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Quincy

Mid to Late May 2019 Severe Threats

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I think one of the primary differences between CAMs that show quick upscale growth and those that show a discrete outbreak is the orientation of the dryline in the TX panhandle.  The NAM nest surges part of the dryline eastward and ends up with a SW to NE oriented dryline, which is close to parallel with storm motions.  Since storm motion vectors end up parallel to the initiation mechanism, a squall line forms fairly quickly.  The HRRR, on the other hand, keeps a more N-S oriented dryline and storm motion vectors are more perpendicular.

Subtle difference but it might end up being a big factor.

 

 

 

HRRR.png

NAM_NEST.png

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I think one of the primary differences between CAMs that show quick upscale growth and those that show a discrete outbreak is the orientation of the dryline in the TX panhandle.  The NAM nest surges part of the dryline eastward and ends up with a SW to NE oriented dryline, which is close to parallel with storm motions.  Since storm motion vectors end up parallel to the initiation mechanism, a squall line forms fairly quickly.  The HRRR, on the other hand, keeps a more N-S oriented dryline and storm motion vectors are more perpendicular.

Subtle difference but it might end up being a big factor.
 
 
 
HRRR.thumb.png.c326bc3d6896431a01c4cb72d9fdec27.png
NAM_NEST.thumb.png.811960184c13b185a51151d6be8a2da1.png
Interesting the HRRR is more aggressive than the NAM with pulling the front north.

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14 minutes ago, OUGrad05 said:
1 hour ago, jpeters3 said:
I think one of the primary differences between CAMs that show quick upscale growth and those that show a discrete outbreak is the orientation of the dryline in the TX panhandle.  The NAM nest surges part of the dryline eastward and ends up with a SW to NE oriented dryline, which is close to parallel with storm motions.  Since storm motion vectors end up parallel to the initiation mechanism, a squall line forms fairly quickly.  The HRRR, on the other hand, keeps a more N-S oriented dryline and storm motion vectors are more perpendicular.

Subtle difference but it might end up being a big factor.
 
 
 
HRRR.thumb.png.c326bc3d6896431a01c4cb72d9fdec27.png
NAM_NEST.thumb.png.811960184c13b185a51151d6be8a2da1.png

Interesting the HRRR is more aggressive than the NAM with pulling the front north.

Could be because of less early day convection along the front in the HRRR

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Wild to me this could occur exactly 6 years after the last Moore monster

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4 minutes ago, cheese007 said:

Wild to me this could occur exactly 6 years after the last Moore monster

Has it really been 6 years?  Time flies...

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00Z HRRR is... concerning. Multiple rounds of semi-discrete supercells east of the dryline and throughout the warm sector. Does exactly what SPC disco referenced with WAA storms becoming surface-based. UH track galore across OK and TX.

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Sitting in Altus right now, eerie feeling for lack of a better term.

The 00z HRRR is pretty frightening with a swarm of warm sector supercells followed by some monsters on the dryline. You don't see this kind of blend of late spring instability and early spring dynamics very often, folks. Could storm mode go awry? Yes. However, even a mixed mode here is likely yielding some high end severe.

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Upstream observations are usually a good clue to what may unfold the day later. These ones speak volumes.

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It's just one solution from guidance, but to have open warm sector, warm front, and dry line supercells like the 00Z HRRR depicts would really be something else. Not sure when the last plains system had a ceiling this high.

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5 minutes ago, 1900hurricane said:

It's just one solution from guidance, but to have open warm sector, warm front, and dry line supercells like the 00Z HRRR depicts would really be something else. Not sure when the last plains system had a ceiling this high.

There isn’t much spacing. That could be a real issue. From a chasing perspective, Texas looks like the play 

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29 minutes ago, 1900hurricane said:

It's just one solution from guidance, but to have open warm sector, warm front, and dry line supercells like the 00Z HRRR depicts would really be something else. Not sure when the last plains system had a ceiling this high.

You would have to go all the way back to 4-14-12, or even 5-22-11...

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That 12z MAF sounding is going to be a sharp indicator of how quickly things could start firing in the morning, assuming it does sample on the east side of the dryline. Data suggests there may not be much convective inhibition remaining with strong instability already in place, which is pretty unusual for a 12z sounding that far west.

Downstream sounding from DRT shows a 69F dew-point as of 00z. While that's not extreme high-end given SPC sounding climo, the 80F dew-point at CRP is close to a record. In fact, it's pretty rare in any month of the year for an 80F dew-point there, as sounding climo records show the all-time record of 83F. That was in September, either associated with a tropical system or return flow off of the Gulf, which reaches peak temperature around that time.

Here is a surface map I put together, highlighting potential tornado threat areas, based on the 00z HRRR. The 00z 3km NAM is not far off and it shows hints of at least semi-discrete convection near/south of I-40 in Oklahoma during the afternoon/early evening. Local climatology suggests backing of low-level flow in central/northern Arkansas given the warm frontal placement tomorrow would support an "enhanced" tornado threat there as well.
HRRR_fronts_thetae.gif.d381908736148a2b110ee7f134f6b277.gif

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I know it's just one model, but the 0z HRRR is trying to send up storms as far south as the DFW area.  I have an afternoon-shift job, and I'm starting to get concerned about the potential for severe weather here in Fort Worth.  Given what I've read it seems most likely to stay in NW TX and OK (and perhaps AR given Quincy Vagell's post), and from what I can tell the other models seem to agree with that perspective.

Wondering if anyone with more expertise might be able to tell if the HRRR might be trying to catch on to something, or if it is overdone for areas this far south.

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00z HRRR rainfall totals till 6am Tues

qpf_acc.us_sc.png

 

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9 minutes ago, BrandonC_TX said:

I know it's just one model, but the 0z HRRR is trying to send up storms as far south as the DFW area.  I have an afternoon-shift job, and I'm starting to get concerned about the potential for severe weather here in Fort Worth.  Given what I've read it seems most likely to stay in NW TX and OK (and perhaps AR given Quincy Vagell's post), and from what I can tell the other models seem to agree with that perspective.

Wondering if anyone with more expertise might be able to tell if the HRRR might be trying to catch on to something, or if it is overdone for areas this far south.

Well, I'm not able to pull sounding data from the HRRR right now (server issue I think), but by 18hr with the 01z run, which lines up with the longer 00z run, there's upwards of 5000 J/kg SBCAPE with negligible convective inhibition in the DFW area. While forcing is weak/nebulous, anything that can initiate in North Texas given the thermodynamic/kinematic fields, would, at least conditionally, have the potential to become supercellular with a tornado threat.

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2 minutes ago, lokee said:

00z HRRR rainfall totals till 6am Tues

qpf_acc.us_sc.png

 

I keep seeing all these models that a pounding swmo with rain, but sgf seems to be down playing the flood potential. 30% chance of rain here tomorrow night, and the model has 5-7 inches of rain. 

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The 00Z HREFs have big UH maxima concentrated in two areas, Central Oklahoma and the Permian Basin of Texas, which matches the warm front/open warm sector and dryline threats, respectively. The NCAR Ensembles are still from about 24 hours ago, but they were highlighting the same areas. I'd probably play dryline tomorrow personally, mainly due to me having a higher confidence that storms will be better spaced with a better chance at staying discrete out there, but won't be playing anything in actuality due to prior commitments.

uh25_004hmax_pb150.sp.f02500.png

hmuh_paintball_150.0_f048_SGP.png

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HRRR going mostly discrete with clusters remaining mostly north of the WF... other CAMs mostly disagree. 

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The 21Z SREF is rather bullish for tornado ingredients. There is a fairly expansive 75 contour and even a 90 bullseye in SW Oklahoma at 0Z. There is certainly model support for a possible convective outlook upgrade at least as things stand right now.

KDFvCXk.gif

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Definitely some people acting like they have inside info that a high risk is coming with the new update. Not sure how legit that is, obviously. 

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1 minute ago, MUWX said:

Definitely some people acting like they have inside info that a high risk is coming with the new update. Not sure how legit that is, obviously. 

Honestly aside from the HRRR, what would give SPC enough confidence in storm mode to pull the trigger at 06Z?

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2 minutes ago, jojo762 said:

Honestly aside from the HRRR, what would give SPC enough confidence in storm mode to pull the trigger at 06Z?

I don’t see it either. I think they should wait until at lease the morning update 

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13z would be the best deciscion to pull the trigger IF they did. It would give them a much better idea of how morning convection will behave and more time to watch overnight CAM runs for any trends. 

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Don’t get me wrong, I’m just as in awe as everyone else at the forecast environment... and it could be a historic day, potentially... but feel like we’ve been burned so many times by precip bombs and boat loads of storms initiating on days that seemed huge. Many of those instances had other issues as well though, that tomorrow likely won’t have. 

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What mind boggles me are the kinematics superimposed on the instability and moisture.  Don't often see that combination to such a degree.

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