Worrying Signs

[Paul Sherman]

Hi All,

1st Post but have been browsing for about a year now. Am coming over for our annual US Storm Chase at the start of May (4th year) but have noticed worrying signs from the GFS That the start of May could be another un-productive pattern, other Models not so doomesday atm but what are your early thoughts on how May could pan out.

Regards

Paul Sherman

 

[Adam Atkins]

Last time I checked we are unable to forecast with any accuracy beyond about 5 days...the global models don't paint a pretty picture? Then you might be chasing some upslope flow days on the front range, but you'll be chasing somewhere, because it's May...

 

[Paul Sherman]

Thank God for that Adam, one thing in our favour i suppose is the GFS Is pretty bad over a week out so i suppose things can change, otherwise as you say, Colorado & New Mexico here we come.

Paul Sherman

 

[afischer]

Your concerns are valid, Paul. Like you, I've got some time off from work in early May, and would prefer if a polar vortex of doom weren't parked over the Great Lakes states.

If you're looking for some insight on the really long-range stuff above and beyond numerical models, you might check out meteorologist Ed Berry's blog. He discusses global circulation patterns with respect to U.S. weather generally through a 4-week period or so. http://weatherclimatelink.blogspot.com/

 

[Paul Sherman]

Thanks for that Link Andy. Am over until 24th May so hopefully should get some action.

Paul S

 

[Mikey Gribble]

Like others said, I wouldn't put too much weight on what the GFS is showing this far out. After looking at the 12Z run out to day 16, I don't see anything that would worry me if I were in your shoes. Time will tell.

 

[Mike Hollingshead]

Then you might be chasing some upslope flow days on the front range, but you'll be chasing somewhere, because it's May...

Or grunge in Indiana.....sigh.

 

[Paul Noble]

My first post too but been lurking since earlier this year.. I will be following Paul S and the team and will feed back any information we have..

Its been great following the recent chases and the respect we have for you guys and gals out there is second to none.

Thanks for the GFS update, 2-5 days is all it can manage in the UK too at the moment.. guess furkin situation??

 

[Dan Robinson]

With models, beyond day 7 is mostly guesswork, beyond 14 days is totally useless. I'm forced to deal with days 7-14 because I don't live in the TX Panhandle or southwest Kansas, I live in West Virginia - where biting on a setup costs me over $300 in gas just to get me there and back, not counting the actual chases and hotels.

Despite the limitations, a tiny bit of guidance CAN be gleaned from the 7 to 14 day model output, especially with run-to-run consistency and multi-model agreement. That said, beyond 14 days is useless to try to speculate. Believe me, if there was a way to do it I'd be the first one to jump on the bandwagon.

May 1 is within the shaky window of the 7-14 day period, and it looks like a downtime until at least May 5 or so. But remember, May has 31 days! Look at how progressive systems have been so far this spring as opposed to last year. Just like May doesn't guarantee a great chase trip, an eastern trough showing up on May 1 does not guarantee a busted season.

And then there's June. 2005 is always getting such a bad rap as a horrible season, but look at June 2005.

 

[Mike Hollingshead]

If I had to make a trip here from a long ways away I think I'd always vote for June over May. It seems to maybe have the slightest edge in being more chaser friendly. It seems I can remember more, longer, bad periods in May than I can in June. Hell anymore I'd do it just to maybe avoid having to chase down south, where it's just more populated. Though yeah, you can still wind up chasing south in June. In the end, I'm probably pretty even on May or June tornadoes.

As for the gfs extended range. I must say I've been pretty darn surprised how well it does do with troughs of decent size, even weeeeellllll out there. It seems I've seen a lot of them lately out around 348hrs that wound up happening close to the same day in the plains.

Best of luck when you get here.

 

[Jim Leonard]

One thing I usually look at is the 30 day cycle. This year it appears to be occuring during the last 10 days of the month as we witnessed during February and March. My plan is to be out in chase country for sure by the 20th of May this year. You can go back many season in the past where big events occured exactly 30 days apart. Some on this forum will remember dates like May 12, 2005 and June 12th 2005, also the same occured on those dates in 2004. Early next week is setting up nearly a month after the eastern New Mexico event. I myself is quite confident late May will be quite interesting.

 

[Jim Tang]

Jim (the other one) is correct. Seems that we get cycles of tornadic activity many times (2006 being the exception). What I am liking right now is the fact we keep getting repeating shots of cold air, which, though has limited moisture advancement, keeps the dynamics intact. The models still indicate a fairly active Pacific with negative height anomalies, which should prevent a polar vortex from sitting over Hudson Bay for more than a week.

I've also learned that a winter in which the NAO (North Atl Oscillation) is predominantly negative tends to lean towards a more inactive season. It was positive last winter. Also, right now there is a weak La Nina developing, which also leans toward increased activity (more troughiness over the West).

As of right now, I'm thinking the severe season could end fairly early (Ninas favor a stronger heat ridge as well, and the dynamics tend to get "used up" by big synoptic bombs over time), but before that, May should be rocking. Of course, everything is still pretty uncertain and lots can still change.

 

[Scott Weberpal]

If the GFS is still looking bleak for early May a week from now, you can then start to worry. The 12z run this morning showed a terrible pattern emerging toward April 30th, and the 18z run showed just the opposite. I believe the GFS up to 180 days and beyond 180 days run on 2 different resolutions.

With my luck May 15-25 will be active. I'll be chasing May 2-13 then again May 25-June 4.

A lot of storm days or not, I'll just be happy to be out there.

 

[Jeff Snyder]

I wouldn't worry much about it at this time. I know I can't really say "well, we can't forecast upper-level patterns very well more than a week in advance", since you have a large vested interest in a medium to long-range forecast (given the money and time involved in your chasecation). If you want a view of long-range forecasts, I suggest reading Ed Berry's blog at http://weatherclimatelink.blogspot.com/ ... He's one of the developers of the GSDM conceptual model, and it provides for another point of view. In addition, in support of what others have noted above, I have also noticed a general 4-8 week periodicity to the mean trough-ridge pattern. Thinking of the past few years, it seems that mean troughing seems to "switch" coasts about every month (sometimes a little longer, sometimes a little shorter). In other words, we could have a 3-4 week stretch of mean northwesterly flow aloft, followed by 3-4 week of mean southwesterly flow aloft. This is far from an objective assessment, but I have noted similar trends that others have mentioned above.

On another note, the 6120 hr CPC forecast valid 22 Dec 2007 shows a nice potential setup in the southern Plains --> see HERE. It looks like the Gulf is open, and the area downstream of the sfc low may be a good play. Strong gradient in thickness indicates likelihood of strong flow aloft... I'm going to see if I can get out of some family and work commitments...

 

[Mike Hollingshead]

On another note, the 6120 hr CPC forecast valid 22 Dec 2007 shows a nice potential setup in the southern Plains --> see HERE. It looks like the Gulf is open, and the area downstream of the sfc low may be a good play. Strong gradient in thickness indicates likelihood of strong flow aloft... I'm going to see if I can get out of some family and work commitments...

Lol I'm sure some can already tell there WILL be tornadoes that day.