Central/Western Summer Medium/Long Range Discussions

[HM]

Right, makes sense. The Euro as you said has the MJO wave being slower to progress and going into the COD in phase 5, whereas the GFS has the MJO progressing all the way to phase 7, which creates more PNA ridging out west. 

 

I'm not worried yet because as I said before, intuitively I would think a Central Canadian block retrograding westward should lead to a split flow/semi-zonal regime where waves can travel underneath that block and make for interesting threats for the central and northern tier. I don't really see a PNA ridge "bridging" with that block, as despite what the GFS is saying, I think the flow is too zonal/fast in the Pacific to allow for that much upstream ridging, especially given the "wall" in Western Canada. 

 

It's just harder to be objectively "emotionless" when it comes to analyzing the data for us chasecationers, since we've spent a decent amount of money on this trip and really, really want to see something happen, lol. 

 

I understand, lol.

 

The good news is that the GEFS did not agree with the operational in the long, long range. The solutions were all over the place but essentially averaged a trough in the West throughout the entire day 10-16 period. The ensemble mean basically outlines the pattern you are suggesting in your post.

[andyhb]

Yes, there are still plenty of issues so I can't be reasonably certain about the threat. Another issue is that if the blocking retrogrades quickly into western Canada, it could force a split and send the southern piece even further south (kinda like what happened with this week's trough) and give room for the northern piece to go north. Even if that occurs, the boundary layer recovery will be much better anyway in comparison.

 

This looks to be what the 12z Euro is doing for the 168-216 hr period, fortunately there looks to be a trough building into the Pacific NW as this is occurring with a strongly negative PNA taking shape by the end of the run.

[Derek30]

Any thoughts on the potential for North Dakota/Minnesota/Manitoba in the coming weeks?

 

I see some signs of hope based on what I've seen. Looks like we could, at least, be in line for some MCS action as the storm track cuts across the far northern US.

[Dsnowx53]

Lots of Euro members have the MJO retreating from early phase 5 back to late phase 4 before going into the COD (image is time sensitive). 

 

[Ian]

New GFS dumps a big trough in late. I mean.. we see that every other run I guess but seems eventually it will try to happen. Might be September.

 

The next weekendish event looks a bit more marginal but still potential. Then a few day break maybe.

 

Might have to go back to only looking to 72 hours out soon for sanity sake.

[Amped]

GFS long range already showing hurricanes. There's how you'll get  tornadoes this year.

[Ian]

GFS long range already showing hurricanes. There's how you'll get tornadoes this year.

1995 analog back in play. /weenie

[jojo762]

Despite how meaningless it is, hr 384 of the 18z GFS looks pretty nice for Kansas, that'd be at the very end of may... Late may seems like the last ditch chance for any meaningful tornado outbreak(s), because much after that and we'll start seeing the usual high LCL's and thermo-nuclear cap. And not to mention the large temperature/ dewpoint spreads.

[brettjrob]

Just not seeing any model support for a respectable event next weekend at this point. The upper flow is just about nonexistent, as another trough deamplifies over the western CONUS and eastern troughing continues to rule the roost. I truly feel sorry for anyone taking their chase vacation the next 10 days or so, as I don't see anything over that period that we'd be discussing in even a 30th-percentile chase year. I respect everyone's opinions here, but I think the bar has dropped so low over the past ~18 months that we're losing perspective. I'm going to be pleasantly surprised if anything better than mesoscale accidents on 2-5% days is served up before Memorial Day.

[Ian]

Just not seeing any model support for a respectable event next weekend at this point. The upper flow is just about nonexistent, as another trough deamplifies over the western CONUS and eastern troughing continues to rule the roost. I truly feel sorry for anyone taking their chase vacation the next 10 days or so, as I don't see anything over that period that we'd be discussing in even a 30th-percentile chase year. I respect everyone's opinions here, but I think the bar has dropped so low over the past ~18 months that we're losing perspective. I'm going to be pleasantly surprised if anything better than mesoscale accidents on 2-5% days is served up before Memorial Day.

this is a fun map

 

 

tho truncation is clearly an issue just flipping past the switch. 

 

i do wonder if EC troughing is overplayed at this time of year.. it's not ideal but there are plenty of events that have had troughing in the northeast especially.

[brettjrob]

i do wonder if EC troughing is overplayed at this time of year.. it's not ideal but there are plenty of events that have had troughing in the northeast especially.

 

It's not a dealbreaker in the sense of moisture return, as is often the case in March and April. In this case, I was referring more to the overall longwave pattern and how big troughs are unable to dig into the Rockies with a big vortex sitting over SE Canada simultaneously (next weekend "event").

[Ian]

It's not a dealbreaker in the sense of moisture return, as is often the case in March and April. In this case, I was referring more to the overall longwave pattern and how big troughs are unable to dig into the Rockies with a big vortex sitting over SE Canada simultaneously (next weekend "event").

 

yeah that's true. it is may though (as you obviously know).. but some bad years have had a similar vortex up near hudson bay/lakes that would never leave for long. it definitely doesn't look great but the op solutions in particular are really chaotic, seem to change every run past a few days out.

[ZackH]

Next weekend's trough sure has trended down, definitely.  But there may be enough for a few nice storms in SD Friday or Saturday.  Nothing respectable like you said, but maybe something local and chaseable for me finally.  Keeping an eye on MN for Tuesday, but as of now, the cap is going to major problem to get anything going.  Shame also, because hodos look nice.

[andyhb]

Next weekend's trough sure has trended down, definitely.  But there may be enough for a few nice storms in SD Friday or Saturday.  Nothing respectable like you said, but maybe something local and chaseable for me finally.  Keeping an eye on MN for Tuesday, but as of now, the cap is going to major problem to get anything going.  Shame also, because hodos look nice.

 

Quite frankly I think the weekend trough on the GFS took an upswing from 12z, it is more consolidated with less splitting of the southern vort max (or just a more dominant southern piece of energy that might work just as well).

[Stebo]

this is a fun map

 

gfs_namer_264_500_vort_ht.gif

 

tho truncation is clearly an issue just flipping past the switch. 

 

i do wonder if EC troughing is overplayed at this time of year.. it's not ideal but there are plenty of events that have had troughing in the northeast especially.

 

The GFS usually takes whatever it shows at 192 and uses that as the theme for the rest of the run from what I have seen, I would be skeptical of prolonged deep EC troughing, unless the NAO goes absolutely into the tank.

 

[Stebo]

Next weekend's trough sure has trended down, definitely.  But there may be enough for a few nice storms in SD Friday or Saturday.  Nothing respectable like you said, but maybe something local and chaseable for me finally.  Keeping an eye on MN for Tuesday, but as of now, the cap is going to major problem to get anything going.  Shame also, because hodos look nice.

 

I think Wednesday though with less instability has a better potential. Not nearly as capped.

[ZackH]

Quite frankly I think the weekend trough on the GFS took an upswing from 12z, it is more consolidated with less splitting of the southern vort max (or just a more dominant southern piece of energy that might work just as well).

 

I agree... I hadn't looked at the entire 00z run yet and was still basing most of my statement on the 18z run.  There's still plenty of time for this thing to amp back up.  A decent event in SD on Friday would be gold for me.

[ZackH]

I think Wednesday though with less instability has a better potential. Not nearly as capped.

 

Yah, but all the instability is outrunning the shear fairly substantially.  That's been a fairly consistent feature for Wednesday.  Still time to change though, obviously.  I guess you could have a nice storm or two in MI up by you, though!

[andyhb]

I agree... I hadn't looked at the entire 00z run yet and was still basing most of my statement on the 18z run.  There's still plenty of time for this thing to amp back up.  A decent event in SD on Friday would be gold for me.

 

Remember, we're still outside truncation on the GFS for the actual ejection of this thing (it still looks good enough in the West before truncation takes over). Obviously the 12z Euro was kind of a mess, but the ensemble mean still showed promise.

[Stebo]

Yah, but all the instability is outrunning the shear fairly substantially.  That's been a fairly consistent feature for Wednesday.  Still time to change though, obviously.

 

The really good shear, yes although I would argue there is still modest to decent shear into the Great Lakes. Might just be too far East for this region on Wednesday.

[ZackH]

Remember, we're still outside truncation on the GFS for the actual ejection of this thing (it still looks good enough in the West before truncation takes over). Obviously the 12z Euro was kind of a mess, but the ensemble mean still showed promise.

 

That is a good point.  It does look strange.  It starts to get its act together pre-truncation and just falls apart right after. Something funny going on.

[andyhb]

That is a good point.  It does look strange.  It starts to get its act together pre-truncation and just falls apart right after. Something funny going on.

 

GEFS mean looks good with a nice western troughing pattern continuing basically until the end of the run.

[brettjrob]

I'm not sure there's anything completely unphysical or even suspicious occurring "post-truncation" with next weekend's system, though. It's just an unimpressive trough with very lackluster height gradients. Even as it comes ashore Thu/Fri prior to truncation, there's a small zone of 40-45 kt flow at H5 east of the trough axis, and that's it.

 

The GGEM does have a more potent and negative-tilt solution, but the upper-tropospheric geostrophic wind would appear relatively weak even there. Of course, with good instability, you don't necessarily need more than 35-40 kt to get the job done -- at least for a localized event. Perhaps we can manage that.

 

[ZackH]

Well, that's basically what I'm playing for at the least here.  A hopeful localized Dakota/Nebraska event with a surprise or two.

[Stebo]

I'm not sure there's anything completely unphysical or even suspicious occurring "post-truncation" with next weekend's system, though. It's just an unimpressive trough with very lackluster height gradients. Even as it comes ashore Thu/Fri prior to truncation, there's a small zone of 40-45 kt flow at H5 east of the trough axis, and that's it.

 

The GGEM does have a more potent and negative-tilt solution, but the upper-tropospheric geostrophic wind would appear relatively weak even there. Of course, with good instability, you don't necessarily need more than 35-40 kt to get the job done -- at least for a localized event. Perhaps we can manage that.

 

GZ_D5_PN_192_0000.gif

GFS has consistently underdone the 500 mb winds all spring for the region, I would proceed with caution if you are biting onto the 40-45kt idea. Plus we are talking about a 7-8 day potential, I would expect changes to still come.

 

[Thundersnow12]

Been watching this coming Tuesday in south TX for the past few days as it looks decent right now with moisture returning up into this area with great directional shear in place and actually pretty nice flow at mid levels (40kts) and upper levels (80kts)

 

Maybe around Del Rio.

[wxmeddler]

this is a fun map

 

It's ok, we can change gears and chase the 384hr gulf tropical storm.

[jojo762]

That 384 hr Tropical Storm near Cancun would suck... Because about a week after that (June 4-11) I'm going to Cancun/ isla mujeres.

[Ian]

GFS looks a bit better for the weekend "event". I'd love to slow it down a day but might be worth hauling west for it. Dakotas chases are fun.   My concern is we'll have nothing after that for like 5-7 days. Guess we'll visit Yellowstone or something.

[Ian]

It's ok, we can change gears and chase the 384hr gulf tropical storm.

 

For some reason I have almost no interest in chasing a tropical system. I'd like to see a major once just to say I have but otherwise sounds kinda miserable.