mb chart. We look for atmospheric waves aloft to indicate areas of rising air. We want to find a point where the 500 mb wave intersects the 850 mb LLJ. If we can find a correlation, then we'll have an idea on where convective initiation will occur. Look at the wave over west Texas and Oklahoma that's created by our main storm to the North. This is where the LLJ pools in from the south. This disturbance aloft is depicted by the WRF model at Midnight on Friday morning.
Most likely convective initiation will occur across western Oklahoma/Texas, and eventually move southeast. The stronger the cold pool, the faster the MCC movement. We'll have to watch our eastern Oklahoma counties closely as we head into the early morning hours on Friday.
Posted by Drew Michaels at 9:45 PM
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Tuesday, May 29, 2007
Added Moisture Means Fog......
This picture was taken from Poteau, Oklahoma from our recent saturated weather pattern. Of course we have all of the ingredients coming together, not only for the rain, but for foggy conditions as well. At 850 mb look at the dominant high over the SE. This high is responsible for pumping moisture off the Gulf of Mexico and straight into our area.
That southerly feed has provided us ample chances for rain during the afternoon; however, at night, the winds have been going calm, and the temperature has quickly cooled to the dewpoint under a partly cloudy sky. This has been the recipe for overnight fog development; moreover, the added rainfall only helps to saturate the layer of air right above the surface, so fog tends to quickly develop where the rain falls.
Posted by Drew Michaels at 8:28 PM
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Monday, May 28, 2007
HAVES & HAVE-NOTS
It was another day of the “haves” and the “have-nots”; where it did rain, there was plenty, where it didn’t, it just remained warm and muggy! A viewer from Heavener, OK was most certainly among the “haves”. I spoke with her earlier in the evening and she said that around 7:45 PM or so she heard a loud “whoosh”. This was while it was raining hard with lightning and thunder, but she just thought that it was an afternoon t-storm… that is, until she heard the “whooshing” noise, which seemed to last for about a minute. When she looked out her front door, much to her dismay, a tree had fallen on her Pathfinder!
Elsewhere, one complex of storms that pushed through Benton County prompted a short-lived t-storm warning for McDonald County in MO. As we lost the heat of the day, the activity dwindled.
The pictures tell a nice story. Plenty of moisture along with significant daytime heating can produce some impressive storms, capable of gusty winds, small hail, dangerous lightning as well as profuse amounts of rain! We’re definitely in spring, and with any one thunderstorm, a significant threat arises.
Posted by Ted Zarras at 9:34 PM
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Sunday, May 27, 2007
ANOTHER SLOW LOW... (a look at the week ahead)
... is going to make you mow!Look over Texas at the blue L. Note how it's sitting in a carved out green line and this line is by enlarge, alone across the southern half of the country as opposed to being among several others, as is the case in the northen half of the states. These lines are isobars, or lines of equal pressure, and the close proximity of the lines along the US / Canadian border represent the region of the fastest moving winds otherwise known as the jetstream. Mr. Texas blue L (TbL) is far removed from this speedy high way. Think of it like this; instead of cruising along, making time, doing 90+ mph, Mr. TbL is lost on a dirt road and struggling to go 5 mph!
TbL spells "trouble" if you're hoping for a dry start to the week ahead.
The dip in the jetstream over Washington, Oregon and Idaho looks to be the saving grace from the rather muggy pattern we've been in for sometime now. This storm system, with a little luck and a prayer, will hopefully drag a cold front across our area by Friday, ushering in a much cooler and dryer air mass. It may not be too long lived, but we'll save that thought for another blog entry. Until then, it's on / off shower and thunderstorm activity, ramped up by daytime heating and a few waves spinning around TbL, throughout most of the week.
If you happen to take a peak at our superdoppler radar and see a window of clear, then start that engine and mow away, either that or wait until the weekend!
Posted by Ted Zarras at 11:30 PM
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STORM PICTURES May 27, 2005
More photos taken by 4029 Storm Tracker Brian Emfinger... THANKS BRIAN!Loosely quoting him:
"This one was taken NE of Ozark. A wall cloud look alike kinda - it's where a wall cloud should be (sw corner of storm - pic is looking east) but it wasn't connected to the tower...so it's a far less impressive shelf cloud."
"Same storm looking north now into heavy rain core."
"and again same storm actually showing a bit of the structure (looking Northwest now). It was really short but plenty of available moisture allowed it to put down some really heavy rain. AND of course there is the look alike Tornado there below the updraft which is just scud. The scud was going up but not very fast at all...however technically speaking the lowering below that updraft base from where the fake tornado is coming down from would be a wall cloud."
Posted by Ted Zarras at 11:25 PM
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A FEW STRONG STORMS TODAY...
4029 Storm Chaser Brian Emfinger sent this photo in today. Thanks!
We saw quite a few terrain induced thunderstorms pop up as we neared peak heating in the mid afternoon. A complex that pushed through regions of Benton and Carroll counties passed right over Beaver lake gathering steam as it pushed into southern MO. A few warnings were issued some time later as the storms continued to move to the north.
The above picture shows a nice rain shaft or perhaps a small-scale wet micro burst, a concentrated area of rain cooled air that falls rapidly from a decaying thunderstorm. In this case not all of the rain was evaporated. There may have been some embedded small hail too.
There is an upper level storm system now over Texas. This is moving very slowly and interaction with a few faster moving waves may likely develop a complex of storms that drops heavy rain across portions of south eastern OK. Just in the last hour, interaction of the upper level low with a wave that has pushed into the pan-handle has exploded into region of heavy rain with embedded thunderstorms.
Remember that just a foot and a half of swiftly moving water can float your vehicle away and just a mere half foot of moving water could knock you down. Please do not try to cross flooded roadways. TURN AROUND DON'T DROWN!
Posted by Ted Zarras at 12:25 AM
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Friday, May 25, 2007
FRIDAY'S FOLLY
So here we are at the unofficial start of summer with the arrival of Memorial Day weekend, but perhaps you’re not quite ready for the hazy, hot and humid stuff and you just didn’t get enough winter... well head south!
High up in the Andes mountains of South America there is snow and plenty of it! Winter is just beginning! Check out the beautiful pictures from Las Lenas, a resort in Argentina… (I’m crying a little that I can’t get a day on those slopes). According to their snow report LAS LENAS, they already have a base depth of 158 inches at the top and 121” at mid-mountain. Ok, enough dreaming, back to home…
We received anywhere from a ¼” to an inch of rain today and this has helped bring rainfall totals for the month even closer to average. We are presently running about a half an inch to an inch shy. This should not be too hard to make up by June 1st.
Yet another wave, cycling around an upper level storm system, is putting down more rain on the Texas panhandle. This complex is moving to the North East an will weaken by morning, though a stray outflow boundary may be a focal point across NE OK tomorrow for a few afternoon t-storms. We’ll be muggy and mild over the course of the holiday weekend with a slow rise in high temps. A few showers and storms will be scattered about in the afternoons, firing off with the heat of the day, though don’t let them spoil your plans. Most will be short lived.
We’re watching a developing system which had promised to cool us down and dry us out by the end of the upcoming week, though the cool-down is now looking less and less likely. There’s still plenty of time to work on that forecast, so for the time being…
HAVE A GREAT HOLIDAY!
Posted by Ted Zarras at 11:20 PM
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Wednesday, May 23, 2007
More Impressive Pictures...
A Storm Chaser Killer.....
Look at the inflow........
This is a great picture of a mesocyclone
Thanks to 40/29 Storm Chaser Brian Emfinger for these shots!
Posted by Drew Michaels at 8:22 PM
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Oklahoma Panhandle Storms
Take a look at these pictures from 40/29 Storm Chaser Brian Emfinger. They were taken from his web camera near Canadian, Texas. He's seen many wall clouds tonight, and that area looks to be active throughout the evening with supercell thunderstorms. The CAP busted around 4 this afternoon, and the storms exploded! There was even a report of softball size hail.
Posted by Drew Michaels at 3:18 PM
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Outflow Boundary....
Look at the outflow boundary from the satellite photo above. On this visible image it shows up as a thin cloud line that is well ahead of the surface cold front which remains in western Oklahoma. This cool air has rushed hundreds of miles ahead of the storms along the front; moreover, it could be the key to future thunderstorm development across our area this afternoon.
With sunshine already breaking out, we'll need to watch where this boundary goes, in order to pinpoint where convective initiation will occur. This is a great example of how satellite data can be very useful when creating a forecast.
Posted by Drew Michaels at 7:36 AM
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Tuesday, May 22, 2007
Next Couple of Days...
Like Ted said in his previous blog entry, even though the best jet dynamics remain to our north over the next couple of days, we'll continue to see chances for showers and storms across the area. It should be an active Wednesday near the panhandle as strong 100 knt jetstreak shakes up the atmosphere. Rapid lift and wind shear should create a large tornado potential, but what about the potential for storms across our area? Let me break down each day in what we're thinking, and remember the key to our storm chances remains in the sunshine!
Wednesday:
The cold front and the trough will remain out to our west; however, with enough daytime heating, temperatures should be able to climb into the 80's, allowing for pop up afternoon showers and storms. The cap won't be much of a factor, so if storms can fire after reaching convective temperature, they may produce small hail and gusty winds. The best spot for storms looks to be around SE OK where CAPE, Moisture, and Theta E look to pool. Dry air aloft could help create strong gusty winds as storms collapse. A moderate risk for severe weather will occur along the cold front/dryline in western Oklahoma where the best dynamics exist. You can see the strong forecasted SRH values in my picture above. The shear will be tremendous.
Thursday:
There will likely be ongoing convection across Kansas and Oklahoma through Thursday morning. An outflow boundary from those storms may move into our area and spark showers and storms ahead of the cold front by Thursday afternoon. Isolated severe weather can't be ruled out, especially ahead of the front. Added sunshine on Thursday will only help to destabilize the atmosphere. Large hail and gusty winds will remain the primary threats since the low level wind shear remains low. The front looks to arrive by Thursday evening, creating a good chance for widespread showers and storms along the front.
Friday:
The same cold front that will provide lift for storms on Thursday will washout over us on Friday. This left over boundary could spark more afternoon and evening storms for Friday evening. Isolated strong to severe cells will be possible if enough sunshine is present. That same boundary should wave north as a warm front throughout the weekend.
Posted by Drew Michaels at 9:46 PM
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UPPER LEVEL DIVERGENCE
As we’ve discussed before on the 4029 weather blog, there are two “sweet spots” associated with a jetsteak; the right entrance region and the left exit region. Both regions develop broad scale convergence and rising motion at the surface due to divergence aloft. They are favorable spots to keep an eye on for thunderstorm development. Sometimes these regions can become overlapped when two jetstreaks are near each other, causing super-enhanced rising motion over an area. Many record breaking snowstorms are a product of such an overlaying of these “sweet spots”.
Take note of the correlation between where the moderate risk is on the map from the SPC and how well it correlates with the positioning of the jetstreak. This is not an accident. In particular, note how the area is more or less superimposed over the right entrance region. Aloft, winds diverge or spread out and at the surface they come together or converge. This region of enhanced lift, coupled with strong wind shear, ample moisture, and a cold front will likely be where most the action is tomorrow.
We may still pop some storms with the heat of the day, though the high test stuff will remain out to our west.
Take note of the correlation between where the moderate risk is on the map from the SPC and how well it correlates with the positioning of the jetstreak. This is not an accident. In particular, note how the area is more or less superimposed over the right entrance region. Aloft, winds diverge or spread out and at the surface they come together or converge. This region of enhanced lift, coupled with strong wind shear, ample moisture, and a cold front will likely be where most the action is tomorrow.
We may still pop some storms with the heat of the day, though the high test stuff will remain out to our west.
Posted by Ted Zarras at 3:57 PM
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Monday, May 21, 2007
Wednesday's Severe Threat
It's going to be a busy couple of days as our long wave weather pattern becomes more active. Hopefully you were able to read Ted's blog below highlighting the severe weather season so far this year, but even though we haven't seen a large quantity of severe weather, that doesn't mean we're done for the season.
Let's Analyze Wednesday's Threat:
Moisture:
Dewpoints in the 60's along with Lifted Index values of -4 to -6 will easily support the threat for isolated severe weather. LI's in this range indicate the possibility for a moderately unstable atmosphere. Notice the bulls eye of dewpoints in SE OK, that may be an area to really watch, especially for convective initiation. Theta E values are also very high across SE OK, indicating the potential for an unstable atmosphere.
Shear:
The shear is low across the area from 0 to 3KM. SRH values help us to identify low level areas of shear, which correlate with possible tornado development. This is good news. The tornado threat will remain low with Wednesday's storms. In addition to a low tornado threat, with a weak shear environment, it's also unusual to see large hail. Large hail needs a strong rotating updraft to support its weight, and we're not seeing that on Wednesday across our area.
CAPE values can also be used as an indicator of hail potential. CAPE is directly related to the maximum potential vertical speed in an updraft; moreover, the larger the CAPE, the faster the updraft. CAPE values are forecast to run from 2500 to 3000 across SE OK, so small hail will be a factor with the stronger storms.
Trigger:
Take a look at the picture above. The main energy from the trough will likely stay to the north on Wednesday, so we're not looking at a substantial cold pool of air aloft to initiate storms; however, strong daytime heating should be enough to break a weak CAP. In addition to small hail, strong gusty winds will also be a factor.
We'll look for showers and storms to develop toward the late afternoon and early evening as our. trigger becomes the sunshine. The most unstable area will remain south of I-40 on Wednesday, so we'll continue to monitor future model runs as we tweak the forecast.
Posted by Drew Michaels at 6:08 PM
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TORNADO STATS SO FAR...
Taking a look at the three year averages for the following tornado statistical categories; Number of Tornadoes, Number of Tornado Deaths, and Killer Tornadoes, it’s been quite an intense year thus far.
The preliminary number of tornadoes this year is 759. The 3 year avg. is 1366. We are presently at 54% of average. Unfortunately the preliminary number of tornado deaths is up to 74, which is substantially higher than the 3 year avg. of 46. Lastly, the preliminary number of tornado deaths is up to 20, which is two higher than the 3 year avg. of 18.
This season has been somewhat light for us, severe weather-wise, due to an anomalous northern placement of the jet stream. Our long-wave weather pattern over the past few months has seen many troughs dig into the country, only to lift out, leaving a spinning cut-off low to our west.
Once again, the best dynamics for severe weather in regards to the weather system that’s beginning to push into our area now will likely remain to our north and west. Several small disturbances moving within the main storm system will likely still spark off some strong thunderstorms over the next few days which we’ll be tracking carefully, though the tornado threat looks to remain low.
The preliminary number of tornadoes this year is 759. The 3 year avg. is 1366. We are presently at 54% of average. Unfortunately the preliminary number of tornado deaths is up to 74, which is substantially higher than the 3 year avg. of 46. Lastly, the preliminary number of tornado deaths is up to 20, which is two higher than the 3 year avg. of 18.
This season has been somewhat light for us, severe weather-wise, due to an anomalous northern placement of the jet stream. Our long-wave weather pattern over the past few months has seen many troughs dig into the country, only to lift out, leaving a spinning cut-off low to our west.
Once again, the best dynamics for severe weather in regards to the weather system that’s beginning to push into our area now will likely remain to our north and west. Several small disturbances moving within the main storm system will likely still spark off some strong thunderstorms over the next few days which we’ll be tracking carefully, though the tornado threat looks to remain low.
Posted by Ted Zarras at 4:19 PM
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NATIONAL SAFE BOATING WEEK 2007
This week (May 19-25) has been declared National Safe Boating Week 2007. The statistics are quite sobering as to how many boating fatalities can be directly attributed to not wearing a life jacket. As the weather continues to warm up around our area and our beautiful lakes and rivers become an increasingly popular destination to beat the heat, keep in mind boating safety and wear your life jacket. If you own a boat or go out on friend’s boats often, share this information with others and let’s not have any stories about accidents this year!
THERE’S NO REASON NOT TO WEAR IT!
It’s too hot! It doesn’t look cool. I know how to swim. Nothing is going to happen to me. These are just some of the many reasons people claim that they do not wear their life jackets. But with approximately 700 people drowning each year from recreational boating accidents, it is imperative for you to wear your life jacket at all times while you are on the water. Life jackets are no longer the orange, hot and bulky vests that are commonly associated with on the water safety gear. New innovations and developments in life jackets have produced a smaller, sleeker, and much more comfortable version of a life jacket, leaving you with no reason not to WEAR IT!!
Much like a helmet to a biker or skate boarder, life jackets are an essential part of your boating safety equipment and should be worn at all times while on the water. In 2004 of the 676 recreational boating fatalities that occurred, 90% of those victims were not wearing their life jackets. Life jackets are now lighter, less obtrusive and more attractive than ever before. The new inflatable life jackets or Personal Flotation Devices (PFDs) allows you the mobility and flexibility that you need when boating, fishing, paddling or hunting and are much cooler in the warmer weather. There are many different varieties of inflatable jackets ranging from those that inflate instantly when you hit the water to those that are manually inflated. All are designed to be more comfortable and wearable than the traditional life jacket.
Accidents can happen at an alarming speed anyplace or anytime you are on the water. Although many boaters stow life jackets on their boat, very few choose to wear it. There just isn’t time to grab a life jacket and put it on properly before you are in the water. If you are faced with a strong current or unfavorable weather conditions you will not only have trouble making sure you are safe and secure in your life jacket, but you will be unable to help your friends, relatives, children or passengers that have accompanied you in your boat. Wearing your life jacket will allow you to be safe in case of an accident and will also allow you the ability to assist others that may be in danger.
This year during National Safe Boating Week, and throughout the boating season remember to practice safe and responsible boating, always wear your life jacket, and be alert and aware while on the water. By practicing these simple steps you can save your life as well as the lives of the people boating with you. Life jackets are now more comfortable and lightweight than ever, with many new styles to fit the style you want. Safe boating saves lives so for this year’s National Safe Boating Week and throughout the boating season remember to Boat Smart. Boat Safe. WEAR IT!
It’s too hot! It doesn’t look cool. I know how to swim. Nothing is going to happen to me. These are just some of the many reasons people claim that they do not wear their life jackets. But with approximately 700 people drowning each year from recreational boating accidents, it is imperative for you to wear your life jacket at all times while you are on the water. Life jackets are no longer the orange, hot and bulky vests that are commonly associated with on the water safety gear. New innovations and developments in life jackets have produced a smaller, sleeker, and much more comfortable version of a life jacket, leaving you with no reason not to WEAR IT!!
Much like a helmet to a biker or skate boarder, life jackets are an essential part of your boating safety equipment and should be worn at all times while on the water. In 2004 of the 676 recreational boating fatalities that occurred, 90% of those victims were not wearing their life jackets. Life jackets are now lighter, less obtrusive and more attractive than ever before. The new inflatable life jackets or Personal Flotation Devices (PFDs) allows you the mobility and flexibility that you need when boating, fishing, paddling or hunting and are much cooler in the warmer weather. There are many different varieties of inflatable jackets ranging from those that inflate instantly when you hit the water to those that are manually inflated. All are designed to be more comfortable and wearable than the traditional life jacket.
Accidents can happen at an alarming speed anyplace or anytime you are on the water. Although many boaters stow life jackets on their boat, very few choose to wear it. There just isn’t time to grab a life jacket and put it on properly before you are in the water. If you are faced with a strong current or unfavorable weather conditions you will not only have trouble making sure you are safe and secure in your life jacket, but you will be unable to help your friends, relatives, children or passengers that have accompanied you in your boat. Wearing your life jacket will allow you to be safe in case of an accident and will also allow you the ability to assist others that may be in danger.
This year during National Safe Boating Week, and throughout the boating season remember to practice safe and responsible boating, always wear your life jacket, and be alert and aware while on the water. By practicing these simple steps you can save your life as well as the lives of the people boating with you. Life jackets are now more comfortable and lightweight than ever, with many new styles to fit the style you want. Safe boating saves lives so for this year’s National Safe Boating Week and throughout the boating season remember to Boat Smart. Boat Safe. WEAR IT!
Posted by Ted Zarras at 9:10 AM
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Saturday, May 19, 2007
VENUS & The Moon
The picture above was taken by 4029 Storm tracker, Brian Emfinger. We had many calls tonight about that bright star / planet by the moon. It was a gorgeous sight to cap off a most beautiful day.
Posted by Ted Zarras at 9:00 PM
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PBL + WAX + Mr. Miyagi = Better MPG's
At low levels in the atmosphere wind is slowed down by friction. This force arises mainly from topographical features on the surface of the earth. Above the Planetary Boundary Layer or PBL, the bottom layer of the troposphere that is in contact with the surface of the earth, wind flows more freely and speed increases. We can actually take this example of a physical process and apply the principle to get better gas mileage!
Interested now?
Believe it or not it has been shown that a clean and waxed car can get up to a 7% increase in mileage, due to the fact that air can flow more freely over the surface. I know it doesn’t sound too impressive but it does become a real savings, even on just one tank of gas!
Let’s say that your car gets 25 miles to the gallon. After waxing and adding in the 7% increase, it now is boosted up to 26.75 mpg. Now let’s say your tank holds 15 gallons. Prior to washing and waxing you could go 375 miles before running out. With the added mileage you are now able to go 401.25 miles. This is a difference of 26.25 additional miles on one tank just because your car is waxed. You’ve just been “given” a free gallon of gas or put $3.50 in your pocket. However you’d like to look at it!
OK, now repeat… “WAX ON WAX OFF, wax on wax off, wax on wax off !”
…but, If you suddenly feel compelled to enter a karate contest don’t blame me.
Posted by Ted Zarras at 8:48 PM
Feel Like Storm Chasing?
I have talked to a few storm chasers recently, and they have all said the same thing, "man, this has been a very boring severe weather season so far." With the jet poised well to our north, it's no surprise the severe weather viewing has been few and very far between across eastern Oklahoma and western Arkansas. Most importantly, cabin fever is not a good situation for any storm chaser to deal with, so I want to help out in any way I can.
If you're looking for an upcoming thrill to get your Memorial Day weekend off to a good start, you better head north my friend. The dominant ridge that has been influencing our weather is set to break down; moreover, in response to energy moving across the Pacific Northwest, a decent trough will soon dig across the Midwest, creating the potential for showers and storms.
We're looking at Tuesday, May 22nd, so let's go through some of the key ingredients to get this recipe just right!
Will the Storms Have Fuel?
When we say fuel, we're referring to moisture. Deep moisture is needed for severe weather to develop. It's the gasoline that fires the engine. Dewpoint temperatures are a direct indicator of moisture in the air, and the map below shows forecasted dewpoints for Tuesday evening. You typically want to see spring dewpoint temperatures in the 60s for severe weather to occur. Look at the plume of deep moisture that stretches from the Gulf to the Canadian border. We'll keep our eyes out within this zone.
Where will the greatest amount of lift occur?
We must look to the jetstream for this answer. The jetstream is made up of many bundles of fast moving winds called jetstreaks, and these jetstreaks help to control atmospheric airflow and pressure by creating their own circulations. The eastern side of the trough is a good place to start in order to find rising air. This is a vertical velocity forecast at 500mb, or 18,000 ft (depicted on the right). Upward vertical velocities indicate rapidly rising air within the atmosphere. Air on the eastern side of the trough rises because of the lower amount of pressure created by diverging winds aloft and warm air advection. VV's look good from Kansas to Minnesota. We'll keep those areas in mind. Now VV's also look impressive in association with an upper level low across the Dakotas, but we'll focus on the eastern side of the trough since that's where the deep moisture exists.
The picture on the right depicts a forecast for Theta E. Theta E is directly related to the amount of heat present in a parcel of air, so it becomes a good indicator of atmospheric instability. The pooling of Theta E can also indicate the potential for a convective burst point. High Theta E is setting up along the eastern side of the ridge, so our case for severe weather to occur across eastern Kansas and Nebraska continues to get stronger.
Where will the wind shear exist?
Look at this area shaded in red and yellow across Kansas. This is a great indicator of low level wind shear from the surface to around 10,000 ft. Storm Relative Helicity (SRH) is a general indicator of low level turning of the winds, which has a direct correlation to tornado potential; however, the SRH value is not used as an indicator for supercell formation, since supercells need deep layer shear in order to develop. A SRH value greater than 250 is an indicator of moderate to strong low level shear. Not only does eastern Kansas have lift, and moisture, it also favors a sheared environment for severe storms to develop.
These are just a few factors for us to start nailing down a severe weather threat area. These conditions will likely change, so it's important to keep up with the changing parameters. You have to look throughout the atmospheric column to properly diagnose where the severe weather will develop.
Posted by Drew Michaels at 4:37 PM
Friday, May 18, 2007
MOSQUITOES!
Well it’s that time of the year again, our favorite flying friends are out and about just waiting to say hello. Mosquitoes have returned! In fact maybe a few have already dropped by your place, uninvited of course, for a little snack!
This is probably some sort of urban legend, but, I once tried to pop a mosquito by over- feeding it. It didn’t work; I remember watching in total and utter dismay as this Mosquito that had swelled up to the size of a house fly, now barely able to support it’s weight in the air, limbered off my arm and somehow just disappeared in the twilight. He / She was a happy camper, let me tell you!
So, when are they most active and what type of weather do the pesky pests like best? Well, between the hours of 5-9 PM and around daybreak, mosquitoes are out in droves, bothering us, and just being a nuisance. Have you ever fell victim to the road-tripping Mosquito, the one that gets you about ten times in the legs while you’re driving, despite the fact that you have all of the windows down? Those mean business and they’re smart too. Ouch! Basically, if winds are light and there’s a little moisture in the air then look out, because there’s likely a mosquito party in the works.
There are a few steps you can take to combat the singing little lovelies. Mosquito larvae grow up in standing water, so spilling any that’s collected around your house can help alleviate breeding grounds. Also, cleaning out drains and gutters can get rid of semi-permanent damp spots, which too are a favorite home to mosquito younglings. Lastly, insect repellent can do wonders, especially one’s with DEET, but, read the labels carefully; some are harmful for infants and young children.
For a number of years, I’ve used Avon skin-so-soft. Sure, it makes you smell a little like your Aunt Betty, but the stuff works!
This is probably some sort of urban legend, but, I once tried to pop a mosquito by over- feeding it. It didn’t work; I remember watching in total and utter dismay as this Mosquito that had swelled up to the size of a house fly, now barely able to support it’s weight in the air, limbered off my arm and somehow just disappeared in the twilight. He / She was a happy camper, let me tell you!
So, when are they most active and what type of weather do the pesky pests like best? Well, between the hours of 5-9 PM and around daybreak, mosquitoes are out in droves, bothering us, and just being a nuisance. Have you ever fell victim to the road-tripping Mosquito, the one that gets you about ten times in the legs while you’re driving, despite the fact that you have all of the windows down? Those mean business and they’re smart too. Ouch! Basically, if winds are light and there’s a little moisture in the air then look out, because there’s likely a mosquito party in the works.
There are a few steps you can take to combat the singing little lovelies. Mosquito larvae grow up in standing water, so spilling any that’s collected around your house can help alleviate breeding grounds. Also, cleaning out drains and gutters can get rid of semi-permanent damp spots, which too are a favorite home to mosquito younglings. Lastly, insect repellent can do wonders, especially one’s with DEET, but, read the labels carefully; some are harmful for infants and young children.
For a number of years, I’ve used Avon skin-so-soft. Sure, it makes you smell a little like your Aunt Betty, but the stuff works!
Posted by Ted Zarras at 5:30 PM
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FOR WHAT IT’S WORTH… 3 Month Outlook
The Climate Prediction Center (CPC), part of the Nation Center for Environmental prediction (NCEP), located in Camp Springs, MD, puts out various long range forecasts regarding both temperature and precipitation. These are based upon long-range teleconnections, such as El Nino and La Nina.One of the products that they offer is the three month outlook. These are probabilistic forecasts that offer a trend as to whether the extended period will be wet / dry and or hot / cold as compared to averages. As seen in the maps above, we have equal chances at this point for slightly warmer, slightly cooler or just about average temperatures and precipitation wise, once again according to the CPC, we’ve got equal chances of being above, below, or right around average through August.
Posted by Ted Zarras at 3:48 PM
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Thursday, May 17, 2007
Warmer Weekend..Storms Next Week?
The wonderful weather will be in full effect throughout the upcoming weekend, so whether you're heading out to Baum stadium to watch the Hogs, or planning on catching the big one in the FLA tournament on Beaver Lake, Mother Nature has you covered.
The ridge will dominate our weather for Sunday and Monday, allowing temperatures to soar into the 80s; however, this ridge will be short lived, as we're watching a strong batch of energy moving south of the Gulf of Alaska which will break down this ridge by the middle of next week. A digging trough could bring a significant chance for severe weather across the Midwest as the trough becomes negatively tilted. A jetstreak that is forecast to be near 100 knt will be the focal point for rotating thunderstorms.
The bulk of the severe weather will most likely stay to our north, but if the trough continues to deepen, we'll be in the zone for strong to severe storms for Tuesday/Wednesday. We'll keep a watch on this developing system.
Posted by Drew Michaels at 8:15 PM
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Wednesday, May 16, 2007
Natural Air Conditioning.....
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What a beautiful couple of days we have ahead of us, unseasonably cool highs, along with a relatively dry air mass to enjoy. Now, we won't be able to repeat this performance throughout the year, so let's take advantage of it while we can. At least our upper level air pattern is on our side. I have included two pictures of the upper level wind flow around 17,000 ft for you to study.
The first picture shows the current location of our jetstream. A dominant ridge is holding the heat out over the west, while a trough begins to deepen over the Great Lakes. Typically, we would see that ridge build over our area after the passing of the trough; however, take a look at what happens in the second picture. An upper level low becomes cut off from the main jetstream, and this low deepens across the southeast, creating a northeasterly flow at the surface. This low will act as a temporary blocker from the heat.
This is what I call a natural air conditioning pattern. As long as that low sits to our east, we'll be able to hold off the heat. Unfortunately, the cut off low is forecast to move east, and we'll eventually warm back up toward the weekend.
Posted by Drew Michaels at 8:18 PM
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A COOL APRIL!
The average temperature in the United Sates over the month of April 2007 was 51.7 F. This was -0.3 F cooler than the 1901-2000 (20th century) average, making it the 47th coolest April in 113 years. The temperature trend for the period of record (1895 to present) is 0.1 degrees Fahrenheit per decade. We’ll just have to wait and see how May turns out, though I’m sure not many of us are complaining about any cooler weather we get, like the fine weather we’ve got now; 100’s will be here soon enough!
Posted by Ted Zarras at 9:34 AM
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Tuesday, May 15, 2007
TWO BATCHES OF SHOWERS / STORMS *12:00 noon update...
Showers and thunderstorms are passing through the River valley and NW AR. These are not in association with a sharp cold front which is still back to our west, more or less aligned with I-44, stretching from Tulsa up to Joplin. This is steadily moving to the south east and will push through our area in the later part of the day, delivering our second batch of showers and storms.
A convergent zone of moisture has helped fuel the cells that are now pushing through our area. These likely popped along an outflow boundary of air from last nights storms in Kansas. A little heat was all that was needed to make these storms fire. Small hail, gusty winds, dangerous lightning as well as heavy downpours will be the primary threats with these storms. Please exercise caution if you are traveling! There may very well be some ponding on the roadways too.
Posted by Ted Zarras at 9:28 AM
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Monday, May 14, 2007
Disagreement with SPC's Threat for Tuesday
Welcome to summer, well, not really, but today's jetstream position is where you would typically find it during the late summer months. As I always say, the severe weather threat remains the highest near the jetsream's upper level support, so why are we under the gun for Tuesday?
Tomorrow the SPC has a good majority of our area under a slight risk; however, I don't necessarily agree with this thinking. I can understand the upper Midwest being contained in the slight risk because of their proximity to the jetstream, but our area's lacking the cold pool aloft, so organized severe weather will be unlikely for Tuesday.
A frontal boundary will create the necessary lift for storms, but the timing of the front is everything, and the computer models take the front across NE OK and NW AR around noon. You don't typically expect severe weather along a cold front at that time of the day.
The greatest severe threat for our area will exist across SE OK and SW AR. Frontal timing will be delayed more toward the late afternoon/early evening, so destabilizing sunshine, combined with the frontal passage could create strong gusty winds and small hail. CAPE values look to run between 1500-2000, along with LI values from -4 to -5 south of I-40 by Tuesday afternoon. There will be a cap to contend with as well, which could limit some storm development.
Significant wind shear will be absent from the atmosphere, so we won't see the rotating updrafts capable of producing large hail.
We'll continue to watch the atmosphere closely on Tuesday, but we're not anticipating widespread severe weather to erupt.
Posted by Drew Michaels at 3:48 PM
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