andyhb

Allow me to describe the 00z GFS mid/long range with the appropriate emoticons:

Long range 12z GFS and now the latest CFS chiclet SCP chart are going bonkers in the latter half of May. 12z Euro also looked to be setting something up in the late goings.

This has been growing less prominent on the GFS runs today. The Euro might not be bad either in central Texas and the Red River Valley as the convection fires early further west and moves into the destabilizing warm sector and a strengthening low level jet with time.

Hmm, 00z GFS not lending too much confidence in Saturday.

Seems to be forecaster preference over anything.

Been awhile since we've seen a May pattern (I suppose you could argue second half in 2013, but I digress) like that. And I see some pretty volatile May analogs showing up here (not just single events either, a few of these were prolonged active stretches)...

Yeah Saturday aside from that almost looks like a prototypical bigger May day, might be the best looking synoptic system we've seen so far with a pretty decent chance of kicking at least neutral tilt if not slightly negative with the upper jet ejecting out the base. LLJ strength looks solid on pretty much every day in this upcoming stretch. Not only that, but something tells me (after looking at ensemble guidance) that we aren't done after this either, i.e. what Thundersnow is mentioning.

Not a huge fan of all the signs of early initiation on Saturday on the models, especially further south into Texas (although that is something that could change fairly easily).

00z GFS looking pretty darn solid all things considered for this upcoming weekend (Saturday 5/9 specifically). Edit: UK/GGEM looking favorable as well.

I really like the LLJ strength on Wednesday, leading to large low level hodographs with relatively typical Plains profiles. Obviously the less than stellar for the season lapse rates (although GFS/Euro still both have 2000+ J/kg SB/MLCAPE in spots), possible early convection and questionable upper level winds are your three biggest issues (a bit better once you approach the OK/KS border and then further south into western/central OK on the left exit region of stronger 300 mb flow), but at least storm initiation/LCL heights seem reasonable.

It has more western troughing developing after that too (as does the GEFS and GEPS). 5/1991 has been showing up a lot in the CPC analog composites over the past few days. I feel like that month gets overlooked a bit given the magnitude of 4/26, but it had 335+ tornadoes, including 5/16/91, which was nearly as good of a chase day as 4/26 (although there weren't any violent tornadoes during the month). Also had the Lazbuddie, TX tornado carousel on 5/10.

Nino doing its work.

I saw his latest ERTAF and he had the week from the 9th to the 16th as above average for activity.

Most ensemble guidance indicates some form of western troughing developing towards the end of the first week of May (possibly with periodic shortwave ejections in advance), looks fairly promising at this time.

Might want to look at the 12z GFS/Euro for Friday. The Euro is particularly impressive.

April showers bring May...tornadoes? I don't think it is any time to panic. I've seen a number of mets with a mid-April lull as far as activity goes. There also hasn't been a dominant -EPO showing up on the ensembles to reinforce the E Pacific ridging being forecast (knock on wood). Even if a -EPO does develop, the wave shortening you mentioned will mean that it won't have the same effect that it did back in winter. There have been a number of very active May/June periods in particular where the EPO was predominantly negative.

Just to tease Brett, the 12z Euro had the best High Plains setup I've seen in several years on D9-10.

A lot of western troughing/ridging over the eastern 2/3 of the country. Speaking for possible severe wx implications of course. I apologize for the initial vagueness there.

Latest Euro weeklies are pretty "wow" through much of April.

Looking at that call looks pretty bleak right now as far as verification and current model guidance. Looks like we did/will have some warming mid-month, but the +PDO-enhanced +PNA ridge and eventual -EPO looks to dominate rather than the Aleutian Low sliding eastward, as seems to have been the overarching pattern over the past year and a half...sigh. Seems foolish to ever go against it these days.

Despite poor model performance as of late, I have a bit of a feeling that something may be coming down the track here as we pass mid month. Shorter range guidance has been consistent in developing another strong N Pacific jet extension (developing in association with the strong ULL currently over northeast Asia), which then progresses and develops into a strong Aleutian low, which pumps the heights in the west and torches western Canada in some solutions, which also blocks cross polar flow from developing. Obviously going further out is getting conjecture-heavy, but the breakdown/progression of said ridge eastward would likely open the door for the jet energy associated with the Aleutian low to move into the Gulf of Alaska and possibly open the door for a western trough/eastern ridge configuration to develop (probably transient as well). As long as the pattern doesn't become significantly blocked up, and with a persistent +NAO and lack of a strong -AO this seems somewhat likely at least over North America, a warming trend seems possible from mid month into the third week of the month, along with a storm or two developing out of the aforementioned western trough (obviously sensible wx impacts are nonsense to consider at this point, but I'm sure most can figure out what such a configuration may lead to). We'll see how this plays out in coming days. I wouldn't call it a forecast per say, more of a pattern recognition observation based on what similar progressions have developed into recently. This is of course rendered more volatile by the aforementioned problems with guidance recently, although large scale synoptic features seem to be relatively consistent across the suite currently at least in the earlier going over the west/central Pacific.

Looks like the 00z GFS came significantly toward the other guidance, although it is still more progressive than them.

Not only that, but the pattern across the N Pacific looks to become increasingly volatile over the next while with a series of strong systems making their way into the Gulf of Alaska region and a corresponding strong negative height anomaly off the NW coast, so the active period might not be over with this system. You can see it there on the Euro run with another very strong impulse in behind the trough of mention. Euro is showing CAPE of 1500-3000 J/kg over central and southern AR @ 150 hrs.

Agreement with the GFS is essentially non-existent with the other three main globals, the GGEM and UK also have a substantial trough dropping into the Central US this weekend.

That was one of the strange things about the 11/17 outbreak last year, the lapse rates that day were one of the things leading to that thermodynamic environment being more volatile rather than less. Helps when you have an absolute powerhouse of a system with a strong mid level dry punch of course.