Pattern Shift?

[Mike Peregrine]

Sounds like a variety of factors are throwing several models into confusion in the long range, resulting in some wild inconsistencies. GGEM appears a little more stable at least for now, pointing to a potential breakup of our not-so-friendly ridge and allowing for a boundary to set up shop from Colorado through the central plains after the 29th. Hopefully the impulses riding this feature will provide enough UMPH to get something going. Still not the powerhouse setup we normally see this time of year, but a zonal regime at least gets us somewhere back in the ballpark of where we would like to be, and would hopefually at least allow for something chaseable. I don't normally like looking this far ahead, but it's all we've got for now.

GEM 84 hr:
http://meteocentre.com/models/glb00_84_e.html

96 hr:
http://meteocentre.com/models/glb00_96_e.html

108 hr:
http://meteocentre.com/models/glb00_108_e.html

 

[Jason McKittrick]

PNA for most of March, April, and May and now a monsoonal pattern at the end of May. Man is our weather screwed up. At this rate it will probably be snowing here in Omaha by August.

 

[Dan Robinson]

The GFS has really gone haywire today. Even the short-term spread on the ensemble spaghetti plots is huge.

 

[Ken Johnson]

The GFS has really gone haywire today. Even the short-term spread on the ensemble spaghetti plots is huge.

I know things can change, but according to the latest GFS, next week, looks worse than any other week so far in the plains. If the latest is correct, there could be a severe weather event in the southeast of all places on Memorial day. I was planning on chasing next week, but if this holds forget it. I think I will stay home and spend time with the wife and kids...

 

[Jeff Snyder]

The GFS has really gone haywire today. Even the short-term spread on the ensemble spaghetti plots is huge.

I know this isn't short-term, but here is the 7-day 500mb ht spreads from the GFS:

http://www.cpc.ncep.noaa.gov/products/pred...riefs/ps_08.gif

Now, there is better agreement on an east-coast trough, but the flow pattern aloft west of the MS River is very much uncertain. Some ensemble members would indicate a small area of southwest flow aloft, while the others (and the mean) would indicate that the ridge in the west will persist, though with decreased amplitude relative to its current state.

The Day 8-14 Mean plot below shows a return to more zonal flow aloft east of the MS River, though the potential for some troughing in the western US. The dashed black line represents the mean, and it would indicate zonal flow across the Plains... Of course, I'll take zonal flow over a massive ridge and pathetic northwest flow aloft.

http://www.cpc.ncep.noaa.gov/products/pred...riefs/ps_10.gif

 

[Amos Magliocco]

Want to read about some mets unhappy with models:

http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html

It's all up for grabs!

 

[Ken Johnson]

12z Euro

http://www.ecmwf.int/products/forecasts/d/...s!2005052612!!/

if this is correct, could be some happy chasers!!!

 

[Dan Robinson]

It's all up in the air. Can't do much now but just laugh and toss a coin. Another one of those 14 hour drives west when I'll get past St. Louis before I find out what I'm getting in to. Might as well go, there's not much time or flexibility left to keep postponing anyway. If it turns to junk, we'll just go home early. Maybe look for a quick 3 to 5 day spot-chase sometime in the future if something turns for the better. At least we'll have Wakita to look forward to - if the pesky slight risk on Day 3 doesn't lure too many away.

 

[Mike Peregrine]

You're right Dan, this is a big coin toss. No one ... the models or the mets ... can find ground on which to agree. If there were truly a major shift coming, we should be able to see some clearer indication of it. As of now, the indications seem to point more in the direction of smaller, gradual changes that could open the door to a more seasonable regime as time goes on. Unfortunately, this is coming as patterns generally start shifting northward as well, so there may only be one or two shots left in the so. plains, if at all.

In my mind - the end of the weekend (after May 29th-30th time frame) starts looking slightly more positive, with more favorable chances not showing up until the first week in June. Not a lot of hope, but just how I'm thinking for now -

 

[Dan Robinson]

Planning a chase trip is like...

 

[Dan Robinson]

Climbing the next hill on the GFS coaster, it looks like a weak trough may swinging through the Plains early in the week. By late in the week, the supposed cutoff low that the GFS develops off the CA coast is trying to look a little less 'cut off' and move east, hopefully nudging into the Plains by next weekend. Low-level flow off of the Gulf looks spotty and questionable, but a few 70F dewpoint spikes are showing up here and there. Not much of a dryline to speak of either.

So, there's nothing screaming 'synoptic outbreak' in the coming days, but then again it's not a deep ridge, so I'm not complaining. Looks like the changing pattern may be chaotic enough to allow something to come together once or twice. These developments look a little better, but will the coaster level off here or are we in for another dive on the next run?

 

[Mike Peregrine]

Things are looking up ... I don't know if I'd classify the past couple months as a roller coaster, though ... more like a gentle paddleboat. hehe

Anyway - I'm starting to get a little more confident that things are falling in order, and thinking now that next week just might pan out after all. I'd almost even say to get those bags packed come on out at this point. 72hr ECMWF now indicating a possible system on Monday (in southern plains), and another more powerful possibility toward the latter half of the week around Thursday-Friday a bit further north. GFS looks to finally be falling in line with progged height falls as well. 72hr NCEP ensemble also shows precip breaking out in the panhandle of Texas on Monday under a zonal flow pattern. The 168hr (yeah, I know ... we're talking a full week out) shows a pretty cool-looking trough over the central plains. Would be nice to hear some other opinions, but it looks to me like we will be chasing again soon after all.

 

[Justin Turcotte]

The GFS just doesn't want to kill persistent troughing on the east coast. That cyclonic flow regime is simply not conducive for getting solid GoMex moisture in the Plains. Ouside of possibly one or two days, the next 16 don't look too exciting. The one benefit I see from recent GFS runs is that temps in the northern plains will finally be more summer-like. Yesterday's high in Grand Forks: 56F. You folks in the southern plains may just have to head to North Dakota to see storms come late June and July. I could easily see some northern state get the tornado numbers trophy this year.

 

[Ken Johnson]

The GFS just doesn't want to kill persistent troughing on the east coast. That cyclonic flow regime is simply not conducive for getting solid GoMex moisture in the Plains. Ouside of possibly one or two days, the next 16 don't look too exciting. The one benefit I see from recent GFS runs is that temps in the northern plains will finally be more summer-like. Yesterday's high in Grand Forks: 56F. You folks in the southern plains may just have to head to North Dakota to see storms come late June and July. I could easily see some northern state get the tornado numbers trophy this year.

I think the weather pattern will favor a late outbreak of severe weather in the northern Plains... Say late June??? I can remember a few years ago, a big tornado outbreak in S. Dakota and Nebraska around the 24th...

 

[Jeremy Bower]

Late season outbreak

Yeah I was there for the June 24, 2003 tornado event in Southeast South Dakota and the storm chasing tour group I helped lead that day were treated to see 22 tornadoes in one day. I leave for Omaha on June 20 and I'll be out there till July 8, so here's to hoping for an active Northern Plains come that time. :wink: