Day 160: A Great Deployment; A Weak Thunderstorm

Posted by pmarsh on 9 Jun 2010 | 0 comments

The VORTEX 2 armada woke up this morning in Denver, Colorado with high hopes for a successful deployment. The forecast over the past few days seemed to indicate that the tornado potential today would be higher than it had been recently. Unfortunately, this did not turn out to be the case. I have to admit that other job responsibilities prevented me from following the weather evolution this afternoon, so I’m not entirely sure why the atmosphere was so devoid of severe thunderstorms in eastern Wyoming and western Nebraska. However, I do know that none of them (up to now and to my knowledge) have produced tornadoes.

With this said, the armada did target a transient supercell-like thunderstorm that developed near 00 UTC (7 PM CDT) in Goshen county, Wyoming. This thunderstorm appeared early on to be a fairly healthy, albeit small, supercell thunderstorm. Unfortunately, it appeared this thunderstorm was unable to draw warm, moist surface air up into it’s updraft. This result in the supercell to remain “elevated” and severely limited the rotation (tornado) chances. This was a real shame because the VORTEX 2 crew had what I consider to be their best deployment in the two years this project has been running. As far as I could tell, every radar was in position, ever mobile mesonet was in position, and all other assets were also in position. Too bad the atmosphere failed to cooperate. The image above is of the target storm moving east into Scottsbluff, Nebraska – a city that has been hit by severe thunderstorms nearly every night for the past several days. This is the town that VORTEX 2 sampled a brief tornado in just a few days ago!

In any event, forecasts continue to indicate that tornado chances are higher tomorrow than today, so the armada should once again have a decent chance at observing a tornado. Let’s just hope that if a tornado does develop, it is in an area where there are sufficient roads for the armada to collect data!

Day 159: An Upcoming West Coast Trough

Posted by pmarsh on 8 Jun 2010 | 0 comments

VORTEX 2 operated in standby mode today before eventually calling things off early this evening without targeting a storm. Ironically, after dark, a tornado was reported 20 miles west of where they armada waited all day. Who says Mother Nature doesn’t have a sense of humor!

In any event, as VORTEX 2 heads into the final days, the crew is hanging its hopes on a storm currently moving on shore (circled in yellow) along the west coast. This storm has a very strong jet (circled in blue below) which should help to provide decent shear over the central plains in the coming days. As you can imagine the forecast is for several good chase days coming up for the VORTEX 2 crews. Let’s hope the field campaign of VORTEX 2 goes out with a bang!

I’m sure I’ll have more to say about this in the coming days.

Day 158: A “Super” Supercell

Posted by pmarsh on 7 Jun 2010 | 0 comments

The VORTEX 2 armada once again intercepted a tornado from a storm moving into, through, and then out of Goshen county, Wyoming. For those of you who don’t remember, this is the county where VORTEX 2 intercepted it’s first (and only) tornado of 2009. I don’t have all the details of the deployment because it was very late, and the armada is still traveling, but what I do know was the several members of the armada saw at least a brief touchdown on the east side of Scottsbluff, Nebraska. The Doppler On Wheels (DOW) trucks were able to collect data on the tornado, and actually saw what appears to have been an additional tornado. Granted, no one “saw” this tornado, we’re just inferring it’s presence from the radar data. Hopefully I’ll have more information in the next few days.

As exciting as this intercept was, the image tonight is of a storm just east of the storm(s) the armada targeted. The above radar image was taken shortly before 10 PM CDT (03 UTC) and clearly shows a very strong supercell thunderstorm (complete with “hook”) beginning to wrap up. It’s a shame this storm didn’t develop earlier in the evening (before dark) so that VORTEX 2 could have targeted it. I can only imagine the dataset a storm like this would provide! Oh well. There is always tomorrow…

Day 157: Northern Plains MCS

Posted by pmarsh on 6 Jun 2010 | 0 comments

I awoke this morning thinking that VORTEX 2 would take a down day or do some light traveling in preparation for tomorrow. I figured that they must be extremely tired from the day-after-day grind. Boy was I mistaken! The principal investigators decided to head west, across the entire state of Nebraska, and target storms coming out of Wyoming. I have to tip my hat to their dedication!

This dedication paid off with two deployments on two separate tornado warned thunderstorms. Although neither storm appears to have produced a tornado, they did drop extremely large hail! I heard at least one report from a probe of numerous vehicles with all the windows smashed out from hail. As was mentioned to me, “hail + high wind + glass = $$$”. How strong was the wind? At least one probe measured a 72 miles per hour wind gust. Just east of this report, the National Weather Service had a report of 80 miles per hour wind gusts. As I mentioned, these storms meant business.

The image above shows what has happened to the thunderstorms since VORTEX 2 ended operations for the evening. The multiple thunderstorms in the area have all grown together (this is known as “growing upscale”) and have become what meteorologists call a “Mesoscale Convective System”, or MCS for short. MCSs tend to last longer than an individual thunderstorm and can travel hundreds of miles fairly quickly, or they can remain nearly stationary. This was is moving at a decent clip to the south and east. It will be interesting to see how far south it makes it before dissipating. Will I wake up to rain in the morning? I’ll see in about 6 hours!

Day 156: Cueing Alanis Morissette

Posted by pmarsh on 5 Jun 2010 | 1 comment

Last night I blogged about AccuWeather’s seasonal tornado forecast. If you haven’t read it, the gist was that their forecast of increased tornadoes across the Great Lakes region and a decrease over traditional Tornado Alley for April through June appeared to be incorrect. So, naturally, a tornado outbreak would occur over the Great Lakes region today! (As a public service announcement I’m compelled to state that there are several tornadoes ongoing as of my writing. If you live in the Great Lakes region, please sleep with a NOAA Weather Radio on tonight.) As tonight’s title implies, Alanis Morissette must be getting ready to sing here hit Ironic.

VORTEX 2 attempted to blast east from central Nebraska to be able to target this evening’s tornado outbreak. Unfortunately it was just too far of a travel for the armada to get in position. Instead, the armada stopped in central Iowa and targeted thunderstorms developing along the cold front. At least one member of the armada did observe a brief tornado, but it was so brief that VORTEX 2 was unable to collect data on it.

And for the record, I still stand by last night’s blog post. A single event does not make (or break) a seasonal forecast.

Day 155: Long Range Tornado Forecasts

Posted by pmarsh on 4 Jun 2010 | 0 comments

The atmosphere once again did not cooperate with VORTEX 2′s mission to study how tornadoes form. The armada was unable to conjure up a thunderstorm today, so the armada is heading back to their hotels in hopes that tomorrow will be a better day. Since there is not much to discuss regarding V2′s activities today, I thought I discuss long range forecasts.

Long range forecasts of weather are hot commodities for a large segment of the business community. Having accurate seasonal weather forecasts are a huge advantage for companies as it allows companies to “stock up” on things that will be in demand. For example, if a winter is forecast to be colder than normal, then heating oil companies might need to prepare by purchasing more heating oil – before the start of winter – when it is in more abundance, and therefore cheaper. In this scenario, the company is able to make a large profit by buying cheap ahead of time, and then selling at the market rate during the season.

Sounds simple enough, right? Well, the flip side to long range forecasts is that if the forecast is wrong, a company stands to lose a lot of money. In the previous example, if the company purchased heating oil before the season, and the winter was warmer than normal, the company would have a lot of heating oil it would need to sell. Law of supply and demand would act to drive the cost of oil downward costing the company a lot of money.

The problem with long range forecasts is that they are extremely hard to get correct. The atmosphere is a very complex fluid, and things evolve in a manner that is not always easily understood. Above is the long range tornado forecast from AccuWeather (valid for April, May, and June). You can read more about this forecast here and here.

So, how has AccuWeather done so far? Below is a graphic depicting the location of all reported tornadoes for April and May.

A large portion of the “High” risk in AccuWeather’s outlook is actually experiencing normal to below-normal numbers of tornadoes this spring. A large number of the tornadoes in Arkansas, western Tennessee, Mississippi, and Alabama were the result of only two events (24 April and 30 April-1 May). In fact, there have been a significant number of tornadoes in the areas forecast to be in the “lowest” risk.

Specific, long range forecasts, like the AccuWeather forecast above, are extremely difficult. The skill in such forecasts varies widely depending on the phenomenon being forecast. Meteorologists have a much better chance at forecasting seasonal temperatures and precipitation patterns, than we do with rare events such as tornadoes. It is my opinion that seasonal forecasts, such as the one issued above, and to a lesser extent hurricane forecasts that include numbers, do more harm than good to meteorologists’ credibility. However, because people want (and like) seasonal forecasts, there will almost always be people to step up and provide such a forecast.

Day 154: Mesoscale Convective Vortex Near Houston

Posted by pmarsh on 3 Jun 2010 | 0 comments

As I write this, VORTEX 2 is currently in the midst of operations across southern South Dakota and northern Nebraska. There is nothing intense ongoing, but the hope is that something will develop in the next couple of hours. Hopefully the atmosphere won’t disappoint, and thunderstorms will develop.

Farther south, away from VORTEX 2, a large mesoscale convective vortex is spinning away just to the northwest of Houston, TX. The radar reflectivity this afternoon looked very similar that of a hurricane, with “feeder bands” drawing warm, moist air into the center of the low pressure. In the annotated image below, I’ve drawn some streamlines that show the air spiraling into the center of the low pressure.