AccuWeather.com

Going 'Round and 'Round with the Models

Jun 10, 2010; 10:30 AM ET

Thursday, 11:30 a.m.

It has been a hectic week, both personally and here at work, and little of that is going to change through the weekend! One of the biggest challenges has been dealing with the day-to-day changes in the computer-generated forecasts that we've become slaves to in the weather industry. Each day, and sometimes each run of the models, has a different take on how things evolve for the rest of the week and through the weekend into next week. Sometimes the changes have been monumental, enough to make you question just how far have we really come from the days of just a couple of simple computer models when I first got into the business!

Before I delve into that, a side note on the busy times outside these walls - I do try to have a life! Over the past couple of years, I've had the honor of setting up and leading some group road rides in my area. This year, the turnout has been steadily growing, and Tuesday night we had our biggest posse ever of 15! I'm sure that must have been an interesting sight for someone driving down the road to see this pack of cyclists rolling along through the countryside of central Pennsylvania! And the weather couldn't have been better - bright sunshine, temperatures around 70 and not much of a breeze!

Now, if only the weather would be that nice this weekend! I'll be participating in the Great Finger Lakes Bicycle Tour, hosted by the Southern Tier Bicycle Club. I went last year not knowing a soul and ended up meeting some absolutely fantastic people that I not only had a great time riding with, but with whom I've kept in contact since last June. I've even had the opportunity to ride with each of them at least once during that time, and we're all stoked for getting together this weekend.

But the weather may play a role in the weekend - again. Last year, after a morning of sunshine on the Saturday rides, the afternoon turned cool and wet with two slow-moving showers that soaked us and the course and dropped temperatures into the low 60s! It even helped contribute to a rash of flats, but I've been assured the reigning 'Flat Queen' has no intentions of defending her title or keeping the crown.

The problem will be with the surge of heat and humidity coming from the west and southwest. The increase in moisture will likely lead to a scattering of showers and thunderstorms - just what I DON'T want to see! None of us do. We're contemplating alternative strategies as to how best to beat the elements. Unfortunately, I've always been told you can never beat the weather. The best you can hope for is a tie. Oh, wait! That's in forecasting!

While I'm on an aside, this cycling thing has let some strange doors open for me. If you had told me that a clinically obese person such as myself would be invited to speak to a nutrition class one day, I'd have said you are out of your mind! But that's exactly what happened a few weeks ago, when one of the nutrition professors at Penn State who rides with our Tuesday evening crew heard my story and thought it might be instructive for her students to hear.

So, yesterday morning I went to the Penn State Campus and stood in her nutrition class before a room full of mainly young adults who all looked fairly fit! I got there as the instructor was wrapping up her presentation on weight loss studies, methods of those who have been effective at it, at maintaining the weight loss, and things that some did not do that contributed to a subsequent weight gain again. It was a nice segue into my story of going from 270 pounds (and I brought in the pictures and some of my XXL clothes to prove it!) five years ago to the low 200s nowadays.

I never saw that invitation coming! It has motivated me to now attack the other side of the equation, and that's the nutrition part. I've more or less solved the output part, as I easily exceed the 200 minutes of exercise a week she presented to her class for those who were successful at losing weight. One goal down, another one to go!

Anyway, thanks for indulging me on the sidebar there. Trust me, if I can make the changes I did, anyone can. If you want to hear more of my story, just drop me a note, and I'd be glad to give you some encouragement!

Now, back to the problems at hand that you're probably more concerned about. We opened the week with a decided chill in the mid-Atlantic and Northeast, while at the same time the cool weather in the Northwest was trying to exit. It actually did get hot in the Southwest, where some records have been set this week.

It tried to get hot across the South, but a funny thing happened along the way. A trough split that developed last week helped to form an upper-level low over the upper Texas coast and Louisiana that has had a life of its own ever since!

I can assure you that had this feature dropped over the Gulf of Mexico for a couple of days, I'm almost 100 percent certain it would have developed a low-level circulation that would likely have turned this thing into a tropical storm. Fortunately, that has not been the case, but talk to the people in South and East Texas over the past few days that have had to deal with it, and the tropical humidity associated with it. Because it has been moving so painfully slow, it has led to some flash flooding and excessive rains, even a few spotty tornadoes. That's all in keeping with what would be seen with a landfalling tropical storm!

This little feature is not going to fade away into oblivion. It is finally moving, and it will roll northeastward out of Texas in the next 24 hours, then pick up a little forward momentum tomorrow and Saturday as it heads farther downstream. As it does so, it will move into an environment that is warming aloft, and that suggests this feature should weaken somewhat. It will be squeezed in between a developing upper-level ridge that will become established over the northeast Gulf and eastern Gulf Coast region, and the southern periphery of the jet stream that by then will have retreated back to the Upper Midwest and across the Great Lakes over to New England.

There's no doubt it will continue to generate heavy showers and thunderstorms for the next two or three days--there's just too much low-level moisture available to it, and even though the environment around it is warming overall, it still represents a localized region of somewhat cooler air aloft. So with some daytime heating thrown in, there will be a notable uptick of showers and thunderstorms during the afternoon and evening hours wherever it goes, followed by a shrinking of said showers and thunderstorms during the late night and early morning hours.

This afternoon and early tonight, the prime target is northeastern Texas into northwestern Louisiana and southern Arkansas. Later tomorrow and early tomorrow night, the most likely 'soak zone,' if you will, should be southern Missouri into southern Illinois and western Kentucky. Later Saturday and Saturday night, that should be over eastern Kentucky, Ohio and West Virginia into southern and western Pennsylvania. By Sunday, most of it should be sliding off the mid-Atlantic coast.

To the north, there will also be a pulsing of showers and thunderstorms, but trying to pin down the exact nature of this convection is even more elusive. In short, the models are having a heck of a time trying to figure out what's a real disturbance or not. Each day, they're changing their guesses on the matter, which makes our job a nightmare. It's why I keep wringing my hands over my weekend cycling plans!

Currently there's a burst of thunderstorms across eastern Nebraska into northern and western Iowa. This has had a history of severe weather, and at the time of day it should be weakening, it's still going strong. It would appear that it should weaken SOME this afternoon as it streaks toward an environment that is not nearly as moist, and it will outrun the low-level jet that feeds it. As it weakens, it should be aimed more at Wisconsin rather than Illinois late this afternoon and tonight.

Another feature is likely to come out of the deepening Western trough late today and tonight to cause another round of severe weather to erupt on the central Plains, as well as back into eastern Wyoming and up into South Dakota. Low pressure will form over Nebraska overnight, and it looks like this will be a trackable feature into the Midwest tomorrow night and across the upper Great Lakes Saturday morning.

Most of the organized shower and thunderstorm activity will likely be along and north of the track of this low. That means areas from the northern Rockies and northern Plains over to the upper Great Lakes should be the prime target for this. That should then track across upstate New York to New England later Saturday and Saturday night and could directly impact the weather where I will be!!!

Meanwhile, in the West, another significant trough is diving in for the weekend. Get the giant eraser out for that recent spell of true summer heat, as it will get wiped out in short order! This strong upper-level low will contribute to showers and thunderstorms later tomorrow into at least Saturday from eastern Nevada to Colorado and up into Wyoming and push temperatures way below average for the middle of June throughout the central Rockies and certainly below normal in the southern Rockies.

Interestingly, the development of this closed low may actually help the Northwest warm up for the weekend, as the heights rise dramatically behind it. With sunshine, it will become much warmer across the region, with somewhat of an offshore flow developing before the next trough approaches Sunday night and Monday. It won't be as strong as recent troughs, but it will quickly wipe out the weekend warm-up.

Back across the country, the surge of tropical air into the Midwest, the Great Lakes and the Ohio Valley over to the mid-Atlantic states and Northeast tomorrow and Saturday will leave most places from the Plains eastward under a very warm air mass. Eventually, a front will come from the north and northwest to push the heat and humidity back, but when? How strong? How far? Well, it all depends! Early in the week, it appeared as if any change would be limited and not for very long. Then it looked as if it could drive a front into the Southeast, and a sprawling high pressure will come into the Midwest and then the East to provide several days of sunshine with below-normal temperatures and a complete lack of humidity. The models have largely backed away from such an extreme scenario.

In the end, it probably cools off for a couple of days in these areas, but south of I-80, it may be hard to get more than two or perhaps three days with temperatures below normal. The tropical air mass will still be hanging around south of there, and any time there's a decent storm coming out of the Rockies, it's likely to pull that heat and humidity back to the north to some extent. It's likely going to mean another hectic week of forecasting, with showers and potentially severe thunderstorms a part of the picture on multiple occasions from the eastern Rockies and central Plains to the mid-Atlantic coast.

Just another day of going 'round and 'round with the models.