The future of the season....

[Jeff Snyder]

I almost cried when I saw the 0z NAM and GFS forecasts, which keep northerly flow across much of the Gulf through the next 5 days. Some of that will begin to modify, but as 850mb and 700mb temps warm as we approach June, it'll become increasingly more difficult to get significant instability in areas of a breakable cap with only modified cP air. As long as we remain between a ridge in the west and a trough in th east, we'll remain in an area of ageostrophic curvature convergence aloft, which results in large-scale subsidence and, generally, high surface pressures. Indeed, I see that the 0z NAM keeps a high pressure system anchored over the Plains through the full forecast period (84hrs). Looks like any real chasing will remain in southern and southwestern TX.

 

[Paul Knightley]

00Z ECMWF run (which I think is a better model than GFS) is more progressive, with a SW upper flow beginning over the Plains just after next weekend - it actually brings a fairly decent upper SW across by 240 hours, but that is pure fantasy at this stage!

 

[Verne Carlson]

In the eighteenth century sailing ships faced the peril of being caught in the doldrums. The doldrums were a belt of calm light winds between the northern and southern trade winds of the Atlantic and Pacific. Here ships might be stuck for months with little to move them. With dwindling supplies and facing starvation some were forced to eat thier livestock and even horses. Eventually the winds would change and the ships could continue on thier way and make it to thier destinations.

We chasers have cast our ships out to the sea of the plains. Making vacation plans, rearranging personal and work commitments and have been caught in the doldrums of the 'Death ridge'. Some are close to port and have been able to paddle back and wait for more favorable winds. Others are no doubt adrift in Motels in Kansas, Oklahoma and Texas already having committed to airfare and chase tours and are stuck to wait it out.

With a week ahead of us and no favorable winds in sight we must know that soon the winds will pick up again, strong troughs will move in from the west, moisture will stream north from the gulf and the chase season will be moving once again.

 

[Scott Olson]

00Z ECMWF run (which I think is a better model than GFS) is more progressive, with a SW upper flow beginning over the Plains just after next weekend - it actually brings a fairly decent upper SW across by 240 hours, but that is pure fantasy at this stage!
[/b]

Sounds like the new 18z GFS:

240hrs:
http://www.nco.ncep.noaa.gov/pmb/nwprod/an...fs_500_240l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod/an...fs_85v_240l.gif

This looks like what it was showing back on Monday-Tuesday before it started looking more grim so perhaps a small glimmer of hope for those planning their chase vacations during this period. Though, plenty of time to go back to block.

 

[Dan Robinson]

Even if the upper air pattern goes to total junk, one positive thing we can take a little comfort in is that surface wind trajectories should improve by the weekend and start bringing some decent moisture back north. There should even be a few surface lows coming off the Rockies to play with. At the very least there should be some Front Range action and maybe some more 'consolation' northwest flow events. Maybe enough to get us out on the road and give it a try.

 

[joel ewing]

In the eighteenth century sailing ships faced the peril of being caught in the doldrums. The doldrums were a belt of calm light winds between the northern and southern trade winds of the Atlantic and Pacific. Here ships might be stuck for months with little to move them. With dwindling supplies and facing starvation some were forced to eat thier livestock and even horses. Eventually the winds would change and the ships could continue on thier way and make it to thier destinations.

We chasers have cast our ships out to the sea of the plains. Making vacation plans, rearranging personal and work commitments and have been caught in the doldrums of the 'Death ridge'. Some are close to port and have been able to paddle back and wait for more favorable winds. Others are no doubt adrift in Motels in Kansas, Oklahoma and Texas already having committed to airfare and chase tours and are stuck to wait it out.

With a week ahead of us and no favorable winds in sight we must know that soon the winds will pick up again, strong troughs will move in from the west, moisture will stream north from the gulf and the chase season will be moving once again.
[/b]

Verne...what a great post! Well done, sir.

 

[Robert Edmonds]

Just goes to show you it's all little bit of luck if you have to choose a chase time. At first I was thinking I'd be kicking myself by now, thinking I'd be hearing of all these great storms. Now with my window to chase being ~19th to the ~4th now I'm wondering if this is too soon. I just hope I got a bit of irish in me right now.

 

[Chris Wilburn]

I dont usually look at models further out than 180 hours and the current 180 hour GFS still shows an East coast trough and the dreaded weak northwesterly 500mb flow. Like others have said models past 180 hours do hint at a possible western trough the last week of May. Too early to get excited, but if it continues to show up with each run and start to appear on the 180 hour GFS in the next week or so we may be in business. I am thinking about a mini chase vacation from June 2nd- June 12th. I just have a feeling the last part of May wont do much and the June time period will be good. I have nothing to base this on other than I dont know if everything can recover that quick to have good outbreaks in the last week of May, esp. since capping may be an issue the further south you go. Oh well, that is just my opinion to add to the thread. One good thing that Jeff pointed out is it looks like we may be getting some decent moisture return from the gulf in the next week or so....but the trough is still a problem. Just have to be patient and see I guess..

 

[Dan Robinson]

While the long-range GFS (past 180 hours) is still doing its typical flip flop (the last 00Z 'flop' being positive), there are a few somewhat good signs finally showing up on the sub-180 hour GFS. After the 21st, the trough might be close enough to start sending some of its energy and at least weak SW flow over the Plains, and moisture is making a comeback. Even hints at a possible dryline to work with after the 22nd. Cons are that the moisture might be too far east and high 700mb temps could mean cap busts.

 

[Paul Knightley]

Well, without wanting to get too excited, today's 00Z GFS looks much better for next week, with the ridge breaking down to a fairly decent spells of upper SW flow...however, it's early days yet, and I want to see how the rest of today's runs pan out. Even so, it's tricky not to be excited, with less than 24 hours to go before departure!

 

[Mike Umscheid]

the 00z GFS certainly offers some hope... but when you compare its 168hr fcst with the Canadian and ECMWF counterparts... it may be too fast with that deep trough. At 168hr, the ecmwf and canadian have the ridge axis still over the intermountain west. Even if the GFS is more correct with its solution... there's going to be one HOT elevated mixed layer spreading out in the southwest flow... given the days and days and days of intense elevated heating over the southern Rockies. GFS shows some disturbing +14 to +15C at 700mb in it's southwest flow scenario. Yikes. It looks like good riddance to chasing south of 40N unless a pacific cold front can move through in the southwest flow... Early-mid next week chasing could very well be wayyy north in the northern high plains... and I doubt we'll be looking at anything worthy of tornadic potential through Day 10.

As others have mentioned... maybe the last 4 or 5 days of May could be a more fruitful pattern for tornadoes if we can squash the southwest/southern Rockies high height anomaly & elevated heating. Regardless, our group will be chasing high plains severe storms even if the tornado potential is extremely low... which I like anyways, it helps keep the "hordes" down :-D

 

[Andrea Griffa]

the 00z GFS certainly offers some hope... but when you compare its 168hr fcst with the Canadian and ECMWF counterparts... it may be too fast with that deep trough. At 168hr, the ecmwf and canadian have the ridge axis still over the intermountain west. Even if the GFS is more correct with its solution... there's going to be one HOT elevated mixed layer spreading out in the southwest flow... given the days and days and days of intense elevated heating over the southern Rockies. GFS shows some disturbing +14 to +15C at 700mb in it's southwest flow scenario. Yikes. It looks like good riddance to chasing south of 40N unless a pacific cold front can move through in the southwest flow... Early-mid next week chasing could very well be wayyy north in the northern high plains... and I doubt we'll be looking at anything worthy of tornadic potential through Day 10.

As others have mentioned... maybe the last 4 or 5 days of May could be a more fruitful pattern for tornadoes if we can squash the southwest/southern Rockies high height anomaly & elevated heating. Regardless, our group will be chasing high plains severe storms even if the tornado potential is extremely low... which I like anyways, it helps keep the "hordes" down :-D
[/b]

With GFS 06Z it seems that the cut off is starting to move eastward.
It's true that at the beginning chasing territories should be on the Northern Plains but in a second moment I'm sure to see something good on the central Plains. I repeat I count on may 29 even if may 24 is still not bad.

http://www.wetterzentrale.de/pics/Rnamavn1801.png

 

[Jason McKittrick]

I have been very encouraged by the long range GFS and ECMWF, that is until this morning. While the GFS is still calling for the Western Atlantic ridge to break down the ECMWF, for the first time in about 3 days is again showing a rather stout polar vortex anchored over Hudson Bay through day 10.

 

[Matthew Crowther]

Well, the 12Z GFS is pretty grim, as a large closed low is forecast to form off the West Coast early next week, reinforcing the ridge over the Rockies. This is more like the ECMWF, which maintains that pattern through 10 days. I am getting very convinced that there will be no chasing at all for another week at least, and perhaps all the way to the Memorial day weekend. I was perusing a few records, and if the Plains and Midwest have no tornadoes for two weeks straight, that would be the longest May period without any 'naders since 1987. I feel for anyone on a chase tour right now.

Matt

 

[Jason Persoff]

Man...tough forecasts ahead. That damned Hudson low really doesn't begin to break down in strength on the latest NCEP/ECMWF until 5/29! The omega block looks transient fortunately, but don't see a lot breakdown of the Ridge of Death until 5/26 when zonal flow returns to the Plains. Ouch. Look here: http://www.cdc.noaa.gov/map/images/ens/z50...h_alltimes.html

If you'd like a laugh, look at all the uncertainty on the spaghetti plots for middle-to-late next week: http://www.cdc.noaa.gov/map/images/ens/spag_us_alltimes.html

Good news: wow is it ever random after a week out. Bad news: wow is it ever random after a week out.

Quite the stressfest.