Future of the Season Pt 3

[Dan Robinson]

The GFS is developing a strong Hudson Bay vortex by the end of the month that keeps the large trough(s) too far west - with the Plains caught in the middle of the dreaded Omega. Hope that is wrong.

The northern shortwave around May 21-24 looks nice, but the moisture is going to be a problem.

 

[Cstok]

A glimmer of hope from Norman AFD (414 AM CDT SUN MAY 13 2007):

LOOKING FURTHER OUT TO THE WEEK PRECEDING MEMORIAL DAY... ECMWF
CONTINUES THE TREND OF A LARGE DEEP TROUGH OVER THE WESTERN
STATES WITH DOWNSTREAM RIDGE AXIS NEAR OR JUST E OF THE MS VALLEY.
LAST FOUR ECMWF RUNS HAVE SHOWN THIS LONGWAVE PATTERN... AND THE
00Z GFS HAS TRENDED DECIDEDLY IN THAT DIRECTION. STRENGTHENING SW
FLOW ALOFT WOULD MOVE OUT OVER THE CENTRAL/S HIGH PLAINS AS EARLY
AS MON 21 MAY... SETTING UP ANOTHER POTENTIALLY ACTIVE PERIOD FOR
THE PLAINS THAT COULD LAST INTO MOST OR ALL OF THE ENSUING WEEK.

And the ECMWF has been fairly consistent with this feature:

http://www.ecmwf.int/products/forec...merica!pop!od!oper!public_plots!2007051300!!/

 

[Dan Robinson]

Am I missing something? This is from the 12Z GFS, very similar to the 00Z last night. We're so far out now that it doesn't really matter, but I don't see a whole lot to be optimistic about on the GFS until after June 1, or unless that big trough moves further east. I hope I'm just missing something. The ECMWF does look
better.

May 20:

May 25:

May 28:

May 29:

 

[Matthew Crowther]

Please, do not even think about using the control run of the GFS beyond 3-4 days for anything but toilet paper, especially in this particular pattern. The European model has been shown by verification statistics to be a vastly better model, and the GFS ensemble mean also has some limited skill. But if you live and die by every run of the deterministic GFS, you will quickly drive yourself crazy.

 

[Jim Leonard]

The gfs is really OTL during the last several days. One day it shows a western trough the next run it shows a ridge in the west, how can you make a forecast from that crapola. The ecmwf however has been consistant for days now with a major trough coming in after the 19th just like it did with the trough of May 4th through 7th. While the next trough is over the pacific the models for the most part are going to have some problems in positioning, movement and strength of the systems.

 

[Dan Robinson]

I agree, the GFS is a nightmare - but I keep seeing it cited with optimism in discussions and was curious what others were getting from it that I wasn't.

 

[Paul Knightley]

The 00Z GFS at 240 hours was not unlike the 00Z ECMWF in that time frame - the 06 and 12Z GFS runs were different, especially the 12Z GFS.

However, the difference is in the movement and development of the same trough, so all of the various outputs have this trough to a lesser or greater degree, but cannot decide on its motion.

Now, what would such a trough do *normally*? Or what have similar troughs done recently? Well, the answer to the latter seems to be that they have moved further south, and slowed up across the 4 Corners region, or somewhere in the vicinity. This tells me that the ECMWF is probably onto something - it has been fairly consistent over the last few runs - if today's 12Z shows something similar again, then we are perhaps getting towards a more likely scenario. If it doesn't then I guess we get a big of a kick in the teeth - however, this will be just 1 more deterministic run, and on their own, they are not especially great. The 00Z ensemble mean from the ECMWF also had the trough, and kept a mean trough over the Intermountain West for much of the last week of May, with a SW uppre flow across the Plains...this is the same set of ensembles which 1 week ago predicted a mean ridge over the Plains for the coming week, and from my experience of using it every day in the UK, I know it's a pretty good set of ensembles.

 

[Brian Stertz]

I am still seeing that the bulk of the upcoming severe wx will be after the Memorial Day weekend. The Euro has maybe something cooking the week before but the GFS trends have been remaining remarkably consistent in pumping up a longwave ridge ahead of several significant Pacific storms in the mean trough. This would realistically delay things until the middle-end of the week after Memorial Day and beyond. Plenty of time for manning the extended forecast desk...so nothing is set in ready-mix concrete yet. I guess just ride the roller coaster of emotions as Jim Leonard said a few posts ago about the extended model fluctuations.

 

[Warren Faidley]

The latest DDC discussion (5-13-PM) sheads some light on the big picture:

http://kamala.cod.edu/ks/latest.fxus63.KDDC.html

Warren

 

[Jay McCoy]

Now thats a discussion. LOL. Looks like the "ridge" breaks down by early next wek and we go active again even though it may be a bit more to the NE of where it has been but from the panhandles to central kansas is cool with me. As long as we dont end up in the dakotas in May. They can wait until June.

Vacation starts Thursday

 

[Cstok]

Interesting to get the perspective around the GFS and ECWMF differences from the Goodland AFD:

SATURDAY AND SUNDAY.,,MODELS DIFFER IN THE DETAILS ON WHAT THE FLOW
ALOFT SHOULD BE LIKE. AGAIN BASED ON THE PREVIOUS REASONING...LIKE
THE ECMWF BETTER. THE GFS DOES NOT LOOK RIGHT AND MAY BE SUFFERING
FROM SOME CONVECTIVE FEEDBACK. ECWMF AND HPC GUIDANCE VERY SIMILAR
IN THE SETUP BOTH DAYS. SURFACE TROUGH NEAR THE WESTERN END OF THE
FORECAST AREA WITH WEAK FLOW ALOFT. ECWMF HAS MORE MOISTURE AT LOW
LEVELS...AND WOULD THINK WITH THE PERSISTENT SOUTHERLY FLOW
MOISTURE WILL INCREASE.

 

[Stuart Robinson]

And just to prove how much the models swing...00z GFS at +H384 has a "proper" Death ridge in place with a HUGE Hudson low ..

 

[Joerg Kachelmann]

As long as you see the precip signals on the 15-day-Ensembles of the Euro (50 perturbations), it's not the real ridge of death. Last year (only 10 days available at that time, though) all lines were pancaked near zero when it came.

http://www.weather.us/new/showloc.php?type=ens&city=OK_OKLAHOMACITY

 

[Jim Bishop]

Never, ever trust the GFS Operational beyond 240 hours by itself. Sometimes it may add a little confidence to yourself if it supports the Ensemble. Otherwise I'd ignore it. Ok, now for my 2 cents.

Last week I favored the big trough moving into the West for a return of a good chasing pattern in the Plains by around May 22-25 into early June.

Since then things have changed. It now seems more probable that the ridge over the West will hold through the 28th. It does appear that one shortwave will break through the top of the ridge around the May 21/22 based on the Euro Operational. So I guess that'll be a possible decent one or two days of northern plains chasing.

But the West ridge will strengthen again post May 23. This is based on the GFS Ensemble & Canadian Ensembles in pretty good agreement. The European Ensemble does indeed develop a trough over the West, but it doesn't progressive it east. It would suggest maybe some setups over the far northern plains, but I think that may be wishful thinking.

Asside from a setup or two over the Northern Plains, I think the return of a good chase pattern will hold until the first week in June, maybe even later. This should give many of us time to save up to pay for high gas prices in June.

 

[Stan Rose]

So I guess that'll be a possible decent one or two days of northern plains chasing...I think the return of a good chase pattern will hold until the first week in June, maybe even later. This should give many of us time to save up to pay for high gas prices in June.

That's pretty pessimistic, so since i'm stuck with a chase vacation in May, i'll put an optimistic spin on it: Even buying the op GFS wholesale, and it's probably on the pessimistic side of the suite, i can foresee respectable chase opportunities possibly as early as the 19th and extending through the 23d. That's 5 days, not 1 or 2. It means covering some miles, possibly from MT to IL or IN, but that's what chasing is about. There feasibly could be decent action further south, but i don't really care, since i prefer the scenery up north anyhow. Rather than visit some rock outcrops or balls of twine, i'm hopeful for some decent photogenic storms.
Beyond the 23d id rather not even speculate, but as for waiting til June, that's about as good an idea as waiting for May. Hope to see all you optimistic chasers on the road.

EDIT: P.S: in this supposed horrible pattern, there were numerous tornado and funnel reports in CO today, along with golf-ball sized hail.
I was stuck close to home, but still got decent lightning pics and a superb mammatus display. ho-hum? The next shortwave should be more impressive.