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August model and weather disco


weathafella
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7 hours ago, OceanStWx said:

I see folks have already confirmed this is tornado debris.

But for those who want to learn you have to use CC in conjunction with other radar variables to confirm. You'll want to pair this CC up with differential reflectivity (ZDR), reflectivity (Z), and velocity (V or SRV). So the drop in CC must be collocated with sufficient Z (> 20 dBZ would be ideal if not higher), a V couplet, and near 0 ZDR (debris tumbles like hail and looks neither tall or wide to the radar). 

Now one caveat is that Z and CC are sampled by the radar first, and then V. So it is possible that the couplet may be displaced slightly ahead of the TDS because of storm motion (especially in fast moving storms), but it shouldn't be far away.

A commonly misidentified TDS is in the inflow region of supercells. Dust, bugs, etc. are all very low in CC too, so a quick check of Z will show that dBZs aren't high enough to be a true TDS. 

Thanks sir.

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Alright ... I'll bite.   Yes there's a burgeoning heat signal between ~ the 17th and ... sometime out there after the 20th. 

Multi telecon index behavior in the projections are converging.  A modest +EPO collapsing toward neutral, which precedes the -PNA mode ... While this is going on, the recent GLAMM trends suggest the mode of that is attempting to go (or go more...) positive. Now ... GLAMM is not a modeled state; this is an extrapolation based upon trend/behavior.  This is the time of the year for such a trend to work ...so, we'll see.  This latter aspect adds confidence, because that being positive is really like the scalar measure of the subtropical ridged circulation mode. So... although telecon correlations become a little less useful in the summer season, these are super-synoptic  forcing signature that are tougher to ignore.  

(I also love the utter suppression of the MJO as it's trying desperately to emerge out of the RMM in phase 8, yet both hemispheres are sitting on it like a playground bully ... but I'm not sure if that has any meaning to this beyond my taking Schadenfreude in watching the El Nino squirm.. lol)

What all that ^ means is that we should see at least a temporary ( how long remains to be seen) relaxation of this weird summer version of a polar jet. It's been unusually coherent, odd season for that behavior... We typically see the hemisphere evolve toward the lower frequency base-state, yet these defined R-waves definitive jets have persistence. It's also interesting that all these insane heat aspects have been observed S of 40 N ( for everywhere in the world except the eastern seaboard of N/A) ..

It doesn't hurt that the distantly framed guidance actually show it some, too.

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8 hours ago, OceanStWx said:

I see folks have already confirmed this is tornado debris.

But for those who want to learn you have to use CC in conjunction with other radar variables to confirm. You'll want to pair this CC up with differential reflectivity (ZDR), reflectivity (Z), and velocity (V or SRV). So the drop in CC must be collocated with sufficient Z (> 20 dBZ would be ideal if not higher), a V couplet, and near 0 ZDR (debris tumbles like hail and looks neither tall or wide to the radar). 

Now one caveat is that Z and CC are sampled by the radar first, and then V. So it is possible that the couplet may be displaced slightly ahead of the TDS because of storm motion (especially in fast moving storms), but it shouldn't be far away.

A commonly misidentified TDS is in the inflow region of supercells. Dust, bugs, etc. are all very low in CC too, so a quick check of Z will show that dBZs aren't high enough to be a true TDS. 

Yep. Wasn’t jumping the gun, but all those did show it nicely. 

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9 hours ago, OceanStWx said:

I see folks have already confirmed this is tornado debris.

But for those who want to learn you have to use CC in conjunction with other radar variables to confirm. You'll want to pair this CC up with differential reflectivity (ZDR), reflectivity (Z), and velocity (V or SRV). So the drop in CC must be collocated with sufficient Z (> 20 dBZ would be ideal if not higher), a V couplet, and near 0 ZDR (debris tumbles like hail and looks neither tall or wide to the radar). 

Now one caveat is that Z and CC are sampled by the radar first, and then V. So it is possible that the couplet may be displaced slightly ahead of the TDS because of storm motion (especially in fast moving storms), but it shouldn't be far away.

A commonly misidentified TDS is in the inflow region of supercells. Dust, bugs, etc. are all very low in CC too, so a quick check of Z will show that dBZs aren't high enough to be a true TDS. 

Great post.  Depending on the azimuthal sampling volume, a function of the distance from the radar, you might well be averaging in potentially high ZDR oblate raindrops along with the debris.  So you would expect a ZDR drop relative to the surrounding regions of the thunderstorm, especially the FFD but maybe also within the RFD, but maybe not getting near zero.  Even legit hail cores in the northeast I think are pretty often contaminated by rain and ZDR stays higher compared with hail storms you might see on the high plains or something.   Probably if you had a high LCL tornado classically formed on the tail end of an RFD and away from the rain shield you would indeed see ZDRs of 0 however so the theory is correct.

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12 hours ago, FXWX said:

While the July wetness footprint does seem to have folded over into August, I don't recall any 7-day period looking like this first 7-day anomaly of August???  Not really screaming torch?  I do expect a rebound of sorts due to occasional periods of high dews and positive overnight mins, but it will take a while to get the monthly departure to normal or above.

 

7dTDeptNRCC.png

What's that weird spot west from BGR?  Somebody's thermometer next to the exhaust of their heat pump motor?

August 1-8 is 4.5° BN here.  Storm total was 3.51", second only to Irene (4.41") for August downpours, 1998 on.

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NOAA has confirmed July 2023 was the hottest month on record for New England, with a mean temperature of 71.0F - an incredible 4.4F above the 20th century mean.

image.thumb.png.6c57eda260a650258d3f42ff2f87c9c7.png

Compounding the intense heat, dewpoints were also at record levels for the month, resulting in an amplified increase to the apparent temperature.

 

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Tomorrow is going to be quite interesting. Biggest challenge is going to be where that sfc low develops and tracks which is going to be heavily influenced by the Ohio Valley/Tennessee Valley convection. I would think the most favorable track for this would be just south of southern New England, but is it across Long Island or just south of Long Island?

In terms of any severe weather potential, this track is key because if the track is across Long Island, the true warm sector and triple point will likely scoot across southern Connecticut, Long Island, Rhode Island, and Cape Cod. There would be potential for some brief tornadoes. If the track is south of Long Island, severe potential is nada (except maybe Nantucket and the Vineyard). 

Regardless, I think we're in line for some flash flooding rainfall. upper-level dynamics are pretty strong and we look to be in a very favored position for enhanced upper-level divergence. Looks like H7 warm front pushes well into the region which will aid in lift as well. In addition, we'll have the nose of a strong low-level jet and a very moist airmass. 

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