Ramblings of a Graduate Student

VORTEX II was once again forced to call a down day because the atmosphere just wasn’t willing to cooperate. Fortunately for the crew, tomorrow appears to hold more promise for thunderstorms in their general area.

So, with all these down days recently, I wondered how the 2010 tornado season has compared to the tornado seasons of years past. I’ve previously mentioned that 2010 has been a below normal year for tornadoes through the first three months of the year. Now that another (almost) 2 months have passed, and VORTEX II has begun, where do things stand now?

In the image above (which I’ve described previously here), the average over the last five years is marked in grey, and actual events for this year are plotted in red. As you can see, we are still nearly 200 tornadoes below the average over the last five years. This is not a good sign for the VORTEX II crew. Here’s to hoping the next few days and weeks are better for researchers.

Below is from the National Weather Service Forecast Office in Jackson, MS. I thought it important enough for it to be it’s own blog post.  EF4 tornado with a maximum width of 1.75 miles.  Simply amazing…

000
NOUS44 KJAN 260230
PNSJAN

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
930 PM CDT SUN APR 25 2010

...PRELIMINARY INFORMATION FROM STORM DAMAGE SURVEYS
TODAY...

FOUR NWS STORM DAMAGE SURVEY TEAMS HAVE BEEN SURVEYING DAMAGE
FROM AROUND THE REGION CAUSED BY THE DEVASTATING STORMS OF
SATURDAY. THE FOLLOWING IS PRELIMINARY INFORMATION REGARDING
THE MAJOR STORM THAT MOVED FROM NORTHEAST LOUISIANA ACROSS
CENTRAL MISSISSIPPI.

NWS SURVEY TEAMS SURVEYED THE PATH OF THE STORM FROM ITS
START WEST OF TALLULAH, LOUISIANA TO AS FAR AS DURANT,
MISSISSIPPI. TORNADO DAMAGE...MUCH OF IT STRONG...WAS FOUND
ALONG THIS ENTIRE PATH...AT LEAST IN THOSE AREAS ACCESSIBLE
BY ROAD.  BASED ON THESE SURVEYS...THIS IS A SUMMARY OF
THE INFORMATION SO FAR:

PATH LENGTH: 97 MILES...THIS LENGTH WILL INCREASE AS MORE
DAMAGE IS SURVEYED EAST OF TODAY`S SURVEY
MAXIMUM WIDTH:  1.75 MILES
RATING: EF4, WITH MAXIMUM WINDS OF 170 MPH
CASUALTIES: 10 TOTAL FATALITIES WITH DOZENS OF INJURIES

A NUMBER OF AREAS OF EF3 DAMAGE WITH ESTIMATED WINDS OF 150 TO 165
MPH WERE FOUND ALONG THE PATH. TWO AREAS OF EF4 DAMAGE WITH MAXIMUM
WINDS OF 170 MPH WERE FOUND...ONE IN YAZOO CITY...AND THE OTHER IN
HOLMES COUNTY.

ANOTHER SURVEY TEAM IS STILL SURVEYING DAMAGE IN CHOCTAW COUNTY
CAUSED BY THE SAME STORM. THIS DAMAGE HAS BEEN DETERMINED TO BE
AT LEAST HIGH END EF3. WHETHER OR NOT THIS IS A PART OF A
CONTINUOUS TORNADO PATH ALL THE WAY BACK TO ITS START IN
NORTHEAST LOUISIANA HAS YET TO BE DETERMINED. NWS SURVEY TEAMS
WILL BE IN HOLMES...ATTALA...AND CHOCTAW COUNTIES AGAIN MONDAY
TO TRY TO DETERMINE THIS...AND WILL ALSO BE ATTEMPTING TO
OBTAIN AERIAL DATA TO HELP CONFIRM A CONTINUOUS PATH.

IT MUST BE STRESSED THAT ALL OF THIS INFORMATION IS PRELIMINARY
AND SUBJECT TO LATER ADJUSTMENT. A TORNADO OF THIS STRENGTH AND
MAGNITUDE REQUIRES A TREMENDOUS AMOUNT OF DAMAGE SURVEYS AND DATA
ANALYSIS. THE NWS WILL CONTINUE TO PROVIDE UPDATES AS ADDITIONAL
INFORMATION IS OBTAINED...AND IS PLANNING TO HOLD A MEDIA BRIEFING
LATER THIS WEEK TO PROVIDE A FULL ANALYSIS OF THE STORM AND THE
DAMAGE SURVEY RESULTS.

THE NWS WOULD LIKE TO THANK ALL OF OUR PARTNERS IN LAW ENFORCEMENT
AND EMERGENCY MANAGEMENT FOR THEIR INVALUABLE ASSISTANCE IN
PERFORMING OUR DAMAGE SURVEYS.

$$

AEG/GRG/SCW/BK

As has been discussed on this blog for much of the past week, a significant tornado outbreak was forecast for today over much of the southeast.  Unfortunately this forecast appears to have verified.  Even as I write this, a large tornado is on the ground in northeast Alabama, bearing down on yet another population center.  (See last image below).

As a meteorologist who specializes in forecasts of high impact weather (particularly severe convective weather which includes tornadoes), today has been one of extremely mixed emotions.  I stand in awe, in amazement at the power and beauty of thunderstorms and tornadoes. They are an incredible creation of nature.  My desire to understand how they develop, behave, and decay and to be able to predict them earlier and more accurately requires that they occur so that I can observe them and learn from them.

However, I get sick to my stomach when I listen to the reports of people’s lives forever being changed through the destruction of belongings and the lives that are lost.  There is a sense of helplessness that overcomes you when you can see a potential significant tornado outbreak days in advance and know that inevitably people’s lives will be forever changed in negative ways and there is nothing you can do to stop it.   This feeling, in some regards, must be very similar to those a doctor must feel when he or she has to deliver bad news to a patient.  You know the incredible heartache that is about to unfold and nothing you can say or do will ever be able to change that.

Meteorologists must continue to improve forecasts and warnings to ensure that everyone has a chance to hear the message.  I long for the day when the all-to-often heard cliche, “it struck without warning” is just a thing of the past.  My heart is heavy tonight with thoughts turned to the lives that were ended so tragically and so soon.  My deepest sympathies to the families that must try and put back together their lives tonight.

For even more radar images from today, please check out my TwitPic page.

Strong rotation as large tornado moved through Yazoo City, MS.

Strong rotation a mere 500 feet above the ground as tornado moves very near Columbus Air Force Base (MS).

Strong rotation near Henderson, TN.

Strong rotation as a tornado moved through Albertville, TN

Today (Thursday, 22 April 2010) I went on my first “real” chase since moving to Norman almost 5 years ago.  (I did a quick “go east less than an hour” chase in 2008.)  At the same time, this was my first Texas Panhandle chase, ever.  We were successful in viewing two separate tornadoes (at a distance) during  daylight.  Later we viewed a cone-shaped cloud structure emanating from a wall-cloud; however, due to our distance we cannot confirm (nor deny) it was in contact with the ground.  Because of this chase, I did not return home until 2 AM CDT on Friday, hence my late post.

While returning from our chase, my chase partners and I began examining forecasts for the next few days via our iPhones.  In perusing this information, all of us became increasingly concerned about a potential long-lived significant severe weather outbreak over a large portion of the southeastern United States.  Because I agree with a lot of what the Storm Prediction Center (SPC) has described in their Severe Weather Outlooks, I have decided to post their images here as my “image(s) of the day”.

All persons across the southeast (and even the central plains) should review their severe weather preparedness plans.  If you do not have a severe weather preparedness plan, please use the contact form on the “About” page to contact me.  I’ll be happy to help discuss this further.

Friday, 23 April 2010 Forecast (Initial Day 1 Outlook)

Friday, 23 April 2010 Forecast (Probability of a Tornado on Day 1)

Friday, 23 April 2010 Forecast (Probability of a Severe Hail on Day 1)

Friday, 23 April 2010 Forecast (Probability of a Severe Wind on Day 1)

Saturday, 24 April 2010 Forecast (Initial Day 2 Outlook)

Satuday, 24 April 2010 Forecast (Probability of a Any Severe Weather on Day 2)

In storm chasing circles “The Day” is known as the day in which all the numerical models forecast a severe weather outbreak.  Often “The Day” has been forecast several days in advance and storm chaser excitement builds as the the event draws closer.  ”The Day Before” is also known in storm chasing circles.  This is the day before “The Day” and is often characterized by high risk, high reward for viewing severe thunderstorms and tornadoes.  In other words, you aren’t guaranteed to see something (high risk), but if a thunderstorm can develop, there is a chance you could be the only “chaser” there to observe it (high reward).  Tonight, I’m going to highlight a potential “Day Before the Day Before” situation.

As I’ve alluded to in recent posts, numerical models are hinting at the possibility of severe thunderstorms on Friday across portions of the central United States.  This would be “The Day”, making Thursday the “Day Before”.  However, there is an extremely high risk, high reward situation setting up on Wednesday.

Above (annotated below) is a forecast from this evening’s 00 UTC (7 PM CDT) run North American Model (NAM) valid 18 UTC (1 PM CDT) on Wednesday.  It shows accumulating precipitation falling across portions of northeast Oklahoma.  This precipitation is forecast to develop late Tuesday in northwest Kansas and northeast Colorado, in the higher elevations.  (I would just like to point out that this is typical of late summer patterns, not late April!!)  This complex of showers and thunderstorms is then forecast to track southeast  overnight and dissipate during the afternoon over western Arkansas.

This is an important feature because the precipitation and associated cloud cover act to keep the temperatures cooler in the wake of the precipitation than the surrounding areas.  At the same time, warm, moist air is forecast to began moving northward in response to the developing low over the southwest United States.  As the warm, moist air advances far enough northward it will impinge upon the rain-cooled airmass forecast to be in place across northern Oklahoma and southern Kansas.  This increasing gradient in temperature is, by definition, a front.  In this case it is a warm, front.  Warm fronts are important in severe thunderstorm and tornado forecasting because they act as a source of low-level convergence which can help aid thunderstorm development.  Also, just north of the warm front winds at the surface tend to be out of the southeast or east and quickly switch to being from the southwest aloft.  This rapid change in wind direction with increasing height is a crucial component for thunderstorms to be able to sustain themselves.  This allows them to become stronger than than otherwise might.

The previous  images (first four) were all valid at 18 UTC (1 PM CDT) on Wednesday.  This last image is valid at 00 UTC Thursday (7 PM CDT Wednesday).  It displays the forecast Convective Available Potential Energy (CAPE) late Wednesday.  This is a measure of how much energy a thunderstorm would have to work with should one develop. Forecast values in the image above in far southwest Oklahoma and northwest Texas are more than sufficient for large updrafts to develop – a key ingredient of severe thunderstorms this time of year.  Couple this large amount of instability with a potential warm front in the area, Wednesday afternoon just might turn out to be “The Day Before The Day Before”.

Lastly, I want to say that this signal has been in the last several model forecasts of both the NAM and the Global Forecast System (GFS) model.  By no means is anything a guarantee, but it is certainly something to watch.  Thursday and Friday, almost certainly have a greater potential to produce severe thunderstorms.  Thus, don’t let your guard down if nothing happens on Wednesday.  There is a reason why it is known as a high risk, high reward kind of day!

With the chance of severe weather returning to the eastern two-thirds of the United States by mid-week, I thought tonight I’d post about this year’s severe weather to date.  If you’ve thought this year has been unusually devoid of severe weather, you’d be correct.

The image above was created by the Storm Prediction Center’s Warning Coordination Meteorologist, Greg Carbin.  It displays the 2010 tornadoes (in red) and 2005-2009 tornado averages in grey.  The vertical bars represent the daily occurrence of tornadoes (2005-2009 in grey; 2010 in red; axis on the left) and the more horizontal bars indicate the running totals (axis on the right).  A quick glance quickly captures how far below recent history we are, with less than 100 preliminary tornado reports through 15 April.  To put it into perspective, the recent average through 15 April is 415!  It isn’t very often that by mid April, January was is one of your bigger tornado producing months!  As we continue to head into peak tornado season, this gap continues to widen for each day that passes without tornado occurrences.

Late this week, the atmosphere may support tornadoes again through portions of the central United States.  I’ll have more on this throughout the week.

Whew!  A very busy today, which included an afternoon tour for the Trinity Junior High Science Bowl team and then an evening full of severe thunderstorms and possible tornadoes.

The image above is a radar image taken earlier this evening showing the severe weather event as it unfolded across the state of Arkansas.  It’s a busy image, so here is what everything means:

• Yellow shaded areas = Active Tornado Watch
• Reddish-Purple shaded areas (NW AR and SW MO) = Active Severe Thunderstorm Watch
• Yellow solid lines = National Weather Service Forecast Office boundaries
• Large area with solid red line and light red color fill (north-south oriented thing from AR into LA) = Active Storm Prediction Center Mesoscale Discussion
• Solid orange lines = Outlines of Active Severe Thunderstorm Warnings
• Red solid lines (no color fill) = Outlines of Active Tornado Warnings

As you can see, it’s a lot to absorb – just look at the number of warnings in effect!  Also, you can see quite a large area was (still is as I write this) under the threat for possible tornadoes overnight.  While the threat of tornadoes has decreased from earlier this evening, it is still an appreciable threat and shouldn’t be taken lightly.