May Chasing 2008

[Mark Sefried]

The European model is usually my choice of models when it comes to long range. I think I remember seeing somewhere a while ago that statistically the European slightly outperforms the GFS when it comes to long range predictions. With the European being consistant with that western trough and now that the GFS is finally catching on, when they both agree it usually happens. With the predicted pattern change still about a week away, things could still change so I would not bank on anything yet. I have May 20-June 9 off for chasing so for me its just a matter of waiting until the pattern becomes favorable and then leave.

 

[Mikey Gribble]

The ECMWF has definitely been the best long to medium range model this season. There really isn't any question about that. I am impressed with its consistency too over the last several runs. A negatively tilted trough with a 75kt mid level jet... that is about all you can ask for. Another reason to be optimistic is that although the GFS doesn't look nearly as good, it has been trending towards the ECMWF solution over the last several runs. Given each models performance this year I expect that trend to continue and we could be looking at a good chase day next Thursday.

 

[Chris Hovanic]

Ed Berry issued a blog update today, in which he released the hounds--literally.

http://weatherclimatelink.blogspot.com/

Suffice it to say he's going with the ECMWF solution, which looks like a wedgefest for the Plains. We'll be in for quite a ride if it verifies, which I'm gaining confidence in since the ECMWF has been so consistent the last few days.

From my experiences reading his blog, Ed Berry is one of the most accurate long range forecasters I've ever witnessed. His knowledge of global circulations and their affect on the 'sensible' weather pattern is really unparalleled in this field.

That being said, it certainly does appear we're headed into an active severe weather period, just in time for my chase vacation (May 27-June 6)!

 

[Mike Hollingshead]

If GFS has been taking baby steps towards the ECMWF, tonight it up'd the ante with a pretty big step towards it. Still has the trough too far east and progressive, but good sign none-the-less.

 

[Paul Knightley]

This morning's ECMWF (00Z) run is still consistent with digging a sharp trough into the SW'ern states. 00Z GFS is trying to come into line, although it still makes less of the initial digging. Even so, it presents several chasing scenarios towards and over Memorial Day weekend.

Just for interest, if we pick Friday on the EC we have:

100+ knot 300 hPa jet across E NM, W OK and TX Panhandles

75 knot 500 hPa jet streak in same place.

50 knot 850 flot across western OK into KS

Surface dews 68-70F across the same areas of OK/KS.

Long way off I know, but I just wanted to give you an idea of the parameters currently predicted.

 

[Paul Knightley]

06Z GFS is very like the recent ECMWF runs, and depicts a major western US trough being carved out.

 

[Andrew Stoller]

Wow, I hope the ECMWF verifies...nicely negative tilted trough next week.

 

[Cstok]

Well last night I pulled the trigger and booked to arrive Denver Tuesday evening and position from there for Wed / Thurs / Fri .. action. The models have pulled into tighter agreement and this far out you cant ask for more.

I also like the HWO from DDC this morning:

SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS PARTS OF CENTRAL AND
SOUTH CENTRAL KANSAS THURSDAY NIGHT INTO FRIDAY NIGHT. VERY LARGE
HAIL AND DAMAGING WINDS ARE POSSIBLE. IN ADDITION...THE WEATHER
PATTERN WILL BE FAVORABLE FOR TORNADOES SINCE A STRONG JET STREAM
AND RICH GULF MOISTURE WILL BE IN PLACE. THE BEST CHANCE OF
THUNDERSTORMS WILL BE ALONG AND EAST OF A LINE FROM HAYS TO
COLDWATER.

 

[Mike Hollingshead]

Yeah, I'm making plans to raid the mini-dv tape section of the local walmart now. They may not have enough for this one! 12z GFS really flying towards the ECMWF now. Funny, now that it does I feel I need to dig up some fashion of caution. The biggest trend for forever has been to be disappointed in the last days before an event. These are pretty big, broad signals though, so it should be fine.

 

[John Wetter]

Yes indeed, the models are coming together quite nicely on a severe weather solution for the last half of next week. Headed into Memorial day weekend, chasers are sure to be plentiful and gas prices are sure to be high. The devil will of course be in the details, but it's nice to see as I haven't been able to partake in anything yet coming from Minnesota.

-John

 

[Mikey Gribble]

Yeah the new 12Z GFS is a thing of beauty with good directional shear and excellent speed at all levels. Moisture will be key. Assuming the timing on the GFS is right and Thursday is the first major chase day I think it is reasonable to expect decent moisture (maybe low 60's), but again if the GFS is on with the timing and everything else now then there should be high quality moisture in place by Friday. If either one of the models can come close to verifying (which it is looking more and more likely that it will) then given the quality moisture, strong wind fields, large spatial coverage, and climatology we will likely have a significant severe weather outbreak. Whether or not it is also a tornado outbreak is going to come down to the details. Quality moisture return and directional shear are my two biggest concerns right now. As is typical with these kinds of classic spring setups the day before the day usually has excellent directional shear, but moisture and capping are typically an issue (Greensburg last year was a day before the day event with excellent directional shear). Then on the main day there is typically strong deep layer shear (due to the trough ejecting into the plains), quality moisture, but you have lost some degree of your directional shear. That being said, if we can have decent moisture on Thursday, which we very well may given the 50-70kt LLJ being forecast 24 hours ahead of this combined with quality moisture residing right off shore, and maintain backed low level winds on Friday, then we may be looking at back to back tornado days.
This is definitely the most optimistic I've been for a setup this year when we were still 6 days out. I think half my optimism is a result of this year sucking so bad and there is finally a good trough being consistently shown by the models, but I also think some of my optimism is well placed given the reliability of the ECMWF this year and the fact that GFS is quickly falling in line with it.

 

[Jason McKittrick]

I am also am looking to load up on mini dv's today. I hope I don't pick the same store as Mike. Also bought my Windex wipes and my rain-x this morning. See you all next week in Kansas.

As fore the outlook it seems to be a little less certain as to which days will be the big days. The ECMWF holds on to the western US trough through next weekend and never really kicks it out. I have informed my chase team that it still looks like a two or three day event. But it now looks like it could just as easily be Fri, Sat, Sun as Wed, Thu, Fri as first thought.

Just looked at the 12z GFS and it is very similar to yesterdays 12z ECMWF with a southern NE event Wed, Western Ks on Thu and potentially a great day over eastern KS & NE on Sat.

That is my 2 cents, gotta go.

 

[Andrew Stoller]

AHHHHHHHHHHH, I can't wait. I wish tomorrow was next Thursday!

GFS even hinting at possible high plains/northeastern CO action WED (5 days out though - moisture is lacking). Maybe the first chance this year of an eastern CO Limon/I-70 corridor mothership.

 

[Mike Kovalchick]

AHHHHHHHHHHH, I can't wait. I wish tomorrow was next Thursday!

GFS even hinting at possible high plains/northeastern CO action WED (5 days out though - moisture is lacking). Maybe the first chance this year of an eastern CO Limon/I-70 corridor mothership.

My initials thoughts are that I will making a beeline from Lansing, MI to NE Co or SW Nebraska Wednesday afternoon. Nothing like starting out the chase vacation with an all night 1000 mile journey!

I think we almost to the point of being able to start a forecast thread on this upcoming event now that all the stars have come into alignment.

 

[cdcollura]

Good day all...

Already pulled the trigger on a chase trip with this active pattern now coming to be ;-)

The pattern is apparently changing in lieu of nearly all computer models, including the bullish GFS, now showing persistant troughing in the west and ridging to the east.

With cheap airfare to Chicago from FL, I'll spend the 19th with good buddy of mine there then take May 20-21 to go west, maybe W Kansas for the 22 and after that, ??? but with a decent troughing what else can go wrong?

June 1 I return to FL for work (new job) but I just sold my home so I would be bored to tears staying in FL and missing anything in the Plains anyway, so what the heck!

It's coming ... And it looks big!