Pattern Shift?

[John Sickels]

I have about 2% of the expertise of most posters here, but looking at some of the long-range models, it looks like we MIGHT see a pattern change in the last week of May and early June to something more progressive and climatalogical for this time of year. Am I reading this right?

 

[Darren Addy]

Not to threadjack, but I'd like to follow-up with a secondary question:

In general, (since Spring comes to the southern latitudes before the more northerly latitiudes), aren't tornadoes normally more plentiful earlier in the south and then later in the north? In other words, if there is a resumption of a "normal" Spring with gulf moisture getting north, are the storms more likely to be found in NE/KS/IA vs OK/TX (as the season "ages")?

Darren Addy
Kearney, NE

 

[Jeff Snyder]

Originally posted by Darren Addy
Not to threadjack, but I'd like to follow-up with a secondary question:

In general, (since Spring comes to the southern latitudes before the more northerly latitiudes), aren't tornadoes normally more plentiful earlier in the south and then later in the north? In other words, if there is a resumption of a \"normal\" Spring with gulf moisture getting north, are the storms more likely to be found in NE/KS/IA vs OK/TX (as the season \"ages\")?

Darren Addy
Kearney, NE

Darren,

Climatology would show that the tornado frequency max does shift into the central and northern Plains by early June. That said, there can certainly be significant events in the OK/TX area in June and July even. Typically, however, the storm track (and upper-level trough pattern) shifts northward as we progress into summer.

That said, this year has not been following climatology very well, so what unfolds may not either.

 

[Mike Peregrine]

Patterns generally begin to shift northward after Memorial Day weekend - but there are no hard and fast rules - and as Jeff mentioned, this is hardly a year we might consider typical in any respect. Anything goes in '05.

Went through the SPC tornado reports page today:

http://www.spc.noaa.gov/climo/torn/monthly...ytornstats.html

While the shear numbers are considerably down (for the month of May alone), if you enlarge the report graph at the bottom of the page, you'll see that we aren't trending that far from what might be considered normal. In fact, it is almost completely concurrent with the 10 year avg. line and quite close to the 2004 line at this point in time last year. As far as May is concerned, it was in the last ten days of the month that things took a dramatic shift last year. And for the year itself, it was only after the introduction of tropical systems that we see the averages begin to skyrocket. So as always - we'll just have to wait to see how the story turns out this year.

 

[Jeff Snyder]

Originally posted by Mike Peregrine

While the shear numbers are considerably down, if you enlarge the report graph at the bottom of the page, you'll see that we aren't trending that far from what might be considered normal. In fact, it is almost completely concurrent with the 10 year avg. line and quite close to the 2004 line at this point in time last year. As far as May is concerned, it was in the last ten days of the month that things took a dramatic shift last year. And for the year itself, it was only after the introduction of tropical systems that we see the averages begin to skyrocket. So as always - we'll just have to wait to see how the story turns out this year.

Mike,
Just a quick note... That graph hasn't been updated for a week, so the 5-22-04 and 5-24-04 events are about to significantly pass us by. Additionally, it's not too far off from the 30-yr average line -- we're probably 80 tornadoes below the 30-yr line. That said, we're close to 200 tornadoes below the 10-yr line. Booo! ;-)

Despite not being tooooo far off from the 30yr line, there really haven't been many tornadoes in the plains outside of the two-three days of cold-core action. There has been a more normal number of tornadoes in the southeastern US, however.

http://www.srh.noaa.gov/oun/tornadodata/ok...tornado2005.php
OK is currently on the path towards a record low tornado year, as only 12 tornadoes have been tallied up so far this year. The currently record is 17 tornadoes, which was almost beat in 2002, when 18 tornadoes were documented in OK. It should be noted that 11 of the 12 tornadoes on OK so far this year occurred on 3-21. There has been one tornado in OK since then March 21st, the single tornado near Harrah on April 10th. There has also only been ONE non-F0 -- the F1 in Sequoyah co. on 3-21.
Additionally, this will be the first tornado in recorded tornado history in which there has not been a single tornado in Oklahoma during May. Granted, that may change, but we're a week from June.

EDIT: Just some quick graphs I threw together...
[Broken External Image]:http://www.tornadocentral.com/now/oktornadoes.png
[Broken External Image]:http://www.tornadocentral.com/now/tornadorange.png

 

[Mike Peregrine]

Well that does deserve a great big BOO doesn't it ...

Yeah, after the 22nd last year it all broke loose. This last week would be pretty hard pressed to catch up anywhere close at this point.

Was talking to a friend of mine here last night and telling her about how dull it's been and she said "well at least people aren't getting killed this year." From that standpoint and the standpoint of most folks, 2005 is a good year ... we're the only ones who seem to be bored silly by all this. Dull chase years make me crazy and I almost have to stop posting to the online boards just to avoid getting snippy with innocent people! lol

I'm starting a study of the online chase community in the form of an essay/thesis that I'm hoping to work on during down periods this summer. Should be an interesting project for those quiet days ... a/k/a everyday so far this year.

 

[Peter Wharton]

Threadjack

Does anyone have an educated response to the original question that John raised in this thread - I'm coming to the Plainson the 28th May for 4 weeks and would be very interested in whether the weather patterns are about to change as outlined in the long range models?

 

[Aaron Kennedy]

Peter, if some how you don't find several good chase days within your 4 week chase vacation, I'll declare you the most unlucky man alive.

Aaron

 

[Mike Peregrine]

Peter - long range models are open to nearly limitless interpretation. Feel free to visit the following pages to make your own assessments:

http://www.cpc.ncep.noaa.gov/products/pred...ictions/814day/

http://www.cpc.ncep.noaa.gov/products/pred...ts/threats.html

http://www.noaa.gov/climate.html

http://lwf.ncdc.noaa.gov/oa/ncdc.html

I subscribe to the Weather America newsletter, which also discusses possible medium and long-range model guidance. I take all of the above with a grain of salt, however.

There seems to be endless fascination with speculating on what the coming months will bring. If you will read back through this thread and almost every other one on the subject, you will see that the conclusion is simple - we have to wait and see. Too many variables when it comes to discussing the future of climatology. As Yoda said "always in motion the future is ... difficult to see."

Hope you have a nice vacation, storms or not.

 

[Amos Magliocco]

Latest models (18z runs of ETA and GFS plus 12z EC) show the
reemergence of the southern jet stream, and a large upper low moving
from western Mexico into the southwestern US, concurrent with a strong
upper low forecast to plow into the Pacific Northwest beginning around
Friday morning.

These systems should make significant impact on the increasingly
narrow western ridge. Ensembles suggest decreasing heights across the
western US in favor of more zonal flow, a solution favored in this
morning's CPC discussion which Mike cited above.

We still have problems to overcome, namely the retrograding eastern
trough which merges with a middle Canadian low to form another monster
cyclone north of the border, creating a confluent zone of northwest
flow aloft over areas north of Interstate 70. However, with the
weakening of the ridge in favor of zonal flow, it's possible we can
finally ship these damn Canadian and east coast lows out to sea.

I have some measure of confidence this is possible. If it happens, I
think the generally progressive pattern we've experienced--despite the
consistent blocking--could continue, paving the way for an active
first half of June as shortwaves ride the zonal flow into the central
US unimpeded and with more impressive boundary layer instability after
a week of ridging.

That's some wishcasting, I know, but I think there's evidence things
may improve on a large scale.

None of this matters much to our friends in the field, who have a red
box and a tornado-warned storm in Yuma County, CO right now. I hope
they find a big, backlit cone and snap 2005 out of her trance.

I intend to leave Bloomington Wednesday for possible chasing in New
Mexico on Thursday and Friday, then the Twister Reunion and Picnic
Saturday in Wakita, followed by whatever Mother Nature has in store
for us during the climatological peak of tornado season this holiday
weekend.

 

[Peter Wharton]

Long Range Outlooks

I realise that I'm in hands of the "weather gods" re: the long range, but it's very interesting to speculate and watch developing patterns. Thanks for the links, Mike - I use with interest

 

[Mike Peregrine]

I really appreciate reading Amos' take on future prospects as well - just hoping now that his perception of the situation holds true. In considering the possibilities raised by his post, I would say that it is at least within the realm of consideration that we will be seeing some changes on the horizon. And if not, we can always look forward to coming back in here and arguing our brains out on whatever pops into our heads.

For myself, I am staying hopeful about Memorial Day weekend and the first week in June ... there is just almost always something somewhere next weekend! If not, I might be moving to New Zealand myself. Wish I didn't have to work and could be on the high plains today as a matter of fact - - -

Have a great time -

 

[Gabe Garfield]

Finally! The GFS is still progging the emergence of a western US trough. The 18z run looks especially promising, with the trough essentially anchoring over the west and "spitting" out shortwave troughs every other day or so. This finally looks to be the pattern change we've all been waiting for...

Looking way too far into the future, GFS (as of the 18z) advertises a much more significant longwave trough somewhere between June 7 and June 10. Of course, at this range, it falls well within the wishcast regime, so I won't say much about it.

Gabe

 

[Dan Robinson]

The existence of this thread puts a smile on my face!!

Of course, this 'season-saving trough' may not come to pass, but it's the first time that something very encouraging has been consistently showing up in the long-range models.

This does look exciting. What a roller coaster it has been for us the past month. Planning a chase from the east coast means we have to rely on the long-range models to plan ahead as best we can. You can guess how that has been for us.

My brother and I actually left for our chase trip back on May 13, then returned after 2 days when the pattern looked grim and my brother fell ill with a bad cold. We had a few down days at the start of the trip, so we drove up to Indy and Chicago to do some city photography. I remember standing on the shore of Lake Michigan that Saturday. We were freezing our tails off. Winds were out of the northwest at 25mph (gusting to 35) with 52F temps, and I thought "this is not what we want to see on the way to the Plains".

So, we've put our chase trip on hold for almost two weeks, what a huge relief it would be to have something to show for our patient waiting. We're still trying to rearrange work schedules (I've been excused from jury duty that was supposed to begin on the 6th, so I'm clear) but I'm hoping to be able to stay out until the weekend of the 11th-12th.

 

[Anthony Silver]

I certainly hope something pops soon, I can't stand these "dry spells" with no severe weather, the boredum is driving me insane. I guess since '03 and '04 was filled with chase days, I expected this year to be about the same. Goes to show you that mother nature should never be second guessed. I hope a more favorable pattern comes about within the next few weeks. Just another wait and see game.