• Member Statistics

    16,019
    Total Members
    7,904
    Most Online
    BlckJckKhoWX
    Newest Member
    BlckJckKhoWX
    Joined
andyhb

Central/Western Medium-Long Range Discussion

Recommended Posts

Tuesday and Wednesday of next week show extremely high CAPE values all across the Central Plains (from the 00z GFS).

And then there's the 6,000+ CAPE values it shows in central Oklahoma on Monday 5/16...

Share this post


Link to post
Share on other sites

Leaving on CoD's trip 2 next Friday..

 

12z op GFS run looks like it came around to the GEFS members idea the last several runs of a good trof signal by next weekend and the week beginning 5/16 along with a good EML being able to come out with an open Gulf. 

 

We will see how things shake out but I'm fairly optimistic 

 

 

Share this post


Link to post
Share on other sites

Very interested in next Monday. GFS shows a pretty potent setup over C OK.

Euro lags behind.

As I've posted in the May 7-10 thread, I'm new at the this and learning which I find fascinating. I just recently scanned the GFS 18Z for 00Z Tuesday May 16. I noticed all the SBCAPE moved south to DFW from C. OK. Am I correct?

It seemed earlier that C. OK looked potent and may still but again just now in infant stages of reading the models.

Share this post


Link to post
Share on other sites

As I've posted in the May 7-10 thread, I'm new at the this and learning which I find fascinating. I just recently scanned the GFS 18Z for 00Z Tuesday May 16. I noticed all the SBCAPE moved south to DFW from C. OK. Am I correct?

It seemed earlier that C. OK looked potent and may still but again just now in infant stages of reading the models.

You are correct. I was referring to 12z GFS.

18z lags behind a bit so sfc response is delayed and the threat area shifts west, as you pointed out. This will undoubtedly change as the GFS shows poor run to run consistency.

Share this post


Link to post
Share on other sites

As I've posted in the May 7-10 thread, I'm new at the this and learning which I find fascinating. I just recently scanned the GFS 18Z for 00Z Tuesday May 16. I noticed all the SBCAPE moved south to DFW from C. OK. Am I correct?

It seemed earlier that C. OK looked potent and may still but again just now in infant stages of reading the models.

 

Don't forget to check winds upstairs. Look for southwest winds at 500 mb and 200 mb; west is even better at 200 mb. Look for nearly straight south at 850 mb, SSE is even better. I wrote a lot more in the May 7-9 severe thread page 26.

 

At any rate the 12Z GFS in on board with winds, and with low press and fronts in the central Plains. Lots of rain shown before peak heating, but it is days away...

Share this post


Link to post
Share on other sites

Don't forget to check winds upstairs. Look for southwest winds at 500 mb and 200 mb; west is even better at 200 mb. Look for nearly straight south at 850 mb, SSE is even better. I wrote a lot more in the May 7-9 severe thread page 26.

At any rate the 12Z GFS in on board with winds, and with low press and fronts in the central Plains. Lots of rain shown before peak heating, but it is days away...

Yes. Thanks. Will do. I'm still not sure if I look for CAPE first then other parameters. It seems to me you need the energy in a specific area is why I look for CAPE first then try to put the puzzle together. I'll get the hang of it soon

Share this post


Link to post
Share on other sites

Very interested in next Monday. GFS shows a pretty potent setup over C OK.

Euro lags behind.

 

 

 

From Dr Forbes

 

 

 

MONDAY 5/16

The potential exists for a substantial severe thunderstorm threat

in the Central and Southern Plains, but computer models differ

enough that I'll hold off on a specific forecast for now.

Share this post


Link to post
Share on other sites

Departing Friday morning and probably chasing northeast/eastern NM on Saturday then some better days to follow across the plains. We'll see how the models shake out 

 

12z GFS is basically suggesting a potential outbreak over a large area of the central/S Plains on Monday. Thing that really gets my attention is how broad the LLJ axis is, with 40-50 kt H85 flow covering much of OK, KS and N TX ahead of the dryline. The low amplitude nature of the shortwave trough was another red flag. Looked at some soundings basically from I-20 north to I-70 and my eyes just about popped out of my head.

 

Euro isn't as enthused, showing a more disjointed trough ejection with weaker wind fields overall, but still plenty of CAPE. Finding it interesting that 5/9 produces majorly (anniversary of last year's CO, KS and Cisco tornadoes) and now 5/16 may try to do it as well (Elmer).

Share this post


Link to post
Share on other sites

12z GFS is basically suggesting a potential outbreak over a large area of the central/S Plains on Monday. Thing that really gets my attention is how broad the LLJ axis is, with 40-50 kt H85 flow covering much of OK, KS and N TX ahead of the dryline. The low amplitude nature of the shortwave trough was another red flag. Looked at some soundings basically from I-20 north to I-70 and my eyes just about popped out of my head.

 

Euro isn't as enthused, showing a more disjointed trough ejection with weaker wind fields overall, but still plenty of CAPE. Finding it interesting that 5/9 produces majorly (anniversary of last year's CO, KS and Cisco tornadoes) and now 5/16 may try to do it as well (Elmer).

Perhaps the best thing about the 12Z GFS was that the LLVL wind field is pretty impressive as early as 18Z, and by 00Z it is even better... Not liking the look it has had for several runs including 12Z of keeping lingering convection across much of the warm sector. Oddly, it appears to have little to no effect on instability or moisture.

 

Still very little model consistency though in where the best threat area would be.

Share this post


Link to post
Share on other sites

Yes. Thanks. Will do. I'm still not sure if I look for CAPE first then other parameters. It seems to me you need the energy in a specific area is why I look for CAPE first then try to put the puzzle together. I'll get the hang of it soon

I am still a little new to this myself, so someone please correct me if I'm wrong on anything.

 

A quick and easy way to check for potential severe weather events is 0-3 km EHI. It is a combination of CAPE and favorable wind shear, which gives you a rough idea for when and where supercells might be possible. Many times you can have high CAPE but no storms, especially in the summer months. Even if high EHI shows up, you will still need good sources of lift, etc. to get storms.

 

When I have time to analyze the models closer, this is the order I usually check them:

 

Winds at 500 mb (longwave and shortwave troughs), 300 mb (anvil-level flow), and 850 mb (low-level jet). The main idea for these wind charts is that you want the direction and speed to change smoothly as you go up in the atmosphere. For example: southerly 850 mb winds, southwesterly 500 mb winds, and westerly 300 mb winds, with each height having stronger winds.

 

Surface dew points and temperatures (moisture quality and dryline / frontal boundary locations) and accumulated QPF (morning convection and storm initiation).

 

0-6 km bulk shear: Values over 35 knots are favorable for rotating updrafts. Also, if the shear vectors are perpendicular to the dryline, storms will usually be more discrete. If the shear vectors are more parallel to the dryline, storms will usually be more linear.

 

0-3 km SRH: Values over 150 are favorable for supercells and tornadoes.

 

SBCAPE: Instability; anything over 2000 is plenty favorable for severe storms and supercells.

 

Hodographs: Check some hodographs for different places in the threat area. Look for things that might limit tornado potential like VBV (Veer-Back-Veer) profiles. Also look for capping in the sounding.

 

Lastly, I check EHI and SigTor parameters. Once you start getting good at reading the various charts, you will already have a good idea at what these will look like.

 

You can use today's 12z GFS forecasts for Monday afternoon as an example of things to look for since it shows a pretty favorable setup for severe weather and tornadoes across the southern and central plains.

Share this post


Link to post
Share on other sites

Trying to chase this upcoming trough. Hopefully Monday follows the GFS's way. It looks very good. 

 

 

A little further out, but this looks pretty interesting too.

 

 

 

 

 

ehi03.conus.png

Share this post


Link to post
Share on other sites

Seems like most of the models aside from the GFS want to eject a lead southern stream wave that basically screws the setup by stealing away the LLJ from the second trough (i.e. Monday's system) and shunts moisture southward.

Share this post


Link to post
Share on other sites

12z NAM has OKC at 48 F on 00z Mon with a 1024 mb high sitting over AR. Where's the gun blowing my brains out smiley?

 

GFS/ECMWF aren't nearly that brutal, but the latter doesn't instill a lot of confidence in Monday's potential setup. It has trended slightly better, though, now allowing moderate instability to lift into the TX PH and W OK.

Share this post


Link to post
Share on other sites

12z NAM has OKC at 48 F on 00z Mon with a 1024 mb high sitting over AR. Where's the gun blowing my brains out smiley?

GFS/ECMWF aren't nearly that brutal, but the latter doesn't instill a lot of confidence in Monday's potential setup. It has trended slightly better, though, now allowing moderate instability to lift into the TX PH and W OK.

NAM also has unrealistic shallow cold air bias. A high in thst location would already have a return flow. 48 isnt happening at 00z Monday.

Share this post


Link to post
Share on other sites

NAM also has unrealistic shallow cold air bias. A high in thst location would already have a return flow. 48 isnt happening at 00z Monday.

 

Right, that would have to be very close to unprecedented for mid May. Just doesn't help ease concerns regarding whether we'll actually get the boundary to lift to the KS border by Monday like the more favorable GFS solution (relative to the ECMWF).

Share this post


Link to post
Share on other sites

Right, that would have to be very close to unprecedented for mid May. Just doesn't help ease concerns regarding whether we'll actually get the boundary to lift to the KS border by Monday like the more favorable GFS solution (relative to the ECMWF).

Never underestimate the strength of the LLJ. I would hedge my bets toward the GFS.

Share this post


Link to post
Share on other sites

The 12z and 18z GFS show that the EML (warm layer) will quickly move over the warm, moist sector Monday night, from 00z to 06z, resulting in with some hundreds of J/kg of CINH by 06z.

Share this post


Link to post
Share on other sites

Last four runs of the Euro (and three runs of the EPS) suggest a more progressive pattern in the mid range than the GFS/GEFS with that large upper trough amplifying in the W later this upcoming week then ejecting eastward (or at least pieces of it) by 5/22-5/24 and really amplifying the flow fields across the Plains. Might be quite the start to many chasecations (including possibly mine) if it turns out to be more on the right track. Would like to see more multi-model consensus on this less blocked idea though.

Share this post


Link to post
Share on other sites

Last four runs of the Euro (and three runs of the EPS) suggest a more progressive pattern in the mid range than the GFS/GEFS with that large upper trough amplifying in the W later this upcoming week then ejecting eastward (or at least pieces of it) by 5/22-5/24 and really amplifying the flow fields across the Plains. Might be quite the start to many chasecations (including possibly mine) if it turns out to be more on the right track. Would like to see more multi-model consensus on this less blocked idea though.

 

Yeah, I don't know how you guys do it - I'd already be to the point of being sick to my stomach every 12 hours!

 

At least you have the "right" model on your side. IIRC, the leadup to the late May 2008 tornadofest had a similar predicament: the Euro and its ensembles wanted to edge that trough out of the Rockies far enough for madness to ensue, while the GFS/GEFS kept holding it back until a few days out. This trough isn't quite the behemoth that one was, but should be plenty sufficient for some good stuff if it ejects properly. I'm cautiously optimistic for at least one solid day, and 1-2 more mesoscale days surrounding it, centered around the 22nd-23rd.

Share this post


Link to post
Share on other sites

GFS (0z) a step in the right direction.

Euro is where it's at. GFS *potentially* trending that direction.

 

Eh, this run of the Euro wasn't so favorable. Trough gets more blocked in the west and the waves tend to shear out as they eject eastward. Need the larger scale trough to make it further east on its initial amplification.

Share this post


Link to post
Share on other sites

Eh, this run of the Euro wasn't so favorable. Trough gets more blocked in the west and the waves tend to shear out as they eject eastward. Need the larger scale trough to make it further east on its initial amplification.

I was referencing prior 0z and 12z euro

Share this post


Link to post
Share on other sites

Tomorrow (5/17) already has an Enhanced Risk for Central Texas. Some crazy 3km EHI figures showing up on the NAM 4K at 00z.

22 0-3KM EHI... 22 STP.  :arrowhead:  One of the craziest soundings i've ever seen, even from the 4NAM. This obviously won't happen, but its hilarious to look at.nam4km_2016051612_036_30.26--99.42.png

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.